Main Topic 1 Etiology& Epidemiology Pathogenesis Clinical Manifestations Diagnosis Treatment Prevention
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🔷 Etiology
Ascariasis is caused by the nematode, or roundworm, Ascaris lumbricoides.
🔷 Clinical Manifestations
The clinical presentation depends on the intensity of infection and the organs involved. Most
Treatment
Although several chemotherapeutic agents are effective
against ascariasis, none has documented utility during the
pulmonary phase of infection.
Adult worms of A. lumbricoides (averaging 30 cm in length) inhabit the lumen 🔹
individuals have low to moderate worm burdens and have no symptoms or signs.
The most common clinical problems are from pulmonary disease and obstruction of the
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Treatment options for gastrointestinal ascariasis include:
🔷Anthelmintic chemotherapy programs can be
of the small intestine. Gravid female worm produces 200,000 eggs per day.
After passage in the feces, the eggs embryonate and become infective in 5-10 🔷
intestinal or biliary tract.
🔹 Albendazole (400 mg orally once, for all ages),
Mebendazole (100 mg orally twice daily for 3 days or 500
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Larvae migrating through these tissues may cause allergic symptoms, fever, urticaria, implemented in 1 of 3 ways:
days under favorable environmental conditions. Ascaris eggs can remain viable
Pathogenesis
After ingestion by the human host, Ascaris ova hatch in the small 🔹
andgranulomatous disease.
The pulmonary manifestations resemble Loeffler syndrome include: 🔹 Diagnosis
A high index of suspicion in the appropriate clinical
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mg once, for all ages), or
🔹 Ivermectin (150-200 μg/kg orally once). 1. offering universal treatment to all individuals in an area of
high endemicity;
at 5-10°C (41-50°F) for as long as 2 yr. Adult worms can live for 12-18 mo. intestine. Larvae are released, penetrate the intestinal wall, and transient respiratory symptoms such as cough, dyspnea, pulmonary infiltrates, & blood eosinophilia.
Nitazoxanide (100 mg orally twice per day for 3 days for
Ascariasis context is needed to diagnose pulmonary ascariasis or 2. offering treatment targeted to groups with high frequency
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migrate to the lungs by way of the venous circulation. children 1-3 yr old; 200 mg twice per day for 3 days for
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Larvae may be observed in the sputum. obstruction of the gastrointestinal tract. of infection, such as children attending primary school; or
The parasites then cause pulmonary ascariasis as they enter into children 4-11 yr; 500 mg twice per day for 3 days for
Epidemiology Adult worms in the small intestine may cause vague abdominal complaints.
(Ascaris lumbricoides) the alveoli and migrate through the bronchi and trachea. They are Microscopic examination of fecal smears reveals the adolescents and adults). 3. offering individual treatment based on intensity of current or
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Serious complication occurs when a large mass of worms leads to acute bowel obstruction, eggs that excreted by adult female worms. past infection.
Ascariasis is the most prevalent human helminthiasis in the world. subsequently swallowed and return to the intestines, where they present with vomiting, abdomin distention, & cramps. In some cases, worms may be passed in the
The treatment of choice for intestinal or biliary
The most effective long-term preventive measures are:
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Ultrasound examination of the abdomen is capable of
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mature into adult worms. obstruction is:
Factors linked with a higher prevalence of infection include: Female Ascaris begin depositing eggs in 8-10 wk.
vomitus or stools. visualizing intraluminal adult worms. Piperazine citrate (75 mg/kg/day for 2 days; maximum Improving education about and practices ofsanitary conditions
🔹 poor socioeconomic conditions, Ascaris worms occasionally migrate into the biliary and pancreatic ducts, where they cause and sewage facilities, discontinuing the practice of using
cholecystitis or pancreatitis. dose: 3.5 g/day), causes neuromuscular paralysis of the
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human feces as fertilizer
use of human feces as fertilizer, and Worm migration through the intestinal wall can lead to peritonitis. Dead worms can serve as a nidus parasite and rapid expulsion of the worms, is administered as
geophagia. Infection can occur at any age, with highest rate is in preschool syrup through a nasogastric tube.
for stone formation.
Chronic infection with A. lumbricoides (often coincident with other helminth infections) impairs Surgery may be required for cases with severe obstruction.
or early school-age children.Transmission is primarily hand to mouth but may Drug resistance has not been reported, but repeated
growth, physical fitness, and cognitive development.
also involve ingestion of contaminated raw fruits and vegetables. treatment for ascariasis may be necessary because
reinfection is common.
🔷 Etiology
Two major genera of hookworms, which are nematodes, or roundworms, infect
humans. Necator americanus, is the most common cause of human hookworm
infection and Ancylostoma duodenale.
The infective larval stages live in a developmentally arrested state in warm, 🔷 Clinical Manifestations
🔷 Treatment 🔷
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Chronically infected children with moderate and heavy hookworm infections suffer from intestinal
Prevention
moist soil. Larvae infect humans either by penetrating through the skin (N.
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blood loss that results in iron deficiency and can lead to anemia as well as protein malnutrition.
🔹 Albendazole (400 mg orally [PO] once, for all ages) In 2001, the World Health Assembly urged its member states to
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americanus and A. duodenale ) or when they are ingested (A. duodenale). Mebendazole (100 mg PO twice daily [bid] for 3 days, for implement programs of periodic deworming (mass drug
Prolonged iron deficiency in childhood can lead to physical growth retardation and
all ages). According to the World Health Organization (WHO), administration) so as to control the morbidity of hookworm
Larvae entering the human host by skin penetration undergo extraintestinal cognitive and intellectual deficits.
children should be encouraged to chew tablets of and other soil-transmitted helminth infections.
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Larvae elicit dermatitis sometimes referred to as ground itch when they penetrate human skin. Cough
Hookworms migration through the venous circulation and lungs before they are
Pathogenesis occurs when larvae migrate through the lungs to cause laryngotracheobronchitis, usually about 1 albendazole or mebendazole, because forcing very young
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Concerns about this approach:
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swallowed, whereas orally ingested larvae may undergo extraintestinal children to swallow large tablets may cause choking or high rates of drug failure from single-dose mebendazole,
wk after exposure. Pharyngitis also can occur.
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The major morbidity of human hookworm infection is a direct
Diagnosis posttreatment reinfection, and
(Necator americanus and migration or remain in the gastrointestinal (GI) tract. result of intestinal blood loss. Each adult
A. duodenale hookworm causes loss of an estimated 0.2 mL of
The onset of eosinophilia coincides with the entry of hookworm larvae into the GI tract. Upper
abdominal pain can occur during this period, but it eventually subsides. Eggs that can be detected by direct fecal examination
asphyxiation.
WHO currently supports the use of benzimidazoles in moreover, the efficacy of mebendazole decreases with
Larvae returning to the small intestine develop to become adult, male & female infected children ≥1 yr old but at a reduced dose (200 mg for frequent, periodic use, leading to concerns about the possible
Ancylostoma spp.) blood/day; blood loss is less for N. americanus. Chronic intestinal hookworm infection is not typically associated with specific GI complaints,
worms (length from 5-13 mm).The buccal capsule of the adult hookworm is
armed with cutting plates (N. americanus) or teeth (A. duodenale) to
although pain, anorexia, and diarrhea have been attributed to the presence of hookworms.
In some cases, children with chronic hookworm disease acquire a yellow-green pallor known 🔹
albendazole) in the youngest age-group (1-2 yr old).
Pyrantel pamoate (11 mg/kg PO once daily for 3 days;
maximum dose: 1 g) is available in liquid form and is an
emergence of anthelmintic drug resistance.
Therefore, mass drug administration alone is not effective for
controlling hookworm in endemic areas. Improvements in
facilitate attachment to the mucosa and submucosa of the small intestine.
Mature
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aschlorosis.
An infantile form of ancylostomiasis resulting from heavy A. duodenale infection
associated with diarrhea, melena, failure to thrive, profound anemia, and has significant
effective alternative to the benzimidazolesReplacement
therapy with oral iron is not usually required to correct
sanitation, health education, and avoidance of human feces as
fertilizer remain critical for reducing hookworm transmission
hookworm-associated iron deficiency in children. and endemicity
A. duodenale and N. americanus female worms produce about 30,000 and mortality.
<10,000 eggs/day, respectively. Eggs that are deposited on soil with adequate
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moisture and shade develop into larvae.
Epidemiology
Hookworm infection is one of the most prevalent infectious diseases of humans
🔷 Etiology
Enterobius vermicularis, is a small (1 cm in length), white, threadlike nematode,
or roundworm, that typically inhabits the cecum, appendix, and adjacent areas
of the ileum and ascending colon. Gravid females migrate at night to the
🔷 Treatment
perianal and perineal regions, where they deposit up to 15,000 eggs. 🔷 Clinical Manifestations 🔷 Diagnosis
Anthelmintic drugs should be administered to infected
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individuals and their family members.
🔷 Prevention
Enterobiasis
Eggs embryonate within 6 hr and remain viable for 20 days. Human infection
occurs by the fecal-oral route typically by ingestion of embryonated eggs that 🔷
Pinworm infection is innocuous and rarely causes serious medical problems.
The most common complaints include itching and restless sleep secondary to nocturnal perianal
A history of nocturnal perianal pruritus in children
strongly suggests enterobiasis.
Albendazole (400 mg orally with a repeat dose 2 wk later
for all age-groups) is the treatment of choice and results in 🔹 Good hand hygiene is the most effective method of
(Enterobius vermicularis or
are carried on fingernails, clothing, bedding, or house dust. After ingestion, the
Pathogenesis
Enterobius infection may cause symptoms by mechanical
or perineal pruritus.
The precise cause and incidence of pruritus are unknown but may be related to the intensity of
Definitive diagnosis is made by demonstration of eggs
on microscopic examination of adhesive cellophane 🔹
cure rates exceeding 90%.
Alternatives include mebendazole (100 mg orally with a 🔹
prevention.
Household contacts can be treated at the same time as the
pinworm infection) 🔷
larvae mature to form adult worms in 36-53 days.
Epidemiology
stimulation and irritation, allergic reactions,and migration of the
worms to anatomic sites where they become pathogenic.
infection, psychologic profile of the infected individual, or allergic reactions to the parasite.
Eosinophilia is not observed in most cases, because tissue invasion does not occur.
tape pressed against the perianal region early in the
morning or by observing worms in the perianal region.
repeat dose 2 wk later) and pyrantel pamoate (11 mg/kg base
orally 3 times for 1 day up to a maximum of 1 g; repeat at 2 🔹
infected individual.
Repeated treatments every 3-4 mo may be required in
Enterobiasis occurs in individuals of all ages and socioeconomic levels. Humans
Aberrant migration to ectopic sites occasionally may lead to appendicitis, chronic salpingitis,
pelvic inflammatory disease, peritonitis, hepatitis, and ulcerative lesions in the large or small
bowel.
Digital rectal examination may also be used to obtain
samples for a wet mount. Routine stool samples rarely
demonstrate Enterobius ova.
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wk).
Morning bathing removes a large portion of eggs. Frequent
changing of underclothes, bedclothes, and bedsheets
circumstances with repeated exposure, such as with
institutionalized children.
are the only known host.
decreases environmental egg contamination and may
The prevalence of pinworm infection is highest in children 5-14 yr of age. It is decrease the risk for autoinfection.
common in areas where children live, play, and sleep close together, thus
facilitating egg transmission. Autoinoculation can occur in individuals who
habitually put their fingers in their mouth.
🔷 Etiology 🔷 🔷 Diagnosis
🔷 Treatment
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Clinical Manifestations 1) Diagnosis of VLM
Caused by dog roundworm, Toxocara canis, (most cases) and cat roundworm,
Toxocara cati (fewer cases).
Three major clinical syndromes are associated with human toxocariasis: VLM, ocular larva migrans
(OLM), and covert toxocariasis. 🔹 Clinical manifestation
Lab finding include eosinophilia (>20%), leukocytosis,
Most patients do not require treatment bec. signs &
symptoms are mild and subside over wks-months. 🔷 Prevention
Infection occur through ingestion of embryonated eggs contaminating soil, 1) VLM occurs most often in toddlers with a history of pica and exposure to puppies. Findings
include fever, eosinophilia, & hepatomegaly (classic presentation); also includes cough, wheezing, 🔹
hypergammaglobulinemia and elevated
isohemagglutinin titers to A and B blood group
Albendazole (400 mg orally twice daily for 5 days for all
ages).
1) Prevent dog feces from contaminating the environment by
keeping dogs on leashes and excluding pets from playgrounds
Toxocariasis (Visceral and hands, or fomites. bronchopneumonia, anemia, leukocytosis, and positive Toxocara serology. Cutaneous manifestations
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antigens. Mebendazole (100-200 mg PO twice daily for 5 days for all and sandboxes that toddlers use. Discourage children from
Ocular Larva Migrans)
The larvae hatch and penetrate the intestinal wall and travel via the circulation Subtopic 1 such as pruritus, eczema, and urticaria can be present.
2) OLM occur in older children without signs or symptoms of VLM. Presenting symptoms include 🔹 Biopsy confirm the diagnosis (reveal granuloma).
Enzyme-linked immunosorbent assay is the standard
ages).
Note: Anthelmintic treatment of CNS and ocular disease
putting dirty fingers in their mouth.Vinyl covering of sandboxes
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to the liver, lung, and other tissues. reduces the viability of T. canis eggs.
unilateral visual loss, eye pain, white pupil, or strabismus that develops over weeks. Granulomas serologic test used to confirm toxocariasis, when biopsy should be extended (3-4 wk).Prednisone (1 mg/kg/day PO for 3) Widespread veterinary use of broad-spectrum
Epidemiology occur on the posterior pole of the retina and may be mistaken for retinoblastoma. cannot be obtained. 2-4 wk) has been recommended to suppress local anthelmintics effective against Toxocara may lead to a decline
Young children are at highest risk of infection because of their unsanitary play 3) Covert or less obvious infection, identified by serologic tests. 2) Diagnosis of OLM: typical clinical findings with inflammation while treatment with anthelmintic agents is in parasite transmission to humans.
Findings include hepatomegaly, abdominal pain, cough, sleep disturbance, failure to thrive, and elevated antibody titers. initiated.
habits and tendency to place fingers in the mouth. headache with elevated Toxocara antibody titers. Eosinophilia (50–75% of cases). 3) Diagnosis of covert toxocariasis: clinical
Other behavioral risk factors include pica and contact with puppy litters. manifestation with eosinophilia and increased IgE.
🔷 Etiology: 🔷 Clinical Manifestations
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In addition to organ-specific morbidities, infected patients frequently demonstrate anemia, chronic
Five schistosome species infect humans: pain, diarrhea, exercise intolerance, and chronic undernutrition manifesting as growth stunting.
Schistosoma haematobium: adult found in the perivesical and periureteral 1) Cercarial penetration of human skin
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venous plexus may result in a papular pruritic rash (known as schistosomal dermatitis or swimmer's itch), edema
🔹 S. mansoni adult found in the inferior mesenteric veins and intense cellular infiltrates in the dermis and epidermis.
2) Acute schistosomiasis (Katayama syndrome) may occur 4-8 wk after exposure; this is a serum
Helminthic 🔹 S. intercalatum, and S. mekongi: adult found in the mesenteric vessels
S. japonicum adult found in the superior mesenteric veins
Humans are infected through contact with water contaminated with cercariae,
sickness–like syndrome manifested by the acute onset of fever, cough, chills, sweating, abdominal
pain, lymphadenopathy, hepatosplenomegaly, and eosinophilia.
3) Chronic urogenital schistosomiasis (S. haematobium): children usually complain of frequency,
Diseases the free-living infective stage of the parasite. 🔷 Pathogenesis
dysuria, and hematuria. Urine exam. shows erythrocytes, parasite eggs, and occasional eosinophiluria.
🔷 🔷 🔷 Prevention
These motile, forked-tail organisms emerge from infected snails and are Both early and late manifestations of schistosomiasis are 🔹
The advanced stages of urogenital schistosomiasis are associated with
🔹 chronic renal failure, 🔹 Diagnosis Treatment Transmission in endemic areas may be decreased by reducing
capable of penetrating intact human skin.
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immunologically mediated.
Acute schistosomiasis, known as snail fever or Katayama 🔹 secondary infections, and
squamous carcinoma of the bladder.
🔹 Clinical manifestation
Diagnosis of S. haematobium infection: a volume of 10
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Praziquantel
40 mg/kg/day/ PO bid for 1 day for S. haematobia,
the parasite load in the human population,this goal is achieved
by the availability of oral, single-dose, effective
Schistosomiasis As they reach maturity, adult worms migrate to specific anatomic sites syndrome, is a febrile illness that represents an immune complex An important complication of S. haematobium infection is female genital schistosomiasis. Eggs
mL of urine should be collected around midday, the time
of maximal egg excretion, and filtered for microscopic
mansoni, and intercalatum. (Note: children <5 yr old with S. chemotherapeutic.
characteristic of each schistosome species.
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disease associated with early infection and oviposition. migrate from the vesical plexus to lodge in the female genital tract where they induce a mansoni may need up to 60 mg/kg/day PO tid for 1 day to Other measures: improve sanitation, antiparasitic treatment
(Schistosoma) The female accompanies the male in a groove formed by the lateral edges of Chronic schistosomiasis: retention of eggs in the host tissues
is associated with chronic granulomatous injury. Eggs may be
granulomatous inflammatory response that can manifest as contact bleeding, pain, and eventual
infertility. Male genital schistosomiasis can also present with hematospermia, pain, and lumpy semen.
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examination.
Other schistosome infections (S. mansoni and S.
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achieve clearance).
60 mg/kg/day PO divided 3 times daily [tid] for 1 day for S.
given at well-child visits, focal application of molluscicidals,
and animal vaccination may prove useful in breaking the cycle
its body. On fertilization, female worms begin oviposition in the small venous japonicum ); stool examination by the Kato-Katz thick
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trapped at sites of deposition (urinary bladder, ureters, intestine) 4) Intestinal schistosomiasis: Children ē chronic S. mansoni, japonica, intercalatum, or mekongi may: japonica and mekongi. A 2nd treatment 4-6 wk after the 1st of transmission.
smear procedure and detection of parasite antigen in
tributaries. Parasite eggs provoke a significant granulomatous inflammatory
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or may be carried by the bloodstream to other organs, most remain subclinical, course may help in eliminating residual infection. Ultimately, control of schistosomiasis is closely linked to
patient serum or urine
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response that allows them to ulcerate through host tissues to reach the lumen frequently the liver and less often the lungs and CNS). have colicky abdominal pain and bloody diarrhea (most common). economic and social development.
Present with late syndrome of hepatosplenomegaly, portal hypertension, ascites, and
of the urinary tract or the intestines. hematemesis.
They are carried to the outside environment in urine or feces (depending on the 5) Schistosome eggs may escape into the lungs, causing pulmonary hypertension and cor
species), where they will hatch if deposited infreshwater. Motile miracidia pulmonale. S. japonicum worms may migrate to the brain vasculature & produce localized lesions
emerge, infect specific freshwater snail intermediate hosts, and divide causing seizures.
6) Transverse myelitis, spinal compression, and other CNS involvement (meningoencephalitis)
asexually. After 4-12 wk, the infective cercariae are released by the snails into are rare but well-known complications in children or young adults with either acute or chronic S.
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the contaminated water. haematobium or S. mansoni infection.
7) Long-term systemic effects of infection include: chronic undernutrition manifesting as growth
Epidemiology stunting, anemia, chronic pain, diarrhea, exercise intolerance, and cognitive imp
Schistosoma spp. primarily infect children and young adult
Tapeworms are adult forms of cestodes, multicellular helminth parasites, that
live in human intestines and cause non–life-threatening illness. Invasive larval
forms (intermediate stage) of cestodes are associated with cysts that lead to
severe human disease such as neurocysticercosis (Taenia solium; 🔷 Diagnosis
🔷 Visual examination for gravid proglottids in the stool is a
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andechinococcosis (mostly Echinococcus granulosa and E. multilocularis. Pathogenesis sensitive test; these segments may be used to identify
Etiology When children ingest raw or undercooked meat containing larval
cysts, gastric acid and bile facilitate release of immature scolices
species. Eggs, by contrast, are often absent from stool
🔷 Treatment
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The beef tapeworm (Taenia saginata), the pork tapeworm (T. solium), and the and cannot distinguish between T. saginata and T. solium.
that attach to the lumen of the small intestine. Infections with all adult tapeworms respond to praziquantel
Clinical Manifestations
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If the parasite is completely expelled, the scolex of each
tapeworm (Taenia asiatica) are long worms (4-10 m) named for their The parasite grows, adding new segments at the base of the
Nonspecific abdominal symptoms have been reported with beef and pork tapeworm infections, but species is diagnostic. (25 mg/kg orally [PO] once).
Prevention
intermediate hosts (T. saginata , T. solium ) or geographic distribution (T. scolex. The terminal segments mature (gravid) and after 2-3 mo Expelled proglottid segments are usually approximately When available, an alternative treatment for taeniasis is
the most bothersome symptom is the psychologic distress caused by seeing proglottids in the stool Prolonged freezing or thorough cooking of beef and pork kills
Adult Tapeworm Infections asiatica ; larval host is the pig).
produce50,000-100,000 eggs, and the eggs or even detached
intact proglottids pass out of the child through the anus (with or or undergarments.
The released segments of the worms are motile (especially those of T. saginata ) andsometimes lead
0.5 × 1-2 × 0.1 cm in size. Molecular methods can
distinguish T. saginata from T. asiatica . Antigen detection
niclosamide (50 mg/kg PO once for children; 2 g PO once for
adults).
the larval cystic forms of the parasite.
Appropriate human sanitation can interrupt transmission by
The adult worms are found only in the human intestine. As with the adult stage separate from defecation). Nitazoxanide is sometimes effective as well.
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to anal pruritus. tests are increasingly available. preventing infection in livestock.
of all tapeworms, their body is a series of 100s or 1000s of flattened segments The surface of proglottids serves as an absorptive organ to The parasite is usually expelled on the day of administration.
“steal” nutritional elements from the child's small bowel for use The adult beef and pork tapeworms are only rarely associated with other symptoms. Differential Diagnosis
Treatment with electrolyte–polyethylene glycol bowel
(proglottids) with an anterior attachment organ(scolex) that anchors the by the parasite.
Anal pruritus may mimic symptoms of pinworm
preparations can increase the yield of passage of scolices.
(Enterobius vermicularis) infection.
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parasite to the bowel wall. There is sometimes a transient eosinophilia before the parasite
Diphyllobothrium latum and Ascaris lumbricoides (a
matures enough to release eggs.
Epidemiology long round worm) may be mistaken for T. saginata or T.
The pork and beef tapeworms are distributed worldwide. The prevalence in solium in stools.
adults may not reflect the prevalence in young children, because cultural
practices may dictate how well meat is cooked and how much is served to
children.
🔷 Etiology
The fish tapeworms of the genus Diphyllobothrium are the longest human
tapeworms, reaching >10 m in length, and have an anatomic organization similar 🔷 Diagnosis
to that of other adult cestodes. 🔷 Pathogenesis
Parasitological examination of the stool is useful because
An elongated scolex, is followed by 1000s of segments looped in the small The adult worm of Diphyllobothrium latum has high affinity
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eggs are abundant in the feces and have morphology
distinct from that of all other tapeworms. 🔷 Prevention
Diphyllobothriasis
bowel.
Gravid terminal proglottids detach periodically but tend to disintegrate before
receptors and efficiently scavenges vitamin B12 for its own use in
the constant production of large numbers of segments and as
many as 1 million eggs per day.
Clinical Manifestations
Infection is largely asymptomatic. Segments may be noted in stool.
The worm itself has a distinct scolex and proglottid
morphology; however, these are not likely to be passed 🔷 Treatment
As with all adult tapeworms, D. latum infections respond to
The intermediate stage is easily killed by brief cooking or
prolonged freezing of fish before ingestion.
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expulsion, thus releasing eggs rather than intact wormsegments in the feces. Those who develop vitamin B12 or folate deficiency present with megaloblastic anemia with spontaneously. Because humans are the major reservoir for adult worms,
As a result, diphyllobothriasis causes megaloblastic anemia in 2– praziquantel (5-10 mg/kg PO once).
(Diphyllobothrium Spp.) In contrast to taeniids, the life cycle of Diphyllobothrium spp. requires 2 9% of infections.
leukopenia, thrombocytopenia, glossitis, and/or signs of spinal cord posterior column dysfunction
(loss of vibratory sense, proprioception, and coordination).
Differential Diagnosis
A segment or a whole section of the worm might be
Niclosamide (50 mg/kg PO in a single dose) is also effective
health education is one of the most important tools for
preventing transmission, together with improved human
intermediate hosts. Small, freshwater crustaceans (copepods) take up the Children with other causes of vitamin B12 or folate deficiency,
confused with Taenia or Ascaris after it is passed. sanitation.
such as chronic infectious diarrhea, celiac disease, or congenital
larvae that hatch from parasite eggs. The parasite passes up the food chain as malabsorption, are more likely to develop symptomatic infection.
Pernicious anemia, bone marrow toxins, and dietary
restriction may contribute to or mimic the nutritional
small fish eat the copepods and are in turn eaten by larger fish. deficiencies associated with diphyllobothriasis.
Consumption of raw or undercooked fish leads to human infection with adult
fish tapeworms. Persons who prepare raw fish for home or commercial use or
who sample fish before cooking are particularly at risk for infection.
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🔹 Treatment
Management of cystic disease should be
individualized and guided by disease stage and location.
For cystic echinococcosis that are <5 cm in diameter,
albendazole alone (15 mg/kg/day orally divided twice daily
for 1-6 mo; maximum 800 mg/day) may result in a high rate of
🔷 🔹
cure.
🔷 Etiology 🔹 Diagnosis
Ultrasonography is the most valuable tool for both
Adverse effects include occasional alopecia, mild
gastrointestinal disturbance, elevated transaminases on
Two major Echinococcus groups of species are responsible for distinct clinical
🔷 the diagnosis and treatment of cystic hydatid disease of prolonged use, and leukopenia (blood counts be monitored at
🔹 🔷 Prognosis
🔹 Clinical Manifestations the liver. Chest radiographs frequently reveal the beginning and every 2 wk during therapy).
presentations. Echinococcus granulosus and related species cause cystic
🔷 Cystic hydatid disease: in the liver, cysts may remain asymptomatic, may regress spontaneously, characteristic rounded masses in lung hydatid disease. For larger cyst, ultrasound- or CT-guided PAIR Factors predictive of success with chemotherapy for cystic
hydatid disease, and Echinococcusmultilocularis causes alveolar hydatid
disease.
Pathogenesis
E. granulosus: the lung is a common site of cysts in children,
or may produce nonspecific symptoms.Symptomatic cysts can cause increased abdominal girth,
hepatomegaly, a palpable mass, vomiting, or abdominal pain. In the lung, cysts produce chest pain, 🔹
Alveolar hydatid disease resembles a diffuse solid tumor.
CT findings are similar to those of ultrasonography
(percutaneous, aspiration, instillation, and reaspiration)is the
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preferred therapy. 🔹
hydatidosis are:
🔹 age of the cyst (<2 yr),
-The adult parasites are small (2-7 mm) tapeworms inhabit the intestines of
canines such as dogs, wolves, jackals, and foxes. These carnivores pass the
whereas in adults up to 70% of cysts develop in the liver. Cysts
can also develop in bone, the genitourinary system, spleen,
chronic cough, or hemoptysis.
Expectorated fluid from ruptured lung cysts is often described as “salty.”Mass effects can be noted
and may at times be useful in distinguishing alveolar from
cystic hydatid disease in geographic regions where both
Spillage with PAIR is uncommon, but prophylactic
albendazole therapy is routinely administered at least 1 wk
before PAIR and 1 mo afterward.
🔹 low internal complexity of the cyst, and
small size. The site of the cyst is not important, although
cysts in bone respond poorly. For alveolar hydatidosis, if
Echinococcosis subcutaneous tissues, and brain. in the brain and bone. Serious complications result from compression of adjacent structures or occur. CT or MRI is also important in planning a surgical
🔹 🔹
eggs in their stool, which contaminates the soil, pasture, and water, as well as The host surrounds the primary cyst with a tough, fibrous spillage of cyst contents. intervention. Note: For hepatic cysts, patients should begin therapy with surgical removal is unsuccessful, the average mortality is 92%
(Echinococcus granulosus and
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capsule.E. multilocularis: almost always involves the liver. Anaphylaxis can occur with cyst rupture or spontaneous spillage, from trauma or Serologic studies: The sensitivity and specificity of albendazole (ideally in combination with praziquantel) for by 10 yr afterdiagnosis
their own fur.
🔹
The lesions grow very slowly and rarely present in children. intraoperatively. Cyst fluid may cause hypersensitivity pneumonitis. the enzyme-linked immunosorbent assay to diagnose several days to weeks preoperatively. . Prevention
Echinococcus multilocularis) -Domestic animals, such as sheep, goats, cattle, and camels, ingest E. cystic echinococcosis may vary from 50– 100% and 40– Antiparasitic drugs should be continued for 4-12 wk
🔹
The secondary reproductive units bud externally and are not Spillage can also be catastrophic long-term, because each the parasite protoscolex can form a new Thorough handwashing,
granulosus complex eggs while grazing. For E. multilocularis, the main confined within a single, well-defined structure. Thus the lesions cyst and fill up the abdominal cavity or rarely the pleural space. Jaundice from cystic hydatid 100%, respectively.
🔹
postoperatively.
🔹 avoiding contact with dogs in endemic areas,
🔹 The sensitivity is higher for hepatic or bone disease, but Surgery is the treatment of choice for complicated
🔹
intermediate hosts are small rodents. -Humans are infected by consuming eggs are invasive and often confused with a malignancy. Furthermore, disease is rare. boiling or filtering water when camping,
the cysts are poorly demarcated from those of the host, making Alveolar hydatid disease: may be diagnosed incidentally, but often the proliferating mass may the false-negative rate may be >50% with pulmonary or cysts, including ruptured cysts, cysts communicating with the
by direct contact with infected canines or from ova in theenvironment. and proper disposal of animal carcasses.
🔹
surgical removal difficult. compromise the biliary system and/or hepatic tissue, causing progressive obstructive jaundice CNS infection. biliary tract, large pulmonary cysts, or cysts of the CNS or
Control or treatment of the feral dog population and regular
-The larvae hatch, penetrate the gut, and are carried by the vascular or
lymphatic systems to the liver, lungs, and less frequently, bones, kidney, brain,
andhepatic failure.
Symptoms also occur from expansion of extrahepatic foci.
Differential Diagnosis
- For hydatid cysts: Benign hepatic cysts and bacterial 🔹
bones.
Small thoracic cysts mayresolve with chemotherapy,
but most cysts require operative removal.Alveolar hydatidosis
praziquantel treatment of pets and working dogs in endemic
areas.
hepatic abscesses
or heart in E. granulosus infection. E. multilocularis larvae infect the liver almost
exclusively.
- Alveolar echinococcosis is often confused with
hepatoma or metastatic tumor hepatectomy, lobectomy, or liver transplantation. 🔹
frequently requires radical surgery, including partial
therapy with albendazole should be continued for 2 yr
Medical
after presumably curative surgery.
In patients who are not operative candidates or whose
lesions are not amenable to surgical cure, albendazole
long-term suppressive therapy should be used to slow
the progression, but the infection generally recurs if
albendazole is stopped.
by fatema okoff
🔷
🔷 Etiology
Ascariasis is caused by the nematode, or roundworm, Ascaris lumbricoides.
🔷 Clinical Manifestations
The clinical presentation depends on the intensity of infection and the organs involved. Most
Treatment
Although several chemotherapeutic agents are effective
against ascariasis, none has documented utility during the
pulmonary phase of infection.
Adult worms of A. lumbricoides (averaging 30 cm in length) inhabit the lumen 🔹
individuals have low to moderate worm burdens and have no symptoms or signs.
The most common clinical problems are from pulmonary disease and obstruction of the
🔹
Treatment options for gastrointestinal ascariasis include:
🔷Anthelmintic chemotherapy programs can be
of the small intestine. Gravid female worm produces 200,000 eggs per day.
After passage in the feces, the eggs embryonate and become infective in 5-10 🔷
intestinal or biliary tract.
🔹 Albendazole (400 mg orally once, for all ages),
Mebendazole (100 mg orally twice daily for 3 days or 500
🔷
Larvae migrating through these tissues may cause allergic symptoms, fever, urticaria, implemented in 1 of 3 ways:
days under favorable environmental conditions. Ascaris eggs can remain viable
Pathogenesis
After ingestion by the human host, Ascaris ova hatch in the small 🔹
andgranulomatous disease.
The pulmonary manifestations resemble Loeffler syndrome include: 🔹 Diagnosis
A high index of suspicion in the appropriate clinical
🔹
mg once, for all ages), or
🔹 Ivermectin (150-200 μg/kg orally once). 1. offering universal treatment to all individuals in an area of
high endemicity;
at 5-10°C (41-50°F) for as long as 2 yr. Adult worms can live for 12-18 mo. intestine. Larvae are released, penetrate the intestinal wall, and transient respiratory symptoms such as cough, dyspnea, pulmonary infiltrates, & blood eosinophilia.
Nitazoxanide (100 mg orally twice per day for 3 days for
Ascariasis context is needed to diagnose pulmonary ascariasis or 2. offering treatment targeted to groups with high frequency
🔷
migrate to the lungs by way of the venous circulation. children 1-3 yr old; 200 mg twice per day for 3 days for
🔹
Larvae may be observed in the sputum. obstruction of the gastrointestinal tract. of infection, such as children attending primary school; or
The parasites then cause pulmonary ascariasis as they enter into children 4-11 yr; 500 mg twice per day for 3 days for
Epidemiology Adult worms in the small intestine may cause vague abdominal complaints.
(Ascaris lumbricoides) the alveoli and migrate through the bronchi and trachea. They are Microscopic examination of fecal smears reveals the adolescents and adults). 3. offering individual treatment based on intensity of current or
🔹 🔹
Serious complication occurs when a large mass of worms leads to acute bowel obstruction, eggs that excreted by adult female worms. past infection.
Ascariasis is the most prevalent human helminthiasis in the world. subsequently swallowed and return to the intestines, where they present with vomiting, abdomin distention, & cramps. In some cases, worms may be passed in the
The treatment of choice for intestinal or biliary
The most effective long-term preventive measures are:
🔹
Ultrasound examination of the abdomen is capable of
🔹
mature into adult worms. obstruction is:
Factors linked with a higher prevalence of infection include: Female Ascaris begin depositing eggs in 8-10 wk.
vomitus or stools. visualizing intraluminal adult worms. Piperazine citrate (75 mg/kg/day for 2 days; maximum Improving education about and practices ofsanitary conditions
🔹 poor socioeconomic conditions, Ascaris worms occasionally migrate into the biliary and pancreatic ducts, where they cause and sewage facilities, discontinuing the practice of using
cholecystitis or pancreatitis. dose: 3.5 g/day), causes neuromuscular paralysis of the
🔹
human feces as fertilizer
use of human feces as fertilizer, and Worm migration through the intestinal wall can lead to peritonitis. Dead worms can serve as a nidus parasite and rapid expulsion of the worms, is administered as
geophagia. Infection can occur at any age, with highest rate is in preschool syrup through a nasogastric tube.
for stone formation.
Chronic infection with A. lumbricoides (often coincident with other helminth infections) impairs Surgery may be required for cases with severe obstruction.
or early school-age children.Transmission is primarily hand to mouth but may Drug resistance has not been reported, but repeated
growth, physical fitness, and cognitive development.
also involve ingestion of contaminated raw fruits and vegetables. treatment for ascariasis may be necessary because
reinfection is common.
🔷 Etiology
Two major genera of hookworms, which are nematodes, or roundworms, infect
humans. Necator americanus, is the most common cause of human hookworm
infection and Ancylostoma duodenale.
The infective larval stages live in a developmentally arrested state in warm, 🔷 Clinical Manifestations
🔷 Treatment 🔷
🔹
Chronically infected children with moderate and heavy hookworm infections suffer from intestinal
Prevention
moist soil. Larvae infect humans either by penetrating through the skin (N.
🔹
blood loss that results in iron deficiency and can lead to anemia as well as protein malnutrition.
🔹 Albendazole (400 mg orally [PO] once, for all ages) In 2001, the World Health Assembly urged its member states to
🔹
americanus and A. duodenale ) or when they are ingested (A. duodenale). Mebendazole (100 mg PO twice daily [bid] for 3 days, for implement programs of periodic deworming (mass drug
Prolonged iron deficiency in childhood can lead to physical growth retardation and
all ages). According to the World Health Organization (WHO), administration) so as to control the morbidity of hookworm
Larvae entering the human host by skin penetration undergo extraintestinal cognitive and intellectual deficits.
children should be encouraged to chew tablets of and other soil-transmitted helminth infections.
🔷
Larvae elicit dermatitis sometimes referred to as ground itch when they penetrate human skin. Cough
Hookworms migration through the venous circulation and lungs before they are
Pathogenesis occurs when larvae migrate through the lungs to cause laryngotracheobronchitis, usually about 1 albendazole or mebendazole, because forcing very young
🔹
Concerns about this approach:
🔹
🔷
swallowed, whereas orally ingested larvae may undergo extraintestinal children to swallow large tablets may cause choking or high rates of drug failure from single-dose mebendazole,
wk after exposure. Pharyngitis also can occur.
🔹
The major morbidity of human hookworm infection is a direct
Diagnosis posttreatment reinfection, and
(Necator americanus and migration or remain in the gastrointestinal (GI) tract. result of intestinal blood loss. Each adult
A. duodenale hookworm causes loss of an estimated 0.2 mL of
The onset of eosinophilia coincides with the entry of hookworm larvae into the GI tract. Upper
abdominal pain can occur during this period, but it eventually subsides. Eggs that can be detected by direct fecal examination
asphyxiation.
WHO currently supports the use of benzimidazoles in moreover, the efficacy of mebendazole decreases with
Larvae returning to the small intestine develop to become adult, male & female infected children ≥1 yr old but at a reduced dose (200 mg for frequent, periodic use, leading to concerns about the possible
Ancylostoma spp.) blood/day; blood loss is less for N. americanus. Chronic intestinal hookworm infection is not typically associated with specific GI complaints,
worms (length from 5-13 mm).The buccal capsule of the adult hookworm is
armed with cutting plates (N. americanus) or teeth (A. duodenale) to
although pain, anorexia, and diarrhea have been attributed to the presence of hookworms.
In some cases, children with chronic hookworm disease acquire a yellow-green pallor known 🔹
albendazole) in the youngest age-group (1-2 yr old).
Pyrantel pamoate (11 mg/kg PO once daily for 3 days;
maximum dose: 1 g) is available in liquid form and is an
emergence of anthelmintic drug resistance.
Therefore, mass drug administration alone is not effective for
controlling hookworm in endemic areas. Improvements in
facilitate attachment to the mucosa and submucosa of the small intestine.
Mature
🔹
aschlorosis.
An infantile form of ancylostomiasis resulting from heavy A. duodenale infection
associated with diarrhea, melena, failure to thrive, profound anemia, and has significant
effective alternative to the benzimidazolesReplacement
therapy with oral iron is not usually required to correct
sanitation, health education, and avoidance of human feces as
fertilizer remain critical for reducing hookworm transmission
hookworm-associated iron deficiency in children. and endemicity
A. duodenale and N. americanus female worms produce about 30,000 and mortality.
<10,000 eggs/day, respectively. Eggs that are deposited on soil with adequate
🔷
moisture and shade develop into larvae.
Epidemiology
Hookworm infection is one of the most prevalent infectious diseases of humans
🔷 Etiology
Enterobius vermicularis, is a small (1 cm in length), white, threadlike nematode,
or roundworm, that typically inhabits the cecum, appendix, and adjacent areas
of the ileum and ascending colon. Gravid females migrate at night to the
🔷 Treatment
perianal and perineal regions, where they deposit up to 15,000 eggs. 🔷 Clinical Manifestations 🔷 Diagnosis
Anthelmintic drugs should be administered to infected
🔹
individuals and their family members.
🔷 Prevention
Enterobiasis
Eggs embryonate within 6 hr and remain viable for 20 days. Human infection
occurs by the fecal-oral route typically by ingestion of embryonated eggs that 🔷
Pinworm infection is innocuous and rarely causes serious medical problems.
The most common complaints include itching and restless sleep secondary to nocturnal perianal
A history of nocturnal perianal pruritus in children
strongly suggests enterobiasis.
Albendazole (400 mg orally with a repeat dose 2 wk later
for all age-groups) is the treatment of choice and results in 🔹 Good hand hygiene is the most effective method of
(Enterobius vermicularis or
are carried on fingernails, clothing, bedding, or house dust. After ingestion, the
Pathogenesis
Enterobius infection may cause symptoms by mechanical
or perineal pruritus.
The precise cause and incidence of pruritus are unknown but may be related to the intensity of
Definitive diagnosis is made by demonstration of eggs
on microscopic examination of adhesive cellophane 🔹
cure rates exceeding 90%.
Alternatives include mebendazole (100 mg orally with a 🔹
prevention.
Household contacts can be treated at the same time as the
pinworm infection) 🔷
larvae mature to form adult worms in 36-53 days.
Epidemiology
stimulation and irritation, allergic reactions,and migration of the
worms to anatomic sites where they become pathogenic.
infection, psychologic profile of the infected individual, or allergic reactions to the parasite.
Eosinophilia is not observed in most cases, because tissue invasion does not occur.
tape pressed against the perianal region early in the
morning or by observing worms in the perianal region.
repeat dose 2 wk later) and pyrantel pamoate (11 mg/kg base
orally 3 times for 1 day up to a maximum of 1 g; repeat at 2 🔹
infected individual.
Repeated treatments every 3-4 mo may be required in
Enterobiasis occurs in individuals of all ages and socioeconomic levels. Humans
Aberrant migration to ectopic sites occasionally may lead to appendicitis, chronic salpingitis,
pelvic inflammatory disease, peritonitis, hepatitis, and ulcerative lesions in the large or small
bowel.
Digital rectal examination may also be used to obtain
samples for a wet mount. Routine stool samples rarely
demonstrate Enterobius ova.
🔹
wk).
Morning bathing removes a large portion of eggs. Frequent
changing of underclothes, bedclothes, and bedsheets
circumstances with repeated exposure, such as with
institutionalized children.
are the only known host.
decreases environmental egg contamination and may
The prevalence of pinworm infection is highest in children 5-14 yr of age. It is decrease the risk for autoinfection.
common in areas where children live, play, and sleep close together, thus
facilitating egg transmission. Autoinoculation can occur in individuals who
habitually put their fingers in their mouth.
🔷 Etiology 🔷 🔷 Diagnosis
🔷 Treatment
🔹
Clinical Manifestations 1) Diagnosis of VLM
Caused by dog roundworm, Toxocara canis, (most cases) and cat roundworm,
Toxocara cati (fewer cases).
Three major clinical syndromes are associated with human toxocariasis: VLM, ocular larva migrans
(OLM), and covert toxocariasis. 🔹 Clinical manifestation
Lab finding include eosinophilia (>20%), leukocytosis,
Most patients do not require treatment bec. signs &
symptoms are mild and subside over wks-months. 🔷 Prevention
Infection occur through ingestion of embryonated eggs contaminating soil, 1) VLM occurs most often in toddlers with a history of pica and exposure to puppies. Findings
include fever, eosinophilia, & hepatomegaly (classic presentation); also includes cough, wheezing, 🔹
hypergammaglobulinemia and elevated
isohemagglutinin titers to A and B blood group
Albendazole (400 mg orally twice daily for 5 days for all
ages).
1) Prevent dog feces from contaminating the environment by
keeping dogs on leashes and excluding pets from playgrounds
Toxocariasis (Visceral and hands, or fomites. bronchopneumonia, anemia, leukocytosis, and positive Toxocara serology. Cutaneous manifestations
🔹
antigens. Mebendazole (100-200 mg PO twice daily for 5 days for all and sandboxes that toddlers use. Discourage children from
Ocular Larva Migrans)
The larvae hatch and penetrate the intestinal wall and travel via the circulation Subtopic 1 such as pruritus, eczema, and urticaria can be present.
2) OLM occur in older children without signs or symptoms of VLM. Presenting symptoms include 🔹 Biopsy confirm the diagnosis (reveal granuloma).
Enzyme-linked immunosorbent assay is the standard
ages).
Note: Anthelmintic treatment of CNS and ocular disease
putting dirty fingers in their mouth.Vinyl covering of sandboxes
🔷
to the liver, lung, and other tissues. reduces the viability of T. canis eggs.
unilateral visual loss, eye pain, white pupil, or strabismus that develops over weeks. Granulomas serologic test used to confirm toxocariasis, when biopsy should be extended (3-4 wk).Prednisone (1 mg/kg/day PO for 3) Widespread veterinary use of broad-spectrum
Epidemiology occur on the posterior pole of the retina and may be mistaken for retinoblastoma. cannot be obtained. 2-4 wk) has been recommended to suppress local anthelmintics effective against Toxocara may lead to a decline
Young children are at highest risk of infection because of their unsanitary play 3) Covert or less obvious infection, identified by serologic tests. 2) Diagnosis of OLM: typical clinical findings with inflammation while treatment with anthelmintic agents is in parasite transmission to humans.
Findings include hepatomegaly, abdominal pain, cough, sleep disturbance, failure to thrive, and elevated antibody titers. initiated.
habits and tendency to place fingers in the mouth. headache with elevated Toxocara antibody titers. Eosinophilia (50–75% of cases). 3) Diagnosis of covert toxocariasis: clinical
Other behavioral risk factors include pica and contact with puppy litters. manifestation with eosinophilia and increased IgE.
🔷 Etiology: 🔷 Clinical Manifestations
🔹
In addition to organ-specific morbidities, infected patients frequently demonstrate anemia, chronic
Five schistosome species infect humans: pain, diarrhea, exercise intolerance, and chronic undernutrition manifesting as growth stunting.
Schistosoma haematobium: adult found in the perivesical and periureteral 1) Cercarial penetration of human skin
🔹
venous plexus may result in a papular pruritic rash (known as schistosomal dermatitis or swimmer's itch), edema
🔹 S. mansoni adult found in the inferior mesenteric veins and intense cellular infiltrates in the dermis and epidermis.
2) Acute schistosomiasis (Katayama syndrome) may occur 4-8 wk after exposure; this is a serum
Helminthic 🔹 S. intercalatum, and S. mekongi: adult found in the mesenteric vessels
S. japonicum adult found in the superior mesenteric veins
Humans are infected through contact with water contaminated with cercariae,
sickness–like syndrome manifested by the acute onset of fever, cough, chills, sweating, abdominal
pain, lymphadenopathy, hepatosplenomegaly, and eosinophilia.
3) Chronic urogenital schistosomiasis (S. haematobium): children usually complain of frequency,
Diseases the free-living infective stage of the parasite. 🔷 Pathogenesis
dysuria, and hematuria. Urine exam. shows erythrocytes, parasite eggs, and occasional eosinophiluria.
🔷 🔷 🔷 Prevention
These motile, forked-tail organisms emerge from infected snails and are Both early and late manifestations of schistosomiasis are 🔹
The advanced stages of urogenital schistosomiasis are associated with
🔹 chronic renal failure, 🔹 Diagnosis Treatment Transmission in endemic areas may be decreased by reducing
capable of penetrating intact human skin.
🔹
immunologically mediated.
Acute schistosomiasis, known as snail fever or Katayama 🔹 secondary infections, and
squamous carcinoma of the bladder.
🔹 Clinical manifestation
Diagnosis of S. haematobium infection: a volume of 10
🔹
Praziquantel
40 mg/kg/day/ PO bid for 1 day for S. haematobia,
the parasite load in the human population,this goal is achieved
by the availability of oral, single-dose, effective
Schistosomiasis As they reach maturity, adult worms migrate to specific anatomic sites syndrome, is a febrile illness that represents an immune complex An important complication of S. haematobium infection is female genital schistosomiasis. Eggs
mL of urine should be collected around midday, the time
of maximal egg excretion, and filtered for microscopic
mansoni, and intercalatum. (Note: children <5 yr old with S. chemotherapeutic.
characteristic of each schistosome species.
🔹
disease associated with early infection and oviposition. migrate from the vesical plexus to lodge in the female genital tract where they induce a mansoni may need up to 60 mg/kg/day PO tid for 1 day to Other measures: improve sanitation, antiparasitic treatment
(Schistosoma) The female accompanies the male in a groove formed by the lateral edges of Chronic schistosomiasis: retention of eggs in the host tissues
is associated with chronic granulomatous injury. Eggs may be
granulomatous inflammatory response that can manifest as contact bleeding, pain, and eventual
infertility. Male genital schistosomiasis can also present with hematospermia, pain, and lumpy semen.
🔹
examination.
Other schistosome infections (S. mansoni and S.
🔹
achieve clearance).
60 mg/kg/day PO divided 3 times daily [tid] for 1 day for S.
given at well-child visits, focal application of molluscicidals,
and animal vaccination may prove useful in breaking the cycle
its body. On fertilization, female worms begin oviposition in the small venous japonicum ); stool examination by the Kato-Katz thick
🔹
trapped at sites of deposition (urinary bladder, ureters, intestine) 4) Intestinal schistosomiasis: Children ē chronic S. mansoni, japonica, intercalatum, or mekongi may: japonica and mekongi. A 2nd treatment 4-6 wk after the 1st of transmission.
smear procedure and detection of parasite antigen in
tributaries. Parasite eggs provoke a significant granulomatous inflammatory
🔹
or may be carried by the bloodstream to other organs, most remain subclinical, course may help in eliminating residual infection. Ultimately, control of schistosomiasis is closely linked to
patient serum or urine
🔹
response that allows them to ulcerate through host tissues to reach the lumen frequently the liver and less often the lungs and CNS). have colicky abdominal pain and bloody diarrhea (most common). economic and social development.
Present with late syndrome of hepatosplenomegaly, portal hypertension, ascites, and
of the urinary tract or the intestines. hematemesis.
They are carried to the outside environment in urine or feces (depending on the 5) Schistosome eggs may escape into the lungs, causing pulmonary hypertension and cor
species), where they will hatch if deposited infreshwater. Motile miracidia pulmonale. S. japonicum worms may migrate to the brain vasculature & produce localized lesions
emerge, infect specific freshwater snail intermediate hosts, and divide causing seizures.
6) Transverse myelitis, spinal compression, and other CNS involvement (meningoencephalitis)
asexually. After 4-12 wk, the infective cercariae are released by the snails into are rare but well-known complications in children or young adults with either acute or chronic S.
🔷
the contaminated water. haematobium or S. mansoni infection.
7) Long-term systemic effects of infection include: chronic undernutrition manifesting as growth
Epidemiology stunting, anemia, chronic pain, diarrhea, exercise intolerance, and cognitive imp
Schistosoma spp. primarily infect children and young adult
Tapeworms are adult forms of cestodes, multicellular helminth parasites, that
live in human intestines and cause non–life-threatening illness. Invasive larval
forms (intermediate stage) of cestodes are associated with cysts that lead to
severe human disease such as neurocysticercosis (Taenia solium; 🔷 Diagnosis
🔷 Visual examination for gravid proglottids in the stool is a
🔷
andechinococcosis (mostly Echinococcus granulosa and E. multilocularis. Pathogenesis sensitive test; these segments may be used to identify
Etiology When children ingest raw or undercooked meat containing larval
cysts, gastric acid and bile facilitate release of immature scolices
species. Eggs, by contrast, are often absent from stool
🔷 Treatment
🔷
The beef tapeworm (Taenia saginata), the pork tapeworm (T. solium), and the and cannot distinguish between T. saginata and T. solium.
that attach to the lumen of the small intestine. Infections with all adult tapeworms respond to praziquantel
Clinical Manifestations
🔷
If the parasite is completely expelled, the scolex of each
tapeworm (Taenia asiatica) are long worms (4-10 m) named for their The parasite grows, adding new segments at the base of the
Nonspecific abdominal symptoms have been reported with beef and pork tapeworm infections, but species is diagnostic. (25 mg/kg orally [PO] once).
Prevention
intermediate hosts (T. saginata , T. solium ) or geographic distribution (T. scolex. The terminal segments mature (gravid) and after 2-3 mo Expelled proglottid segments are usually approximately When available, an alternative treatment for taeniasis is
the most bothersome symptom is the psychologic distress caused by seeing proglottids in the stool Prolonged freezing or thorough cooking of beef and pork kills
Adult Tapeworm Infections asiatica ; larval host is the pig).
produce50,000-100,000 eggs, and the eggs or even detached
intact proglottids pass out of the child through the anus (with or or undergarments.
The released segments of the worms are motile (especially those of T. saginata ) andsometimes lead
0.5 × 1-2 × 0.1 cm in size. Molecular methods can
distinguish T. saginata from T. asiatica . Antigen detection
niclosamide (50 mg/kg PO once for children; 2 g PO once for
adults).
the larval cystic forms of the parasite.
Appropriate human sanitation can interrupt transmission by
The adult worms are found only in the human intestine. As with the adult stage separate from defecation). Nitazoxanide is sometimes effective as well.
🔷
to anal pruritus. tests are increasingly available. preventing infection in livestock.
of all tapeworms, their body is a series of 100s or 1000s of flattened segments The surface of proglottids serves as an absorptive organ to The parasite is usually expelled on the day of administration.
“steal” nutritional elements from the child's small bowel for use The adult beef and pork tapeworms are only rarely associated with other symptoms. Differential Diagnosis
Treatment with electrolyte–polyethylene glycol bowel
(proglottids) with an anterior attachment organ(scolex) that anchors the by the parasite.
Anal pruritus may mimic symptoms of pinworm
preparations can increase the yield of passage of scolices.
(Enterobius vermicularis) infection.
🔷
parasite to the bowel wall. There is sometimes a transient eosinophilia before the parasite
Diphyllobothrium latum and Ascaris lumbricoides (a
matures enough to release eggs.
Epidemiology long round worm) may be mistaken for T. saginata or T.
The pork and beef tapeworms are distributed worldwide. The prevalence in solium in stools.
adults may not reflect the prevalence in young children, because cultural
practices may dictate how well meat is cooked and how much is served to
children.
🔷 Etiology
The fish tapeworms of the genus Diphyllobothrium are the longest human
tapeworms, reaching >10 m in length, and have an anatomic organization similar 🔷 Diagnosis
to that of other adult cestodes. 🔷 Pathogenesis
Parasitological examination of the stool is useful because
An elongated scolex, is followed by 1000s of segments looped in the small The adult worm of Diphyllobothrium latum has high affinity
🔷
eggs are abundant in the feces and have morphology
distinct from that of all other tapeworms. 🔷 Prevention
Diphyllobothriasis
bowel.
Gravid terminal proglottids detach periodically but tend to disintegrate before
receptors and efficiently scavenges vitamin B12 for its own use in
the constant production of large numbers of segments and as
many as 1 million eggs per day.
Clinical Manifestations
Infection is largely asymptomatic. Segments may be noted in stool.
The worm itself has a distinct scolex and proglottid
morphology; however, these are not likely to be passed 🔷 Treatment
As with all adult tapeworms, D. latum infections respond to
The intermediate stage is easily killed by brief cooking or
prolonged freezing of fish before ingestion.
🔷
expulsion, thus releasing eggs rather than intact wormsegments in the feces. Those who develop vitamin B12 or folate deficiency present with megaloblastic anemia with spontaneously. Because humans are the major reservoir for adult worms,
As a result, diphyllobothriasis causes megaloblastic anemia in 2– praziquantel (5-10 mg/kg PO once).
(Diphyllobothrium Spp.) In contrast to taeniids, the life cycle of Diphyllobothrium spp. requires 2 9% of infections.
leukopenia, thrombocytopenia, glossitis, and/or signs of spinal cord posterior column dysfunction
(loss of vibratory sense, proprioception, and coordination).
Differential Diagnosis
A segment or a whole section of the worm might be
Niclosamide (50 mg/kg PO in a single dose) is also effective
health education is one of the most important tools for
preventing transmission, together with improved human
intermediate hosts. Small, freshwater crustaceans (copepods) take up the Children with other causes of vitamin B12 or folate deficiency,
confused with Taenia or Ascaris after it is passed. sanitation.
such as chronic infectious diarrhea, celiac disease, or congenital
larvae that hatch from parasite eggs. The parasite passes up the food chain as malabsorption, are more likely to develop symptomatic infection.
Pernicious anemia, bone marrow toxins, and dietary
restriction may contribute to or mimic the nutritional
small fish eat the copepods and are in turn eaten by larger fish. deficiencies associated with diphyllobothriasis.
Consumption of raw or undercooked fish leads to human infection with adult
fish tapeworms. Persons who prepare raw fish for home or commercial use or
who sample fish before cooking are particularly at risk for infection.
🔷
🔹 Treatment
Management of cystic disease should be
individualized and guided by disease stage and location.
For cystic echinococcosis that are <5 cm in diameter,
albendazole alone (15 mg/kg/day orally divided twice daily
for 1-6 mo; maximum 800 mg/day) may result in a high rate of
🔷 🔹
cure.
🔷 Etiology 🔹 Diagnosis
Ultrasonography is the most valuable tool for both
Adverse effects include occasional alopecia, mild
gastrointestinal disturbance, elevated transaminases on
Two major Echinococcus groups of species are responsible for distinct clinical
🔷 the diagnosis and treatment of cystic hydatid disease of prolonged use, and leukopenia (blood counts be monitored at
🔹 🔷 Prognosis
🔹 Clinical Manifestations the liver. Chest radiographs frequently reveal the beginning and every 2 wk during therapy).
presentations. Echinococcus granulosus and related species cause cystic
🔷 Cystic hydatid disease: in the liver, cysts may remain asymptomatic, may regress spontaneously, characteristic rounded masses in lung hydatid disease. For larger cyst, ultrasound- or CT-guided PAIR Factors predictive of success with chemotherapy for cystic
hydatid disease, and Echinococcusmultilocularis causes alveolar hydatid
disease.
Pathogenesis
E. granulosus: the lung is a common site of cysts in children,
or may produce nonspecific symptoms.Symptomatic cysts can cause increased abdominal girth,
hepatomegaly, a palpable mass, vomiting, or abdominal pain. In the lung, cysts produce chest pain, 🔹
Alveolar hydatid disease resembles a diffuse solid tumor.
CT findings are similar to those of ultrasonography
(percutaneous, aspiration, instillation, and reaspiration)is the
🔹
preferred therapy. 🔹
hydatidosis are:
🔹 age of the cyst (<2 yr),
-The adult parasites are small (2-7 mm) tapeworms inhabit the intestines of
canines such as dogs, wolves, jackals, and foxes. These carnivores pass the
whereas in adults up to 70% of cysts develop in the liver. Cysts
can also develop in bone, the genitourinary system, spleen,
chronic cough, or hemoptysis.
Expectorated fluid from ruptured lung cysts is often described as “salty.”Mass effects can be noted
and may at times be useful in distinguishing alveolar from
cystic hydatid disease in geographic regions where both
Spillage with PAIR is uncommon, but prophylactic
albendazole therapy is routinely administered at least 1 wk
before PAIR and 1 mo afterward.
🔹 low internal complexity of the cyst, and
small size. The site of the cyst is not important, although
cysts in bone respond poorly. For alveolar hydatidosis, if
Echinococcosis subcutaneous tissues, and brain. in the brain and bone. Serious complications result from compression of adjacent structures or occur. CT or MRI is also important in planning a surgical
🔹 🔹
eggs in their stool, which contaminates the soil, pasture, and water, as well as The host surrounds the primary cyst with a tough, fibrous spillage of cyst contents. intervention. Note: For hepatic cysts, patients should begin therapy with surgical removal is unsuccessful, the average mortality is 92%
(Echinococcus granulosus and
🔷
capsule.E. multilocularis: almost always involves the liver. Anaphylaxis can occur with cyst rupture or spontaneous spillage, from trauma or Serologic studies: The sensitivity and specificity of albendazole (ideally in combination with praziquantel) for by 10 yr afterdiagnosis
their own fur.
🔹
The lesions grow very slowly and rarely present in children. intraoperatively. Cyst fluid may cause hypersensitivity pneumonitis. the enzyme-linked immunosorbent assay to diagnose several days to weeks preoperatively. . Prevention
Echinococcus multilocularis) -Domestic animals, such as sheep, goats, cattle, and camels, ingest E. cystic echinococcosis may vary from 50– 100% and 40– Antiparasitic drugs should be continued for 4-12 wk
🔹
The secondary reproductive units bud externally and are not Spillage can also be catastrophic long-term, because each the parasite protoscolex can form a new Thorough handwashing,
granulosus complex eggs while grazing. For E. multilocularis, the main confined within a single, well-defined structure. Thus the lesions cyst and fill up the abdominal cavity or rarely the pleural space. Jaundice from cystic hydatid 100%, respectively.
🔹
postoperatively.
🔹 avoiding contact with dogs in endemic areas,
🔹 The sensitivity is higher for hepatic or bone disease, but Surgery is the treatment of choice for complicated
🔹
intermediate hosts are small rodents. -Humans are infected by consuming eggs are invasive and often confused with a malignancy. Furthermore, disease is rare. boiling or filtering water when camping,
the cysts are poorly demarcated from those of the host, making Alveolar hydatid disease: may be diagnosed incidentally, but often the proliferating mass may the false-negative rate may be >50% with pulmonary or cysts, including ruptured cysts, cysts communicating with the
by direct contact with infected canines or from ova in theenvironment. and proper disposal of animal carcasses.
🔹
surgical removal difficult. compromise the biliary system and/or hepatic tissue, causing progressive obstructive jaundice CNS infection. biliary tract, large pulmonary cysts, or cysts of the CNS or
Control or treatment of the feral dog population and regular
-The larvae hatch, penetrate the gut, and are carried by the vascular or
lymphatic systems to the liver, lungs, and less frequently, bones, kidney, brain,
andhepatic failure.
Symptoms also occur from expansion of extrahepatic foci.
Differential Diagnosis
- For hydatid cysts: Benign hepatic cysts and bacterial 🔹
bones.
Small thoracic cysts mayresolve with chemotherapy,
but most cysts require operative removal.Alveolar hydatidosis
praziquantel treatment of pets and working dogs in endemic
areas.
hepatic abscesses
or heart in E. granulosus infection. E. multilocularis larvae infect the liver almost
exclusively.
- Alveolar echinococcosis is often confused with
hepatoma or metastatic tumor hepatectomy, lobectomy, or liver transplantation. 🔹
frequently requires radical surgery, including partial
therapy with albendazole should be continued for 2 yr
Medical
after presumably curative surgery.
In patients who are not operative candidates or whose
lesions are not amenable to surgical cure, albendazole
long-term suppressive therapy should be used to slow
the progression, but the infection generally recurs if
albendazole is stopped.
by fatema okoff
