NEMATODES NOTES: DOC LIGHT
GENERAL CHARACTERISTICS
Basically, referred to as “roundworms”
With unsegmented, elongated and cylindrical bodies.
Their bodies are covered by a thick hyaline protective covering called “cuticula “ (appers like noodles/spaghetti)
they are provided with a complete set of digestive system equipped with a mouth and an anus which are
important in further diagnosis.
Sexes are separate.
Males are smaller and with dorsally curved tail, females are longer and with straight tail
Equipped with sensory organs or chemoreceptors
a) Amphids - paired sensory organs located at the level of cephalic papillae an found in all nematodes (“cephalic
chemoreceptors “)
b) Phasmids - paired structures found posteriorly (caudal)
They maybe “homoxenous “(with only one host) or “heteroxenous “(with more than one host)
They have a simple cycle starting from the egg stage followed by the larval and adult stages.
With lung migration in the cycle ASH (kaya nagcocause ng pneumonitis)
Pneumonitis is due to Migration of larva to the lungs.
(sputum is tested) Can be detected thru sputum exam
Can be detected thru PERIANAL E. vermicularis
SWAB/SCOTCH TAPE SWAB
Largest intestinal nematode Ascaris lumbricoides
Smallest intestinal nematode Strongyloides stercoralis
Can cause retroinfection & autoinfection Enterobius vermicularis
A facultative parasite Strongyloides stercoralis
Parthenogenic – can produce eggs even
without male
Pruritis ani Itchiness at anal region caused by E. vermicularis
Intestinal Ascariasis These are intestinal infections which can be detected thru
Trichuriasis STOOL EXAM.
Hookworm infection Diagnosis is made by finding EGGS/OVA in feces
Capillariasis
Strongyloidiasis An intestinal infection which can be detected thru stool
exam
Diagnosisis made by finding RHABDITIFORM LARVAE in
feces
Regarded as the “UNHOLY 3” HAT
RHABDITIFORM LARVA o 1st stage larva of Hookworms & Strongyloides
o Considered as FEEDING stage
o Larvae with open mouth, shorter & robust than filariform larva
o NOT INFECTIVE
FILARIFORM LARVA o 2nd stage larva considered as the NON-FEEDING STAGE
o Larvae with closed mouth
o Longer and slender than rhabditiform larva
OVIPAROUS o Classification given to adult female nematode that can develop eggs w/out fully
developed larva in its shell
With adult females classified o ATH
as OVIPAROUS
o Classification given to adult female nematode that can develop eggs with fully
OVOVIPAROUS developed larvae in its shell
, o Those that can produce eggs that are already embryonated
OVIVIPAROUS o Eggs that are already infective
With adult females classified o E&S
as OVOVIPAROUS/
OVIVIPAROUS
VIVIPAROUS o All adult female FILARIAL WORMS are classified as
o Eggs are NOT laid in the INTESTINAL TRACT in the case of
o Regarded as NOCTURNALPARASITE since laying of eggs/egg deposition
or oviposition happens at night
Trichinella spiralis
viviparous/larviparous nematode
no egg stages
infective stage: ENCYSTED LARVAE
specific mode of transmission: consumption of inadequately cooked pork containing the encysted larva
can cause TRICHINOSIS/TRICHINELLIASIS
Symptoms:
1. abdominal pain & diarrhea
2. fever & rheumatic pains
3. swelling & pain at the site of larval encystment
4. INTENSE EOSINOPHILIA
Accurate diagnosis is through MUSCLE BIOPSY
Other diagnostic tests: Bachmann Intradermal Test & Bentonite Flocculation test
FILARIAL WORMS / NEMATODES
MICROFILARIA (man to vector): Infective stage of filarial worms to vector
- also, the diagnostic stage
Filarial worms in general can cause FILARIASIS. We examine the BLOOD to detect infection.
MICROFILARIA of FILARIAL WORMS exhibits periodicity
PERIODICITY – refers to the rhythmical appearance of microfilaria in the blood. We consider periodicity in the
collection of blood for the diagnosis of filariasis
SPECIES PERIODICITY of MICROFILARIA
W. bancrofti Nocturnal periodic
8pm-2am or 10 pm -4am
B. malayi Nocturnal subperiodic
*microfilaria goes to the blood both at day and night time but the greatest number
of microfilaria in the blood is at night
Loa loa Diurnal periodic
11am-1pm
O. volvulus
M. ozzardi Non-periodic
M. perstans
In Onchocerca volvulus, specimen for diagnosis is SKIN SNIPS (a biopsy specimen) because its microfilaria
does not go to the peripheral blood
GENERAL CHARACTERISTICS
Basically, referred to as “roundworms”
With unsegmented, elongated and cylindrical bodies.
Their bodies are covered by a thick hyaline protective covering called “cuticula “ (appers like noodles/spaghetti)
they are provided with a complete set of digestive system equipped with a mouth and an anus which are
important in further diagnosis.
Sexes are separate.
Males are smaller and with dorsally curved tail, females are longer and with straight tail
Equipped with sensory organs or chemoreceptors
a) Amphids - paired sensory organs located at the level of cephalic papillae an found in all nematodes (“cephalic
chemoreceptors “)
b) Phasmids - paired structures found posteriorly (caudal)
They maybe “homoxenous “(with only one host) or “heteroxenous “(with more than one host)
They have a simple cycle starting from the egg stage followed by the larval and adult stages.
With lung migration in the cycle ASH (kaya nagcocause ng pneumonitis)
Pneumonitis is due to Migration of larva to the lungs.
(sputum is tested) Can be detected thru sputum exam
Can be detected thru PERIANAL E. vermicularis
SWAB/SCOTCH TAPE SWAB
Largest intestinal nematode Ascaris lumbricoides
Smallest intestinal nematode Strongyloides stercoralis
Can cause retroinfection & autoinfection Enterobius vermicularis
A facultative parasite Strongyloides stercoralis
Parthenogenic – can produce eggs even
without male
Pruritis ani Itchiness at anal region caused by E. vermicularis
Intestinal Ascariasis These are intestinal infections which can be detected thru
Trichuriasis STOOL EXAM.
Hookworm infection Diagnosis is made by finding EGGS/OVA in feces
Capillariasis
Strongyloidiasis An intestinal infection which can be detected thru stool
exam
Diagnosisis made by finding RHABDITIFORM LARVAE in
feces
Regarded as the “UNHOLY 3” HAT
RHABDITIFORM LARVA o 1st stage larva of Hookworms & Strongyloides
o Considered as FEEDING stage
o Larvae with open mouth, shorter & robust than filariform larva
o NOT INFECTIVE
FILARIFORM LARVA o 2nd stage larva considered as the NON-FEEDING STAGE
o Larvae with closed mouth
o Longer and slender than rhabditiform larva
OVIPAROUS o Classification given to adult female nematode that can develop eggs w/out fully
developed larva in its shell
With adult females classified o ATH
as OVIPAROUS
o Classification given to adult female nematode that can develop eggs with fully
OVOVIPAROUS developed larvae in its shell
, o Those that can produce eggs that are already embryonated
OVIVIPAROUS o Eggs that are already infective
With adult females classified o E&S
as OVOVIPAROUS/
OVIVIPAROUS
VIVIPAROUS o All adult female FILARIAL WORMS are classified as
o Eggs are NOT laid in the INTESTINAL TRACT in the case of
o Regarded as NOCTURNALPARASITE since laying of eggs/egg deposition
or oviposition happens at night
Trichinella spiralis
viviparous/larviparous nematode
no egg stages
infective stage: ENCYSTED LARVAE
specific mode of transmission: consumption of inadequately cooked pork containing the encysted larva
can cause TRICHINOSIS/TRICHINELLIASIS
Symptoms:
1. abdominal pain & diarrhea
2. fever & rheumatic pains
3. swelling & pain at the site of larval encystment
4. INTENSE EOSINOPHILIA
Accurate diagnosis is through MUSCLE BIOPSY
Other diagnostic tests: Bachmann Intradermal Test & Bentonite Flocculation test
FILARIAL WORMS / NEMATODES
MICROFILARIA (man to vector): Infective stage of filarial worms to vector
- also, the diagnostic stage
Filarial worms in general can cause FILARIASIS. We examine the BLOOD to detect infection.
MICROFILARIA of FILARIAL WORMS exhibits periodicity
PERIODICITY – refers to the rhythmical appearance of microfilaria in the blood. We consider periodicity in the
collection of blood for the diagnosis of filariasis
SPECIES PERIODICITY of MICROFILARIA
W. bancrofti Nocturnal periodic
8pm-2am or 10 pm -4am
B. malayi Nocturnal subperiodic
*microfilaria goes to the blood both at day and night time but the greatest number
of microfilaria in the blood is at night
Loa loa Diurnal periodic
11am-1pm
O. volvulus
M. ozzardi Non-periodic
M. perstans
In Onchocerca volvulus, specimen for diagnosis is SKIN SNIPS (a biopsy specimen) because its microfilaria
does not go to the peripheral blood
