INTRODUCTION TO CLINICAL o Ex. Ticks, lice
PARASITOLOGY • Infection- means you have an
endoparasite
• Infestation- presence of ectoparasites
Definition of Terms • Pathogen- anything that is able to
cause disease
• Symbiosis- relationship between 2
o Disease if there is clinical
analyte or 2 different organisms from
manifestation
different species, genera, or families,
and the interaction that they have is PARASITES
symbiosis
o Symbiosis- living together • Obligate parasite- organism where at
least 1 life stage in the life cycle has
• Parasitism-type of symbiotic
to be parasitic, obligatory step.
relationship where one organism
o Even all life stage as long as it
benefits at the expense of another
has to be parasitic or no option
o Parasite benefits at the
to be free living
expense of the host
o Organism/parasite has an • Facultative parasite- organism that
intimate relationship with its has the potential to be parasitic or free
host (lives inside or body living
surface of the host) o Can complete aa life cycle
o Parasite knowns to kill their where all stages are free living
host o Have the option to be parasitic
o Ex. Ticks, flees and lice either part of the life cycle
• Predation- predator and prey, the • Accidental parasite- parasite of one
predator benefit at the expense of the animal but accidentally affected
prey another animal or human that its not
o Predator only comes to its its usual host
prey during feeding time • Permanent parasite- organism where
o Ex. Mosquitoes (micro- all its life stages are parasitic
predators) • Temporary parasite- organism where
• Commensalism- can be an intimate only part of the life cycle is parasitic
relationship, commensal benefits o Can be facultative or obligate
from its host without harming the host parasite
• Mutualism- both parties benefit from o Obligate cannot be facultative
the relationship • Spurious parasite- free living
o Mutualists organism that may be mistaken for a
• Endoparasite- parasite that lives parasite
inside the body of the host o Spurious- not real
o Ex. Helminth or worm HOSTS
infection (hookwork)
• Ectoparasite- parasite that lives in the • Definitive host- final host, animal or
body surface human that harbors parasite in its
, adult stage and/or during sexual VECTORS- small animal that serves as a
reproduction vehicle for transmission of disease
• Intermediate hosts- harbors parasite
• Vector borne infection- only used
in its larval stage and/or its asexual
when the disease is associated with
reproduction
arthropod vectors (mosquitoes, flies,
o Definitive or intermediate-
sand flies, ticks)
only if you have 2 or more
• Biologic Vector- serves as a host,
hosts in the life cycle and this
either definitive or intermediate
hosts have different roles and
must harbor a parasite that its • Mechanical Vector/Phoretic Vector-
either still undergoing mechanical vehicle (cockroaches or
developmental change while flies), may not serve as actual host
inside the host or participating EXPOSURE AND INFECTION
in reproduction
▪ More than 1 type of • Exposure- coming in contact with the
host in the life cycle parasite, if that organism did not
▪ Parasite while inside establish himself in the body
the host should be o Dies immediately
developing or • Infection- parasite is able to establish
participating in itself, find its suitable environment
reproduction and start feeding/growing, and
▪ Similar roles- just host eventually replicate
• Paratenic host- harbors the parasite o Intermediate- parasite will
that does not undergo any proceed to the next
developmental change or does not developmental stage
participate in reproduction o Paratenic host- should be able
o Leave the host in the same to find its suitable
stage of development environment inside and stay
o Cannot be a definitive or there.
intermediate host • Incubation period
• Reservoir host- refers to an o Clinical vs Biological
animal/plant (no human) that is a o Clinical- period of time
source of infection for the human between point of infection and
o Continuous source for human the start of clinical
• Carrier- human being that is a source manifestation
of infection for other human being ▪ Shorter in some
o Asymptomatic carrier- o Biological- (pre-patent
infected with parasite with no period), period of time
clinical manifestation but can between point of infection and
be a source for other human first appearance of diagnostic
stage
▪ Could be egg or ova
, • Autoinfection- phenomena where a • Blood transfusion
person is already infected with a • Organ transplants
parasite gets reinfected by himself
HOST-PARASITE RELATIONSHIP
o A person become his/her
source of reinfection • Perpetuation of species of parasite
o Ex. Pinworm (eggs can go depends on its ability to ensure
into clothing) transmission from one host to the next
• Superinfection- infection on top of a • Dependent on:
preexisting infection o Availability of hosts-
• Hyperinfection- state where a host accessible to parasite
has an unusually high/heavy levels of o Protection from host’s
infection defenses
o Can be a result of o Survival in external
autoinfection environment
o Can be caused by • What is the origin of parasites?
immunodeficiency
EFFECTS ON THE HOST
SOURCES OF INFECTION
➢ Mechanisms that cause injury
Most Common Sources • Elaboration of substances that
• Soil- particularly when contaminated interfere with the host’s vital
with fecal material processes
• Water- contaminated with fecal • Invasion and/or mechanical
destruction of host tissue
• Food- either contaminated with soil
o Leads to functional deficiency
or water, or host for development of
parasites • Stimulation of adverse immune
reaction
• Vectors-mosquitoes
o Hypersensitivity reaction
• Human-to-human- sexual route,
• Depriving the host of essential
blood transfusion, direct contact,
nutrients either because they compete
transplacental
or tissue damage that they cause leads
• Animal-to-human (zoonoses)-
to a loss of essential nutrients
particularly if vertebrate animal
o Maybe because of bleeding
MODES OF TRANSMISSION inside
• Obstruction- maybe because of large
• Ingestion- most common
parasites or migrate to the vessels
• Inhalation o Parasitic can cause stroke or
• Skin penetration- hookworms when heart attack
bare o Ascaris can cause obstruction
• Vector transmission in blood vessel of bile duct
• Congenital
• Transmammary-breastfeeding
• Sexual transmission
, EFFECTS ON THE PARASITE ORIGIN OF THE PARASITE
• Specific immune response is • Evolution of Parasite
predominantly of the cell-mediated o Majority of the scientist
branch (parasitic) believed that there were free
o Majority of parasite are larger living organisms that evolve
than WBC to parasite
• IgG and IgM production is generally o Comparing closest free living
ineffective organisms
• Some parasites induce IgE production o Able to found out that there
and eosinophilia are 4 differences between
o IgE- associated with allergic these two groups :
infection o Mechanism of entry (infection
o Presence of increase IgE may and re-infection)-
indicate parasitic infection successfully enter its target
o When IgE is produced the host , progeny should be able
effect is hypersensitivity to infect other host
reaction o Mechanisms of protection
o Eosinophil can attach to the from hosts defenses- must
parasite and release occur in an environment
substances to damage parasite where there is a pressure, or
• Absolute immunity occurs very rarely provide the evolving parasite
• Acquired immunity may only modify an advantage
the severity of disease o Increased reproductive
capacity- parasites generally
GROUPS OF PARASITES produce more progeny as
• Protozoa- single cell organism like compared to the free-living
amoeba or malarial parasite organism
▪ Advantageous to the
• Nematodes- roundworms like ascaris
parasite
and hookworms
▪ Parasite need to
• Cestodes- tapeworms
produce more progeny
• Trematodes- flukes
o Streamlining (loss of non-
• Arthropods- lice, mites, ticks essential structures and
functions)- parasitic
organisms are simpler
▪ Does not need
eyesight, complex
motility, complex
digestive system
▪ They live in an
environment where
PARASITOLOGY • Infection- means you have an
endoparasite
• Infestation- presence of ectoparasites
Definition of Terms • Pathogen- anything that is able to
cause disease
• Symbiosis- relationship between 2
o Disease if there is clinical
analyte or 2 different organisms from
manifestation
different species, genera, or families,
and the interaction that they have is PARASITES
symbiosis
o Symbiosis- living together • Obligate parasite- organism where at
least 1 life stage in the life cycle has
• Parasitism-type of symbiotic
to be parasitic, obligatory step.
relationship where one organism
o Even all life stage as long as it
benefits at the expense of another
has to be parasitic or no option
o Parasite benefits at the
to be free living
expense of the host
o Organism/parasite has an • Facultative parasite- organism that
intimate relationship with its has the potential to be parasitic or free
host (lives inside or body living
surface of the host) o Can complete aa life cycle
o Parasite knowns to kill their where all stages are free living
host o Have the option to be parasitic
o Ex. Ticks, flees and lice either part of the life cycle
• Predation- predator and prey, the • Accidental parasite- parasite of one
predator benefit at the expense of the animal but accidentally affected
prey another animal or human that its not
o Predator only comes to its its usual host
prey during feeding time • Permanent parasite- organism where
o Ex. Mosquitoes (micro- all its life stages are parasitic
predators) • Temporary parasite- organism where
• Commensalism- can be an intimate only part of the life cycle is parasitic
relationship, commensal benefits o Can be facultative or obligate
from its host without harming the host parasite
• Mutualism- both parties benefit from o Obligate cannot be facultative
the relationship • Spurious parasite- free living
o Mutualists organism that may be mistaken for a
• Endoparasite- parasite that lives parasite
inside the body of the host o Spurious- not real
o Ex. Helminth or worm HOSTS
infection (hookwork)
• Ectoparasite- parasite that lives in the • Definitive host- final host, animal or
body surface human that harbors parasite in its
, adult stage and/or during sexual VECTORS- small animal that serves as a
reproduction vehicle for transmission of disease
• Intermediate hosts- harbors parasite
• Vector borne infection- only used
in its larval stage and/or its asexual
when the disease is associated with
reproduction
arthropod vectors (mosquitoes, flies,
o Definitive or intermediate-
sand flies, ticks)
only if you have 2 or more
• Biologic Vector- serves as a host,
hosts in the life cycle and this
either definitive or intermediate
hosts have different roles and
must harbor a parasite that its • Mechanical Vector/Phoretic Vector-
either still undergoing mechanical vehicle (cockroaches or
developmental change while flies), may not serve as actual host
inside the host or participating EXPOSURE AND INFECTION
in reproduction
▪ More than 1 type of • Exposure- coming in contact with the
host in the life cycle parasite, if that organism did not
▪ Parasite while inside establish himself in the body
the host should be o Dies immediately
developing or • Infection- parasite is able to establish
participating in itself, find its suitable environment
reproduction and start feeding/growing, and
▪ Similar roles- just host eventually replicate
• Paratenic host- harbors the parasite o Intermediate- parasite will
that does not undergo any proceed to the next
developmental change or does not developmental stage
participate in reproduction o Paratenic host- should be able
o Leave the host in the same to find its suitable
stage of development environment inside and stay
o Cannot be a definitive or there.
intermediate host • Incubation period
• Reservoir host- refers to an o Clinical vs Biological
animal/plant (no human) that is a o Clinical- period of time
source of infection for the human between point of infection and
o Continuous source for human the start of clinical
• Carrier- human being that is a source manifestation
of infection for other human being ▪ Shorter in some
o Asymptomatic carrier- o Biological- (pre-patent
infected with parasite with no period), period of time
clinical manifestation but can between point of infection and
be a source for other human first appearance of diagnostic
stage
▪ Could be egg or ova
, • Autoinfection- phenomena where a • Blood transfusion
person is already infected with a • Organ transplants
parasite gets reinfected by himself
HOST-PARASITE RELATIONSHIP
o A person become his/her
source of reinfection • Perpetuation of species of parasite
o Ex. Pinworm (eggs can go depends on its ability to ensure
into clothing) transmission from one host to the next
• Superinfection- infection on top of a • Dependent on:
preexisting infection o Availability of hosts-
• Hyperinfection- state where a host accessible to parasite
has an unusually high/heavy levels of o Protection from host’s
infection defenses
o Can be a result of o Survival in external
autoinfection environment
o Can be caused by • What is the origin of parasites?
immunodeficiency
EFFECTS ON THE HOST
SOURCES OF INFECTION
➢ Mechanisms that cause injury
Most Common Sources • Elaboration of substances that
• Soil- particularly when contaminated interfere with the host’s vital
with fecal material processes
• Water- contaminated with fecal • Invasion and/or mechanical
destruction of host tissue
• Food- either contaminated with soil
o Leads to functional deficiency
or water, or host for development of
parasites • Stimulation of adverse immune
reaction
• Vectors-mosquitoes
o Hypersensitivity reaction
• Human-to-human- sexual route,
• Depriving the host of essential
blood transfusion, direct contact,
nutrients either because they compete
transplacental
or tissue damage that they cause leads
• Animal-to-human (zoonoses)-
to a loss of essential nutrients
particularly if vertebrate animal
o Maybe because of bleeding
MODES OF TRANSMISSION inside
• Obstruction- maybe because of large
• Ingestion- most common
parasites or migrate to the vessels
• Inhalation o Parasitic can cause stroke or
• Skin penetration- hookworms when heart attack
bare o Ascaris can cause obstruction
• Vector transmission in blood vessel of bile duct
• Congenital
• Transmammary-breastfeeding
• Sexual transmission
, EFFECTS ON THE PARASITE ORIGIN OF THE PARASITE
• Specific immune response is • Evolution of Parasite
predominantly of the cell-mediated o Majority of the scientist
branch (parasitic) believed that there were free
o Majority of parasite are larger living organisms that evolve
than WBC to parasite
• IgG and IgM production is generally o Comparing closest free living
ineffective organisms
• Some parasites induce IgE production o Able to found out that there
and eosinophilia are 4 differences between
o IgE- associated with allergic these two groups :
infection o Mechanism of entry (infection
o Presence of increase IgE may and re-infection)-
indicate parasitic infection successfully enter its target
o When IgE is produced the host , progeny should be able
effect is hypersensitivity to infect other host
reaction o Mechanisms of protection
o Eosinophil can attach to the from hosts defenses- must
parasite and release occur in an environment
substances to damage parasite where there is a pressure, or
• Absolute immunity occurs very rarely provide the evolving parasite
• Acquired immunity may only modify an advantage
the severity of disease o Increased reproductive
capacity- parasites generally
GROUPS OF PARASITES produce more progeny as
• Protozoa- single cell organism like compared to the free-living
amoeba or malarial parasite organism
▪ Advantageous to the
• Nematodes- roundworms like ascaris
parasite
and hookworms
▪ Parasite need to
• Cestodes- tapeworms
produce more progeny
• Trematodes- flukes
o Streamlining (loss of non-
• Arthropods- lice, mites, ticks essential structures and
functions)- parasitic
organisms are simpler
▪ Does not need
eyesight, complex
motility, complex
digestive system
▪ They live in an
environment where
