5 Parasitology Flashcards
define parasitism
a symbiotic relationship in which one organism (the parasite) benefits at the expense of the host
name 2 general types of parasites
endoparasite
ectoparasite
endoparasites are found ____
internally
ectoparasites are found ____
on skin & hair (eg. lice, fleas, ticks)
name 2 groupings of parasites
protozoans
helminths
name 3 characteristics of protozoa
- eukaryotes
- single celled simple animals
- classified based on locomotion
name 2 forms that protozoa exist in
trophozoite
cyst
protozoa which are actively growing within a host are in what form?
trophozoite
protozoa which are waiting statically in the environment are in what form?
cyst
method of locomotion of sporozoa
none
method of reproduction of sporozoa
simple fission followed by sexual reproduction (2 cycles)
name 3 species of sporozoa
plasmodium
toxoplasma
cryptosporidium
what is the most common species of sporozoa?
plasmodium
what is the etiologic agent of plasmodium?
plasmodium species
what is the most virulent type of plasmodium?
plasmodium falciparum (malaria)
what is the vector of malaria?
anopheles mosquito
plasmodium falciparum is the most prevalent species in what location?
sub-Saharan Africa
what is the second most significant species of plasmodium and where is it prevalent?
plasmodium vivax
Southeast Asia and Latin America
describe the asexual and sexual life cycles of plasmodium
- mosquito releases sporozoites which act on the liver
- organism undergoes asexual cycle, infecting RBCs
- production of gametocytes
- transmission to next mosquito
what is the most prevalent parasitic disease worldwide?
malaria
febrile illness of malaria is caused by ____ infection of ____
plasmodium
RBCs
hemoglobinuria
black water fever
etiologic agent of toxoplasma
toxoplasma gondii
vector of toxoplasma
feces of infected domestic cats
treatment for toxoplasma
not required unless symptoms are severe, except for pregnant women
in pregnant women, toxoplasma may cause…
miscarriage or severe neurological damage to the fetus
toxoplasma is an important cause of ____
AIDS-related dementia
how is cryptosporidium transmitted?
fecal-oral transmission usually via water
what is the most common symptom of cryptosporidium?
watery diarrhea
cryptosporidium is commonly called ____
crypto
what is the most primitive of all protozoans?
rhizopods
how do rhizopods reproduce?
binary fission
method of locomotion of rhizopods
pseudopods (‘false foot’)
rhizopods can exist as ____ in periods of environmental stress
cysts
rhizopods are ____
amoebas
what is the etiologic agent of amebiasis?
entamoeba histolytica
amebiasis causes what 2 diseases?
- Montezuma’s revenge
- New Delhi belly
what is the vector of amebiasis?
fecal-oral
amebiasis colonizes the ____
colon
acute symptoms of amebiasis
- diarrhea (occ. bloody)
- flatulence
- cramping
- abdominal pain
chronic symptoms of amebiasis
alternating bouts of diarrhea and constipation
what is the largest class of locomotive parasites to infect humans?
mastigophora
how does mastigophora reproduce?
binary fission
mastigophora can exist solely in ____ form
trophozoite
what is the vector of trichomonas vaginalis?
STD
name 4 species of mastigophora
- trichomonas vaginalis
- tryponosoma
- giardia
- leishmania
chronic long-term infection by trichomonas vaginalis in males
prostatitis and urethritis
characteristics of trichomonas vaginalis
- non-invasive
- petechial hemorrhaging
- non-toxin producing
- persistent vaginitis
- exists only in trophozoite form
what is the etiologic agent of the tryponosoma species?
trypanasoma
what is the vector of tryponosoma species?
tsetse fly
what is the common name of the tryponosoma species?
sleeping sickness
african sleeping sickness is confined to ____
central Africa
pathogenesis of african sleeping sickness
- localized inflammation at bite followed by hematogenous and lymphatic spread
- colonize small BVs of heart & brain
- fever, headache, impaired mental status leading to coma and death
- exist only in trophozoite form
what is the etiologic agent of giardia?
giardia lamblia
vector of giardia
fecal-oral
giardia is commonly called ____
beaver fever
pathogenesis of giardiasis
- diarrhea (steatorrhea)
- cramping
- flatulence
- anorexia
- exists in both cyst & trophozoite stage
the leishmania species causes the ____
oriental sore
vector of leishmania species
sand flea
pathogenesis of leishmaniasis
- appear weeks to months after bite
- itchy pustules
- lymphadenopathy
- spontaneous healing in 5-12 months
- depigmented scar
- confined to skin, no further issues once scar forms
how many ciliates infect humans causing intestinal disease?
only 1: balantidium coli
vector of balantidium coli
fecal-oral involving swine (pig) feces
name 3 characteristics of helminths
- eukaryotes
- simple to complex animals
- 2 phyla of worms
name the 2 phyla of worms
- plastyhelminthes: flatworms
- nemahelminthes: roundworms
name 3 classes of worms
- cestodes: tapeworms
- trematodes: flukes
- nematodes: roundworms
what is the largest of the worms?
cestodes
describe characteristics of cestodes
- lack vascular and respiratory systems
- hermaphrodites
- nutrients absorbed across cuticle
- adults consist of 3 parts
what are the 3 parts of adult cestodes?
scolex
regenerative neck regions
long segmented body
what is the scolex used for?
attachment
describe the regenerative neck region
segmented portion of a tapeworm: proglottid
what is the sexually maturing section of a tapeworm?
mature proglottids
what are gravid proglottids?
ready to break away and release eggs
pathogenesis of tapeworm infection
- need primary and secondary host: humans usually incidental
- can live in humans for decades
- may reach lengths of 10-25ft
- cause gastric discomfort, nausea, diarrhea, weight loss
describe the characteristics of trematodes
- flukes
- bilateral symmetry
- mm to cm in length
- hermaphrodites or schistosomes (sexual)
what type of fluke is paragonimus westermani?
lung fluke
vector of paragonimus westermani
ingestion of improperly cooked crab
pathogenesis of paragonimus westermani
- eosinophilia and inflammation resulting in formation of a fibrous capsule
- swell and erode into bronchioles
- can also rupture pleura
- may travel to intestine and brain
what is the most common trematode worldwide?
clonorchis sinesis
what type of fluke is clonorchis sinesis?
chinese liver fluke
vector of clonorchis sinesis
ingestion of improperly cooked fish
pathogenesis of clonorchis sinesis
- larvae released into duodenum and travel to common bile duct
- migration may cause fever, chills, mild jaundice, eosinophilia, hepatomegaly
- cause fibrosis, bile stones, and associated w bile duct carcinoma
- can migrate to pancreas
- can survive for 50yrs in human host
what type of fluke is the schistosoma species?
blood fluke
vector of schistosoma
fecal-oral
what is the only trematode that is cylindrical in shape and have both genders?
schistosoma
pathogenesis of schistosoma
- cylindrical body
- sexual reproduction: M + F join for life
- begin infection in portal vv and travel to ascending colon
- eggs laid in colon rupture into bowel or bladder
- adult worms in bladder can result in kidney failure
- adult worms in intestinal tract causes abdominal pain and bloody diarrhea
- can live in host for 30yrs
nematodes are all ____
roundworms
what are the 2 types of nematodes?
intestinal
tissue
characteristics of intestinal nematodes
- fusiform body shape
- tough outer cuticle
- M + F
- thousands of offspring
- eggs must incubate outside host to become infective
- larval form
etiologic agent of enterobiasis (pinworms)
enterobius vermicularis
common infections of enterobiasis
- 200,000,000 new infections annually
- most in children
- temperate climates
pinworms attach to ____
cecal mucosa
female pinworms migrate to…
perianal tissue to lay eggs
pathogenesis of enterobiasis
- eggs cause hypersensitivity response
- eggs stick to tissue, bedding, towels, and fingers
- eggs can be inhaled or swallowed
- eggs hatch in upper intestine
- larva migrate to cecum
what is the test to detect pinworms?
scotch tape test
what is the largest and most common intestinal nematode?
ascaris lumbricoides
characteristics of ascaris lumbricoides
- females can lay 250-500 thousand eggs per day
- resistant to environmental pressure
- remain viable in soil up to 6yrs
pathogenesis of ascariasis
- eggs picked up from soil and inhaled/swallowed
- larva penetrate intestinal mucosa and invade liver
- larva exit hepatic v and go through heart to lung
- larva mature and are coughed up and swallowed
infection of ascariasis may occur in ____ or ____
lung or intestines
severity of infection by ascariasis depends on ____
worm load
what are the symptoms of a heavy ascariasis wormload?
- fever
- coughing
- wheezing
- shortness of breath
- intestinal blockage or rupture
ascariasis worms may pass out of the body via…
- vomiting
- stool
- crawling out of nose, mouth, ears, anus
characteristics of tissue nematodes
- discharge live offspring called microfilariae
- circulate through blood or tissue
- can be ingested by blood sucking insects
where does trichinella spiralis live and where is it found?
- lives in duodenum of flesh-eating mammals
- found in swine and bears
pathogenesis of trichinosis
- human infection caused by ingestion of undercooked meat
- over 1,000,000 americans carry living or dead worms
- encapsulates in skeletal m
- viable for 5-10yrs
- most infections are asymptomatic
what are arthropods?
animals with segmented bodies, hard external skeletons, and jointed legs
what are biological vectors?
arthropods that carry pathogenic microorganisms
representative classes of arthropods
- arachnida - 8 legs
- crustacea - 4 antennae
- insecta - 6 legs
name 6 examples of arthropods
mosquito
tick
lice
rat flea
deer fly
kissing bug
