Parasitology - Helminths Flashcards
What type of reproduction do nematodes (round worms) undergo?
sexual
What type of reproduction do flat worms (tapeworms, fluke worms) undergo?
asexual
What causes whip-worm disease?
Trichuris trichiura
Explain life cycle of trichuris trichiura.
- ingest larval egg
- larva hatch in small intestine
- migrate into colon (1-3 mo. to mature)
- worm digs head into intestinal mucosa to feed
- impregnated egg excreted with stool
Symptoms of whipworm disease?
- usually asymptomatic
- stomach ache
- diarrhea
- appendicitis can happen
Treatment for whip worm disease (Trichuris trichiura)?
- Mebendazole
- albendazole
What is the pathogeny of helminths?
obligate pathogens
(must cause disease to be transmitted from one host to another)
Diagnosis of whip worm disease?
- sample stool, detection of eggs
What is the mode of transmission of ascaris lumbricoides?
- fecal-oral transmission
- -> typically contaminated food
Symptoms of ascaris?
- weight loss
- malnutrition
- obstruction at ileocecal valve or biliary obstruction
Life cycle of ascaris?
- ingest eggs
- larvae emerge in small intestine
- larvae penetrate intestines, go into blood stream, travel to lungs
- grow in alveoli
- cough up, swallow back into intestines
- mature into adult worms
Diagnosis of ascaris lumbricoides?
- sample stool: eggs in stool
- high eosinophil count in blood smear (b/c of tissue invasion, eosinophils increase)
Treatment for ascaris lumbricoides?
- mebendazole (intestinal stage)
- thiabendazole (migrating stage)
Life cycle of enterobius vermicularis?
- ingest eggs
- hatch in duodenum
- mature in colon
- female lays eggs in perianal folds
What causes pinworm disease?
Enterobius vermicularis
Symptoms of pinworm disease (enterobius vermicularis)?
-perianal itching at night
(anal pruritis)
-neurotic complaints, appendicitis
Diagnosis of pinworm disease?
- adhesive tape at perianal area
- anal swab
Treatment of pinworm disease?
- mebendazole
- albendazole
How is trichinella spiralis transmitted?
- undercooked meat (often pork, or wild game)
- possibly fecal-oral
What does trichinella spiralis cause?
Trichinellosis
Symptoms of trichinosis (trichinella spiralis)?
- fever
- vomiting
- nausea
- periorbital edema
- myalgia
Diagnosis of trichinella spiralis?
-muscle biopsy: larva detection
What type of worm is the trematode class?
Fluke worm
What type of worm is the cestode class?
Tape worm
What type of worm is a nematode?
Round worm
What does the taenia species cause?
- cysticercosis (T.solium)
- taeniasis
How do you treat cysticercosis?
praziquantel
How do you contract cysticercosis? (T. solium)
Ingesting eggs that are in food contaminated with human faces
Where do larvae encyst in cysticercosis (Taenia solium)?
- brain
- skeletal muscle
If cystercici reach the brain, what does it cause?
Neurocysticercosis
How does taenia solium progress in the body?
- if you ingest the eggs, the larva dig into gut wall
- migrate into muscles by blood circulation
- encyst in muscle and brain
- cause cysticercus
How can you diagnose cysticercosis?
Tissue biopsy
How do you detect taeniasis?
Detection of proglottids in stool
What does echinococcus granulosus cause ?
Hydatid cysts in liver
How is taeniasis contracted?
Ingestion of taenia cysts and/or larvae
How is cysticercosis contracted?
Ingestion of eggs in fees contaminated water
What disease occurs if you ingest taenia cysts and/or larvae?
Taeniasis
What disease occurs if you ingest taenia eggs in feces contaminated water?
Cysticercosis
–> if reaches brain, causes neurocysticercosis
What does fasciolopsis buski cause?
Gut fluke disease
What is gut fluke disease caused by?
Fasciolopsis buski
trematode, ie fluke worm
What is/are the a) definitive host
b) intermediate host
of gut fluke disease?
a) D. host = human
b) I. host = swine, dog, rabbit
Symptoms of gut fluke disease (fasciolopsis buski)?
- diarrhea
- stomach cramps
- mucosal exulcerations
Treatment for gut fluke disease?
Praziquantel
What disease does wuchereria bancrofti cause?
Elephantiasis
What is elephantiasis caused by?
Wuchereria bancrofti
How is wuchereria bancrofti transmitted?
via mosquitos:
- female anopheles
- aedes
- culex
What type of parasite is wuchereria bancrofti?
Tissue nematode
Symptoms of wuchereria bancrofti?
- lymphangitis (inflammation of lymph vessels)
- fever
- lymphadenitis (swelling of >1 lymph node)
- cellulitis
Treatment for elephantiasis?
- Diethylcarbamazine
- Mebendazole
What is the host of schistosoma species?
Fresh water snails
What are the 3-phase disease symptoms of schistosomiasis?
1) Dermatitis - allergic inflamm., erythema, itching (as cercariae penetrate skin)
2) Katayama syndrome - fever, chills, hives, splenomegaly (as eggs laid in venous system)
3) Chronic fibrosis - fibrosis in organs and vessels
(as the body tries to wall off the eggs that are on the organs and vessels)
In chronic inflammation, what causes urinary bladder cancer?
Schistosoma haematobium
invades venous system of urinary bladder
Treatment for schistosomas?
Praziquantel
Life cycle of schistosoma spp.?
-eggs hatch in fresh water
-find freshwater snails and mature
-mature larvae (cercariae) released by snail into water, & are freely-swimming
-penetrate human swimmer’s skin
-migrate to portal blood and mature into adults
-some adults migrate to bowel/rectum
(eggs circulate to liver and/or shed in stools)
