Parasitology Flashcards
How is pinworm transmitted?
Ingestion of eggs; direct person to person
Pinworm is also called _____
Enterobius vermicularius
What is the pinworm definitive host? Intermediate host?
Definitive host: Humans
Intermediate host: Not needed
Describe pinworm life cycle
Female comes out at night and emerges from anus; lays up to 20,000 eggs. Perianal scratching and transfer to mouth -> auto-reinfection. Eggs in bedclothes easily transmitted to others, eggs swallowed, hatch in intestines. Adults mate and migrate to COLON.
What immunity is present with pinworm?
None; reinfection is possible and common
How do you diagnose pinworm?
Persistent perianal itch, restlessness, insomnia
Observation of eggs, scotch tape test
Whipworm is also known as:
Trichuris trichiura
Whipworm definitive host?
Humans only
How is whipworm transmitted?
Ingestion of embryonated eggs
NO DIRECT PERSON TO PERSON
Explain the whipworm life cycle
Eggs swallowed, hatch in intestine, adults mate and migrate to colon (just like PINWORMS!)
Adults attach in colon, larvae passed in feces (3,000 - 20,000), eggs mature in soil for about 10 days. (OBLIGATE SOIL TIME)
How do you diagnose whipworm?
Only way is by eggs in stool
Pathology of whipworm is based on _____ and leads to _____
Worm burden.
Low - moderate: none, bleeding, bacteremia
High: disrupted colonic mucosa, blood stool, prolapse, anemia
Heavy burden: in children, leads to impaired growth cognitive ability
What are the features of Ascariasis? Location, host, transmission?
Location: Adults free in upper intestine
Definitive host: humans
Transmission: ingestion of eggs from soil, NO DIRECT PERSON TO PERSON
Explain life cycle of ascariasis
Eggs swallowed, larvae hatch and invade intestinal mucosa, enter venous circulation to the lungs (coughed up and swallowed again)
Mature and mate in small intestine, females lay 200,000 eggs/day, passed in feces, OBLIGATE SOIL TIME, eggs mature in soil for 3 weeks and swallowed
How do you diagnose ascariasis?
Eggs in stool
Pathology of ascariasis?
Usually none with low/moderate worm burden
Heavy worm loads can lead to intestinal obstruction
*Stressed worms can migrate to nose, ear, peritoneal, through body wall
Hookworms are also known as:
Necator americanus (global) Ancylostoma duodenale (asia)
Hookworms location, definitive host, transmission?
Location: small intestine
Definitive host: humans
Transmission: invasive skin in contact with soil, NO DIRECT PERSON TO PERSON
Describe hookworm life cycle
Larvae invade skin, goes to circulation, lodges in lungs. Larvae is coughed up and swallowed, matures to adults in intestines, eggs in feces matures in soil to larva and then infectious larva
How do you diagnose hookworms?
Anemia, confirmed by eggs in stool
Hookworm pathology?
Initial pruritis at penetration sites
Can cause bronchitis, pulmonary systems
Exsanguination, anemia
Reduced mental and physical development in children
Which parasite would you want to give shoes to people as a prevention method?
Hookworms, strongyloides
Strongyloides is also called:
Strongyloides stercoralis
Strongyloides location, definitive host, transmission?
Small intestine, humans, filariform larvae penetrates skin
Strongyloides life cycle?
3 alternatives
(1) DIRECT/NO AMPLIFICATION: similar to hookworms, except it’s larvae in feces, not eggs
(2) INDIRECT/ENVIRONMENTAL AMPLIFICATION: sexual reproduction in soil -> eggs/larvae in soil
(3) AUTOINFECTION/HOST AMPLIFICATION: larvae mature in host, enter through colonic mucosa or perianal skin
How do you diagnose strongyloides?
Larvae in stool or sputum
Eggs not seen in fecal specimens
Would you see strongyloides eggs in fecal specimens?
No; you see eggs in hookworms, NOT strongyloides
Trichinosis organism is:
Trichinella spiralis
Trichinella location, definitive host, incidental host, transmission?
Location: adults in intestine, larvae in muscle
Definitive host: meat eating mammals (bears, swine)
Incidental host: humans are dead end hosts
Transmission: raw/undercooked meat (pork) containing encysted larvae
Trichinella life cycle?
Eat undercooked meat (pork) containing encysted larvae, larvae released to gastric environment, adults develop, male dies, female lives and embeds into mucosa.
LIVE larvae birthed (no eggs), female dies, larvae enter lymphatics/blood, encyst in muscle, larvae develop into encapsulated spiral, viable up to 10 YEARS
How do you diagnose trichinosis?
Eosinophilia, periorbital edema, myositis, fever
Which parasite do you find proglottids in feces?
Taenia solium
What are the two flagellated protoza we learned? Also called kinetoplastid
Leishmania and Trypanosoma
How is leishmania transmitted and its reservoir?
Vector/sandfly
Reservoir: wild and domestic animals, in india humans are reservoir for L. major
Where are infections caused by Leishmania?
Cutaneous: starts as bump -> lesion, spontaneous healing, strain-specific immunity
Mucocutaneous: metastasis months to years after primary lesion heals, ulceration of nasopharynx tissues, chemotherapeutic cure leads to immunity
Visceral: onset at 2-12 months, fever and wasting, splenomegaly/hepatomegaly, chemotherapeutic cure leads to immunity
Giemsa stain is used to diagnosis which parasites?
Leishmania and malaria
Which strain of plasmodium causes cerebral malaria?
P. falciparum
Other than cerebral malaria, plasmodium causes:
RDS
Acute respiratory failure
Anemia
Which strains of plasmodium causes anemia? Through what mechanism?
F. plasmodium and F. vivax
- increased rate of removal of UNinfected RBC from circulation
- suppression of erythropoiesis
- etc
What methods are there to diagnose malaria? Specifically for P. falciparum?
Microscopic: Geimsa stain of thin and thick smears
Non-microscopic: Rapid dipstick immunoassay, PCR
Falciparum: microscope - multiple rings per RBC, no trophozoites or schizonts, banana shaped gametocytes
Describe immunity to malaria
Slow to develop (requires multiple infection) Short lived (lost when leaving endemic area) Easily reinfected (return to endemic area)
The tsetse fly is able to transmit disease through most of Africa. True or false?
False. Only in 36 sub-saharan African countries due to vector control and the tsetse fly’s low reproductive rate
A patient comes in with lymphadenopathy, enlarged lymph nodes, on his back. This is also called _______ sign and is an indication of ______.
Winterbottom’s sign; african typanosomiasis
Which strain of trypanosoma brucei develops quicker?
T. brucei gambiense is chronic, with a human reservoir
T. brucei rhodesiense is rapid (1-4 weeks), wild game reservoir
What causes Chagas’ disease?
Trypanosoma cruzi
What is the reservoir for Trypanosoma cruzi? Transmission?
Rats, cats, dogs, opposums, etc. Lots.
Transmission: vector/reduvid bugs, transfusion, transplanation, IV drug use
What is a distinct clinical sign of Chagas/Trypanosoma cruzi?
Romano’s sign; reduvid bug bit near eye/soft tissue
