Parasitology

Question 1

3 differences between strongyloides and hookworm larvae on microscopy

Answer 1

1. Buccal Cavity - Hookworm has a large buccal cavity, strongioides has a short buccal cavity
2. Genital primordium - Hookworm is inconspicuous, strongiloides is visible
3. End - Strongiloides has a notched end while hookworms is tapered

Question 2

3 risk factors for severe disease with Babesia

Answer 2

1) Increasing Age
2) Splenectomy
3) Immune Compromise

Question 3

Treatment of Babesia

Answer 3

Atovaquone 750 mg po q12h PLUS
Azithromycin 1 g po x 1, then 500 mg po daily
x 7-10 days

Do not treat if mild, asymptomatic disease

Question 4

Name 3 helminths in which Wolbachia species play a symbiotic role

Answer 4

1) Brugia malayi
2) Onchocerca volvulus
3) Wuchereria bancrofti

Question 5

What do Giardia Antigen tests detect?

Answer 5

Cyst wall proteins

Question 6

3 ways of acquiring Giardia infection?

Answer 6

1) Ingestion of cysts from contaminated water
2) Person-person spread (fecal oral ie. daycare, MSM)
3) Food borne

Question 7

How many Giardia cysts have to be ingested to develop symptomatic infection?

Answer 7

10-25
(Varies between isolate and assemblage)
2 assemblages infect humans: A and B

Question 8

Where in the body do Giardia trophozoites multiply?

Answer 8

Upper small bowel

Question 9

Incubation period of Giardia lamblia?

Answer 9

1-2 weeks

Question 10

3 extraintestinal manifestations of Giardia?

Answer 10

1) Urticaria
2) Eye complaints
3) Reactive Arthritis

Question 11

Sn and Sp of Giardia Antigen EIAs?

Answer 11

Sn = 85-95%
Sp = 90-100%

Question 12

Treatment for Giardia

Answer 12

Metronidazole 250 mg po TID x 7 days

Question 13

2 Alternative treatment for Giardia?

Answer 13

1) Albendazole 400 mg po daily x 5 days

2) Parmomycin 500 mg po TID x 5-10 days

Question 14

1 post Giardia complication?

Answer 14

Lactose intolerance

Question 15

4 parasites that can cause gastrointestinal symptoms and peripheral eosinophilia

Answer 15

1) Dientamoeba fragilis
2) Strongiloides
3) Ascaris
4) Hookworm

Question 16

Organism associated with Dientamoeba infections?

Answer 16

Enterobius vermicularis (pinworm)

Question 17

5 clinical manifestations of Cryptosporidium infection in AIDS patients besides diarrhea and abominal pain?

Answer 17

1) Cholecystitis
2) Cholangitis
3) Hepatitis
4) Pancreatitis
5) Respiratory tract involvement

Question 18

4 stains used to detect Cryptosporidium?

Answer 18

1) Modified Acid Fast Stain (Kinyoun)
2) Hematoxylin & Eosin
3) Geimsa
4) Malachite Green

Question 19

What is the treatment for Cryptosporidium infection in healthy patient and patient with AIDS?

Answer 19

Healthy = No treatment, self limiting
AIDS = Optimize HIV medications plus Nitazoxanide 500-1000 mg PO BID x 14 days

Question 20

Life cycle of Toxoplasmosis?

Answer 20

Humans infected by either eating cysts in the tissue of animals, or eating the decal oocysts from cat feces. The disease circles between cats and animals. In humans the cysts become tachyzoites and infect tissues including placenta and fetus.

Question 21

Triad of congenital toxoplasmosis?

Answer 21

1) Hydrocephalus
2) CNS calcifications (diffuse, CMV around ventricles)
3) Chorioretinitis

Question 22

Treatment for neonatal toxoplasmosis?

Answer 22

Sulfadiazine + Pyrimethamine

Question 23

If fetus infected with toxoplasmosis what is the treatment?

Answer 23

Sulfadiazine + Pyrimethamine

Question 24

If mom is infected but amniocentesis is negative how to prevent transmission to the fetus?

Answer 24

Spiramycin