Parasitology

Question 1

Apicomplexia

Answer 1

Protozoa, include parasites that affect the GI tract and parasites that may affect blood and tissue

Question 2

Plasmodium

Answer 2

Include vivax, ovale/malariae, falciparum. Causes malaria

Question 3

Describe the life cycle of malaria

Answer 3

1. anopheles mosquito bites human
2. Sporozoite enters liver cell, matures into merozoite and enters blood
3. Develop into trophozoite, RBC rupture releasing merozoite
4. Some become gametocytes which are ingested by mosquito
5. Gametocytes develop into sporozoite in mosquito, cycle begins

Question 4

Clinical presentation of malaria

Answer 4

Hx of recent travel to tropics and subtropics. Fever due to RBC rupture. Anemia due to RBC destruction

Question 5

Taenia saginata

Answer 5

cestode, beef tapeworm

Question 6

Taenia solium

Answer 6

cestode, pork tapeworm

Question 7

Cysticercus

Answer 7

larval of taenia solium which forms in human tissue. Most commonly in brain causing neurocysticercus

Question 8

Cysticercosis

Answer 8

cyst like lesions in the muscle, skin and brain caused by the ingestion of T. solium eggs. “measly” lesions look similar to infected pork

Question 9

How do we diagnosis intestinal taenia infections?

Answer 9

Finding characteristic eggs in the patient’s stool.

Cysticercosis is dx by specific EIA and confirmed by radiographic evidence of multiple tissue cysts

Question 10

Diphyllobothrium latum

Answer 10

fish tapeworm

Often seen in northern Europe and Japan. Megaloblastic anemia due to B12 deficiency

Question 11

schistosomiasis

Answer 11

trematodes- contact with freshwater contaminated with larval forms of schistosomes which penetrate skin.

Include: S. Mansoni, S. Japonicum (blood flukes) and S. Haematobium (bladder fluke)

Question 12

S. Mansoni and S. Japonicum

Answer 12

Acute infection: “katayama’s fever” including abdominal pain, diarrhea, fever and hepatosplenomegaly

Diagnosed by stoop O&P for recovery of ova

Question 13

S. Haematobium

Answer 13

causes bladder infection- hematuria and pyuria.

Diagnosed by urine for recovery of ova

Question 14

nematodes

Answer 14

multicellular metazoan

have a cylindrical body and complete digestive tract

Also called roundworms. Can infect the GI tract or the blood and tissues of humans

Question 15

Enterobius vermicularis

Answer 15

pin worm- most common helminthic infection in US

often in children, transmitted via fecal-oral

perianal itching

Question 16

Trematodes

Answer 16

flukes

Definitive host (humans) 
Intermediate host (fresh water snails) 

transmission: penetration of the skin or ingestion of cysts in undercooked fish or crab

Question 17

cestodes

Answer 17

tapeworms

Consists of Scolex (rounded head) and flat body

Transmission: ingestion of undercooked meat/fish containing larvae

infects GI or blood/tissue

Question 18

protozoa

Answer 18

single celled

reproduce sexually or by simple binary division

Trophozoite: mobile feeding and reproducing form

Cyst: non-mobile, dormant form

Question 19

Classes of protozoa

Answer 19

amoebas, flagellates, ciliates and apicomplexia

Question 20

How is Giardia acquired?

Answer 20

one of the most common parasitic infections in the US.

Acquired by drinking contaminated water. Trophozoite coats the small intestine, interfering with fat absorption.

greasy diarrhea

Question 21

How do we diagnosis Giardia

Answer 21

stool O&P
stool or serum for antigen testing
serology

Question 22

treatment for Giardia

Answer 22

Metronidazole (Flagyl)

Question 23

Trichomonas

Answer 23

Flagellate that causes STD

frothy, green, malodorous discharge.

Question 24

Amebiasis

Answer 24

caused by Entamoeba histolytica.

Causes dysentery so pts may present with blood diarrhea. Can also go to liver from colon and cause liver abscess.

Ingested RBCs can be seen in cytoplasm

Question 25

Name the 4 protozoa that cause malaria

Answer 25

Plasmodium falciparum-most common/deadly Plasmodium vivax- chronic liver disease Plasmodium ovale Plasmodium malaria

Question 26

Clinical presentation of malaria

Answer 26

fever, chills, sweats. hx of recent travel

Question 27

life cycle of malaria

Answer 27

1. Mosquito (vector) carries organisms within its salivary glands and injects them into humans while it feeds 2. Sporozoites enter liver and sporozoites mature into merozoites 3. organism grows in liver and spread RBCs which then burst 4. Can lead to anemia and sticky RBCs that clot in organs 5. Plasmodium vivax and plasmodium ovale create hypozoites in liver (latent form) which causes relapses.

Question 28

How do we diagnosis malaria?

Answer 28

exam blood under microscope (can see trophozoites in RBCs) antigen detection tests

Question 29

how can we prevent malaria

Answer 29

long sleeved clothes/pants insect repellant prophylactic drugs prior to travel

Question 30

Trichuris trichiura

Answer 30

whipworm usually seen in tropical climates pts often asymptomatic but may have abdominal pain and diarrhea

Question 31

Ascaris lumbricoides

Answer 31

large intestinal worm most common helminthic infection worldwide may be asymptomatic worms vomited up/removed from nares

Question 32

Necator americanus

Answer 32

hookworm causes severe nutritional deficiency seen in sub-saharan Africa, latin america and Caribbean

Question 33

Anclyostoma duodenale

Answer 33

hookworm causes severe nutritional deficiency

Question 34

Strongyloides stercoralis

Answer 34

can result in life-threatening, disseminated hyper infections in immunosuppressed people

Question 35

Trichinella spiralis

Answer 35

usually acquired by eating undercooked pork

Question 36

Echinococcus granulosus

Answer 36

hydatid disease- pain as cyst containing the larva grow in the liver and lung. Intermediate hosts: sheep, goat and pigs. Definite host: dogs

Question 37

Echinococcus multilocularis

Answer 37

alveolar disease

Question 38

Acanthamoeba

Answer 38

CNS infection. Keratitis in people who wear contacts free living in contaminated water and soil

Question 39

Naegleria fowleri

Answer 39

trophozoite enters nasal mucosa goes to CNS. Causes amebic meningoencephalitis (fatal) contracted during recreational water activities in fresh and warm water

Question 40

Trypanosoma brucei rhodeisense and Trypanosoma brucei gambiense

Answer 40

African sleeping sickness by tsetse fly causes changes in behavior, confusion and changes in sleeping cycle

Question 41

Trpanosoma cruzi

Answer 41

Chagas disease by reduviid (kissing bug)

Question 42

Leishmania

Answer 42

sandfly bites human, transmitting promastigote, infecting macrophages

Question 43

Cryptosporidium parvum/hominis

Answer 43

severe chronic diarrhea in HIV patients

Question 44

Cyclospora cayetanensis

Answer 44

severe diarrhea in immunocompromised acid-fast stain