Parasites

Question 1

Protozoa

Answer 1

single celled eukaroytes, active replicating form (trophozoite) to inactive stage (cyst). cyst is the resistant stage and is infective to human host

Question 2

4 types of protozoa

Answer 2

classified based on organs of locomotion. amoebas, flagellates, ciliates, sporzoans

Question 3

Helminthes (2 types)

Answer 3

worms! cestodes (flatworms/tapeworms) and nematodes (round worms)

Question 4

Plasmodium species (4)

Answer 4

Sporozoan. known commonly as malaria. consists of 4 species: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae.

Question 5

Plasmodium Life cycle

Answer 5

mosquitoes inject sporozoites into humans when they bite, infect hepatocytes (1 to 2 week development), hepatocytes rupture and merozoites infect RBC, RBC rupture and release schizonts, infect other RBCs. Attack lasts 6-10 hours.

Question 6

Plasmodium falciparum

Answer 6

mature trophozoite and schizont have ability to sequester in the deep venous microvasculature. PfEMP-1 expressed on infected RBCs.

HbS trait and HbC protect against P. falciparum malaria

Question 7

Leishmania species (Leishmaniasis)

Answer 7

Flagellate. sand fly bite. could result in cutaneous (skin sores), visceral, or mucosal leishmaniasis.

Question 8

Typanosoma (Chagas’ disease/sleeping sickness)

Answer 8

Flagellate. transmitted by bloodsucking triatomine insects (kissing bugs). bug feces contain infective forms. fever or swelling around site of inoculation.

usually around child’s eye (Romana’s sign)

Question 9

Babesia species (Babesia microti)

Answer 9

transmitted by ticks. 1 to 6 week incubation period. fever/weakness/malaise with chills, sweats, headache, myalgia, arthralgia, anorexia

Question 10

Giardiasis (Giardia lamblia)

Answer 10

Flagellate. enteric parasite. results in diarrhea. transmitted via contaminated water.

Question 11

Cryptosporidiosis (Cryptosporidium parvum)

Answer 11

transmission via ingestion of oocytes. resistant to chlorine, affects swimming pools, water parks. results in watery diarrhea and lasts 1 to 2 weeks.

Question 12

Amebiasis (entamoeba histolytica)

Answer 12

amoeba. associated with intestinal and extraintestinal infections. transmission via ingestion of contaminated water by human fecal matter. results in amebic diarrhea without dysentery. could result in amebic liver abscess.

Question 13

Trichomoniasis (Trichomonas vaginalis)

Answer 13

associated with STDs. symptoms in women include vaginal discharge, pruritus, irritation.

Question 14

Ascariasis (ascaris lumbricoides)

Answer 14

nematode. live and mate in the jejunum. larvae can invade lung tissue and provoke an immune mediated hypersensitivity response

Question 15

Whipworm infection (trichuris trichiura)

Answer 15

soil transmitted helminth. shed in stool where they undergo maturation. after ingestion, eggs hatch in GI tract and matures into adult worm. could lead to rectal prolapse. common in poor rural areas with poor sanitary conditions.

Question 16

Hookworm (anacylostoma duodenale and necator americanus)

Answer 16

soil transmitted helminth, occurs in areas where human feces is used as fertilizer. larvae penetrates bottom of foot and carried through blood vessels to lungs. Penetrates alveoli and up pharynx to be swallowed. larvae reach small intestine where they live and mature into adults.

Question 17

Enterobiasis (enterobiasis vermicularis)

Answer 17

human pinworm. common with school aged children. results in itchy anal region. eggs are deposited around anus.

Question 18

Intestinal cestodes (tapeworms)

Answer 18

flat segmented worms that live in the intestines. result of eating uncooked meat. taenia saginata (beef), taenia solium (pork), diphyllobothrium latum (fish)

cows and pigs become infected after feeding in areas contaminated with human feces. eggs hatch in intestine and move to muscle to develop into cysticerci.

Question 19

Diphyllobothrium latum

Answer 19

fish tapeworm. largest tapeworm can grow up to 30 feet. resides in the small intestine

Question 20

cysticercosis

Answer 20

result of pork tapeworm (T. solium). eggs hatch in the intestine, invade intestinal wall, migrate to striated muscles, brain, liver, other tissues. neurocysticercosis if they localize in brain.