Parasites

Question 1

Intermediate host vs definitive host

Answer 1

Intermediate = larval/asexual

Definitive = adult/sexual

Question 2

Cause of dysentery-like illness or liver abscesses, see inverted flask shaped lesions in large intestine, cysts are transmitted via fecal-oral route, diagnose by cysts in stool

Answer 2

Entamoeba histolytica

Question 3

Attaches to duodenal wall and causes malabsorption leading to steatorrhea, cysts transmitted via fecal oral route, falling leaf motility, fecal antigen test has replaced string test

Answer 3

Giardia lamblia

Question 4

Most common parasitic cause of persistent watery diarrhea in AIDS patients, cysts transmitted in undercooked meat, acid fast round oocysts seen in stool

Answer 4

Cryptosporidium parvum

Question 5

Persistent watery diarrhea in AIDS patients, causes steatorrhea via malabsorption, fecal oral transmission, acid fast elliptical oocysts seen in stool

Answer 5

Isospora belli

Question 6

Trophozoite transmitted sexually, corkscrew motility, frothy vaginal discharge with fish like odor and strawberry cervix, treated with metronidazole

Answer 6

Trichomonas vaginalis

Question 7

Associated with swimming in fresh water, primary amebic meningoencephalitis leads to severe prefrontal headache and altered sense of smell, rapid onset and fatal

Answer 7

Naegleria

Question 8

Associated with contact lens solution, causes keratitis or granulomatous amebic encephalitis, slow onset but encephalitis progresses to death

Answer 8

Acanthamoeba

Question 9

In malaria, fever spikes are due to what?

Answer 9

Erythrocytic schizont rupture

Question 10

Which two forms species of Plasmodium tend to relapse and why? What treatment consideration is needed?

Answer 10

Vivax and ovale tend to relapse due to tendency to remain in liver as hypnozoites. Primaquine is added to drug regimen which addresses liver stage.

Question 11

Irregular fever spikes with multiple ring forms and crescent shaped gametes, resistant to chloroquine

Answer 11

Plasmodium falciparum

Question 12

Plasmodium associated with 72 hr fever spikes and band forms

Answer 12

malariae

Question 13

Diagnosis of any form of Leishmaniasis?

Answer 13

Look for amastigotes in macrophages

Question 14

Initially presents as swelling around the eye (Romana sign), usually in children, disease caused by inflammatory response to trypomastigotes and leads to cardiac, liver, brain, and colon involvement

Answer 14

Chagas disease - Trypanosoma cruzi with the Reduviid bug vector

Question 15

Cause of African Sleeping Sickness, causing a hemolymphatic disease with fever, chills, and anorexia. Diagnose with trypomastigotes in blood film. What is the hemoflagellate and vector?

Answer 15

Trypanosoma brucei gambiense (West) or T. brucei rhodesiense (East)

Tsetse fly vector

Question 16

3 variations of Leishmaniasis and their vector?

Answer 16

1) Visceral (L. donovani) - Kal Azar and hepatosplenomegaly
2) Cutaneous - ulcerating sore
3) Mucocutaneous (braziliensis) - most severe and disfiguring

All transmitted by sandfly bite, treat all with stibogluconate

Question 17

Malaria-like illness transmitted by Ixodes tick, can be co-infection with Borrelia (but no response to doxycycline), maltese cross on Giemsa strain

Answer 17

Babesia

Question 18

What are risks to the fetus of a primary Toxoplasmosis infection in utero?

Answer 18

• if early in pregnancy, congenital infection is severe and can see hydrocephaly and intracerebral calcifications
• if late in pregnancy, infection may be inapparent but leads to progressive blindness later in teen years

Question 19

What disease does Toxoplasmosis cause in AIDS patients?

Answer 19

leading cause of focal CNS disease with ring enhancing lesions

Question 20

First intermediate hosts of trematodes (flukes)

Answer 20

Snails

Question 21

Trematode that is associated with intestinal disease, is acquired by penetrating intact skin (often associated with rice field workers, as they are in standing water for extended periods), causes itching and granulomas in liver, egg has subterminal spine

Answer 21

Schistosomiasis mansoni

S. japonicum is also presents the same, but egg has no subterminal spine

Question 22

Trematode that is associated with bladder disease, penetrates intact skin and matures in bladder veins, egg has a terminal spine. Chronic infection, as would be seen in Egypt or Africa, increases risk of bladder squamous cell carcinoma

Answer 22

Schistosomiasis haematobium

Question 23

Trematode associated with intensely itchy dermatitis and self resolves, eggs are operculated

Answer 23

Non-human schistosomes - usual host is birds and cannot survive long in human

Question 24

Ingestion of rare beef or pork leading to an intestinal tapeworm. Can lead to cysticerosis and inflammation, including adult onset epilepsy.

Answer 24

Taenia saginata (beef tapeworm) or T. solium (pork tapeworm)

Question 25

Intestinal tapeworm associated with eating fish and developing a Vitamin B12 deficiency and subsequent megaloblastic anemia

Answer 25

Diphyllobothrium latum

Question 26

Tapeworm associated with sheep raising areas and hydatid cyst disease. Treat with surgical removal and be careful not to break the cyst - it will cause anaphylactic shock!

Answer 26

Echinococcus granulosus

Question 27

Associated with alveolar hydatid cyst disease - cysts are very aggressive and bud off frequently, making treatment difficult

Answer 27

Echinococcus multilocularis

Question 28

Pinworm - perianal itching, eggs transmitted person to person or back to self, diagnose with scotch tape test

Answer 28

Enterobius vermicularis

Question 29

Whipworm - associated with appendicitis or rectal prolapse, eggs are ingested and barrel shaped with bipolar plugs

Answer 29

Trichuris trichiura

Question 30

Largest roundworm - Bile stained knobby eggs that cause pneumonitis and may obstruct intestine

Answer 30

Ascaris lumbricoides

Question 31

Visceral Larva Migrans - larvae are confused by different host, wander around aimlessly until they die and cause inflammation, caused by handling pets

Answer 31

Toxocara canis or cati

Question 32

Most frequent helminth parasite in US vs worldwide?

Answer 32

US - Enterobius vermicularis (pinworm)

Worldwide - Ascaris lumbricoides

Question 33

Hookworm - New world, associated with pneumonitis and anemia, larva penetrates intact skin of bare feet

Answer 33

Necator americanus

Question 34

Cutaneous Larva Migrans - intense itching, tunnels through skin, can’t mature in humans

Answer 34

Ancylostoma braziliense or caninum (dog and cat hookworms)

Question 35

Threadworm - can cause chronic disease due to autoinfection, pneumonitis and diarrhea eventually lead to malabsorption and ulcers

Answer 35

Strongyloides stercoralis

Question 36

Associated with hunting bear and presents as fever, myalgias, splinter hemorrhages, and eosinophilia

Answer 36

Trichinella spiralis

Question 37

Mosquito vector causing elephantiasis

Answer 37

Wucheria bancrofti

Question 38

Mango fly vector causing itching and swelling in eye - does not progress to blindness

Answer 38

Loa loa

Question 39

Black fly vector causing itchy leopard rash, nodules, and progresses to blindness

Answer 39

Onchocerca volvulus

Question 40

Guinea worm that erupts from skin and needs very slow removal to avoid breaking it and inducing anaphylaxis

Answer 40

Dracunculus medinensis