Protozoans

Question 1

These amoebic protozoans are found worldwide. They are transmitted through fecally contaminated water, poor sanitation, flies, oral-anal sex practices via ingestion of cysts which germinate in the duodenum and attack intestinal mucosa and invade organs (esp liver). THEY ARE ID’D BY INGESTED RBCs!

Answer 1

Entamoeba histolytica, E. dispar, and E. coli

Question 2

What disease do Entamoeba histolytica, E. disbar, and E. coli cause?

Answer 2

intestinal amebiasis - abdominal pain, colitis, bloody stools

Question 3

These amoebic protozoans are free-living in soil and contaminated warm water; infections follow swimming, or inhalation of cysts in dust; eye infections occur after using non-sterile fluids to was contact lenses. They are ID’d by finding trophs in sterile fluids, corneal scrapings, and can be cultured with e. coli.

Answer 3

Naegleria fowleri and Acanthamoeba sp.

Question 4

What disease do Naegleria fowleri and Acanthamoeba sp. cause?

Answer 4

1. Granulomatous amebic encephalitis (Acanthamoeba)
2. Keratitis which can lead to CNS involvement (Acanthamoeba)
3. Meningoencephalitis - fatal in 7-10 days (Naegleria)

Question 5

This flagellated protozoan is found worldwide. Its reservoir is beavers and muskrats. Infection follows 9-15 d after ingestion of 10-25 cysts from fecally contaminated water. It is the most common cause of waterborne diarrhea in the US. Classic example of this is people who go camping and drink river water. It is ID’d by a FACE-LIKE APPEARANCE OF TROPHOZOITES

Answer 5

Giardia lamblia

Question 6

What diseases does Giardia lamblia cause?

Answer 6

1. Giardiasis - non-invasive disease of upper intestine

2. Mild diarrhea to malabsorption syndrom - foul smelling, fatty shits

Question 7

This flagellated protozoan is found worldwide. Its trophozoites may possibly be transmitted in pinworm eggs or fecal/oral and anal/oral. There is no known cyst stage - absence of cysts and small size is how it’s ID’d

Answer 7

Dientamoeba fragilis

Question 8

What disease does Dientamoeba fragilis cause?

Answer 8

asymptomatic to intermediate diarrhea

Question 9

This flagellated protozoan is found worldwide. It has no cyst stage. Its trophozoites are transmitted sexually; men are the reservoir. It is ID’d by smears of discharge with trophozoites; immunofluorescence.

Answer 9

Trichomonas vaginalis

Question 10

What disease does Trichomonas vaginalis cause?

Answer 10

1. asymptomatic disease - for most females and nearly all males
2. vaginitis - burning, itching, frothy green maldorous discharge, strawberry cervix, urethritis, cystitis
3. prostatitis

Question 11

These flagellated protozoans are hemoflagellates, classically seen in the middle east but also found in asia, africa, europe, and south america. They are transmitted to humans via sand-fly bite. Their reservoir is rodents, dogs, foxes, cats, etc. They infect by losing their flagella to invade reticuloendothelial tissues and then reproduce causing tissue damage. They are ID’d by tissue samples with cells filled with amastigotes

Answer 11

Leishmania donovani, L. topica, L. brazilienis

Question 12

What diseases do Leishmania donovani, L. topica, L. brazilienis cause?

Answer 12

Leishmania donovani: Visceral leishmaniasis - fever, diarrhea; liver, spleen, kidney damage, fatal after 2 years w/o treatment

L. topica: Cutaneous leishmaniasis - disfiguring scars in skin at site of bite

L. brazilienis: Mucocutaneous leishmaniasis - ulcers -> scarring and disfigurement and eventually death by asphyxiation

Question 13

These flagellated protozoans are found in Africa; their reservoir is humans and animals and are transmitted by Tsetse fly bite; trypomastigote in saliva enters blood and eventually CNS. They are ID’d by thick and thin blood smears that show trypomastigotes.

Answer 13

Trypanosoma brucei gambiense and T. b. rhodesiense

Question 14

What disease do Trypanosoma brucei gambiense and T. b. rhodesiense cause?

Answer 14

African Sleeping Sickness - neurological damage, ultimately fatal disease; winterbottom’s sign = cervical lymphadenopathy

Question 15

This flagellated protozoan is confined to North (Texas and CA) and South America (Brazil); its transmitted via the kissing bug which bites around the mouth. The infection is spread by the bug pooping in the bite - when the human scratches it, the infection gets to the bloodstream where it travels to the heart, liver, or brain

Answer 15

Trypanosoma cruzi

Question 16

What disease does Trypanosoma cruzi cause?

Answer 16

1. asymptomatic disease
2. acute (pediatric) and chronic (adults) form of Chaga’s disease - often fatal due to widespread tissue damage, especially in the heart

Question 17

This ciliated protozoan is found worldwide. Its reservoirs are swine and monkeys; fecal-oral transmission involving contaminated water and food handlers. It’s ID’d by fecal smears w/ ciliated trophs

Answer 17

Balantidium coli

Question 18

What disease does Balantidium coli cause?

Answer 18

1. asymptomatic carriage in pig handlers

2. diarrhea - watery, tenesmus, blood and pus, intestinal ulceration

Question 19

In regards to malaria (Plasmodium), what type are duffy individuals resistant to? SCD patients?

Answer 19

duffy: P. vivax
SCD: P. falciparum

Question 20

What are the symptoms of malaria?

Answer 20

fever, chills, rigors, vomiting, diarrhea; anemia, organ damage

Question 21

Which type of malaria is the fulminating disease?

Answer 21

P. falciparum - sticky RBCs and fragments clog capillaries - tissue damage; blackwater fever

Question 22

How are P. vivax and P. ovale ID’d?

Answer 22

enlarged RBCs with Scuffner’s dots, round gametocytes

Question 23

How is P. malariae ID’d?

Answer 23

normal sized RBCs, fewer merozoites, Ziemann’s dots

Question 24

How is P. falciparum ID’d?

Answer 24

multiple ring forms in “applique” position, Maurer’s dots, sausage-shaped gametocytes

Question 25

This sporozoan is widely distributed on the east and west coasts. It is transmitted via Ixodes bite. Its reservoir is deer, cattle, and rodents. Trophozoites invade fresh RBCs; people with Lyme disease tend to carry antibodies against it. It’s ID’d by thick and thin blood smears showing ring forms resembling P. falciparum

Answer 25

Babesia microti

Question 26

What disease does Babesia microti cause?

Answer 26

1. asymptomatic most common

2. mild malaria without periodicity

Question 27

This sporozoan is found worldwide. Its reservoir is birds and animals, especially cats (definitive host); ingestion of oocysts in cat feces or from undercooked pork causes infection. It’s ID’d by cysts in tissue samples, CSF, and amniotic fluid.

Answer 27

Toxoplasma gondi

Question 28

What diseases does Toxoplasma gondi cause?

Answer 28

1. mononucleosis - like disease
2. congenital disease - presence of calcified cysts in CNS and eye
3. AIDS-associated encephalitis

Question 29

This sporozoan is found worldwide; transmitted fecal-oral; vegetarians are at high risk

Answer 29

Cryptosporidium

Question 30

This sporozoan is an obligate intracellular parasite whose infection is caused by ingestion of spores. It causes chronic diarrhea in AIDS patients and is ID’d by spores in gram stain of intestinal tissues, urine, and CSF

Answer 30

Microspora, Microsporidia