Parasitic protozoa II - Tissue + blood

Question 1

Triad of chorioretinitis, hydrocephalus, intracranial calcifications

Answer 1

Toxoplasma gondii

Question 2

Widespread infxn that causes flu-like symptoms and then typically bcomes dormant
- can be reactivated if immunocompromised

Answer 2

toxoplasmosis

Question 3

Toxoplasma gondii

• intra or extracellular?
• infects what?

Answer 3

Intracellular parasite that can infect any cell

Question 4

How are toxplasma gondii transmitted?

Answer 4

fecal oocysts

–> cysts multiply in muscles (raw meat)

Question 5

If maternal of toxoplasmosis infection occurs during 1st trimester, incidence of fetal infxn?

Answer 5

15%, but disease in neonate is most severe

Question 6

If maternal infection of toxoplasmosis occurs during 3rd trimester, incidence of fetal infxn?

Answer 6

65%

Neonate is usually asymptomatic at birth but may have more learning disabilities and neurological sequelae

Question 7

If maternal infxn of toxoplasmosis occurs how many mo b4 conception, risk of fetal infxn increases as mother may not have developed enough immunity.

Answer 7

less than 6 mo

Question 8

Toxoplasmosis

• dividing form
• dormant form

Answer 8

• dividing form: tachyzoites

- dormant form: bradyzoites

Question 9

How does the triatomine bug (reduviid bug) infect you with trypanosoma cruzi?

Answer 9

It bites and takes blood meal form you –>
it poos on you –>
you scratch it –>
it gets into blood

Question 10

Chagas disease

Answer 10

1. dilated cardiomyopathy
2. Atypical atrophy
3. Megacolon
4. megaesophagus
5. Unilateral periorbital edema (romana sign)

Question 11

Leishmaniasis

• Intra or extracelluar
• INfects what cells?
• transmission?

Answer 11

Intracellular parasite of macrophages

Bite of infected sand flies

Question 12

Visceral leishmaniasis

Answer 12

Spiking fevers
Hepatosplenomegaly
Pancytopenia

Question 13

Trypanosoma brucei

• causes what disease?
• transmission?

Answer 13

African sleeping sickness

Tsetse fly

Question 14

How to dx:
Toxoplasma gondii
Naegleria fowleri
Trypanosoma brucei

Answer 14

Toxoplasma gondii- serology, biopsy (tachyzoites)

Naegleria fowleri
- Amoebas in spinal fluid

Trypanosoma brucei
- blood smear

Question 15

Malaria (P. vivax) sx

Answer 15

fever, HA, anemia (really bad in preggos), splenomegaly

Paroxysms:
fever on 1st day and 3rd day (48 hrs apart)
- cold, then hot, then sweating phase

Question 16

Which plasmodium species have paroxysmal attacks occuring every 2nd day? 3rd day?

Answer 16

2nd: falciparum, vivax, ovale

3rd:
malariae

Question 17

People negative for Duffy blood group (protein)

Answer 17

resistant to infxn by P vivax

*so are heterozygotes for sickle cell

Question 18

Dx babesia

Answer 18

Blood smear

Maltese cross

Serology, PCR

Question 19

Life cycle and pathogenesis of Toxoplasma gondii

Answer 19

Ingest bradyzoites in cysts
(undercooked, inadequately frozen meat)
Or
Ingest oocysts (in food contaminated with cat feces) -->
Oocyst transform into tachyzoites -->
localize in neural and muscle tissue -->
develop into tissue cyst bradyzoites

Question 20

Most common protozoan infxn in US

Answer 20

T. gondii

Question 21

Life cycle and Pathogenesis of Trypanosoma cruzi (Chagas disease)

Answer 21

Triatomine (reduviid) bug takes blood meal from hu –>
releases trypomastigotes in feces near site of bite wound –>
Trypomastigotes enter host thru wound or thru intact mucosal membrane (conjunctiva) –>
Invade host IN cells near the site of inoculation –>
Trypomastigotes differentiate into intracellular Amastigotes –>
Amastigotes multiply by binary fission –>
differentiate into extracellular Trypomastigotes –>
Release into blood stream –>
Cycle betwn Trypomastigotes and Amastigotes (clinical manifestations) –>
Kissing bug feeds on infected human or animal blood containing circulating parasite –>
Ingested Trypomastigotes transform into Epimastigotes in vector’s midgut –>
Multiply and
differentiate into infective Trypomastigotes in hindgut

Question 22

Life cycle and pathogenesis of Leishmania donovani

Answer 22

Female sandfly bite hu –>
Inject the promastigotes (infective stage) –>
Phagocytized by macrophages –>
Promastigotes transform into amastigotes (tissue stage) –>
Multiply by simple division –>
Infect other mononuclear phagocytic cells –>
Sandflies ingest infected cells during blood meals –>
In sandflies, Amastigotes transform into Promastigotes

Question 23

Life cycle and pathogenesis of Trypanosoma brucei

Answer 23

Tsetse fly painfully bites hu –>
Injects metacyclic trypomastigotes into skin –>
Enters lymphatic system and pass into bloodstream –>
Transform into bloodstream trypomastigotes –>
carried throughout body and reach other body fluids (lymph, spinal fluid) –>
replicate by binary fission

Question 24

Life cycle and pathogenesis of PLasmodium spp.

Answer 24

Anopheles mosquito inoculates hu host w/ sporozoites –>
Infect liver cells –>
Mature into schizonts –> Schizonts rupture and release merozoites –>
Merozoites infect RBC –>
Becomes immature trophozoite (ring stage) –>
mature into RBC shizonts –>
Rupture and release merozoites –>
Some differentiate into sexual erythrocytic stages (gametocytes of Plasmodium) –>
Blood stage parasites = clinical manifestations –>
Ingested by anopheles mosquito –>
multiply inside via sporogonic cycle

Question 25

Most severe plasmodium spp?

Answer 25

P. falciparum

- can invade RBCs of all ages