Parasitic Protozoa II

Question 1

Toxoplasmosis

Answer 1

• Caused by toxoplasma gondii
• Widespread infection causing flu-like symptoms
• Reactivated in immunocompromised
• Transplacental transmission leads to serious problems
• Intracellular parasite that can infect any cell

Question 2

Transmission of toxo among animals

Answer 2

• Transmission from contaminating oocysts (cats) - come from birds or rats getting eaten by cats who get the tissue cysts, and then comes out as a fecal oocyst
• Eating improperly cooked meat, transfusions, etc.

Essentially you can either get the tissue cysts or fecal oocysts

Question 3

If someone is seropositive for toxo long before getting pregnant, is the baby at risk for toxo?

Answer 3

No you should have immunity against toxo, and so the baby should be protected.

Question 4

If the maternal infection of toxo is

Answer 4

Probably not, the risk is pretty high

Question 5

If maternal infection of toxo occurs during the first trimester, what disease of the neonate is possible?

Answer 5

• miscarriage
• stillborn
• chorioretinitis, hydrocephalus, intracranial calcifications, hepatosplenomegaly, jaundice, fever, anemia

Question 6

If maternal infection of toxo occurs during 3rd trimester, what might happen?

Answer 6

• baby will be asymptomatic at birth but may have more learning disabilities and neurological sequelae

Question 7

Can you directly identify toxo?

Answer 7

No, it’s pretty difficult. Do serology and PCR

Question 8

Prevention of toxo

Answer 8

• No vaccine
• Change litter daily if you own a cat
• Keep cat indoors
• Dont eat undercooked meat

Question 9

Tachyzoites vs. Bradyyzoites

Answer 9

• Tachy = dividing forms in a cell

- Brady = dormant forms in a cell

Question 10

Chagas disease

Answer 10

• Infection that causes an acute and chronic phase
• Caused by trypanosoma cruzi
• There is a blood and tissue form
• Transmission = via kissing bug bite, congenital, blood transfusion, organ transplant

Question 11

Life cycle of Chcagas

Answer 11

• You or dog is infected
• Bloodstream form gets transmitted to kissing bug
• Kissing bug feeds on human - bites you and then poops so that when it itches and you scratch, you scratch the parasites into the open wound (almost all other vectors use saliva)
• Gets into blood - travels to muscle cells (heart and intestine are its favorites)

Question 12

Acute Chagas presentation

Answer 12

Initially mild symptoms at site of inoculation and in blood phase (often asymptomatic)

Question 13

Chronic Chagas presentation

Answer 13

Asymptomatic tissue phase in most, but 20-30% will develop heart abnormalities and dilated esophagus or colon (die of heart attack)

Question 14

Triatomine

Answer 14

Kissing bug

Question 15

What’s the problem with a serological test for Chagas?

Answer 15

Doesn’t tell you if you are actively infected, or if you have any of the muscle form.

Question 16

Why is chronic Chagas harder to diagnose?

Answer 16

Trypomastigotes are not found in blood and so you have to do a biopsy or some faulty serology

Question 17

How to prevent Chagas

Answer 17

Don’t get bitten and pooped on.

• Feed at night
• Bugs breed in the cracks of poorly constructed homes
• Spray the houses

Question 18

Leishmaniasis

Answer 18

3 types = cutaneous, mucocutaneous, visceral

• caused by Leishmania
• Intracellular parasite of macrophages (phagolysosome is a happy living place for them)
• Transmission: bite from sand flies or cutaneous contact

Question 19

Life cycle of Leishmaniasis

Answer 19

Sand flies bite someone infected –> macrophage bursts and amastigotes transform into promastigotes, and then sand fly bites you and gives you the promastigotes. These go visceral to the spleen or cutaneous

Question 20

Clincal presentation of the forms of Leishmaniasis

Answer 20

1. Cutaneous - skin lesions/ulcers
2. Mucocutaneous - partial or total destruction of mucous membranes of the nose, mouth and throat
3. Visceral - irregular bouts of fever, weight loss, enlargement of spleen and liver

Question 21

Diagnosis of Leishmaniasis

Answer 21

ID of parasites within cells in a biopsy

- rRNA its PCR

Question 22

Best way to prevent leishmaniasis

Answer 22

People should sleep under bed nets, and the bed nets should be impregnated with an insectiscide

Question 23

African sleeping sickness

Answer 23

Trypanosomiasis (tsetse fly vector)

• Hemoflagellate parasites
• Daylight biters, and can fly long ways
• Multiply in blood stream and can eventually enter CNS

Question 24

Presentation of trypanosomiasis

Answer 24

• Wasting with fever, severe headaches, irritability, fatigue, lymph nodes, aching muscles and joints

Question 25

Control of trypanosomiasis

Answer 25

- Reduce the disease reservoir controlling the tsetse fly vector - Treatment

Question 26

Why can't the immune system take out trypanosomiasis?

Answer 26

Because it undergoes antigenic variation - keeps changing its colors. You wipe yourself out trying to chase it, and you end up getting wasting, neurological involvement and eventually coma.

Question 27

Malaria

Answer 27

- Plasmodium infects RBCs | - Most serious parasitic disease (50% of deaths are in children

Question 28

Incubation of malaria

Answer 28

9-14 days

Question 29

Life cycle of malaria

Answer 29

Mosquito has it, goes through the sporogenic cycle - bites a hooman and injects sporozoites - sporozoites go to the liver first -- eventually ruptured schizont gets into human blood and goes through erythrocytic cycle

Question 30

Control of malaria

Answer 30

- bed nets! | - Prophylactic drugs

Question 31

How long does a classical malaria attack last?

Answer 31

6-10 hours - cold stage - hot stage - sweating stage Tertian parasites have attacks every 2nd day Quartan parasites have attacks every 3rd day

Question 32

Malaria pathogenesis

Answer 32

1. Infection and destruction of RBCs 2. Anemia 3. Blockage of blood vessels, particularly in the brain 4. Cytoadherence in P. falciparum - sticky adherence to endothelial cells. Leads to rosetting of RBCs and clumping 5. Rosettes cause clogging and hemorrhaging 6. Cytokine response leads to endothelia getting stickier

Question 33

Malaria diagnosis

Answer 33

1. Symptoms 2. Blood smear (thick or thin) 3. Antigen detection, molecular diagnosis, serology

Question 34

What is sterile immunity?

Answer 34

Once you get infected, you can completely clear the bug

Question 35

Malaria immunity

Answer 35

- No sterile immunity known - Variants and antigenic variation - Ineffective malaria vaccine for now...

Question 36

Control and prevention of malaria

Answer 36

- Mosquito control - Reduce mosquito bites - Prophylactic treatment -- leads to resistance - Treatment -- need new drugs but we're overly reliant on drug treatment

Question 37

What genetic mutation provides resistance for malaria?

Answer 37

Sickle cell trait (heterozygous for abnormal HbS) G6P deficiency Thalassemia

Question 38

What does the duffy blood group have to do with RBC resistance to infection by P. Vivax?

Answer 38

If you are negative for the duffy blood group, then you are protected.

Question 39

Babesiosis

Answer 39

- Infected RBCs by Babesia microti | - Spread by deer ticks or blood transfusion

Question 40

Clinical presentation of babesiosis

Answer 40

- asymptomatic to life threatening - worse in immunocompromised Diagnosis via blood specimens and RBCs