Leishmaniasis / Toxoplasmosis / Trypanosomiasis

Question 1

What is the definitive host of Toxoplasma gondii?

Answer 1

Cats

Question 2

How long is someone infected with Toxoplasma gondii?

Answer 2

Lifelong

Question 3

Who will present with Toxoplasma gondii infection?

Answer 3

Most people are asymptomatic

Disease manifests in immunocompromised or neonates infected in utero

Question 4

What are the 3 stages of the life cycle of Toxoplasma gondii?

Answer 4

Oocysts - excreted in feces of cats (definitive host)
Tissue cysts - intracellularly in muscle of intermediate hosts
Tachyzoites - replicate within cells

Question 5

What are modes of transmission of toxoplasmosis?

Answer 5

Oocysts - soil, cat litter
Tissue cysts - undercooked meat (espec pork and lamb)
Tachyzoites - transplacentally, transplant, transfusion

Question 6

In what environment is toxoplasmosis common?

Answer 6

Places where meat is undercooked (steak tartar, pork)

Question 7

How does toxoplasmosis present in healthy host?

Answer 7

Acute infection - tachyzoites
- Usually asymptomatic, occasionally lymphadenopathy

Chronic infection - tissue cysts
- Asymptomatic, lifelong

Question 8

How does toxoplasmosis present in immunocompromised host?

Answer 8

Usually reactivated infection
Cerebral infection (lesions) more common than cardiac or pulmonary

Question 9

How does toxoplasmosis present in pregnancy?

Answer 9

Maternal infection early in pregnancy can cause miscarriage, abortion, severe neurological or ocular disease, generalized illness

Most congenitally infected infants are asymptomatic at birth but high risk for sequelae later in life

Question 10

What is the presentation of ocular toxoplasmosis?

Answer 10

Common sequela of congenital toxoplasmosis

Focal necrotizing retinitis
Granulomatous inflammation of choroid
Blurred vision, pain
Focal scars with permanent loss of vision

Question 11

How is toxoplasmosis diagnosed?

Answer 11

Serology
Appearance of lesions on MRI or CT
Atypical: brain biopsy

Question 12

What is the treatment of choice for toxoplasmosis?

Answer 12

Pyrimethamine + sulfadiazine

Question 13

How can toxoplasmosis be managed in pregnancy?

Answer 13

Spiramycin

Question 14

How can toxoplasmosis be prevented?

Answer 14

Get rid of cat or change litter better

For HIV-infected <200 CD4 - TMP-SMX preventive therapy

Question 15

What is the agent of Chagas disease?

Answer 15

Trypanosoma cruzi

Question 16

What is the vector of Chagas disease?

Answer 16

Riduviid bugs

Question 17

How is Chagas disease transmitted?

Answer 17

Vector borne - riduviid bug takes blood meal and defecates, rub feces into bite wound
Transplacental, transfusion, transplantation
Oral (unusual)

Question 18

What is the life cycle of Trypanosoma cruzi?

Answer 18

Riduviid bug takes blood meal and defecates
Rub bite and innoculate parasite into wound
Goes through circulation to muscle, tryptomastigotes invade cells
Differentiates into amastigote and replicates
Amastigotes become trypomastigotes and rupture cell, enter blood stream

Question 19

What is the clinical presentation of acute T. cruzi infection (acute Chagas disease)?

Answer 19

Usually asymptomatic
Mononucleosis-like febrile illness
Rarely - acute myocarditis (see amastigotes in cardiac myocytes), meningoencephalitis

Question 20

What is the clinical presentation of chronic T. cruzi infection (chronic Chagas disease)?

Answer 20

Usually asymptomatic
Cardiomyopathy (destruction of cardiomyocytes and replaced with fibrotic tissue) - can get arrhythmias and complete heart block
GI disease - megaesophagus, megacolon

Question 21

How is Chagas disease diagnosed?

Answer 21

Direct visualization of parasites in blood

Serology (IgG for chronic/past infection, IgM suggests acute)

Question 22

What is the treatment for Chagas disease?

Answer 22

Nifurtimox

Benznidazole

Question 23

What is the vector for Leishmania?

Answer 23

Sand fly

Question 24

What is the life cycle of Leishmania?

Answer 24

Sand fly takes blood meal, innoculates parasite into skin
Promastigote stage ingested by macrophage
Multiplies and transforms into amastigotes inside macrophages
Sand fly takes another blood meal and ingests macrophages containing amastigotes

Question 25

What immune response is required to control Leishmaniasis?

Answer 25

Cellular

Question 26

What immune response dominates in visceral leishmaniasis?

Answer 26

Only humoral, no cellular (cannot control parasite well with just antibodies)

Question 27

What immune response dominates in treated visceral, cutaneous, or mucosal leishmaniasis?

Answer 27

Cellular

Question 28

What is the clinical presentation of visceral leishmaniasis (kala-azar)?

Answer 28

Hepatosplenomegaly (parasites in macrophages, macrophages building up)
Spiking fevers

Question 29

What is the clinical presentation of mucosal leishmaniasis?

Answer 29

Almost all Leishmaniasis braziliensis
Lesions on nose
Immunological hyperreactivity but failure to clear parasites

Question 30

What is the clinical presentation of disseminated leishmaniasis?

Answer 30

Lack of immunological reactivity

Get lesions filled with parasites

Question 31

What is the clinical presentation of cutaneous leishmaniasis?

Answer 31

Small lesions on skin

See cells filled with amastigotes on histology

Question 32

How is the diagnosis for visceral Leishmaniasis made?

Answer 32

Smears, cultures, PCR
Serological tests
Leshmanin skin test negative

Question 33

How is the diagnosis for cutaneous Leishmaniasis made?

Answer 33

Smears, cultures, PCR
Sological tests
Leishmanin skin test positive

Question 34

What is the treatment for Leishmaniasis?

Answer 34

Pentavalent antimony - Sodium stibogluconate (but very toxic)
Liposomal ampho B (treatment of choice in US)
Miltefosine (recently approved)