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HDID Block 2 > Protozoan parasites > Flashcards

Protozoan parasites Flashcards

1
Q

The definitive host of Toxoplasma gondii is __

A

Cat

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2
Q

The __ form of toxoplasma gondii is excreted in feces; infective stage (takes a day or so for it to actually become infectious)

Which form lives in tissue cysts? Which form is slow growing vs fast growing?

A

Tissue cysts: contain bradyzoites >> slow growing form

Tachyzoites: fast growing and replicative form (invades cells and get transformed to become tissue cysts)

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3
Q

How is toxoplasma transmitted?

A

Transmission:

Ococysts: contaminated food/water, cat litter

Tissue cysts: present in undercooked meat (pork, lamb)

Tachyzoites: transplacentally, organ transplant, blood transfusion

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4
Q

Which toxoplasma form is responsible for acute toxoplasmosis?

Which form is responsible for chronic infection?

A

Acute: mediated by tachyzoites. Infection = generally subclinical, can cause chorioretinitis if severe (rare)

Chronic: mediated by tissue cysts aka bradyzoites. Infection = mainly asymptomatic (these things activate the imune response which keeps infection at a low level, but can also cause reactivation)

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5
Q

How does a baby get congenital toxoplasmosis?

A

Congenital toxoplasmosis:

Result of acute maternal infection **during** first part of pregnancy (the earlier along the pregnancy that mom gets infected, the worse the outcome. Can result in a bunch of things going wrong later in life, including ocular toxoplasmosis)

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6
Q

What immunodeficiency state/disease is toxoplasmosis closely ass’d with? (hint: itsthe same one TB is ass’d with)

A

HIV

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7
Q

How do you diagnose toxoplasmosis acute/chronic/congenital infection? (hint: 2 antibodies measured)

A

Dx: IgM and IgG titers (see below for specifics)

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8
Q

3 things that make up presumptive Dx of toxoplasmosis

A

History

Presence of hypodense lesions enhancing with contrast on CT/MRI

+ve antibody test for toxoplasmosis

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9
Q

How do you confirm Dx of toxoplasmosis?

A

Dx confirmation:

If patient is improving upon therapy

CSF culture/staining + PCR based assay

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10
Q

Rx for toxoplasmosis

A

Rx for toxoplasmosis:

Pyrimethamine + sulfadiazine + Leukovorin (folic acid suppl)

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11
Q

Rx for toxoplasmosis in pregnancy

A

Rx for toxoplasmosis in pregnancy:

If infection suspected, start spiromycin

Confirm infection using amniotic +/- fetal blood sample PCR

  • infected fetus, continue spiromycin until delivery; + infected fetus, terminate pregaz or use triple therapy (pyrimethamine, sulfadiazine, leucovorin)
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12
Q

Which drug is used for maintenance therapy for toxoplasmosis prevention in HIV patients

A

TMP/SMX

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13
Q

___ causes Chagas disease and is transmitted by ___

A

Trypanosoma cruzi causes Chagas disease and is transmitted by triatomine bugs

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14
Q

Describe the lifecycle of trypanosoma cruzi

A

Triatomine blood meal >> bugs inside triatomine feces >> host scratches bite site >> bug entry into host cells > invasion of muscle tissue >> differentiation into amastigotes >> replication and exit as trypomastigotes >> invasion of other cells

Transmission of Trypanosoma cruzi: triatomine bug takes a blood meal and then defecates. The parasite is inside the feces and when the human host scratches the bite site, the feces make their way into the host and invade muscle cells (smooth or cardiac muscle.

Inside the muscle, the bug differentiates into an amastigote which multiples within the cell then releases more bugs (now trypomastigotes that invade other cells)

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15
Q

Presentation and Dx of acute Chagas disease

A

Acute Chagas disease: presents with non specific symptoms/symptoms mimicking mononucleosis

Dx: blood smear and Giemsa stain

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16
Q

2 issues caused by chronic Chagas disease are __(hint: one of them involves your favorite organ!)

A

Cardiac disease

GI issues

17
Q

Chronic Chagas cardiomyopathy can cause what syndromes of heart disease?

A

Congestive heart failure

Arrhythmias

Complete heart block

Sudden death

Thromboembolism

18
Q

GI disease caused by chronic Chagas disease can manifest as ___ and ___ (hint: they’re both megas)

A

Megaesophagus and megacolon

19
Q

Dx of Chagas disease (non-chronic)

A

Blood smear +/- wet mount

Serology

20
Q

Dx of Chagas disease (chronic infection)

A

Serology

Parasite isolation from blood culture or xenodiagnosis

PCR

Imaging/ECG/ +/- GI studies

21
Q

Rx for Chagas disease (2 drugs)

A

NiFURtimox (like fur, you know, the kind that people wear)

BENZnidazole (like a mercedes benz)

22
Q

Leishmania spp cause __ and are transmitted by ___

A

Leishmania spp cause Leishmaniasis and are transmitted by phlebotomine sand flies

23
Q

Name the 3 kinds of Leishmaniasis that exist

A

Cutaneous

Mucosal

Visceral

24
Q

Describe the Leishmania life cycle

A

Leishmania infect host macrophages >> transformation into amastigotes >> replication and spread to other macrophages

**note that the promastigote stage is inside the sand fly

25
Q

How is leishmanisis controlled by the immune system? (which cytokines are released?)

A

Interferon-g, IL-12, IL-1, TNF-a

26
Q

List the type of immune response (humoral/visceral) seen in each type of leishmaniasis

A

Full blown visceral disease (symptomatic): (ineffective) humoral response

Visceral subclinical/treated: + cellular (some humoral)

Cutaneous: mostly cellular

Mucosal: Mostly cellular

(see below)

27
Q

Visceral leishmaniasis is characterized by __ and __

A

Visceral leishmaniasis: characterized by hepatosplenomegaly and infected macrophages

28
Q

Visceral leishmaniasis is caused by ___

A

Visceral leishmaniasis is caused by Leishmania donovani

29
Q

Mucosal leishmaniasis is mediated by ___ and is caused by which spp of Leishmania?

A

Mucosal leishmaniasis is mediated by a dysregulation of the immune response to infection

L braziliensis

30
Q

Disseminated cutaneous Leishmaniasis: due to __

Which spp of Leishmanisis causes disseminated cutaneous Leishmaniasis?

A

Disseminated cutaneous Leishmaniasis: due to lack of cell mediated response

L. amazonensis, mexicana

31
Q

What disease process is this and which bug causes it?

A

Cutaneous leishmaniasis (sand fly bites host and leaves area of central necrosis with infected macrophages)

Caused by L amazonensis or mexicana

32
Q

Cutaneous leishmanaisis in the Middle East and Africa are is caused by which Leishmania spp?

A

L tropica and L major (zoonotic)

33
Q

Ways to Dx visceral leishmaniasis (3)

A

Bone marrow culture/smear

Serology

Leishmanin skin test (starts out -ve but becomes +ve w/ treatment)

34
Q

Ways to Dx cutaneous leishmaniasis (4)

A

Biopsy

Serology

Leishmanin skin test

Speciation

35
Q

Rx for Leishmaniasis (which 2 drugs are used in the US and which one is used elsewhere in the world?)

A

Liposomal amphotericin B

Miltefosine

(not in US): pentavalent antimony

HDID Block 2 (28 decks)

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