Lecture 71 - Leishmaniasis, Toxoplasmosis, and Trypanosomiasis Flashcards
toxoplasma Gondii
- what kind of parasite is it?
- what is the definitive host?
-
Single celled protozoa
Cats are the definitive host
what are the forms of the Toxoplamsma Gondii?
- which are infective?
- which are diagnositic?
- describe the transmission?
Oocysts — infective form which is excreted in feces; fecal oral transmission; contaminated soil, vegetables, water, cat litter
Tissue Cysts – infective form which forms intracellularly in muscle and brain. Can be acquired from eating undercooked pork, lamb
Tachyzoites – the diagnostic stage–localized in brain and muscle tissue. Develop into tissue cyst bradyzoites. Can be transmitted transplacentally, blood tranfusions
What are the different disease forms of Toxoplasmosis
Acute Acquired Toxoplasmosis (tachyzoites)
chronic toxoplasmosis – (Bradyzoites)
Reactivated infections
Congenital Toxoplasmosis
Ocular Toxoplasmosis
Compare acute vs chronic toxoplasmosis
Acute – Tachyzoites infection
Usually subclinical – asymptomatic
may present with LAD, myalgias
Symptoms more common in immunocompromised
Disease is contained by Th1 response; leads to chronic cystic state
Chronic state – Bradyzoites:
Asymptomatic, lifelong infection
Cysts form in brain and neural tissue
source of reactivation
Congential Toxoplasmosis
- when would a child become infected?
- -what are the outcomes of severe infection?
- -outcomes for most infants?
Child infected if the mother becomes infected during gestation
Severe infection – miscarriage, neurological disease, ocular disease, generalized illness (HSM, LAD, Fever)
most – asymptomatic at birth but can have manifestations of occular or cerebral disease later in life
Occular Toxoplasmosis
- peak age of incidence
- symptoms and manifesations
Peak age of incidce – 20s, 30s from post acute or reactivated disease
Focal necrotizing retinitis; granulomatous inflammation, blurred vision.
Focal scarring can lead to permanent vision loss
Other manifestations of toxoplasmosis, for example in the immunocompromised
The disease can remain latent.
Tropism for brain and muscle tissue
Can manifest as cerebral disease, such as encephalaitis
Some association with schizophrenia
Diagnosis of Toxoplasmosis:
- Serologic: acute, chronic inactive, immunodeficient active
- what do you do for cerebral toxoplasmosis?
Serologic Profiles;
Acute – IgM + rising IgG
Chronic inactive – no IgM, + IgG
immunodef active – no IgM, +IgG
Other: Cerebral toxoplasmosis
- Imaging, brain bx
Treatment of Toxoplasmosis:
what is the treatment regimen for toxo during pregnancy
Regimen: Pyrimethamine + Sulfadiazine
(Leukovorin is always given with pyrimethamine)
Pregnancy:
Spiramycine
If Fetus infected:
terminate pregnancy or treat with Pyrimethamine + Sulfadiazine + leucovorin
Prevention of toxoplasmosis
Focus on women of child-bearing age and immunocompromised persons
Proper handling of cat liter
Wash hands when handling meat
Chagas Disease -- what is the bug? what is the vector? what is the technical term for the infection? Where does it most commonly occur?
Bug: Trypanosoma Cruzi
Vector: Triatomine bugs
Name: American Trypanosomiasis
Epi: Mostly in Latin America. Major cause of cardiac disease and mortality
Most cases in the US are from infected immigrant populations
Describe the lifecycle of the Trypanosoma cruiz? How does it infected humans ?
The parasite resides in the Gut of the Triatomine vector
Bug takes a blood meal, and defecates out Trypomastigotes on human hosts
Auto-innoculation; rub the feces in eye or wound. Trypomastigoes enters muscle, cardiac or smooth muscle
Differentiates into Amastigotes
Replication leading to rupture of the cell and differentiates back to trypomastigoes
Spreads throughout the blood stream.
Taken up in another blood meal
How is trypanosoma transmitted ?
Vector Born –
Trans placental
Ingestion – rare (eg bugs on fruit)
Describe the acute vs chronic phases of trypanosomiasis?
- symptoms and manifestations
Acute: 1-2 months following transmission
Fever, mononucleosis
High levels of parasitemia
Symptomatic < 1%
May lead to acute myocarditis; meningoencephalalitis
Chronic –
Few parasites in the blood
descrtruction of cardiac myocytes; replaced by fibrotic tissue; leading to CHF, arrythmias, complete heart block and thrombo-embolism
the disease is life long and may reactive when immunosuppressed
What are the manifestations of trypanosomiasis?
- cardiac
- Gi
acute myocarditis
CHF, arrhythmias, complete heart block, thromboembolism
Gi - mega colon, mega esophagus
Diagnosis of Trypanosomiasis
acute vs chronic
Acute –
Mircosopy – visualization of purple crescent parasites in the blood
Serology – IgMs
Chronic –
Serology – IgGs
ELISA, IFA
EKG changes, CXR
Treatment of Trypanosomiasis
acute, congenital and reactive vs chronic
Treatment for acute, congenital, reactivated infection: Nifurtimox Benznidazole
Chronic: Symptomatic treatment, pacemakers, cardiac therapy; Transplant; surgery for GI disease
Leishmaniasis –
what causes the disease?
what is the vector?
what are three categories of disease?
Protozoan Parasite —
Genus – Leishmania
Many different species
Vector: Sandfly
Disease:
Cutanenous – skin
Mucosal – skin and nasopharynx
Visceral – Entire Reticuloendothelial system
Describe the life-cycle of Leishmania
Sandfly takes blood meal and injects promastigotes
Promastigotes phagocytized by macrophages
Transform to amastigotes and begin to replicate
Rupture of macrophage and mastigotes begin to spread
and infect other macrophages
Sandfly takes another blood meal ingesting a macrophage infected with amastigoes
differentiate back into promastigotes
How is the disease controlled in most immuno competent persons?
what are the immunity profiles for persons with mucosal vs cutaneous vs visceral disease?
Control:
Cellular response is necessary for control of disease:
- Activated macrophages, IFN gamma, IL-12, TNF Alpha
Viseral Disease: lack cellular response
Visceral Leishmanisasis:
- what tissues/cells are infected?
- what is full blown disease called?
- ## what are the manifestations?
Tissues: Reticulo endotheial system (macrophages) of the skin, liver, spleen and bone marrow
Kala-azar
Signs and symptoms: Hepatosplenomegaly, fatigue, fever, anemia
Can lead to bleeding, CHF
Persons die of infections
- What species cause the Visceral leishmaniasis disease ?
- risk factors for the disease?
zoonotic Species:
L chagasi
L Infantum
Anthroponotic:
L. donovani
Risk factors:
Poverty, malnutrition, HIV co-infection
Refugee populations
Cutaneous Leishmaniasis:
what are the old world parasites:
what are the new world parasites:
what is the manifestation?
Old world: Zoonotic and Anthroponotic
L. Tropica, major, infantum
New world: L brazileinses (same as mucosal)
Manifest: single cutaneous lesion
painless unless infected with bacteria
contracted by many soldiers in Operation Desert Storm (L. tropica)
Mucosal Leishamaniasis
- what is the causative species?
- what is the reason for the disease?
Manifestations?
late manifestations?
Disease of hyper-reactivity of the immune system (DTH)
Over-reactive response that doesn’t kill the parasites
Nearly all. L braziliensis
Treatment is difficult
Cutaneous ulcer
lesions of nasopharynx
can lead to gross mutilation of the nose and palate
Disseminated cutaneous leishmaniasis disease:
What bugs?
why not localized disease?
L amazoenensis
L mexicana
Failure of cell mediated immunity results in lepromatous like nodular lesions over body and face; very chronic; resistant to treatment.
Methods for Diagnosis of leishmaniasis
What are the tests and results for cutaneous vs visceral disease ?
Methods:
Giemsa smear and Stain
Leishmania Skin Test (similar to PPD, looking for DTH)
Serology
ELISA and PCR for species identification
Cutaneous disease:
Serology Negative
Skin test positive
Visceral –
Skin test negative with active infection
Test positive after treatment
Serology – postive with active disease
Treatment of Leishmaniasis:
cutaneous vs visceral
Side effects
alternatives?
Prevention?
Cutaneous:
Pentavalent antimonials
Side effects: myalgias, N, V, D, abd
Rare – pancreatitis
Visceral: Lipo AmphoB
alternative –
Paramomycin
Prevention: bug spray; long sleeve shirts and pants
