Trypanosomes II Flashcards
What is the “motor’ of trypanosomes?
Kinetoplasts
- Contain DNA organized into minicircles and maxicircles
- -> similar to mitochondrial DNA
What causes Human African Trypanosomiasis (HAT)?
T.b. gamiense
Palpalla group is vector
T.b. rhodesiense
Morsitans group is vector
Tsetse fly is vector (subdivided into groups)
Incidence of sleeping sickness is increasing
**East African Disease ismuch more aggressive, much more “mortal“ = mortisans groups**
What is the pathogenesis of HAT?
Infected Tsetse fly bites: metacyclic trypomastigotes are injected
–> chancre occurs at innoculation site –> haemo-lymphatic stage occurs
–> spreads and meningo-encephalitic stage occurs
What are symptoms of the haemo-lymphatic stage of HAT?
fever
pruritus
headaches
muscular pain
Winterbottom’s sign: posterior cervical adenopathy
Diagnosed by puncture of cervical node looking for trypanosomes (low sensitivity)
How is meningo-encephalitic stage (stage 2) of HAT diagnosed?
LP done to determine stage of infection (+LP = stage 2)
- however, negative result doesn’t rule out HAT
Mott cells, large, eosinophilic plasma cells containing IgM that failed to secrete, is characteristic
Other CSF findings include:
elevated WBC count
elevated IgM levels
elevated TP levels
elevated intracranial pressure
What are symptoms of HAT?
Acute: Nodule (chancre) forms at bite site
fever and enlarged lymphoh nodes occur w/in 2-3 wks
sometimes rash
Subacute: (Rhodesian, East Africa): CNS invasian w/in 3-6 wks
Myocarditis
Death in 6-9 months
Chronic: (Gambian, West Africa): CNS invasion months-yrs later
Gradual onset of meningo-encephalitis
behavior change
vacant expression
inanition (lack of mental vigor)
psychosis
paralysis
seizures
coma, death
How is HAT diagnosed?
- *Giemsa-stained blood smears for Stage 1**
- antigenic variation causes periodic absence of trypanosomes in periphery
- LN aspirate may be helpful
- *LP for Stage 2**
- Tryp. hard to find
Card Agglutination Trypanosomiasis Test (CATT)
for T. b. gamiense
What is the treatment for HAT?
**Stage 1:** Pentamidine IM (gambiense) Suramin IM (rhodesiense)
**Stage 2:** Melarsoprol IV (both gam. and rhod.) Eflornithine IV (gamb.) Nifurtimox (used to avoid arsenic melarsoprol)
What are major side effects of Melarsoprol?
Tx for Stage 2 HAT
Painful injection
Encephalopathy
Cardiac toxicity
Peripheral neuropathy
Death
How is Chaga’s disease transmitted?
- *Trypanosome cruzi** is transmitted by triatoma infestans and Rhodinius prolixus (“kissing bug” or “assassin bug”)
- -> but poops when it bites and human scratches parasite into the wound
Nonvector transmission:
Blood transfusion
Vertical transmission (mother –> baby)
Organ transplant
Foodborne transmission (sugar cane juice, juiced with infected bug vector)
What are symptoms of the acute phase of Chagas disease?
Romania’s sign - unilateral, painles, periorbital edema
Chagoma: indurated lesion at site of parasite entry
What are symptoms of congenital Chagas disease?
Severe respiratory distress
meningoencephalitis
hepatosplenomegaly
myocarditis
What is the evolution of chagas diseaes?
Acute phase
–> goes to:
Subacute form
Death
or
Chronic phase (initial indeterminate form)
–> goes to
Permanent indeterminate form
Digestive form
or
Chronic Cardiac form
–> goes to
Mild cardiopathy (can lead to serious cardiopathy)
or Serious cardiopathy
What are symptoms of Chronic Chagasic Cardiopathy?
Conduction disorders
Arrhythmia
Sudden cardiac death
Cardiomyopathy
Heart failure
Secondary thromboemobolism
apical aneurysm
What are symptoms of the digestive form of Chagas?
Mega-esophagus
Mega-colon
“Chagasic colopathy”
