TRYPANSOMIASIS (Sleeping Sickness) / MedUrgent

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TRYPANSOMIASIS (Sleeping Sickness)







Trypanosomiasis is caused by the extracellular protozoon haemoflagellate Trypanosoma brucei gambiense (West Africa), T.b.Rhodesiense (Central and East Africa), and T.b.cruzi (Central and South America). Trypanosomes are transmitted to man by the bite of the tsetse fly Glossina (Africa) and by reduviid bug faeces (Central and South America). The reservoir is wild and domestic animals (pigs, dogs, antelopes and bush bucks). Transmission may also occur through blood transfusion, during organ transplant, transplacental or from infected food and drink. Incubation period for T.b. rhodesiensis is 3 - 21 days, T.cruzi 1 - 14 days and for T gambiense ranges from months to years. Mortality rate in untreated cases is very high.

They have the following stages in their life-cycle:

1- Amastigote this is the diagnostic stage in leishmania.

2- Promastigote. This is the infective stage in man.

3- Epimastigote: It is in this form that trypansoma exist in the vector's intestine and may be produced in laboratory on artificial media.

4- Trypomastigote: This is the diagnostic stage for trypansomiasis. In general the trypomastigote is pleomorphic and many shape variations have been found. 

African Trypanosomiasis (Sleeping Sickness)

 1-Early stage 

a) Trypanosoma Rhodesiensis 

This is an acute illness which develops within days or weeks after inoculation. It presents with fever, cutaneous papule or "chancre", anemia, thrombocytopenia, myocarditis, hepatitis and DIC.

 b) Trypanosoma Gambiense 

This is a chronic disease in which a nodule or a chancre appears after a few days of inoculation. Systemic manifestation of the disease appear months or years later and include fever, malaise, weight loss, arthralgia, skin rash, edema and posterior cervical lymphadenopathy. 

2-Late stage

In T.b.rhodesiensis: this stage takes around 3 weeks to develop while in T.b. gambiense it takes months to years to develop. In this stage the parasite infect the CNS leading to meningoencephalitis with behavioral changes, headache, hallucinations, delusions and somnolence especially during the day. Coma and convulsions are terminal events. Children are at a lesser risk of exposure to the disease because of the pattern of dressing and lesser outside home activities, however, the disease is often fulminant with early CNS involvement in infected children 

American Trypanosomiasis (Chagas disease)

Vector is the triatomine insect (the kissing bug) that feeds on blood but transmit the trypanosomes through its faeces that are deposited on the skin of the victim leading to severe itching, scratching and spread of the parasite through blood.

In American trypanosomiasis the acute parasitemic phase lasts for a few weeks while the chronic phase is lifelong.

1-Early stage

This is an asymptomatic phase. A red nodule at the site of inoculation appears (Chagoma), commonly on the face and arms, which is then followed by edema. Involvement of the eye lid leads to edema, conjunctivitis and local lymphadenitis (Romana sign). After a few days, fever, malaise and generalized lymphadenopathy appear. Hepatosplenomegaly, myocarditis and rarely, meningoencephalitis may follow.

2-Late stage

This is the stage of gross organ damage. Cardiomyopathy, heart failure, megaoesophagus, megacolon and myositis appear after some years. Congenital infections presents with low birth weight, hepatosplenomegaly, meningoencephalitis, seizures and tremors.







Investigations

• Fluid aspiration: this is a direct means that requires searching for the motile trypomastigole or the immotile form in the sample by fixation and staining.

• Card Agglutination Trypanosoma Test (CATT): mainly for T. gambiensis

• Lymphnode aspirate

• Thick blood film

• Chancre aspirate

• C.S.F. (after double centrifugation) ELISA PCR .

• (IgM)

• Polyclonal hyperglobulinaemia

• Animal inoculation with infected C.S.F.: mainly for T. rhodesiensis

• Culture of aspirate in GLSH media, NNN and other media.

• Xeno diagnosis: Feeding a bug on the blood of a suspected patient and then examining the intestinal contents of the bug for T. cruzi 25 - 30 days later.








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