Diagnosis

• Presumptive: serological: card agglutination trypanosomiasis test (CATT): for T. b. gambiense only or immunofluorescent assay for T. b. rhodesiense mainly and possibly for T. b. gambiense.

• Confirmative: parasitological: detection (microscopy) of trypanosomes in blood, lymph node aspirates or CSF

Case management

Early screening and diagnosis are essential, as treatment is easier in the first stage of the disease (fewer injections required, no psychiatric disorders), carries a lower risk and can be administered on an outpatient basis. Diagnosis and treatment require trained personnel, and self-treatment is not possible. Most available drugs are old, difficult to administer where resources are limited, and by no means always successful.

T. b. gambiense

Recommended regimens

• First stage of the disease (without cerebrospinal fluid involvement)

Pentamidine (4 mg/kg body weight per day) intramuscularly for 7 consecutive days on an outpatient basis.

• Second stage (with cerebrospinal fluid involvement)

Melarsoprol - Hospitalization with 3 series of daily injections administered with a rest period of 8 to 10 days between each series. A series consists of one injection of 3.6 mg/kg/daily melarsoprol intravenously for 3 consecutive days.

In case of melarsoprol treatment failure, use eflornithine 400 mg/kg per day administered in four daily slow infusions (lasting approximately 2 hours). Infusions are given every 6 hours, which represents a dose of 100 mg/kg per infusion.

T. b. rhodesiense

Recommended regimens

• First stage of the disease (without cerebrospinal fluid involvement)

Suramin - The recommended dosage is 20 mg/kg per day with a maximum dose of 1 g per injection. The drug is administered intravenously at the rate of one injection per week. The treatment course is 5 weeks for a total of 5 injections.

• Second stage of the disease (with cerebrospinal fluid involvement)

Melarsoprol - Hospitalization with 3 series of daily injections administered with a rest period of 8 - 10 days between each series. A series consists of one injection of 3.6 mg/kg per day melarsoprol intravenously for 3 consecutive days.

Note: Melarsoprol causes reactive encephalopathy in 5-10% of patients, with fatal outcome in about half the cases. The treatment has a 10-30% rate of treatment failure, probably due to pharmacological resistance.

Increasing rates of resistance to melarsoprol (as high as 25%) have been reported from various African countries, such as Sudan and Uganda, leading to greater use of eflornithine.

Procurement of equipment and drugs

Since 2001, a public-private partnership agreement signed by WHO has made all these drugs widely available. The drugs are donated to WHO. Requests for supplies are made to WHO by governments of disease-endemic countries and organizations working in associations with these governments. Stock control and delivery of the drugs are undertaken by Médecins Sans Frontières in accordance with WHO guidelines. All the drugs are provided free of charge: recipient countries pay only for transport costs and customs charges.

Prevention

• Human reservoirs should be contained through periodic population screening and chemotherapy.

• Tsetse fly control programmes should be conducted, using traps and screens (may be impregnated with insecticide).

• Public education should be undertaken on personal protection against the bites of the tsetse fly.

• Donation of blood by those who live or have stayed in endemic areas should be prohibited.

Control measures in epidemic situations

Control measures comprise surveys to identify affected areas; early identification of infection in the community, followed by treatment; and urgent implementation of tsetse fly control measures.

Drug resistance monitoring

Melarsoprol treatment failure can be as high as 30% in some areas. A melarsoprol resistance surveillance network has been established by WHO.

Further reading

WHO report on global surveillance of epidemic-prone infectious diseases: African trypanosomiasis. Geneva, WHO, 2000 ( WH0/CDS/CSR/ISR/2000.1). Human trypanosomiasis: a guide for drug supply. Geneva, World Health Organization, 2001 (document WHO/CDS/CSR/EPH/2001.3).

Programme against African trypanosomiasis (PAAT), 2004. ISSN 1812:2442.

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