The Burden of Human African Trypanosomiasis

Abstract:

Human African Trypanosomiasis (HAT), a once largely forgotten disease, is back on the agenda. A public-private partnership between the World Health Organization (WHO), pharmaceutical companies and international donors succeeded in curbing the recent epidemic, but active transmission is still ongoing in several countries. The burden of the disease in affected individuals is high. Untreated the disease is always fatal and estimates of the Disability Adjusted Life Years (DALYs) lost per premature death range from 25 to 33 years. Even for successfully treated patients, the burden on households and livelihoods is high – between 1.5 and 10 months’ income, even when diagnostics and HAT drugs are provided for free. Costs ranging from $10–17 per DALY averted for case-finding and treatment places the control of T.b. gambiense HAT firmly in the category of highly cost-effective health interventions.

Appendix

Key Facts for Human African Trypanosomiasis (HAT)

• HAT is transmitted by tsetse flies.

• There are two forms of the disease. In East Africa HAT presents as an acute syndrome caused by T.b. rhodesiense, and is maintained by an animal reservoir. West African HAT is caused by T.b. gambiense, has a much more protracted course than East African HAT and is transmitted in a man-fly-man cycle. The role of an animal reservoir still needs to be clarified.

• There are two stages of the disease, an early stage (hemolymphatic stage), with few or aspecific symptoms, and a late (meningo-encephalitic) stage.

• Main symptoms of HAT are neuro-psychiatric, including behavioral problems, personality disorders, sleep disturbances and coma. It almost invariably results in death, if left untreated.

• Treatment of patients in the meningo-encephalitic stage requires more expensive and toxic drugs. Melarsoprol, still the most commonly used drug for second stage, kills between 5 and 10% of the patients. The only alternative, eflornithine, is expensive and difficult to administer.

• Ninety percent of HAT cases in the world are caused by T.b. gambiense. T.b. gambiense often occurs in epidemics. Active case finding conducted by mobile teams has been the cornerstone of the control of HAT since colonial times.

• If treated at a late stage, sequelae, mainly persistence of personality disorders and decreased mental capacities, are very frequent and pose a huge burden on the community long after the HAT epidemics are brought under control.