Tsetse flies transmit a similar disease to humans, called African trypanosomiasis - human African trypanosomiasis (HAT) or sleeping sickness. An estimated 70 million people in 20 countries are at different levels of risk and only 3-4 million people are covered by active surveillance. The DALY index (disability-adjusted life years), an indicator to quantify the burden of disease, includes the impact of both the duration of life lost due to premature death and the duration of life lived with a disability. The annual burden of sleeping sickness is estimated at 2 million DALYs. Since the disease tends to affect economically active adults, the total cost to a family with a patient is about 25% of a year's income.