Tsetse flies are widespread in Africa. They feed on blood and are the source of the dreaded sleeping sickness, an infection that can be lethal, damages the nervous system and, in its final stage, causes a dozy state, which gave the disease its name. Sleeping sickness is a real danger for people in tropical Africa, but tsetse flies can also transfer the disease to cattle. This leads to huge losses in milk, meat and manpower. The damage caused by the flies in Africa is estimated to be nearly $5 billion a year.
