The epidemic of sleeping sickness in Central Kavirondo was introduced about 1903 from Usoga across a chain of islands, and finally from Mageta Island to the coast of Kadimu close by. Mageta was evacuated, and subsequent return of the population brought back the disease, leading to a second evacuation, second return, and renewal of the disease about 1920–21, leading to final evacuation two years ago.

Glossina palpalis occurs plentifully along the 100 miles of coast examined, between the Sio River and the mouth of the Kavirondo Gulf, except just south of Sio, and in the neighbourhoood of the mouths of the Yala and Nzoia Rivers. Ample evidence was obtained that non-mammalian blood is much preferred to that of the hippopotamus, which was the only source of mammalian blood, except man and cattle at some localities.