Trypanosomiasis and Tsetse Control with Insecticidal Pour-ons- Fact and Fiction?

Insecticidal pour-ons that are applied directly to cattle have been promoted widely in the last decade as a new means of controlling tsetse flies in Africa. Tsetse attracted to treated cattle get a lethal dose of insecticide and die. Following a large trial in Kenya, Matthew Baylis and Peter Stevenson argue here that the reduction in trypanosomiasis incidence caused by pour-ons exceeds that expected from the impact (if there is any) on the tsetse population and that certain other (as yet unknown) factors must also be involved.