[Is vector control needed in the fight against sleeping sickness? A biomathematical approach]

Vector control and the detection (followed by treatment) of infected individual are the two methods currently available for the control of sleeping sickness. The basic reproduction rate of a compartmental model (Kermack and McKendrick) is used to analyze and compare the two strategies. The model shows that when there is a long first stage characteristic of an endemic situation, the detection of sick individuals is more efficient than vector control. This higher efficiency of detection decreases in a epidemic situation. In this case vector control in the form of a decrease in vector density and/or an increase in vector mortality is relatively more efficient than detection. Because it is squared in the basic reproduction rate, the probability of a tsetse blood meal on humans is an important and sensitive parameter in the study of control strategies. This sensitivity has been observed previously and empirically by field workers. When the probability of a tsetse blood meal on humans is above a certain value, vector control becomes warranted or even necessary.