IS VECTOR CONTROL NEEDED IN THE FIGHT AGA INST SLEEPING SICKNESS - A BIOMATHEMATICAL APPROACH

Vector control and the detection (followed by treatment) of infected i ndividuals are the two methods currently available for the control of sleeping sickness. The basic reproduction rate of a compartmental mode l (Kermack and McKendrick) is used to analyze and compare the two stra tegies. The model shows that when there is a long first stage characte ristic of an endemic situation, the detection of sick individuals is m ore efficient than vector control. This higher efficiency of detection decreases in a epidermic simulation. In this case vector control in t he form of a decrease in vector density and/or an increase in vector m ortality is relatively more efficient than detection. Because it is sq uared in the basic reproduction rate, the probability of a tsetse bloo d 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 blo od meal on humans is above a certain value, vector control becomes war ranted or even necessary.