Trypanosomiasis: Prevention and control

African trypanosomiasis is a very serious disease for the individual patient. A major danger of sleeping sickness is the risk of attaining epidemic proportions. Systematic detection and treatment of cases requires active searching (specialised mobile service, vertical strategy). An initial screening with CATT (Card Agglutination Test for Trypanosomiasis), and detection of suggestive clinical signs is generally used for Trypanosoma brucei gambiense. If one or both of these is positive, a lymph node aspiration is carried out. If negative, this is followed by a parasitological blood examination. If positive, a lumbar puncture should be carried out.

Passive treatment of patients who come to the hospital is less expensive but also less effective. There are in fact infected persons who can sometimes remain asymptomatic for a long time. Their role in the epidemiology is yet to be elucidated. It is practically impossible to control the disease by treating only the ill patients. Chemoprophylaxis with pentamidi­ne is not used, except in very exceptional situations.

Vector control can yield good results. Active participation of the population is needed in order to set up and maintain tsetse fly traps. These usually consist of a piece of textile of a certain colour, size and shape, that may or may not be impregnated with an insecticide ("imitation cows"). Various models have been developed. One of the more frequently used types is the biconical Challier-Laveissière trap. Other types used for control include for example Vavoua, Ngu, Lancien, pyramidal and bipyramidal traps. Some traps are preferentially used for sampling (glue traps, epsilon and F3 traps). Mobile electric traps can also be used for this latter purpose. Older, no longer used traps include Morris, Harris, Moloo, Swynnerton and Langridge traps. The effectiveness of various traps is increased by baits and attractants (octenol, acetone, butanone, carbon dioxide (CO₂), propylphenol, methylphenol). The use of pour-on insecticides on cattle looks very promising. The insecticide is applied directly to the hide. Cattle-dips, where cattle walk or swim through insecticide-containing water, were primarily developed for tick control (control of “East Coast fever”, a severe infection caused by Theileria parva), but could also play a role in tsetse fly control.

Category: Medicine Notes