Can the causal model approach contribute to the study of the epidemiology and the control of sleeping sickness?

A causal model links together, in an hierarchical manner, a set of hypotheses about the causes of, and mechanisms leading to, a phenomenon under study. Initially used in nutrition studies for identifying the variables to be observed, such models have proven useful in the choice and evaluation of interventions, as well as in the selection of relevant special studies to be carried out inside a broader research programme. The authors describe a technique of model building used by nutritionists, and argue that this approach could be of benefit in the study and control of african trypanosomiasis. Their hypothesis is that although causal models do not substitute for mathematical models, the latter ones, and epidemiological models in general, would be (1) more correct logically; (2) fitting reality more closely; and (3) more useful for the analyst, the decision maker and the field worker, if they were built from an preceding causal model.