The particular and the general. Issues of specificity and verticality in the history of malaria control.

Several ideas have currency through long periods of malaria control history and important issues in controlling many communicable diseases have often been fought out over malaria. Health administrators view complex problems of malaria control through these apparently simple ideas. The most important concepts concern the need for specific methods to combat particular features of the spread of malaria and how far this is reflected by the development of specific health services. This paper follows these ideas through the last century and argues that the dead hand of history has played too large a role in determining malaria control generally, and especially over the last two decades, while the whole period provides an illuminating commentary on conceptualization in tropical health and its evolution. The two decades following discovery of the mosquito transmission of malaria saw increasingly specific knowledge about the vectors and approaches to preventing breeding. This required "odd" health workers who poured oil on water and did fresh-water biology and later special engineers who could design reservoirs and irrigation systems hostile to anopheline breeding and apply "species sanitation". The expertise required lay outside the health sector. Later, the DDT phase focused on a single highly specialized control technique, total coverage house spraying, and led on to attempted eradication, whose activities were vertically grouped. Malaria eradication became autonomous within the health department. It became the archetypal vertical programme whose funding levels and early successes made it a model to be emulated. But the need for active case surveillance to be integrated with general health services was a major reason for failure in some countries. The subsequent reaction to failed eradication emphasized horizontal or general health services, and these are very relevant to current pre-occupations with morbidity and mortality reduction by early diagnosis and prompt treatment. The future needs a complex mixture of interventions that cut across traditional views of either specificity or of the horizontal/vertical split in programmes, and development of effective control with imperfect tools requires a more sophisticated analysis of control methods and organizations than is provided by a simple vertical/horizontal debate.