Malaria hotspots and targeting

Heterogeneity exists in the risk of malaria – both between different areas and between individuals in the same area. The old maxim states “malaria is a local and focal disease”. Targeting malaria control interventions (nets, spraying, etc) is thus, a time-honored activity. Countries which undertook malaria eradication efforts have stratified populations at-risk for intervention delivery since  in the 1950s-60s.

In recent years a spate of papers (here, here, and a policy piece here) have emerged on the idea of hotspots and ‘hitting them’ for high-impact control. What do these papers add? These studies quantified the heterogeneity in risk at the individual and household levels and their change with time. Another innovation in measuring the concentration of transmission was the use of serological in addition to parasitological data – although the two studies conflicted on which serological measurement was better. Finally, the papers recommend individual or household-level targeting of certain control interventions (vaccines, mass drug administration, specific vector control activities) at certain times based on annual surveys. What do these studies miss? First, as with many studies, particularly those conducted or focused in sub-Saharan Africa (all of the above), they suffer from a lack of historical perspective. Enamored with the idea of novelty, the authors fail to acknowledge decades of experience in ‘hitting hotspots’ using different data and different units of selection elsewhere in the world. Second, these studies do not assess, deductively or empirically, the direct and indirect costs of targeting. What are the training, delivery, coverage gaps and leakage implications of using serological data compared to parasitological data or of using household level stratification compared to village or area stratification? Without the comparative and programme perspectives such key questions remain unasked.

Using and improving targeting is an important area of work in malaria control. But the detection of these hotspots therefore, does not necessarily lead to their use in control work. Long-standing, sophisticated malaria control programmes face considerable difficulty in targeting activities using much coarser criteria. Conclusions and recommendations should follow from study results. This is a basic principle of scientific writing, and possibly, the most violated due to well-meaning intentions to ‘do something’ along with the less noble imperative to overstate one’s work. Academic research and publication will always favor the new over the credible, future possibilities over present realities. This is not necessarily a bad thing. We need to aim high and we need to look ahead. Programme managers and other practical consumers of the literature should be prudent in the promotion of such work. What worries me is the academic-donor nexus which prevents this caution and brings in varying degrees of distraction.


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  1. 1 Top 25 Public Health Blogs of 2012 Trackback on January 8, 2013 at 6:16 pm
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