topnaman | Malaria blog

Truly beautiful studies – well designed, well thought, even examined cost and service delivery – were recently conducted for regular, presumptive antimalarial treatment (using SP and amodiaquine) of children in Mali and Burkina Faso in settings where treated bed-nets are already in use (PLoS Medicine – open access!). The intervention was effective at reducing clinical burden – from malaria incidence, the primary target, to secondary endpoints such as anemia, all-cause mortality, and stunting.

There is one important caveat here – IPTc is only “effective” where the transmission is quite high. In the communities in Burkina Faso and Mali where the study was conducted transmission was  very intense (3-13 infective mosquito bites per person per month). At medium and low levels of transmission (last two rows of the table) the strategy becomes rather untenable, expending a lot of drug (which wastes money and risks side effects and resistance), for preventing a single case. Caveat to my caveat – the interpretation of rates differences in number needed to treat calculations is not always straightforward though I believe valid in this case.

Table: Number need to treat (NNT) and post-intervention incidence rate across varying baseline transmission and IPTc efficacy

Interestingly, similar to the famous Garki project the reductions in incidence appear to be much greater than reductions in prevalence – likely due to the seasonal nature of the intervention against a high vectorial capacity and thus risk of exposure.  Since the focus here is burden reduction, and not transmission reduction as in Garki, it doesn’t matter though.