A decade ago, I helped the US Presidential Malaria Initiative get its start in Angola. Since then the Malaria Initiative (the US PMI) has expanded under Tim Ziemer to 19 African countries, protecting 30 million people. Consequently, over the last decade these 30 million people have lost their immunity to malaria. Now that might seem obvious and maybe a good thing. But since they live in regions where malaria is endemic, it raises a serious issue about durability of the PMI strategy.
The Resistance Treadmill
When we started the Malaria Initiative we were spraying pyrethroid biocides which were relatively cheap and safe. However - as we warned Tim in the beginning - because they limited their strategy to the ephemeral WHO methods of drugs, biocides, and bednets, they soon found themselves on the Resistance Treadmill. Besides encountering resistance to the drugs, since 2005 the insecticides they use have gone from pyrethroids to carbamates to organo-phospates, which are much more expensive. The Malaria Initiative budget is $0.6 billion - steady but not infinite - so each year PMI has to decrease the number of people they protect with spraying, because of the growing expenses for drugs and biocides.
The Immunity Trap
From a peak of 30 million people protected in 2012, only 17 million are protected now. Thus 13 million people in the Malaria Initiative are squarely facing the Immunity Trap. They lost their immunity during the decade when the PMI could cover them. But now they have no protection - and no immunity. So what to do? (NOTE: The reality of the Resistance Treadmill and the Immunity Trap are both documented in published papers by others, in the first two articles in the 'Global Malaria News' on the 28 June - MalariaWorld page ! ).
The Swiss Cheese Strategy
The best solution is to adopt the Swiss Cheese Strategy, in which we recognize that any single method has holes in it, thus many methods - or layers of cheese - are needed for a good sandwich – Emmentaler anyone? If placed properly, the holes will not match, and complete, durable coverage will be achieved. The best candidate for addition - a permanent method - is the improvement of housing, including closing of eaves and metallic screen on doors and windows. Management of larval breeding sites is another. These methods have both been implemented successfully in the field. If they are not added, what will become of the 13 million folks who have lost their immunity?