The WHO Malaria Report for 2016 mentions an alarming increase in the number of people no longer receiving protection from indoor spraying, and thus an increase in the number of people in endemic areas who have lost their immunity, due to previous intense spraying. For Africa, 10.5% of the populations were covered in 2010, but this had dropped to 5.7% by end of 2016.
malaria and immunity
There is dangerous obstacle - we call it the Immunity Trap - in malaria prevention strategies which is most dangerous for countries which have relied on the ephemeral methods recommended by WHO and used by PMI, but which have not included permanent methods. In the 19 African countries in the US Presidential Malaria Initiative administered by the PMI for the last decade, of the 30 million who have lost their immunity, about half are also no longer protected by house spraying because of the high cost of new biocides.
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