Prioritizing Interventions – Targeting IRS to Maximize Effectiveness

By Annie Martin on October 30, 2018 in Malaria, News

Malaria kills a staggering number of people every year — nearly half a million. That number is unacceptable given malaria is both preventable and treatable and somewhat surprising given donors and governments spend hundreds of millions of dollars each year attempting to control malaria.

So why is that number still so high? Well, first of all, malaria is primarily in countries with largely rural and hard to reach populations. Getting to those populations is logistically complicated and costly. Secondly, the mosquitos that transmit malaria quickly adapt to resist insecticides and to evade interventions. Thirdly, the scale of the problem is massive. While there are half a million deaths and over 200 million cases annually, the population at risk is even larger – half of the global population. Half of seven billion people are at risk for malaria.

A team of IRS spray operators prepare for the 2017 spraying season.

With this context, hundreds of millions of dollars in control efforts begins to sound like a drop in the bucket. In order to make the most of the resources at hand, we must maximize the impact of each dollar spent. For example, interventions like indoor residual spraying (IRS) – where spray operators move household to household spraying the walls of homes with insecticide in order to kill the malaria transmitting mosquitoes – are very effective at killing mosquitoes and reducing malaria. However, IRS is expensive. We need to ensure we are distributing IRS resources in the most strategic and likely most impactful way.

In 2017, Akros worked with the Zambia National Malaria Elimination Centre (NMEC), the Africa Indoor Residual Spray (AIRS) Project implemented by Abt Associates, and the U.S. President’s Malaria Initiative (PMI) to conduct a comparison control trial of IRS prioritization strategies. The question was simple: If we do not have enough resources to spray every house, where should we spray to see the greatest decreases in malaria incidence? Should we spray one condensed geographic area? Should we spray the areas near the health centers with the highest burden of malaria? Or, should we spray the areas predicted to have the most mosquitoes? Each of these questions defined an arm of the study; one arm targeted IRS by concentrating it in one geographic area, one arm targeted IRS by prioritizing its delivery by health facility-measured malaria burden, and one arm targeted IRS by prioritizing its delivery by predicted mosquito density due to ecological factors. The NMEC implemented each arm in two districts of Eastern Province during the 2017 IRS operations.