An analysis led by ISGlobal identified areas in Africa where the administration of ivermectin in cattle may have had the greatest impact on malaria transmission. The results, published in Scientific Reports, point particularly to West Africa, under the Sahel, where the prevalence of malaria is very high.
Between 2000 and 2015, it is estimated that 663 million cases of malaria were avoided in the world, thanks in large part to the use of insecticide-impregnated mosquito nets and to fumigation inside houses. However, these measures do not protect against mosquitoes transmitting malaria that bite during the day and outside the houses, which also feed on livestock. Ending this “residual” transmission requires a strategy that goes beyond the walls of the home.
Ivermectin has been used for many years in cattle to control parasites that live on animals (such as ticks) or inside them (for example, intestinal worms). Recent studies show that ivermectin can also kill mosquitoes that feed on cattle treated with the drug, making it an attractive complementary vector control tool, particularly in areas of high transmission of the disease.
In this study, Carlos Chaccour, an ISGlobal researcher, and colleagues conducted a mapping exercise to identify areas of Africa where a high prevalence of malaria coincides with a high density of livestock and the presence of the mosquito Anopheles arabiensis, which feeds on both humans and cattle. In other words, they sought to identify areas where the treatment of cattle with ivermectin would have a greater impact on malaria control.
Burkina Faso, Guinea, Benin and Togo are some of the countries that would benefit most from these measures, according to ISGlobal.
The analysis shows that the West African region under the Sahel (particularly Burkina Faso, Guinea, Benin and Togo) is the one that would benefit most from treating cattle with ivermectin. In addition, it is the region with the highest prevalence of malaria in children under ten years of age.
“This strategy represents additional benefits for the community, since it improves the health of the livestock,” explains Chaccour. The advantage, he says, is that ivermectin can be effective even against mosquitoes that are resistant to insecticides.
More studies are needed to assess whether this strategy is effective in reducing malaria transmission, is accepted by communities, and is cost-effective. This is precisely one of the objectives of the BOHEMIA project, financed by Unitaid and led by ISGlobal. The project, which started recently, will evaluate the impact of the massive administration of ivermectin on populations and/or livestock in two African countries (Tanzania and Mozambique).
“In fact, the places chosen for BOHEMIA are shown on the maps as areas of special interest for the use of ivermectin in livestock,” says Chaccour.