Mosquito vector-borne diseases are serious global health threats. Malaria alone claims the lives of about 600,000 people annually. With such high death tolls, controlling vectors and the pathogens that they carry is of critical importance. This is evidenced by this year’s Nobel Prize in Physiology or Medicine going to researchers who developed medications that work to combat some of the most pervasive mosquito vector-borne diseases, like lymphatic filariasis and malaria. Two of the three researchers that received the Nobel Prize were honored for their role in the development of Avermectin, the parent compound of the widely used drug Ivermectin. Ivermectin is a broad spectrum antiparasitic medication that can be used both internally and topically for the treatment of myriad parasites, including filarial worms, gastrointestinal parasites, and scabies. And, as it turns out, ivermectin can even kill mosquitoes.
A blood smear showing Plasmodium falciparum, one of the parasite species that causes malaria.
Scientists have shown that having humans in an entire village take ivermectin can disrupt transmission of malaria and other vector-borne diseases. However, it can be logistically difficult to administer these prophylactic doses to enough people to have an effect, and there is also concern about the safety of having continuous ivermectin blood levels high enough to knock down biting mosquitoes. That’s where pigs come in.
A novel alternative to mass human ivermectin administration comes from researchers at the University of Barcelona. They put soft ivermectin-releasing silicone implants under the skin of pigs. These implants function in much the same way that oral ivermectin does in humans, by killing mosquitoes and potentially disrupting disease transmission pathways. A benefit of this livestock-based approach is that animals can safely tolerate high levels of ivermectin, so health effects are not a concern as they would be with humans. However, this control approach depends on mosquitoes biting animals, so it may not be effective against disease-transmitting mosquitoes that strongly prefer to bite humans. Regardless, this approach holds promise as it can potentially be used in other animals aside from pigs, and can be an inexpensive way to provide poor farmers some disease prevention that they may not get otherwise.
As you sit down to the Thanksgiving dinner table tomorrow, don’t forget to give thanks to the delicious ham and turkey on your plate; they may be on the front line of vector-borne disease defense.
