An Antiparasitic Drug Joins the Fight against Malaria

A study led by Dr. Carlos Chaccour, from ISGlobal, in collaboration with researchers from the University of Navarra, shows that maintaining steady levels of ivermectin in the blood is safe and efficiently eliminates malaria transmitting mosquitoes. The results, published in Malaria Journal, open new avenues in the design of vector control strategies.

Ivermectin is a widely used broad spectrum antiparasitic drug that kills mosquitoes feeding on animals or humans treated with the drug.  However, its effect is limited in time since one oral dose of ivermectin is not sufficient to maintain high drug levels in the blood. For this reason, the researchers designed a slow-release formulation and tested its safety and efficacy. The study was performed in rabbits that received a silicon implant containing varying doses of ivermectin. The authors measured drug levels in plasma, toxicity and impact on malaria transmission by determining survival of mosquitoes feeding on the treated animals. The results show that the implants led to sustained blood levels of the drug (up to 24 weeks) capable of killing more than 50% of Anopheles mosquitoes that fed on the implanted rabbits. In addition, no side effects were observed.  

Insecticide-treated nets are one of the main strategies in malaria eradication, but they only protect inside homes and during the night. Thus, mosquito resistance to insecticides, together with the selection of mosquito populations with external and/or crepuscular activity, represent new challenges in the fight against malaria. This study paves the way for new strategies aimed at eliminating mosquitoes that feed by day and outside. As Dr. Chaccour explains, "this study was a proof-of-concept and the results are very encouraging. Now our goal is to find new formulations that allow maintaining high blood levels of the drug without having to inject it". The advantage is that the drug can also protect people from other parasitic diseases such as onchocerciasis (river blindness), and that mosquitoes have not yet developed resistance to ivermectin.  

Despite considerable progress in disease control during the last decade, malaria still represents a huge public health threat and caused more than half a million deaths in 2013. The design of new vector control strategies like those described in this study will be crucial for stopping disease transmission and achieving its eradication.