Drugs for malaria: something old, something new, something borrowed

Abstract

Malaria was estimated to cause 800,000 deaths and 225 million cases worldwide in 2010. Worryingly, the first-line treatment currently relies on a single drug class called artemisinins, and there are signs that the parasite is becoming resistant to these drugs. The good news is that new technology has given us new approaches to drug discovery. New drugs generated this way are probably 10-15 years away from the clinic. Other antimalarials that may offer hope include those rehabilitated after not being used for some time, those that act as inhibitors of resistance mechanisms, those that limit infection while allowing protective immunity to develop, and those which are drugs borrowed from other disease treatments. All of these offer new hope of turning the tables on malaria. In parallel with the effort to develop vaccines that interrupt malaria transmission, drugs that target the parasite during transmission to the mosquito or during its pre-erythrocytic development in the liver, may allow us to terminate the parasite's spread.

Figure 1.. Life cycle of the malaria parasite

Sporozoites inoculated into skin enter blood vessels and are carried to the liver, where they multiply to form liver stage merozoites. Liver stage merozoites released into the blood stream infect individual host red blood cells to initiate the erythrocytic (blood) stages. Along with the disease-causing asexual blood stage parasites, sexual stages, known as gametocytes, also emerge during blood stage development and serve to transmit the infection to mosquitoes that suck the blood of infected humans. See [69] for a more in-depth summary. Abbreviations: RBC, red blood cell. Reproduced from Figure 1, panel B from http://www.sciencedirect.com/science/article/pii/S1471492211000353. Figure reproduced with kind permission of authors Robert J. Schwenk and Thomas L. Richie and Trends in Parasitology (copyright license obtained) [69].