Dye kills malaria parasites at speed not seen before

Research shows that the dye methylene blue is a safe antimalarial that kills malaria parasites at an unprecedented rate.

Within two days, patients are cured of the disease and no longer transmit the parasite if they are bitten again by a mosquito. This discovery was made by Radboud university medical center scientists and international colleagues during a research project conducted in Mali.

The results were published in The Lancet Infectious Diseases on February 6, 2018.

The pressure is on when it comes to antimalarial medicines, as malaria parasites are increasingly resistant to the artemisinin-based combination therapies that are currently used. In addition, these medicines do very little to stop the spread of malaria, as the parasites remain in the blood for a long time, with the chance that other mosquitos are infected if they feed on the patient.

The parasites split in the patient’s red blood cells, forming male and female sex cells (gametocytes). If another mosquito bites the patient, it sucks up the sex cells and these are fertilized in the mosquito’s stomach. The offspring then find their way to the mosquito’s salivary glands, where the cycle starts again.

The gametocytes can stay in a person’s body for several weeks following treatment for malaria. In the new study in Mali, Radboudumc researchers added methylene blue to the artemisinin-based combination therapy. Methylene blue is a blue dye that is used in laboratories to distinguish dead cells from living cells. Adding the dye to the antimalaria medicine ensured that patients no longer infected other mosquitos, within as little as 48 hours.

Patients who were not given methylene blue were able to infect other mosquitos for at least a week. Researcher Teun Bousema (Radboudumc) coordinated the study which was conducted together with the University of California (UCSF) and the Malaria Research and Training Center (MRTC). Bousema: “We noted that the male parasites disappeared from the bloodstream more quickly than the female parasites.”