Findings by a research team at Radboud University (Nijmegen, Netherlands) show that the use of methylene blue was rapidly effective for curing patients and preventing the transmission of the Plasmodium Falciparum parasites.
The methylene blue dye has been found to be an antimalarial substance capable of killing malaria parasites in record time while remaining safe to patients. Those treated with the dye are able to recover within two days and be cured of the disease, while also being unable to act as transmitters for further infections should they be bitten again by a mosquito.
This finding is of particular significance as malaria parasites have become increasingly resistant to the widespread artemisinin-based combination therapies. Adding more pressure to the current treatment options, they have little impact in blocking further transmissions of malaria. This, as the Plasmodium falciparum parasites can remain in a patient’s blood for a long time despite the recovery, and enable other mosquitoes to become infected if they feed on a recovering patient.
In a context in which current figures stand at 430,000 deaths due to malaria per year globally, finding safe, effective and quicker methods for both cure and prevention is crucial. It is important to notice that 90% of all malaria-related deaths occur in Africa, of which most are children. Although improvements on anti-malaria policies that include the use of mosquito nets and insecticides have led to a 50% drop of deaths in the last decade, the risk of treatment resistance and the lack of effective transmission prevention keeps driving current research.
Once the parasite enters the host through the mosquito bite, it splits in the patient's red blood cells into male and female gametocytes (sex cells). When another mosquito bites the human host, the extracted human blood enters the mosquito stomach, where the sex cells are fertilized and ready to spread in the next human, as the fertilized parasites place themselves in the mosquito’s salivary glands. Even if a human recovers from the infection, the gametocytes are able to stay in a human body for several weeks after treatment.
In the new study, researchers mixed methylene blue to an artemisinin-based combination therapy, a widely used present-day treatment of the parasites. Methylene blue is normally used in laboratories to differentiate dead and living cells, but in this experiment, the substance was observed to block any infections within a little as 48 hours. It was also observed that the dye caused a quicker elimination of male parasites over female parasites in patients’ blood. By comparison, the control group of infected patients that were not treated with methylene blue was able to infect other mosquitos for up to a week following treatment and recovery.
Methylene blue potential lies not only in the speed of its effects but also on its capacity to stop the spread of the disease following treatment, in itself a novelty. The research found the dye to be safe and tolerated by patients although the only side effect was the discharge of bright blue urine by those undergoing the treatment. This aspect is also under the attention of the research team, as they believe this outcome may deter patients from using the dye. This research was conducted in Mali by a team from the Radboud University Medical Center and in cooperation with the University of California (UCSF) and the Malaria Research and Training Center (MRTC).
Sources:
Efficacy and safety of primaquine and methylene blue for prevention of Plasmodium falciparum transmission in Mali: a phase 2, single-blind randomised controlled trial. Dicko, Alassane et al.
The Lancet Infectious Diseases, Volume 0, Issue 0
https://doi.org/10.1016/S1473-3099(18)30044-6