Are there new ways to contain malaria?
Malaria is a life-threatening disease that is particularly widespread in African countries. Researchers have now found that two drugs could be used to safely and effectively prevent malaria transmission.
The University of California, San Francisco researchers found that two drugs could prevent the spread of the most common form of malaria in Africa. The doctors published the results of their study in the English-language journal "The Lancet Infectious Diseases".
Drug-resistant form can also be treated
The use of two drugs could help reduce the spread of a type of malaria called P. falciparum, including its drug-resistant forms, the experts say. This could make significant progress in eradicating the disease.
Millions of people could be protected from malaria
Although both drugs have been in existence for more than half a century, this is the first time that the exciting and impressive effects of each of these drugs on malaria transmission have been shown so clearly in a comparative study, explains study author Professor Dr. Roly Gosling from the University of California, San Francisco. The effectiveness of antimalarial drugs used for seasonal so-called malaria chemoprevention can be significantly improved. The discovery has the potential to end the threat of malaria to millions of people across West Africa.
How does malaria spread?
Malaria has several forms. The disease spreads through a recurring cycle in which it is transmitted from mosquitoes to humans and back again, the experts explain. When a person is bitten by an infected mosquito, malaria parasites migrate through the liver into the bloodstream, where they circulate for several weeks. The majority of the parasites replicate in asexual forms in the red blood cells. But a small percentage develops into male and female cells called gametocytes. These play an important role in the transmission of the disease to mosquitoes.
Transmission to mosquitoes must be prevented
Because these gametocytes are not killed by the anti-malarial drugs used to treat P. Falciparum (the most common form of malaria in Africa), people can spread the infection to mosquitoes for weeks after treatment, the scientists say. For this reason, something needs to be added to the treatment regimen to block such transmission.
How do primaquin and methylene blue work?
The current study examined the safety and efficacy of Primaquin, which has been used to treat another form of malaria (P. vivax) for decades. A laboratory dye called methylene blue, which has been used to distinguish dead from living cells for almost a century, was also examined. When injected into the bloodstream, methylene blue also acts as an antimalarial. The researchers found that each of these compounds, when added to different antimalaria treatment regimens, prevented P. falciparum gametocytes from malaria parasites from getting into mosquitoes from infected people.
More research is needed
"Patients who were not given these drugs were able to infect mosquitoes for at least a week after the treatment," explains Dr. Alassane Dicko in a press release from the University of California, San Francisco. The researchers say the results could accelerate malaria elimination in affected countries. However, further studies are still needed to identify the optimal scenarios in which these drugs can be used.
Transmission is blocked quickly
The researchers conducted a phase 2 study to compare the efficacy of the two substances in preventing gametocyte transmission in people with asymptomatic malaria. They found that adding a single dose of primaquine to sulfadoxine-pyrimethamine and amodiaquine treatment or adding three doses of methylene blue to dihydroartemisinin-piperaquine treatment resulted in almost complete blocking of transmission within 48 hours. This could become very important in the future because the WHO warns of a large return of malaria. (as)