Rapid and Specific Action of Methylene Blue against Plasmodium Transmission Stages

Abstract

Malaria eradication relies heavily on blocking the transmission of Plasmodium parasites from humans to mosquitoes. Methylene blue (MB), one of the oldest synthetic antimalarials, has shown promise in targeting the parasite's sexual stages. This study investigated MB's transmission-blocking potential and its activity against key life cycle stages responsible for transmission. Using Plasmodium falciparum field isolates in ex vivo direct membrane feeding assays (DMFA), robust inhibition of transmission to Anopheles gambiae was observed, even with brief MB exposure. However, MB had limited effects on Plasmodium berghei oocyst development and sporozoite formation in An. stephensi. Additionally, MB partially inhibited hepatocyte invasion and liver stage development in both P. yoelii and P. berghei models. These findings reinforce MB's potential to block P. falciparum transmission and highlight its potential for further evaluation in clinical settings to reduce malaria transmission.