Artemisinin-based combination therapies are the main treatment for malaria. But resistance to artemisinin in Plasmodium falciparum is already spreading. What about Plasmodium vivax, the second most common malaria parasite?

In Cambodia, researchers studied 161 P. vivax infections from 87 patients treated with artesunate over 7 days. Parasite levels were closely monitored during treatment, and genomic and gene expression analyses were performed.

Good news: all infections were cleared by day 3.

However, nearly one third of infections showed slower parasite clearance. About 6% had particularly slow responses. This was not linked to patient characteristics or infection stage.
Gene analyses revealed that slow-clearing parasites had a delayed biological response to treatment, including reduced activity in genes involved in haemoglobin digestion. This may decrease the effectiveness of artesunate.

Why does this matter?

Slower clearance could allow parasites to survive long enough to develop resistance to partner drugs in combination therapies, threatening malaria elimination efforts.
This study highlights the importance of continued monitoring of P. vivax treatment response in Southeast Asia.
Read the full publication: https://pubmed.ncbi.nlm.nih.gov/41662857/