In recent research published in the journal Nature Genetics, scientists have shown that Plasmodium vivax evolves rapidly and is adapting to conditions in different areas. P. vivax is a protozoal parasite carried by mosquitoes that causes malaria in humans. Malaria has become increasingly difficult to treat and this new research shows that P. vivax is quickly evolving to become resistant to the standard antimalarial medications.
Researchers from the Wellcome Trust Sanger Institute and Wellcome Trust Centre for Human Genetics, both in the United Kingdom, analyzed the genomes of over 200 samples. They took the samples from infected patients in different parts of Southeast Asia, one of the hotbeds for malaria infection. The researchers found that P. vivax had evolved differently in areas that had used different drugs in treatment. For example, P. vivax evolved differently in Thailand than it did in Cambodia. In Papua, Indonesia, chloroquine is normally the first drug used when treating malaria. The scientists found that the P. vivax in that area had evolved quickly to become resistant to chloroquine.
There are a few factors contributing to this rapid drug resistance in P. vivax. Often, a patient may carry two different parasite species, both P. vivax and the more commonly studied P. falciparum. Both species would then be exposed to the drug used in treatment, allowing P. vivax to become resistant to drugs used to treat P. falciparum. The authors also note that unsupervised drug use plays a role in drug resistance. Patients may take the first antimalarial medication they can find, rather than the best one for their strain. They also may take improper doses of the drug.
The researchers hope that malaria treatment can be made more efficient by utilizing genomic data. By identifying the exact strain a patient is infected with, doctors can choose the medications that would be most effective. This research also provides the foundation for future studies that may help us understand how drug resistance works in P. vivax, allowing us to develop better malaria treatments.
Richard Pearson et al. Genomic analysis of local variation and recent evolution in Plasmodium vivax. Nature Genetics (2016).