An Anopheles stephensi mosquito is obtaining a blood meal from a human host through its pointed proboscis. Credit: CDC
Key points:
- Researchers used genomic surveillance to identify malaria-causing parasites with mutations that made them resistant to treatment and undetectable by diagnostic tests.
- In a sample from Ethiopia, 8.2% of drug-resistant malaria parasites carried deletions of the protein-expressing gene that rapid diagnostic blood tests use for detection.
- Understanding how these mutations emerge, interact and spread can help scientists develop new treatments and vaccines.
Antimalarial drug resistant parasites have previously been found in Uganda, Tanzania and Rwanda. Other malaria strains that are resistant to diagnostic tests were found in the Horn of Africa. Now, researchers have identified malaria-causing parasites that are both resistant to treatment and undetectable by common diagnostic tests.
The results from their genomic surveillance study, published in Nature Microbiology, were the first confirmation of a double-resistant malaria strain.
“We’re essentially seeing the worst-case scenario: parasites with the mutation that make them resistant to treatment have also picked up the chromosomal deletions that make them invisible to the diagnostic tests,” explained Jeffrey Bailey, professor at Brown University. “It will be harder to detect people who are infected, and then when infected people are treated with antimalarial drugs, that may not work to stop them from spreading the disease.”
The detected mutations provided resistance to artemisinin, which is part of the typical first-line combination therapy treatment. Many of these same parasites also had deletions of protein-expressing genes that are detected by rapid diagnostic blood tests. In fact, comparative genomic analysis along with molecular sequencing found that 8.2% of drug-resistant parasites carried the deletions of the protein-expressing gene—making them undetectable by diagnostic tests.
With the concerning double-resistant malaria strain, researchers concluded that monitoring the spread of combined drug- and diagnostic-resistant parasites is crucial. Understanding how mutations emerge, interact, and spread will be key for controlling and eliminating malaria across Africa.
As these mutations complicate efforts to eradicate malaria, there is an increased need to develop new therapies and vaccines to aid in treatment and prevention. The research team is working toward these goals along with building the capacity for genomic surveillance in Ethiopia and other parts of Africa.