May 18, 2020 / 7:08 PM / 14 days ago

Antibody panel accurately detects recent Plasmodium vivax infection

NEW YORK (Reuters Health) - A panel of antibodies can accurately detect recent liver-stage Plasmodium vivax infection, researchers report.

Current diagnostics cannot detect clinically silent liver-stage P. vivax parasites, called hypnozoites, which can be responsible for more than 80% of all blood-stage infections. This remains a major hurdle for malaria elimination.

Dr. Ivo Mueller of Walter and Eliza Hall Institute of Medical Research and the University of Melbourne, in Australia, and colleagues measured IgG antibody responses to 342 P. vivax proteins and selected the eight most identified proteins that accurately predicted recent infections.

These eight serological exposure markers (SEMs) classified P. vivax infections in the previous nine months in cohorts from Thailand, Brazil, and the Solomon Islands with 80% sensitivity and specificity.

Based on this level of sensitivity, at least 80% of individuals with hypnozoites could be targeted for treatment, with less than 20% of the population treated unnecessarily, the team note report in Nature Medicine.

According to a mathematical model of P. vivax transmission, this approach would result in an estimated 59% to 69% reduction in P. vivax prevalence.

“We have shown that a carefully selected panel of SEMs can specifically detect recent exposure and could be used in a programmatic setting (surveillance as an intervention),” the authors conclude. “Application of our SEMs for serological testing and treatment holds promise for an effective elimination strategy using primaquine or tafenoquine to target dormant hypnozoites.”

“Given the risk of hemolysis in G6PD-deficient individuals treated with primaquine or tafenoquine, our tool has the potential to ensure such elimination strategies are targeted and therefore a safer, more acceptable and more effective option in malaria-endemic communities,” they add.

The study had no commercial funding.

Dr. Mueller did not respond to a request for comments.

SOURCE: Nature Medicine, online May 11, 2020.

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