Blood Test To Predict Anemia Risk Post Malaria Treatment

Highlights

Anemia frequently affects patients treated for severe malaria with artemisinin drugs which kills malarial parasites.

But the deparasitized red blood cells retain the parasite histidine-rich protein 2 (HRP2).

HRP2 can be measured with a rapid diagnostic dipstick test that then can be used to predict the risk for delayed hemolysis and anemia.

An estimated 3.2 billion people in 95 countries are at risk of malaria infection, and even though treatment with a class of drugs called artemisinins is associated with fatality rates lower than 5%, some patients receiving these agents develop severe anemia weeks after clearance of the parasite. Researchers have adapted an existing diagnostic test for malaria to predict the dangerous complications that sometimes arise after the parasite is eradicated from patients' blood.

Clinicians lack reliable methods to pinpoint which patients will experience widespread destruction of their red blood cells following therapy with the artemisinin artesunate - a condition called post-artesunate delayed hemolysis (PADH).

Episodes of PADH have been linked with severe kidney failure, which is one reason why the World Health Organization has noted an urgent need for a simple and reliable test. Here, Papa Alioune Ndour and colleagues repurposed a diagnostic already in use - the BinaxNOW malaria kit - to predict PADH with 89% sensitivity and 73% specificity.

The assay measures remnants of a malaria protein named HRP2 on red blood cells, and was successfully validated using diluted blood samples from 95 Bangladeshi patients and 53 French travelers, all of whom received artesunate.

Notably, a separate cohort of 49 patients that were administered quinine (which is not associated with post-treatment anemia) did not have persistently high HRP2 levels. The authors say the accuracy of the test must be confirmed in larger-scale prospective studies, and may be preferable to current recommendations for mandatory 28-day monitoring of all malaria patients - to help high-risk patients achieve better post-treatment outcomes.

Facts on Malaria

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• Over 40% of the world’s population is at the risk of malaria, according to the WHO. There were almost 200 million recorded malaria cases in 2013, with around 584,000 of them resulting in fatalities.
• In 2015, there were 212 million cases of malaria with a fall in global incidence by 21% between 2010 - 2015.
• There was a 29% decrease in global malaria mortality rates between 2010 and 2015.
• Malaria remains a major killer of under-fives, claiming the life of 1 child every 2 minutes.
• Artemisinin-based combination therapies (ACTs) are highly effective against P. falciparum, the most prevalent and lethal malaria parasite affecting humans.

Reference

1. Papa Alioune Ndour et al., Measuring the Plasmodium falciparum HRP2 protein in blood from artesunate-treated malaria patients predicts post-artesunate delayed hemolysis, Science Translational Medicine (2017).

Source-Medindia