A health official takes a drop of blood to test a woman for malaria in Lagos in 2016.

Pius Utomi Ekpei/AFP/Getty Images

Revolutionary malaria tests have unexpected downsides

A simple fix to a major public health challenge has turned out to be not so simple after all.

In the early 2000s, researchers developed rapid diagnostic tests (RDTs) for malaria, a major childhood killer. Simple as a home pregnancy kit, RDTs need just one drop of blood from a finger prick to detect the malaria parasite. They enabled health workers in remote villages in Africa and Asia to accurately and almost instantly diagnose malaria, making them less likely to overuse the new generation of “wonder drugs,” artemisinin-based combination therapies (ACTs), which were in danger of being lost to drug resistance.

The use of RDTs skyrocketed after the World Health Organization in 2010 recommended that all suspected cases of malaria be confirmed by a test before treatment; roughly 314 million tests were procured in 2014. Together with ACTs, they have transformed malaria treatment in poor countries.

But now the largest analysis of RDT use yet, in poor settings in Africa and South Asia, suggests that along with its enormous benefits, the roll-out had unintended—and undesirable—effects. Where RDTs were used, the number of ACT prescriptions dropped, as hoped. But antibiotic prescriptions surged; at most study sites, 40% to 80% of patients walked away with the drugs, considerably more than needed them. (In one study in Zanzibar, just 22% of children with fever needed an antibiotic.) Such overuse could contribute to the global rise in antibiotic-resistant infections; it’s a classic example of when fixing one problem exacerbates another, says Heidi Hopkins of the London School of Hygiene & Tropical Medicine (LSHTM), who, along with colleague Katia Bruxvoort, led the international team.

It shouldn’t come as a big surprise that community health workers and private shopkeepers in some of the world’s poorest countries have a hard time diagnosing and prescribing drugs correctly.

Chris Plowe, University of Maryland School of Medicine

Even more concerning, Hopkins says, is that in several settings more than 30% of patients who tested negative for malaria received ACTs, whereas more than 20% who were positive did not, leaving them at risk of severe disease or death.

The work is a synthesis of data from 10 studies conducted by the ACT Consortium in five sub-Saharan countries and Afghanistan between 2007 and 2013, covering 562,368 individual patient visits—an “extraordinary” number, says Patricia Walker, president of the American Society of Tropical Medicine and Hygiene in Oakbrook Terrace, Illinois, which published the paper online yesterday. The prescribers tended to be volunteers from the community trained as health workers, or shopkeepers who sell toilet paper and soft drinks along with dispensing medicine.

The researchers don’t have firm explanations for the unexpected effects of RDT introduction, which varied from place to place. Health care workers are doing their best, Hopkins says, but they lack a simple test  to tell which fevers are caused by bacterial infections, much less which antibiotic to use. So when a malaria test is negative, they may think it’s safer to prescribe drugs than not.

What’s more, patients come with clear expectations. If a mother has trudged many kilometers with a feverish child, it’s hard for a health worker to send her away without something “powerful,” such as an antibiotic or an antimalarial, Hopkins says. That may help explain why fewer than 25% of patients were given fever-suppressing drugs such as ibuprofen or paracetamol to relieve their symptoms, when that might have been all they needed. 

Why some patients diagnosed with malaria did not receive ACTs is more baffling, because there was no shortage of these drugs in the study settings. Hopkins speculates that prescribers who were used to frequent shortages may have saved ACTs for the sickest patients. Figuring out why health workers make these decisions is key, the authors say.

“It’s not so easy to get physicians in the United States to follow recommendations, so it shouldn’t come as a big surprise that community health workers and private shopkeepers in some of the world’s poorest countries have a hard time diagnosing and prescribing drugs correctly,” says Chris Plowe, who heads the Institute for Global Health (IGH) at the University of Maryland School of Medicine in Baltimore. “If anything, this study probably overestimates how well things are done by workers with even less training and follow up.”

Monitoring can help, says Abigail Pratt, who spent 10 years working on malaria with Population Services International (PSI) in remote parts of Southeast Asia and Africa and is now getting her doctorate at LSHTM. (She was not involved in the study.) In Cambodia, for instance, PSI collects bags of used RDTs from health providers each month and crosschecks the results with ACT use, with follow-up training, if needed.

But she and others see a bigger need: Community health workers must be equipped to diagnose and treat fever from all causes, not malaria alone. That means donors need to move beyond funding specific diseases to helping build up the health system, says Myaing Myaing Nyunt, also of IGH. And scientists need to replicate the RDT revolution for bacterial infections.