Until recently, nearly every child with a temperature above 38.5°C was treated for malaria in regions where the disease is endemic. It was one of the most common and deadliest causes of fever, and there was no easy way to rule it out: A definitive diagnosis required a microscope and a skilled technician—unavailable in many places. To be safe, health workers were trained to treat most fevers with a dose of antimalarial medicine. Public health campaigns helped spread the word: If your child has a fever, get them treated for malaria!
In the past decade, malaria RDTs—which use antibodies to detect the parasite's proteins—have transformed the landscape. The tests help reduce unnecessary prescriptions for malaria medicines, but they have exposed a new problem: the previously hidden prevalence of "negative syndrome"—feverish kids who don't have malaria. Even in places with the highest rates of malaria, only about half of fevers are actually due to the disease. In many places, that figure is 10% or less. In 2014, the World Health Organization (WHO) estimated that 142 million suspected malaria cases tested negative worldwide.
Negative test results pose a dilemma for health care workers, who in remote areas may be community volunteers with minimal training. When their one diagnostic test comes up negative, they are left empty-handed, with nothing to offer except some advice: Return if the child gets sicker. But often the family lives hours from the nearest clinic and even farther from a hospital. And patients, or their parents, expect to receive some sort of treatment. So health workers "usually give all the medicine they have," says Didier Ménard, a malaria expert at the Pasteur Institute in Paris. That approach often means antibiotics.
No simple fix
But even if such a test proves both reliable and durable enough to withstand tough field conditions, it would not be a quick fix for the problem of diagnosing fever. Often, says Clare Chandler, a medical anthropologist at LSHTM, tests that seem mobile and simple "aren't really simple at all." Even the rapid malaria tests, for example, have several unexpected pitfalls, she and her colleagues found: They take 15 minutes to get results, a strain for clinic workers who might have dozens of people waiting to see them. The lancets used to prick fingers pose another problem. After one use, they need to be disposed of. "You need a sharps bin, which has been a huge issue," she says. "We've seen people just throwing them on the floor, or trying to put them down latrines, not really knowing how to destroy them."
"We need to learn from our experience with malaria tests" and consider the potential downsides of new diagnostics, Hopkins agrees. Another problem: Because viruses are the most common cause of fever, the tests will often end up steering health workers away from giving improper treatment—rather than toward something that can help. "The tests are perceived as gatekeepers, to keep people from things we don't want them to have," Chandler says. That situation can frustrate both the patients and the people caring for them. In one study of RDTs, Chandler notes, patients avoided the clinic that offered the tests because they were less likely to receive medicine.
Chandler and others say the only lasting solution to the fever dilemma is to build stronger health systems with highly qualified health workers, a reliable supply of essential medicines, and well-equipped hospitals to treat severe disease. "In the end, it's not just the tool that's going to improve patient care and save lives. You need to reorganize the system," says IHPI member Lee Schroeder, a pathologist and diagnostics expert at the University of Michigan in Ann Arbor. That's an effort that will take decades. But in the meantime, knowing what to offer a feverish child would make an immeasurable difference.