Malaria rapid diagnostic tests (mRDTs) received mixed reviews in a study published in the American Journal of Tropical Medicine and Hygiene. Administered to patients in malaria-endemic regions in sub-Saharan Africa and Afghanistan, the tests improved targeting of antimalarial drugs but led to higher usage of antibiotics in cases of nonmalarial fevers. The concern is this could drive up the risk of antibiotic-resistant infections. In another unsettling finding, investigators discovered that not all malaria patients were getting needed treatments.

“Since 2010, the World Health Organization has been recommending that all suspected cases of malaria be confirmed with parasite-based diagnosis before treatment. These guidelines represent a paradigm shift away from presumptive antimalarial treatment of fever,” the authors explained in a summary of the results.

The objective of rapid malaria diagnostic tests is to appropriately target artemisinin-based combination therapies (ACT) to confirmed malaria cases, thus leading to better management of patients with nonmalaria fevers.

To evaluate the test’s impact across a wide variety of healthcare settings in malaria-endemic regions, investigators led by the London School of Hygiene & Tropical Medicine did an analysis of drug prescriptions written for 562,368 outpatient encounters over a 10-year period. The data was taken from a series of studies conducted by global research initiative the ACT Consortium in sub-Saharan Africa and Afghanistan.

In this data, the investigators noticed a correlation between reduced use of ACTs and a rise in antibiotic use.

Among the various settings, at least three quarters of patients received a prescription either for an antibiotic or an ACT. In most of the areas, between 40% to 80% of patients received antibiotics—even though their malaria tests were negative.

Doubts over how to treat nonmalaria fevers may explain why so many providers prescribe antibiotics in the case of a malaria negative test.

“A key challenge is that we don’t currently have a reliable way to determine which fevers are evidence of a bacterial infection that requires a specific antibiotic treatment and which fevers will resolve with supportive care only,” said Katia Bruxvoort, BS, MPH, PhD, an epidemiologist with the London School of Hygiene & Tropical Medicine, in a statement.

Overall, “mRDTs were associated with significantly lower ACT prescription (range 8–69% versus 20–100%),” according to the findings. In a majority of the African settings, the tests led to “statistically significant” fewer ACT prescriptions, compared with settings that did not use mRDT as an intervention.

Despite the progress reported with reduced overuse of malaria treatments, the tests didn’t always lead to desired results across settings. In some areas, patients who tested negative received ACTs, whereas patients testing positive did not. In Cameroon and Ghana, for example, between 39% to 49% of patients with negative tests received ACTs. Comparatively, more than 20% of the malaria-positive patients in 5 of the 8 African studies did not receive these drugs.

The reasons for this are unclear, Bruxvoort said.

“Drug supply issues did not seem to be a problem in most of the areas where these patients sought treatment,” she explained. “There might be other reasons either patients or providers are not using ACTs in these contexts, but the issue of undertreating malaria, even when there is clear evidence of the disease, is troubling and deserves further study.”