Nairobi — Malaria rapid diagnostic tests (mRDTs) introduced to improve the use of antimalarials may have unintended negative consequences, such as overuse of antibiotics, a study has found.
A WHO policy change in 2010, requiring that malaria cases should be confirmed before treatment, has increased the use of mRDTs on a large scale, according to the team of researchers from countries including Afghanistan, Ghana, Nigeria, Sweden, Tanzania, Uganda and the United Kingdom.
Heidi Hopkins, co-author of the study and an associate professor of malaria and diagnostics at the UK-based London School of Hygiene and Tropical Medicine, says that negative test results for malaria prompted a significant shift to antibiotic prescriptions - thus trading one potential problem of overuse of malaria drugs with overuse of antibiotics.
"To our knowledge, this is the largest and most comprehensive analysis that directly compares treatment practices in settings with and without mRDTs," Hopkins tells SciDev.Net.
The study was published in the American Journal of Tropical Medicine and Hygiene this month (7 August)
The researchers analysed harmonised data from ten artemisinin-based combination therapy (ACT) Consortium studies conducted between 2007 and 2013. Looking at more than 500,000 patient visits across five African countries - Cameroon, Ghana, Nigeria, Tanzania and Uganda - and Afghanistan, they found that even patients who were not confirmed by mRDTs as having malaria were prescribed ACTs, and some who had malaria were denied ACTs.
"Prescribing did not always adhere to malaria test results," write the authors. "In several settings, ACTs were prescribed to more than 30 per cent of test-negative patients or to fewer than 80 per cent of test-positive patients. Either an antimalarial or an antibiotic was prescribed for more than 75 per cent of patients across most settings."
Simon Kariuki, chief research officer at the Kenya Medical Research Institute, says that the findings are not totally unexpected given that the introduction of mRDTs was meant to curb the indiscriminate use of antimalarials.
He adds that the increase in antibiotic prescriptions is an interesting and significant finding, although again not totally unexpected: "This is because many countries in Sub-Saharan Africa don't have the laboratory capacity to investigate other causes of fever in those who are mRDT negative, which could be due to viral or bacterial infection."
Whereas mRDTs help healthcare workers diagnose malaria, there are still no such simple point-of-care diagnostics for other common illnesses that cause fever. This means that when a malaria test is negative, healthcare workers are not sure what to do, Hopkins explains.
Unnecessary use of antimalarials and antibiotics drives malaria resistance. Hopkins says there is a need to ensure that the benefits of introducing mRDTs do not come at the cost of increasing antibiotic use.
According to Kariuki, the findings call for an urgent need to strengthen diagnostic capacities in malaria-endemic areas when mRDTs are introduced.
To prevent the complex situation where those who test positive are not being treated with an antimalarial, or those who test negative are being treated with the drugs, Kariuki says the measures to be taken involve training for healthcare workers, patient perceptions and the lack of availability of antimalarials at certain times.
"These findings call for strengthening of health systems in malaria-endemic areas, especially diagnostic capacity and training of healthcare workers at all levels," he tells SciDev.Net.
This piece was produced by SciDev.Net's Sub-Saharan Africa English desk.