Simple blood test proves powerful ally in the fight against malaria

Apr 30 2009

Scientists at the Swedish medical university Karolinska Institutet have shown that rapid diagnostic tests (RDT) for malaria infection can provide valuable support for healthcare in low and mid-income countries in the fight against the disease.

The RDT procedure is based on a simple blood test and, according to the results, helps to ensure that a greater number of patients receive the right treatment at no extra cost for the healthcare services.

"Since the existing test methods are too complicated and expensive for most primary health care clinics in Africa people are prescribed malaria treatment based on presence of fever only", says Dr Anders Björkman, who led the study at Karolinska Institutet's research centre in Zanzibar, Tanzania. "With an improved diagnostic tool, treatment can be targeted to patients with confirmed malaria infection."

Malaria RDT is a relatively new diagnostic method which measures the presence of a protein produced by the malaria parasite Plasmodium falciparum in a sample of blood taken from the finger. The test requires no advanced laboratory equipment or training, and is already in clinical use. The study by Dr Björkman and colleagues, which is published in the journal PLoS Medicine , is the first broad-front evaluation of the test in clinical operation. It involved four clinics on Zanzibar and data from 1,887 adults and children who all had fever within 48 hours prior to enrolment in the study.

The subjects were divided into two groups, one that was given a regular medical examination and diagnosed on the basis of symptoms only, and one that was also tested with RDT. All patients who were diagnosed with malaria, regardless of method, were prescribed artemisinin-based combination therapy (ACT), a treatment based on a Chinese plant called Artemisia annua.

When the patients were followed up two weeks after treatment, it was observed that significantly fewer patients who had been tested with RDT received ACT treatment: 36 per cent, as opposed to 85 per cent of the control (non-RDT) group. However, more antibiotics were prescribed for the RDT group. The number of patient revisits made on account of the perceived ineffectiveness of ACT was also lower in the RDT group.

"This might well prove a minor revolution in the treatment of malaria in the poor countries that are most severely affected," says Dr Björkman. "It also means that we'll get a better picture of the spread of the disease, which will make it possible to develop new, improved control strategies."

It is estimated that some 300 million people a year become infected with malaria, and that approximately one million die of the disease or its complications. Particularly vulnerable are children under five years and pregnant women, in low and mid-income countries in Africa and Asia. The study was conducted in association with the Zanzibar Malaria Control Programme, Médecins Sans Frontières, the Nordic School of Public Health and the WHO.