Evaluation of Rapid Diagnostic Tests

Situation:

Diagnosis of malaria must be prompt as even a few hours delay in treatment can mean the difference between life and death. There are three methods for diagnosis: microscopy, which is skilled and labour intensive, relying on laboratory facilities; clinical diagnosis, which relies on treating almost all fever cases, and therefore can treat false positives; or Rapid Diagnostic Tests (RDTs).

RDTs are quick and easy to use, requiring just a spot of blood from a finger prick. In about 15-20 mins, a result detects presence or absence of malaria in the blood. However RDTs are not infallible - false positives can arise if treatment has been administered recently; the tests are sometime not sensitive at low levels of infection and therefore can give false negatives; the tests can seem expensive especially when used infrequently, compared to preventive treatment.

Response:

The Malaria Consortium is involved in three studies in Uganda evaluating the cost effectiveness, suitability, sensitivity and performance of RDTs in field settings, in comparison with microscopy or clinical diagnosis. One is looking at sensitivity and specificity of an RDT (funded by COMDIS), one is a pilot study on the suitability of RDTs in health centres (in partnership with DFID Drugman) and one (in partnership with WHO TDR, Ugandan Institute of Public Health and Mbarara University) is on the use of RDTs at a community level looking at cost effectiveness, suitability and reliability.

In Ethiopia, a development of a strategy for quality assurance of RDTs is being carried out.

In northern Sudan (Darfur) local health workers have been trained by the Malaria Consortium on the correct use of RDTs.

Points to note:

To support a more targeted and effective use of new antimalarial drugs, accurate diagnosis needs to be fully implemented. Wherever possible, microscopy should be used and where not, RDTs provide a feasible alternative, eg at community level. Either method requires robust systems of quality control and assurance and proper, ongoing training of workers. The limitations and strengths of either method also must be fully understood by policy makers so that they can devise the most effective strategies for utilizing these tools.

Photos: William Daniels/Dolce Vita and Malaria Consortium