Parasitological confirmational of malaria diagnosis. Report of a WHO technical consultation. Geneva; 2009

Background

The WHO guidelines for the treatment of malaria2 strongly recommend confirmation of a diagnosis of malaria in all suspected cases before administration of treatment. This new recommendations emphasizes the importance of high-quality microscopy or, where not available, quality-assured RDTs. It recognizes the latter as a valid alternative to microscopy for the diagnosis of falciparum malaria infection.

Much progress has recently been made in quality assessment and quality assurance of diagnostic tools for malaria. The WHO/TDR/FIND Malaria RDT Evaluation Programme, jointly coordinated with the United States CDC, completed the first round of product-testing in 2009. The published results allow comparative assessment of RDTs in relation to parasite density thresholds for detection, stability, false-positivity rate, invalid test results and ease of use. The optimal parasite density threshold and optimal standards for other performance criteria may, however, differ according to the malaria situation and patient age group. The implications of using these thresholds for disease management and disease outcomes were still unclear at the time this report was published. Product-testing and lot-testing allow procurement agencies to make informed decisions; other tools will, in the near future, allow standardized lot-testing at national level and will facilitate standardized testing of the quality of RDTs at clinic level. The WHO guidelines for quality assurance of malaria microscopy,3 published in 2009, provide new, practical approaches for quality assurance in malaria microscopy, including methods for accreditation of national expert microscopists and routine validation of slide examination. Revised WHO malaria training manuals and bench aids4 with an accompanying CD-ROM, were published in early 2010.

Widescale introduction of expensive antimalarial medicines, decreasing trends in malaria morbidity in many countries due to effective control interventions and strong demand from countries to strengthen both microscopy and malaria RDTs indicate the importance of reviewing international quality assurance systems to improve clinical management of malaria in different epidemiological settings. The programme elements for strengthening laboratory diagnosis of malaria must be defined for countries undertaking malaria control, elimination and intensified surveillance, including defined thresholds for the sensitivity and specificity of diagnostic tools to ensure successful management of febrile illness.