On the use of rapid diagnostic test kits for malaria.

The Permanente Journal/ Spring 2007/ Volume 11 No. 2 Since I wrote in The Permanente Journal (TPJ) (Fall 2005) about post-tsunami malaria in Indonesia, there have been several requests from TPJ readers regarding access to and anticipated availability of rapid diagnostic test kits (RDTs) for malaria. It is with regret that I relate that there is no intent to market these in the United States. There are several reasons for this, some valid, some not. Worldwide, the use of RDTs is a vital part of the World Health Organization’s program for malaria control, to preserve the use of newer, more expensive regimens for actual malaria cases. The Centers for Disease Control and Prevention (CDC) often opposes the use of these kits for diagnosis of malaria. In a conversation with the malaria officer on duty, my suggestion that they were of use was disparaged. Unfortunately, as is sometimes the case, an organization such as the CDC does not respond to the requirements of actually delivering care. When an organization has ready availability of world-class parasitologists, there is little need for RDTs. On the other hand, few of us practice in such an environment. Kain et al described an average delay of three days between the time of ordering a malaria smear and confirmation of the diagnosis in nonspecialist Canadian medical centers. In view of the rarity of malaria in this country, our best laboratory technicians are inexperienced in making this diagnosis and even experienced parasitologists can make errors in their reading of blood smears. Our average hospital laboratory is likely inferior in sensitivity to RDTs and probably in specificity as well, particularly if we consider only P falciparum, the only species that is rapidly fatal. One published small series from Bethesda Naval Hospital reviewed the diagnostic accuracy of these two modalities among Marines with febrile illness evacuated from Liberia. Ten of 32 cases were accurately identified by RDTs and the same ten by thick smear. One of 32 patients had a positive RDT and a thin smear that was originally read as negative, but confirmed subsequently to have been positive. In 2004, in the US there were only 1324 reported cases, 49% of these were P falciparum. This seems to be a strong argument that our local labs will not be able to enhance their expertise in this disease. This would be even more significant for smaller hospitals in On The Use of Rapid Diagnostic Test Kits for Malaria