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Invasive procedures for diagnostic or therapeutic purposes bear a relative risk of transmission of serious blood-borne infectious disease. In this study, a noninvasive approach to malaria diagnosis using polymerase chain reaction (PCR) for the detection of parasite DNA in saliva, buccal mucosa and urine (alternative samples) was examined. Saliva, buccal mucosa and urine samples were collected simultaneously with blood samples from 93 patients with microscopically confirmed Plasmodium falciparum infection. Species-specific primers detected the parasite DNA only in blood samples. However, when the PCR analysis was repeated using MSP1 and MSP2 primers in a subgroup of 21 complete sets of samples, the parasite DNA was detected in all except 3 samples, which were found to be negative with the MSP2 primers. Parasite density, body temperature or patient age did not influence the PCR results. In conclusion, P. falciparum parasite DNA was detected equally in saliva, buccal mucosa and urine of malaria patients, regardless of their ages, body temperatures or parasite density. Surprisingly, the parasite DNA was not amplified by species-specific primers in the alternative samples whereas it was in the blood samples.

Presumptive malaria treatment (PMT) is a common strategy in many areas of the world, especially in settings where the facilities for diagnosis are limited. The subjects of a recent study in central Sudan, in an area with a low level of Plasmodium falciparum transmission, were 322 individuals who had each presented at one of seven suburban health facilities, complaining of repeated febrile episodes. Although all were found bloodsmear-negative for malarial parasites, all were presumptively diagnosed as cases of malaria and prescribed artemisinin-based combination therapy. When pretreatment samples of blood were, however, checked for P. falciparum histidine-rich protein 2, using a rapid diagnostic test (RDT), and for Plasmodium DNA, using a PCR-based assay, only one (0.03%) of the cases was found RDT-positive and none was found PCR-positive. Although more studies are needed, in different areas and seasons, to see if these results mirror the general situation, it appears that the wide use of PMT in central Sudan, among patients who are bloodsmear-negative, is unjustified, of little, if any, benefit, and a waste of resources that are already limited. An international consortium for the revision of the conceptual aspects of malaria diagnosis and PMT is suggested.