A comparative study of diagnosis by the polymerase chain reaction and by current clinical methods using biopsies from Colombian patients with suspected leishmaniasis.

The results of a preliminary trial are reported in which the diagnostic value of a Polymerase Chain Reaction (PCR) specific for Leishmania of the subgenus Viannia was compared with that of currently recommended methods. These methods were microscopic examination of dermal scrapings, in vitro culture of both patient biopsies and aspirates, an in vitro culture of hamster aspirates following inoculation with patient biopsies. The tests were performed on biopsies of Colombian patients with leishmaniasis or with nonleishmanial ethiologies. The outcome of this trial was that PCR was consistently more sensitive than any of the four currently recommended methods of diagnosis, an gave results much faster than the three culture-based methods. Clinical specificity did not match the absolute specificity obtained in the laboratory when tested against purified kDNAs from various Leishmania species. This is thought to be due to the small sample size and to possible subclinical presence of the parasite in the population. The results nevertheless show that, given a more extensive trial directed at clinical validation, PCR can provide the means for early and rapid diagnosis of leishmaniasis. This should reduce morbidity and treatment costs. Further improvements to the method, its introduction in endemic settings and its possible further clinical uses are also discussed.