Leishmaniose tegumentar : influência de alterações ambientais na frequência de flebotomíneos e detecção de Leishmania

Abstract

The group of diseases collectively known as leishmaniasis is caused by protozoan parasites of the genus Leishmania, and these occur worldwide. Studies of the sandfly vectors are useful to assess the vulnerability of hosts in endemic regions, and to develop control measures. Laboratory methods should be evaluated to improve the diagnosis. This study evaluated the sandfly fauna, the natural infection rate of sandfly species by Leishmania, and the effects of environmental changes on the density of these insects. Also, the accuracy of the polymerase chain reaction (PCR) technique in diagnosing patients suspected of cutaneous leishmaniasis (CL) was estimated. An atypical case of CL is reported. Sandflies were collected in municipalities of the state of Paraná, by means of Falcão and Shannon traps, during severalstages of the study. Changes were made in the local environment (peridomiciles and animal shelters) between collections, in order to reduce the frequency of sandflies in the domiciles. Some female sandflies, after dissection and identification of the species, were subjected to multiplex PCR to detect Leishmania (Viannia). Samples from patients suspected of CL were examined by means of PCR, to detect Leishmania (Viannia). Subsequently to the environmental changes, the sandflies were collected mainly in domestic-animal shelters. Although none of the dissected females showed flagellates, DNA of Leishmania (Viannia) was detected by multiplex PCR in 0.46% of the specimens of Nyssomyia neivai and in 1.12% of the specimens of Nyssomyia whitmani. Among patients with CL, 83.87%, 51.67%, 64.52%, 85.71% and 96.10% were positive in the PCR of lesion (PCR-L), PCR blood (PCR-B), directparasite search, Indirect Immunofluorescence and Montenegro skin test, respectively. In five patients only the PCR-L was positive, and in two other patients only the PCR-B was positive. It is important to keep the peridomestic environment clean in order to prevent the formation of sandfly breeding sites. Ny. neivai and Ny. whitmani are susceptible to infection byLeishmania. The multiplex PCR technique, because of its specificity, sensitivity and feasibility, can be used in epidemiological studies to assess natural infection rates. PCR-L is indicated in patients with chronic lesions or reinfection with Leishmania, which can progress to mucosal lesion. PCR-B is indicated in patients with negative results from conventional tests, or for patients without lesions or with atypical lesions.