Caracterização epidemiológica de município sem autoctonia para leishmaniose tegumentar americana

Abstract

The knowledge about epidemiology of American Cutaneous Leishmaniasis - ACL still has gaps. The influences of environmental and peridomestic characteristics over its occurrence are not well defined. This study aimed to investigate the asymptomatic occurrence of Leishmania (Viannia) braziliensis in humans and dogs, and to evaluate the natural infection of phlebotomine vectors at Engenheiro Paulo de Frontin, a disease-free of autochthonous ACL municipality, part of an endemic region. An epidemiological inquiry was developed from march/2006 to december/2007 with the support of the Family Health Program of the Municipality Health Secretary Office in the five sanitary areas. Fifty families participated in the study, yielding a total of 95 volunteers who were exposed or not to known risk factors. Procedures involved structured interviews, Montenegro skin Test (IDRM), serology done by Enzime Linked Immunossorbent Assay (ELISA), and Indirect Immunofluorescence (IIF). All the volunteers had their dogs examined by the serology procedures and including a clinical exam. The existing environment was reported and phlebotomine sand flies were captured in the peridomestic environment to have all the present species identified. Infection by L. (V.) braziliensis was also determined by using polymerase chain reaction (PCR). Observed frequencies for positive results in humans were: 9%, 6.4% and 13.8% for IDRM, ELISA and IFI, respectively. Of 39 dogs examined, 5.1% were positive for ELISA and 23% for IFI, and from the seven species of phlebotomine sand flies captured, Lutzomyia migonei (59%) and L. intermedia (20.9%) were the most frequent. Natural infection rate of phlebotomine vectors were 5% or less, by PCR. The absence of active cases and the low percentage of positive tests found in humans and dogs, and the non-matching results, lead to the suggestion that there is no extra forest transmission of L. (V.) braziliensis in the county, despite of the high natural infection rate of phlebotomines sand flies. Large areas of preserved forests scattered around 52% of the municipality appears to be the only and main difference from the surrounding municipality, thus allowing maintenance of the ecological niches of the phlebotomine sand flies and reducing the pressure for adaptive changes.