Canine visceral leishmaniasis in Barra de Guaratiba, Rio de Janeiro, Brazil: assessment of risk factors

Abstract

Barra de Guaratiba is a coastal area of the city of Rio de Janeiro where American visceral leishmaniasis (AVL) is endemic. Although control measures including killing of dogs and use of insecticides have been applied at this locality, the canine seroprevalence remains at 25% and during 1995 and 1997 eight autochthonous human cases were notified. In order to evaluate factors related to the increase of the risk for Leishmania (Leishmania) chagasi infection in dogs we have screened 365 dogs by anti-Leishmania immunofluorescent antibody test (IFAT) and captured sandflies in the domestic and peridomestic environment. Some variables related to the infection were assessed by uni- and multivariate analysis. The distance of the residence from the forest border, its altitude and the presence of the opossum Didelphis marsupialis in the backyard, were found predictor factors for L. (L.) chagasi infection in dogs in Barra de Guaratiba. The presence of Lutzomyia longipalpis in the peridomestic environment indicates the possibility of appearence of new human cases. Our data also suggest the presence of a sylvatic enzootic cycle at this locality.

Fatores ambientais associados à ocorrência de leishmaniose visceral canina em uma área de recente introdução da doença no Estado do Rio de Janeiro, Brasil

“…There was no association between L. infantum infection and the dog's sex, age, or degree of confinement, corroborating other studies 24,34,35,36,37 . The household's proximity to forest areas also failed to show an association with L. infantum infection.…”

“…CVL prevalence in this study (21.65%) was similar to rates in Rio de Janeiro State both in areas of recent introduction (25.2% in Itaipuaçu, Maricá; 18.1% on Ilha de Marambaia, Rio de Janeiro) and in areas classified as endemic (25% in Barra de Guaratiba, Rio de Janeiro) 15,23,24 , notwithstanding differences in methodologies. Prevalence rates can vary due to the diagnostic test used and the way dogs were recruited for the study 25 The geographic expansion of CVL has been recorded in other states of Brazil, attributed to various factors such as difficulties in eliminating reservoirs, epidemiological diversity of the affected regions, high financial costs of sustaining control measures, the vector's high capacity to adapt to the peridomicile, and insufficient control measures 26 .…”

Transmission, reservoir hosts and control of zoonotic visceral leishmaniasis

“…The failure of dog culling to reduce the number of human cases in Brazil has been suggested to indicate the existence of other reservoirs, but this failure can be readily explained by logistical and dog demographic factors (see below). Risk factor studies can suggest sylvatic reservoirs, such as the association between human infection and opossums in a Brazilian study (Cabrera et al 2003), but ruling out other confounding factors is essential. Spatial scale is also important for risk factor studies since the vector is mobile : there is often no association between human infection and dog ownership at the household level, whereas such an association is more likely observed at the village level, as demonstrated in Iran (Mazloumi Gavgani et al 2002 b).…”

Leishmaniose visceral canina em Maricá, Estado do Rio de Janeiro: relato do primeiro caso autóctone

“…Souza e cols 12 detectaram Lutzomyia intermedia em Inoã, no entanto, L. longipalpis ainda não foi descrita nessa localidade. A proximidade da residência do animal com a mata favorece o contato com animais sinantrópicos, que podem atuar como elo de transmissão de Leishmania chagasi 1 .…”