Use of sentinel animals to demonstrate active leishmanial transmission in an area with low frequency of human lesions in Western Venezuela

RESUMO

One-hundred healthy animal of differents species, including dog (8), fox (1), donkey (1), goat (1), opossum (3), rabbit (8), hamster (33) and guinea pig(45), kept under natural conditions, were used as sentinel animals (SA) to prove active and constant leishmanial transmission, in an area where human cutaneous lesions are rarely observed. The investigation was carried out in a field station located at the Andean region of Western Venezuela, where both sand flies species and Leishmania-parasites have been perviously reported. The study consisted of a follow-up using serological techniques. Blood samples from the SA were taken monthly and the sera processed to demonstrate seroconversion by detecting anti-Leishmania circulating antibodies (Abs). In 56 percent of the used animals belonging to 8 species of susceptible mammals, seroconversion was detected during the time of observation. To corroborate the serological results, 68 serum samples were selected for a PCR assay with 32 (47 percent) of them showing positive results. The results indicate that combination of seroconversion and PCR in SA are useful tools to demonstrate constant and active Leishmania transmission in areas where clinical manifestation is uncommonly observed in the human population. The potential of using SA as a promising method to investigate leishmanial activity under field conditions is stressed and the epidemiological implications of the present findings is discussed.