DESCRIPTION OF THE OCCURRENCE OF CANINE DIROFILARIASIS IN THE STATE OF RIO-DE-JANEIRO, BRAZIL

In order to evaluate the prevalence of canine heartworm in the State o f Rio de Janeiro, a multicenter survey was carried out in two phases. The survey involved 1376 dogs from two cities: Rio de Janeiro and Nite roi, and its surroundings, including the eastern shore and mountain re sorts, which were further divided into sections. In the first phase, 7 95 dog blood samples were examined by the modified Knott test for the detection of microfilariae. A total of 134 samples (16.85%) were micro filaremic: 8.61% from Rio de Janeiro, 21.76% from Niteroi and its surr oundings, 33.33% from the eastern shore and 30.43% from the mountain r esorts. In the second phase, 595 dog blood samples were examined first by the modified Knott test and the amicrofilaremic samples were subse quently examined by an immunoenzymatic test (ELISA) for antigen detect ion. In summary, 83 samples (13.95%) were microfilaremic and 44 (7.98% ) of the amicrofilaremic samples were positive for heartworm antigen ( occult infections). In Rio de Janeiro, 13.68% of the dogs were infecte d (i.e., antigen-and/or microfilaria-positive) and 8.51% of the dogs h ad microfilaremic infections. In comparison, Niteroi and its surroundi ngs showed values of 24.46% and 17.30% and the eastern shore showed va lues of 52.46% and 31.15%. lit contrast the mountain resorts showed 20 % microfilaremic only.