MOSQUITO FREQUENCY AND FEEDING-HABITS IN AN ENZOOTIC CANINE DIROFILARIASIS AREA IN NITEROI, STATE OF RIO-DE-JANEIRO, BRAZIL

Heartworm, a chronic fatal mosquito-borne canine disease, is frequentl y diagnosed in dogs from the State of Rio de Janeiro, where its preval ence is 29.7% in the city of Niteroi. Nevertheless it is rarely detect ed in cats (0.8%) from the same state. Dogs are the primary source of infection to mosquitoes, because cats either do not demonstrate microf ilaremia or it is too low and transient for transmission. A mosquito s urvey was conducted in Itacoatiara, Niteroi, from March 1995 to Februa ry 1996, using canine, feline and human baits. A total of 21 mosquito species (3,888 females) was collected and biting frequency was highest at dusk. The four species collected most frequently (88.9%) were: Aed es taeniorhynchus (30% of the total catch; with the peak in May/June); Culex quinquefasciatus (22.5%; August/October); Aedes scapularis (19. 4%; August, October/November and January) and Cutex declarator (17%; N ovember/January). Human baits were attractive to these species and dog s were significantly more attractive to them than cats. Ae. taeniorhyn chus, Cx. quinquefasciatus, Ae. scapularis, Cx. declarator and Cx. nig ripalpus are the most likely mosquito species to transmit Dirofilaria immitis parasites to dogs and may transmit the parasite to humans. It is also suggested that the vector to cats belongs to the genus Culex.