Un total de 50 caninos de áreas rurales de los estados Lara, Yaracuy, Carabobo y Falcón, Venezuela, fueron examinados visualmente y mediante palpación cutánea con el fin de detectar la presencia de garrapatas. Ninguno de los animales se encontró parasitado por Rhipicephalus sanguineus, la garrapata común del perro. Se colectaron 139 especimenes adultos del género Amblyomma Koch, 1844: 72 hembras y 65 machos de la especie Amblyomma ovale Koch, 1844, y dos hembras de la especie Amblyomma triste Koch, 1844. La identificación de los especimenes se realizó mediante observación en lupa estereoscópica y con la ayuda de claves taxonómicas. Los Estados donde se colectó el mayor número de ixódidos fueron Falcón con 52 especimenes y Lara con 49, representando 38 y 36%, respectivamente. A. ovale ha sido reportada como vector natural de Hepatozoon canis en áreas rurales. La especie A. triste fue colectada sólo en un canino del estado Yaracuy. Esta especie ha sido incriminada como el vector biológico de varios agentes rickettsiales patógenos, tanto para humanos como para animales domésticos y salvajes, por lo que se resalta la importancia del género Amblyomma en la transmisión de enfermedades zoonóticas.

Fifty dogs from the rural areas of Lara, Yaracuy, Carabobo and Falcón States of Venezuela were sampled through the visual and touch techniques in search of the presence of ticks. All the dogs were free of the brown dog tick Rhipicephalus sanguineus. A total of 139 adult ticks of the genus Amblyomma Koch, 1844 were collected: of them, 65 males and 72 females were identified as Amblyomma ovale Koch, 1844, whereas two females belonged to the species Amblyomma triste Koch, 1844. The observation through stereomicroscope, as well as the use of taxonomic keys, were employed in the identification of the collected specimens. Most of the ticks were collected in Falcón and Lara States, totalling 52 (38%) and 49 (36%), respectively. The species A. ovale has been reported as a natural vector of the protozoan Hepatozoon canis in rural areas. A. triste was collected only in one dog in Yaracuy State. This species has been incriminated as a biological vector of several rickettsial agents to the men and animals. The actual role of the genus Amblyomma as vector of zoonotic disease agents is highlighted.

This study investigated rickettsial infection in animals, humans, ticks, and fleas collected in five areas of the state of São Paulo. Eight flea species (Adoratopsylla antiquorum antiquorum, Ctenocephalides felis felis, Polygenis atopus, Polygenis rimatus, Polygenis roberti roberti, Polygenis tripus, Rhopalopsyllus lugubris, and Rhopalopsyllus lutzi lutzi), and five tick species (Amblyomma aureolatum, Amblyomma cajennense, Amblyomma dubitatum, Ixodes loricatus, and Rhipicephalus sanguineus) were collected from dogs, cats, and opossums. Rickettsia felis was the only rickettsia found infecting fleas, whereas Rickettsia bellii was the only agent infecting ticks, but no animal or human blood was shown to contain rickettsial DNA. Testing animal and human sera by indirect immunofluorescence assay against four rickettsia antigens (R. rickettsii, R. parkeri, R. felis, and R. bellii), some opossum, dog, horse, and human sera reacted to R. rickettsii with titers at least four-fold higher than to the other three rickettsial antigens. These sera were considered to have a predominant antibody response to R. rickettsii. Using the same criteria, opossum, dog, and horse sera showed predominant antibody response to R. parkeri or a very closely related genotype. Our serological results suggest that both R. rickettsii and R. parkeri infected animals and/or humans in the studied areas.