Ixodofauna e circulação de Rickettsia parkeri em cães na região de Guaxupé em Minas Gerais

Abstract

Ticks are hematophagous ectoparasites of extreme importance to public, human, and animal health, acting as vectors for many diseases, such as spotted fever. In Brazil, a wide variety of tick species is found distributed across different biomes and climates, with the genus Am-blyomma holding the greatest importance regarding public health. Considering its significance, recent studies highlight the relevance of Amblyomma ovale, which is responsible for harboring and transmitting the bacteria Rickettsia parkeri strain Atlantic rainforest. This bacteria causes a variant of Brazilian spotted fever that is, however, non-lethal and presents milder symptoms. Considering the dog as an important host for the adult stages of Amblyomma ovale, along with the interface between humans, dogs, and the Atlantic Forest, the favorable biome for this tick, we will seek to evaluate the occurence of this ectoparasite in the city of Guaxupé, Minas Gerais. Additionally, we aim to determine the presence of Rickettsia parkeri strain Atlantic rainforest in both ticks and host dogs with access to forest areas within the municipality. A total of 188 ticks were collected from 30 dogs, R. sanguineus linnaei (adults, n = 113), follo-wed by A. ovale (adults, n = 67), A. sculptum (nymphs, n = 4; adult, n = 1), and R. microplus (adults, n = 3). Of the 30 dogs with evaluated serology, 46.9% were seroreactive to R. parkeri, 50% to R. rickettsii, and 21.9% to R. bellii. The highest titers were found in 5 dogs for R. par-keri: 2 with a titer of 1024, 1 with 2048, and 2 with 4096. No amplification was observed for any rickettsial gene in the ticks subjected to DNA extraction and PCR. The tick with the highest intensity and abundance of infestation was R. linnaei, which is associated with dogs exhibiting more domiciled behavior, while the most prevalent was A. ovale, thus indicating the dogs' frequent access to humid forest areas, the habitat of this tick species. The occurrence of A. sculptum nymphs is associated with the study period coinciding with its peak activity sea-son and the predominance of this stage in dogs, and the R. microplus found is associated with the roaming behavior of dogs, accessing areas with cattle circulation, the host of this species. The dogs' serology showed high reactivity to spotted fever group (SFG) bacteria, with the highest titers for R. parkeri CMA. The correlation between dogs with high titers for R. parkeri CMA and the prevalence of A. ovale may indicate Guaxupé (MG) as a probable risk area for Atlantic rainforest spotted fever.