Epidemiology of Dirofilaria immitis and Acanthocheilonema reconditum in dogs from non-endemic municipalities at different altitudes in the State of Rio de Janeiro, Brazil.

Dirofilaria immitis and Acanthocheilonema reconditum are filarial parasites transmitted to canine hosts by arthropods. This study aimed to assess the prevalence, spatial distribution, and potential epidemiological factors associated with D. immitis and A. reconditum in dogs from non-endemic municipalities at different altitudes in the State of Rio de Janeiro using qPCR. Blood samples were collected from 378 dogs from Barra do Piraí, Paracambi, Petropolis, and Teresopolis. The overall prevalence rates of D. immitis and A. reconditum were 1.32 % (5/378) and 10.58 % (40/378), respectively. The frequency of A. reconditum in Barra do Pirai was 7.4 % (8/108), while D. immitis was not detected. Paracambi exhibited frequencies of 16.66 % (15/90) for A. reconditum and 3.33 % (3/90) for D. immitis, including one co-infected animal. Petropolis had a frequency of 5.75 % (5/87) for A. reconditum and 1.15 % (1/87) for D. immitis. Teresopolis showed an A. reconditum frequency of 8.60 % (8/93), with no detection of D. immitis. Epidemiological analyses were conducted based on the positive findings for A. reconditum; however, it was not feasible to perform multivariate analyses for D. immitis because of its low frequency of occurrence. Epidemiological analysis revealed a significant association between the presence of wild animals, sex, vegetation close to the residence, and access to pasture. The frequency of A. reconditum infections emphasizes the need for differential diagnoses to prevent erroneous clinical interventions. This study highlights the presence of D. immitis and A. reconditum in non-endemic areas of autochthonous animals, necessitating further investigation into their differentiation and distribution in Brazil.