Dogs infected by Dirofilaria immitis: a threat to the health of human and non-human animals in Rio de Janeiro, Brazil

This study aimed to investigate the presence of Dirofilaria immitis microfilaremia in dogs from two regions of the state of Rio de Janeiro, Brazil, where heartworm infections are highly prevalent. Blood samples were collected from dogs aged > 12 months, independent of the use of preventatives. All samples obtained and analyzed using Knott's modified test by the investigators. A total of 133 blood samples were tested, and D. immitis microfilariae were detected in 29 of them, resulting in an occurrence of 21.8%. The percentage of dogs with microfilaremia detected raises concerns for pet families, one health professionals, and small animal practitioners. Microfilaremic dogs are the richest source of infection for the mosquitoes, increasing the risk of transmission. Therefore, the stakeholders in One Health must raise concerns regarding the health of wild animals, as wild canids and other species of wild animals are exposed to the risk of D. immitis infection. In addition, humans can get infected and develop human pulmonary dirofilariasis. In conclusion, the presence of dogs with microfilaremia potentiates opportunities for D. immitis transmission, exposing all animals, wild or domestic, human or non-human to the disease.