Frequency of Dirofilaria immitis infection in blood donor dogs of the Rio de Janeiro state

Dirofilariasis, a parasitic disease caused by the nematode Dirofilaria immitis, commonly known as heartworm, primarily inhabits the pulmonary artery and right heart of dogs and other animals. The disease is transmitted through diptera, predominantly from the Culex, Aedes, and Anopheles genera. Dirofilariasis is cosmopolitan in nature, endemic in coastal regions and tropical climates. Factors such as temperature, humidity, vector density, and the presence of definitive hosts significantly contribute to the spread of this parasitic disease. In the state of Rio de Janeiro, a prevalence of 58.6% of D. immitis infected animals has been recorded in municipalities like Niterói. Given that blood transfusions are routine clinical procedures and blood bags are not always accurately evaluated, an investigation into D. immitis infection in blood donor dogs from the metropolitan region of Rio de Janeiro was conducted. A total of 1044 blood donor dog files from a blood bank in Niterói, RJ, collected from January 2019 to December 2022, were analyzed. These samples, originating from kennels in various municipalities in the Metropolitan Region, were tested for the presence of microfilariae through direct examination using tubes and microhematocrit evaluated in optical microscopy. Additionally, the search for antigens was conducted using the enzyme-linked immunosorbent assay technique. Out of the 1044 records evaluated, 17.8% (186/1044) were positive for heartworm infection, with 2% (21/1044) samples positive for microfilariae and 14.8% (154/1044) positive for D. immitis antigens. The high prevalence rate indicates that canine D. immitis infection remains prevalent in the state of Rio de Janeiro, necessitating effective guidelines for prescribing preventive medications by veterinarians and an increase in epidemiological surveillance in the region.