Canine and feline dirofilariosis in a highly enzootic area: first report of feline dirofilariosis in Greece

Dirofilaria immitis (heartworm) is enzootic in many areas of the world and quite prevalent in southern European countries. Although dogs are the main host of the parasite, cats may also be infected, and the prevalence of feline dirofilariosis is associated with the respective prevalence of canine infection in any given area. The aim of the present study was to investigate the proportion of D. immitis infection among dogs and cats that were not under any kind of prophylactic treatment and were living in a heartworm enzootic area. In total, 180 stray animals (148 dogs and 32 cats) living in a shelter in Northern Greece were examined for heartworm infection by the Knott’s test and serology (antigen and in cats also antibody detection), and additionally echocardiography in the infected cats. Thirty-seven (25%, CI 18.7–32.5%) of the dogs and 3 (9.4%, CI 3.2–24.2%) of cats were found to be positive, by at least one of the tests applied. In 2 of the infected cats, the parasites were also detected by echocardiography. One of the positive cats died suddenly 1 year after diagnosis and at necropsy two decomposing D. immitis were found in the right ventricle and pulmonary artery. This is the first report of confirmed feline dirofilariosis in Greece. The detected proportion of infection in cats was 38% of the respective canine infection in the examined shelter. The results of the present study underline the high risk of infection of cats living in enzootic areas and the imperative character of preventive measures in such conditions.