Canine filariosis in Umbria: an update of the occurrence one year after the first observation of autochthonous foci.

Following the first observation of two autochthonous foci of canine filariosis occurred in Umbria region in the year 2001, a survey on prevalence and risk factors was conducted 12 months later to better understand the actual entity of the Dirofilaria problem in Umbria region. Blood samples were collected between January and December 2002 from 2406 dogs living in a total of 7 towns located in the identified areas at risk. Blood samples were tested by a modified Knott's technique to evaluate the microfilaraemia and, by a commercial ELISA kit, to detect in the sera adult antigens of D. immitis. The results were subject to statistical analysis. A total of 439 dogs were found to be infected. The true prevalence (LC 95%) was of 18%. Microfilariae of D. immitis were detected in 286 dogs (13%) while 112 dogs (6%) showed only microfilariae of D. repens and 41 dogs (1.6%) microfilariae of both D. immitis and D. repens. The prevalence ratio (PR) for each species of Dirofilaria (LC 95%) calculated in association with different risk factors (age, sex, use, outdoor night status, position, living together with other dogs, breed) and the statistical significance between the risk factors and the presence/absence of the infection, evaluated for each species of Dirofilaria, are discussed.