Detection of Dirofilaria repens microfilariae in a dog from Portugal

Dirofilaria repens causes subcutaneous infection in dogs and cats, and is the main agent of human dirofilariosis in Europe. Detection of D. repens is described in a dog from Portugal, a finding that simultaneously represents the first presumable case of autochthonous infection with the parasite in any animal host species in the country. A mixed D. repens/Dirofilaria immitis infection (20:1 ratio) was found, with an overall density of 1267 microfilariae per millilitre of blood. Morphological features, including morphometry, and acid phosphatase histochemical staining confirmed identity of the two filarioids. Distribution of D. repens in Portugal should be further assessed at the population level both in vertebrate hosts and in vectors. Due to the zoonotic potential of the parasite, preventive measures such as the administration of microfilaricides and insect repellents should be put into practice to protect animals and public health.