The Canary Islands as a model of risk of pulmonary dirofilariasis in a hyperendemic area.

We assessed the risk of human pulmonary dirofilariasis in the Canary Islands, hyperendemic for canine heartworm (Dirofilaria immitis), a zoonotic vector-borne infection. For this purpose, 1479 inhabitants were tested for anti-D. immitis antibodies. Four of the 7 islands presented high seroprevalences (from 6.2 to 12.7%), therefore high exposure to the parasite and risk of zoonotic infection. These corresponded to those islands with high canine prevalences of dirofilariasis and favourable climatic conditions for the development of mosquito vectors. The lowest prevalences (from 0 to 1.6%) were found in the desert islands and those with low canine prevalences of heartworm. Seroprevalences were very variable inside each island as well, being related to the climate and demographic factors. Human pulmonary dirofilariasis is an emerging zoonosis worldwide which frequently goes undiagnosed. Serological studies could be useful for the correct evaluation of the risk of infection among the human population, and study of the health implications of the continuous contact with the parasite in endemic areas. Sanitary authorities should be aware of the current epidemiological data, and physicians should include human dirofilariasis in the differential diagnosis of pulmonary nodules.