Dirofilariasis in Man

Human dirofilariasis is a rare, nonlife-threatening zoonotic disease found throughout the world where Dirofilaria sp. are common. The incidence of reports of infections is increasing, partly because of a heightened awareness of the disease by the medical profession and partly because of its spread in the definitive host in recent years. For example, in Australia canine dirofilariasis is spreading southwards, ¹ while in the U.S. there has been a recent spread into the Mississippi River valley. ² Several species belonging to two subgenera, Dirofilaria and Nochtiella, ³ of the genus Dirofilaria have been recorded infecting man. The dog heartworm, D. immitis, is usually seen in the lungs as a “coin lesion”, but has been recorded in the cardiovascular system, ⁴ subcutaneous tissue, ⁵ eye, ⁶ abdominal cavity, ⁷ and bladder. ⁸ D. repens, a subcutaneous parasite of the dog, and D. tenuis and D. ursi, natural parasites of the raccoon and bear, respectively, have been found in a variety of subcutaneous tissues of man. The name D. conjunctivae has been used to describe the subcutaneous parasite of man, but it is now accepted that D. conjunctivae is not a separate species but has been used to describe human infections with D. repens or D. tenuis. ^9,10