The first
documented case of human Dirofilaria infection occurred in 1887
by de Magalhaes, who reported a subcutaneous infection in a male child
from Brazil. In the United States, the first case of subcutaneous
dirofilariasis to be reported occurred in 1941 in New Orleans, in which
Dirofilaria
infection was discovered in a female cadaver (Shah).
Before this, although D. immitis was known to be the infectious
agent of dog heartworm, it was not thought that members of the genus, Dirofilaria,
were capable of infecting humans.
The first
case of human pulmonary dirofilariasis was not reported until 1961 (Shah).
Before this (mainly in the 1950s), chest x-ray examinations showed pulmonary
nodules in many patients, which were misdiagnosed as carcinomas.
Surgical resection of these nodules revealed immature filariae within the
nodules. When these cases were later reviewed, the filariae were
identified as D. immitis.