In 2009, the CDC confirmed infections with parapoxvirus in two deer hunters in the eastern U.S., according to a brief report.
As is typical of human parapoxvirus infection, lesions and eventually nodules developed slowly on both individuals' fingers where they had nicked themselves while field-dressing deer that appeared healthy at the time of death, Inger Damon, MD, PhD, of the CDC, and colleagues reported in the Dec. 30 issue of the New England Journal of Medicine.
Such infections may become more common as deer populations continue to increase, putting them in greater contact with both humans and cattle, according to the researchers.
Human infection with parapoxviruses -- which results from direct contact with infected ruminants, including cattle, goats, sheep, and deer -- can be an occupational risk for farmers, animal healthcare providers, and others who have close contact with animals, and can be prevented through the use of protective equipment, especially gloves.
If prevention fails, "anecdotal data suggest that imiquimod may be effective in the treatment of parapoxvirus infection in patients with underlying health conditions, to prevent the spread of virus, autoinoculation, and the need for surgical debridement," the authors wrote.
How widespread parapoxvirus infection is in humans is unclear because there is little surveillance of domestic animals and wildlife, and infections may be underreported because they might not necessarily require medical intervention. Three cases previously reported to the CDC were related to deer, two with direct contact and one with close proximity.
Damon and her colleagues described the two 2009 cases, which were characteristic of parapoxvirus infection, beginning with an incubation period of three to seven days, followed by the development of one or more erythematous maculopapular lesions that, over the course of several weeks, developed into nodules.
The first case was a 52-year-old wildlife biologist who cut his finger while dressing a white-tailed deer in eastern Virginia. There were no lesions on the animal's muzzle or head.
The cut would not heal and within two weeks, a tender raised area began to form at the injury site. Within a month, it had enlarged to form a violaceous nodule, at which point the hunter sought medical attention.
The nodule was excised, and no bacteria, atypical mycobacteria, or fungal pathogens were found in the specimen. The wound appeared to be healing normally, but about two months after the initial cut, the lesion recurred. It was excised again, and the specimen was sent to the CDC. The wound healed, but the hunter reported lingering mild pain about eight months after the injury.
In the second case, that of a 60-year-old hunter from Connecticut who cut his finger while field-dressing a white-tailed deer, the infection followed a similar course. About seven weeks after the injury, the patient sought treatment for a violaceous nodule.
The lesion was biopsied, and a histopathological examination revealed intracytoplasmic viral inclusions within keratinocytes, suggestive of poxvirus infection. The specimen was sent to the CDC.
At CDC, electron microscopy, histologic examination, and genetic analysis revealed that both infections were caused by a unique strain of parapoxvirus.
Primary source: New England Journal of Medicine
Source reference: Roess A, et al "Novel deer-associated parapoxvirus infection in deer hunters" N Engl J Med 2010; 363: 2621-2627.