People can develop skin lesions from goats and sheep infected with the orf virus through meat preparation or when slaughtering the animals, a U.S. federal health agency warned on Thursday in a report.

The report, mainly directed at doctors in ethnically diverse communities, said that the orf virus, which is sometimes misdiagnosed as a more severe disease like anthrax, typically spreads to humans on farms, according to the U.S. Centers for Disease Control and Prevention.  The agency said the virus has also been reported in children who visited petting zoos and livestock fairs.

However the latest report emphasized the virus could also be contracted when processing infected sheep or goat meat for household use or when slaughtering the animals by describing four such cases. 

"In ethnically diverse communities, health-care providers might be unaware of patients having this type of animal contact and of the seasonal increases in contact associated with religious events," the report said. "The popularity of hobby farming and home butchering also increases opportunities for household orf exposures."

The report said that in April 2011, a 35-year-old man in Massachusetts cut his left thumb with a knife while slaughtering a lamb for s part of Easter festivities.  The man had washed and disinfected his wound, but he later suffered a thumb lesion. 

In another more recent case in June 2011, a 28-woman in Virginia had cut her right hand while preparing a Sudanese lamb dish that was bought from a local butcher and later small dime-sized crusted lesions appeared on her right palm near her wrist. 

“Although human orf cases most commonly are reported as a result of occupational exposure to infected sheep and goats, household meat preparation and animal slaughter also pose risks for orf infection,” the CDC noted.

Doctors should be knowledgeable about household risks and should be able to recognize signs of orf infection, the CDC said.  Human orf lesions typically appear on fingers, ands, or forearms three to seven days after being exposed.  They lesions typically progress from a small bump on the skin to a large nodule with a red center, white halo inflamed bump that weeps, ulcerates, and crusts over.

Most lesions heal within a few weeks and treatment consists of basic wound care, and often cases like these might be misdiagnosed leading to unnecessary treatment of orf lesions, which do not usually require any specific treatment, the report said.