MADISON, Wis. — A Wisconsin nurse may have contracted monkeypox from a patient in what would be the first known case of the disease spreading from one person to another in the United States, officials said Thursday.
Wisconsin state epidemiologist Jeff Davis said health officials are testing tissue specimens to confirm whether the unidentified health-care worker is infected with the exotic African virus.
Until now, health officials investigating the weeklong outbreak in the U.S. have said that the virus was being spread by pet prairie dogs. But the disease can also be transmitted from one person to another, something that has happened in Africa.
"In this case there was no animal exposure," Davis said of the health-care worker. "The only contact was with a human."
Davis would not release other details, but Patrice M. Skonieczny, infection control coordinator at St. Francis Hospital in Milwaukee, said the sick worker is a nurse at the hospital.
Skonieczny said the nurse cared for a Milwaukee pet distributor who was being treated for a possible case of monkeypox. The nurse wore a mask, gloves and a gown when treating the patient, Skonieczny said.
Last weekend, several days after caring for the patient, the nurse developed flu-like symptoms and a rash, but they "kind of faded away in a couple of days," Skonieczny said. The nurse has stayed home since developing the symptoms, she added.
Officials at the federal Centers for Disease Control and Prevention said Thursday they are looking into the report of human-to-human transmission.
"The issue right now is it's still early. We have not completed testing," CDC spokesman Llelwyn Grant said.
Herb Bostrom, director of the Wisconsin Bureau of Communicable Diseases, suggested that the finding is not necessarily reason for alarm.
Monkeypox "spreads much more readily from animals to humans than it does from human to human," Bostrom said. "You're not going to get it from somebody sitting on the bus or walking down the hall."
As of Thursday, U.S. health officials had confirmed 12 human cases of the disease: four each in Wisconsin, Indiana and Illinois. Also, 54 possible cases had been reported -- 25 in Indiana, 17 in Wisconsin, 11 in Illinois and one in New Jersey.
No one has died from the disease in the United States.
Davis said the prairie dogs appear to be infecting people through bites or when people touch discharges from the animals and then rub their eyes or noses. The Wisconsin health worker may have contracted the illness before word of the monkeypox outbreak became public last week, Davis said.
Monkeypox, a disease never before seen in the Western Hemisphere, is related to smallpox but is not as lethal. It causes blisters, rashes, chills and fever.
Federal health officials have traced the outbreak to prairie dogs distributed by Phil's Pocket Pets of Villa Park, Ill. The prairie dogs were apparently infected at the business by a Gambian giant rat, officials said.
Prairie dogs from Phil's Pocket Pets may have been sold to numerous buyers in 15 states, according to investigators.
On Wednesday, the government recommended smallpox vaccinations for people exposed to monkeypox.