Four monkeypox cases confirmed in Wisconsin
Another 29 suspected infections being monitored
(CNN) -- Health officials have confirmed four cases of monkeypox and are watching another 29 suspected cases in the Midwest in what is believed to be the first outbreak among humans in the Western Hemisphere.
No human deaths have been reported, and there has been no sign yet of monkeypox being transmitted from person to person, said Dr. Steve Ostroff, an official with the Centers for Disease Control and Prevention.
Authorities suspect that the disease was passed to humans by prairie dogs sold by a pet distributor in Wisconsin. All four confirmed cases are in Milwaukee, said Raquel Madrid-Berkel, a spokeswoman for the city's Health Department.
"At this point, there is no vaccine for monkeypox," she said. "[The suspected cases are] being monitored on a daily basis, and they're requested to be isolated in their home."
Six people have been hospitalized, and one has been released after treatment. Ostroff, the deputy director of the National Center for Infectious Diseases in Atlanta, Georgia, said he expects that other cases will be confirmed soon.
"We certainly do expect to have additional results today on additional human and animal specimens," he said.
Of the 33 total cases under scrutiny, 18 are in Wisconsin, 10 are in Indiana, and five more are in Illinois, Ostroff said. Most victims have suffered rashes that he called "fairly characteristic" of the disease.
"The vast majority of these individuals have also experienced fever," he said. "More than half of them have also had respiratory symptoms."
Monkeypox occurs primarily in the rain forests of Central and West Africa. Symptoms include fever, chills and coughing, followed by a rash. Symptoms can be accompanied by diarrhea, swollen lymph nodes, a sore throat and mouth sores, and in some cases, a victim might have trouble breathing.
It is similar to but less infectious than smallpox. Monkeypox is typically fatal in 1 percent to 10 percent of human cases, the CDC said.
According to the CDC, the pet distributor got the animals from an Illinois distributor who had kept the prairie dogs in a container with a Gambian rat, another popular rodent pet. Health officials said they suspect the rat was the source of the infection because tests have shown Gambian rats have antibodies to monkeypox.
Close contact with prairie dogs or Gambian rats could put people at risk, Dr. James Hughes, director of the National Center for Infectious Diseases at the CDC, said Sunday.
"It's very important that a physician, veterinarians and the public should be aware of this very unusual outbreak and be on the lookout for symptoms," he said. "The public, if they experience illness in themselves or family members, should report this promptly to their physicians."
Monkeypox, first recognized in 1971, has been shown to be susceptible to Cidofovir, an antiviral agent used to treat smallpox, said Dr. Peter Jahrling, a scientific adviser for the U.S. Army Medical Research Institute for Infectious Diseases.