At least 19 people in three Midwestern states have contracted a
disease related to smallpox, marking the first outbreak of the
life-threatening illness in the United States, federal heath
officials said yesterday.
The federal Centers for Disease Control and Prevention, concerned
that the illness could spread, issued a nationwide alert to doctors
and public health officials to be on the lookout for more cases.
"We have an outbreak," said James Hughes, director of the CDC's
National Center for Infectious Diseases in Atlanta. "I'd like to
keep it relatively small. I don't want any more cases. We're doing
everything we can to try to contain this."
The disease, known as monkeypox, usually only occurs in central
and western Africa. It is caused by a virus known as an orthopox
virus, which is the family of viruses that includes the smallpox
virus, one of the most dangerous diseases known to man and a feared
Officials said there was no indication that bioterrorism was
involved. The disease was apparently spread by rodents known as
prairie dogs, which have become popular as pets. The animals may
have acquired the infection from another creature, known as a
Gambian giant rat, sold by the same dealer of exotic animals,
The monkeypox virus causes symptoms that are very similar to
smallpox -- fever, headache, cough and an extremely painful rash of
pus-filled sores that spreads across the body.
While much about the monkeypox virus is unclear, it does not seem
to be as deadly as smallpox. Authorities estimate that monkeypox has
a mortality rate of between 1 percent and 10 percent, compared with
a mortality rate of about 30 percent for smallpox.
The monkeypox virus is believed to spread through physical
contact with a sick person or infected animal, or through infected
body fluids, although health officials said it apparently is not as
easily spread as smallpox, which is highly infectious.
Monkeypox is untreatable, although there is some indication that
an antiviral drug may have some usefulness. Because the disease has
never been seen before in this part of the world, the severity of
the threat is not completely clear. All patients and infected
animals have been isolated -- and pet shops and one house where the
prairie dogs lived have been quarantined -- to prevent spread of the
The smallpox vaccine is believed to be protective against the
monkeypox virus. The federal government recently launched a campaign
to vaccinate thousands of emergency workers against smallpox so the
country would be prepared in the event of a bioterrorist attack.
"This is an unusual event. As far as we can tell, there's never
been a human or animal illness in the community setting in the
Western hemisphere by a virus that is either a monkeypox virus or a
very close variant of the monkeypox virus," said Hughes, who held a
hastily arranged telebriefing last evening to announce the outbreak
after CDC scientists confirmed that a monkeypox virus or one very
close to it was involved.
"We've got a disease that's not been seen before in the Western
Hemisphere, so it's prudent to take it very seriously," Hughes said
in a telephone interview after the briefing.
Of the 19 cases reported so far, four of the victims have been
hospitalized; none has died, Hughes said.
The outbreak came to light on May 16, when a 3 1/2-year-old child
became ill, according to John Melski, who treated the child at the
Marshfield Clinic in Marshfield, Wis.
The child's parents had bought two prairie dogs as a Mother's Day
present for the child's mother. Both the mother and father
subsequently became ill as well, although all appear to have
Officials determined that the prairie dogs had been purchased
from a Villa Park, Ill., exotic pet dealer, who also became ill. The
dealer also had a Gambian rat, which was ill. It is believed that
animal passed the virus to the prairie dogs the dealer was selling.
The dealer sold the animals to SK Exotics, a Milwaukee pet
distributor, which then sold the apparently infected prairie dogs to
two pet stores in Milwaukee and at a "pet swap" in northern
Most of the rest of the cases have been reported in the Milwaukee
area, and are believed to have involved people who either worked at
the stores or who handled the animals in the stores. Seventeen of
the cases occurred in Milwaukee, with one case each having been
reported in Illinois and Indiana.
Melski and his colleagues at the Marshfield Clinic contacted
state health officials when they identified what appeared to be an
orthopox virus in the sick family. State health officials then
contacted the CDC, which confirmed the involvement of a
monkeypox-like virus yesterday, prompting the nationwide alert and
The state of Wisconsin has temporarily banned the sale of prairie
"The full impact is hard to predict," said Seth Foldy,
Milwaukee's health commissioner. "Our goal would be to isolate and
eliminate the virus from both human and animal populations to the
best of our ability. We do not know if it is the kind of agent that
would or could thrive in North America, and we're not very
interested in finding out that it is."
The last time a new infectious disease arrived in the United
States was in 1999, when the West Nile virus was first reported.
That disease, which is transmitted by mosquitoes, has since spread
Further tests are planned to confirm the identity of the pox-like
The outbreak comes as the global epidemic of severe acute
respiratory syndrome (SARS) appears to be coming under control.
"This is yet another reminder of why it's important to learn as
much as you can about diseases that occur in faraway places," Hughes