Image: Monkey Pox Lesions
The hand of a patient with monkeypox is shown June 5 in this CDC photo. An extensive rash consisting of raised bumps filled with fluid is one of the primary symptoms of the illness.
msnbc.com staff and news service reports
updated 10/31/2003 6:18:46 PM ET 2003-10-31T23:18:46

Public health authorities are scrambling to combat the United States’ first outbreak of monkeypox, even going so far as to announce a controversial recommendation of smallpox vaccinations for people who may have been exposed. Monkeypox has never before been found outside of Africa, and many questions about the virus still linger.

What is monkeypox?

Monkeypox is a rare virus related to smallpox — both belong to a group called orthopoxviruses, which also includes the cowpox virus and the virus used to make the smallpox vaccine (vaccinia). The virus is called “monkeypox” because it was first identified in 1958 in laboratory monkeys. Scientists later discovered that other animals can contract the monkeypox virus, including squirrels, rats, mice and rabbits.

The illness was first identified in humans in 1970 and is usually only found among villagers in remote tribes of Central and West Africa. The outbreak in the Midwest marks the first time the disease has been reported outside of Africa.

How is it transmitted?

In Africa, the disease is usually transmitted to people from squirrels and primates through a bite or contact with the animal’s blood. The U.S. Centers for Disease Control says the virus was transmitted to humans in the Midwest through close contact with infected prairie dogs, which were being kept as pets. The prairie dogs had likely been infected by a sick Gambian rat imported from Ghana at a Chicago pet store.

In general, people can get monkeypox from a sick animal if they are bitten or if they touch the animal’s bodily fluids or its rash.

The illness can also spread through close contact with a sick person. A person’s respiratory droplets can transmit the virus, as can their body fluids or contaminated objects, such as clothes or bedding.

What are the symptoms?

In humans, monkeypox begins with fever, exhaustion, headache, muscle aches, backache, swollen lymph nodes and general discomfort. One to three days after the fever starts, the patient develops an extensive rash consisting of raised bumps filled with fluid. The rash often starts on the face and then spreads to other parts of the body. Eventually the bumps scab over and fall off.

The disease lasts two weeks to four weeks. On average, symptoms take 12 days to appear after a patient is first exposed.

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Is it fatal?

In Africa, the death rate among those with monkeypox ranges from 1 percent to 10 percent, with the highest rates among young children. Officials say the virus may be less lethal in the United States because of better nourishment and medical care. So far, no one in the U.S. outbreak has died.

Is there a treatment?

The CDC says there is no proven safe treatment for monkeypox. The illness must run its course.

Can it be prevented?

The smallpox vaccine has been reported to reduce the chance of contracting monkeypox. The CDC recommends that people investigating the outbreak or caring for patients or animals with the disease get a smallpox vaccination.

Smallpox vaccinations are also recommended for people who have had close personal contact with infected people or animals. They can be vaccinated up to 14 days after exposure to the disease. The smallpox vaccine is widely available because of concerns about bioterrorism.

Aren’t there risks from the smallpox vaccine?

Based on studies from the 1960s, experts estimate that 15 out of every 1 million people vaccinated against smallpox for the first time will face life-threatening complications, and one or two will die.

There are approximately 130 million Americans who have never been inoculated against smallpox before. Experts would expect nearly 2,000 from that group to face life-threatening complications and 125 to 250 of them to die. Of the 158 million Americans being revaccinated, nearly 800 would face life-threatening complications and about 40 would die.

The most common serious reaction comes when vaccinia escapes from the inoculation site, often because people touch the site and then themselves or someone else. For instance, the virus transferred to the eye can cause blindness. A more deadly complication is encephalitis, which can cause paralysis or permanent neurologic damage.

Also fatal though very rare is progressive vaccinia, in which the vaccination site does not heal and the virus spreads, eating away at flesh, bone and gut.

Typical minor reactions include sore arms, fever and swollen glands.

Have these problems been occurring among people getting the smallpox vaccine?

Three people have died of heart attacks, but they were at risk for heart problems before they were vaccinated. Two people have reported cases of angina, or chest pain. It is possible that the vaccine is triggering heart problems in people who are already prone to difficulty; it also is possible the heart problems are unrelated to the vaccine.

Who is at greatest risk from the vaccine?

Among those at greatest risk are people with weak immune systems — those with HIV, cancer and transplanted organs, and pregnant women. People with eczema risk developing a serious, permanent rash.

Officials administering the vaccine will ask detailed questions to try to screen out such people.

The CDC is recommending smallpox vaccinations, even for pregnant women, children and people with eczema, if they have been exposed to animals infected with the monkeypox virus.

Why give a risky vaccine to people to prevent a mostly nondeadly disease?

The CDC is concerned about preventing a more widespread U.S. outbreak of monkeypox that could spread from person to person and could potentially prove more deadly.

“There is concern that we don’t know enough about the disease yet and about person-to-person transmission,” said Dr. Joanne Cono, an epidemiologist at the CDC.

A CDC committee concluded that “the risk from the disease outweighed the risk from the vaccine for most people,” she said.

Cono pointed out that with smallpox, there are no current cases of the disease. But with monkeypox, “we’re in the middle of an outbreak, and that’s where the risk and benefit changes,” she said.

MSNBC.com’s Molly Masland and The Associated Press contributed to this report.

© 2013 msnbc.com

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