Updated

Until the outbreak in the U.S. Midwest, monkeypox (search) has been a rare human illness confined to the rain forests of Central and West Africa.

Like its cousin smallpox (search), the viral illness causes pus-filled sores, although it is not nearly as contagious or as fatal as smallpox. But because monkeypox has been less intensively studied than many other microbes, much uncertainty exists about how this exotic virus will behave in the United States.

Here are answers to what is known:

Q: What is the incubation period?

A: About 12 days.

Q: What are the symptoms?

A: It starts with fever, headache, body ache, chills, drenching sweat and sometimes a cough. This is followed one to 10 days later by a rash with pustules that eventually crust over. They can occur almost anywhere on the body, including the palms of hands and soles of feet.

Q: How dangerous is it?

A: In Africa, fatality rates range from 1 percent to 10 percent. In the current outbreak here, no one has died.

Q: Can it be prevented?

A: The smallpox vaccine is effective at stopping infection. Those who got vaccinated before smallpox shots were discontinued in the 1970s may still have at least partial protection.

Q: How do people catch it?

A: In the U.S. outbreak, victims have caught the virus through close contact with sick animals. Most handled the animals and were bitten or had breaks in their skin.

Q: Can I catch it from another person?

A: Yes, especially if they have sores. In Africa, close household contacts of infected people have about a 10 percent chance of catching monkeypox if they never received the smallpox vaccine. After being passed from person to person a few times, the virus typically stops spreading.

Q: What animals can be infected?

A: In Africa, squirrels are thought to be a common source of the virus. Rabbits and a variety of other rodents can also carry it, as well as apes and monkeys. The disease is called monkeypox because the virus was first identified in monkeys.

Q: How do I keep from catching it?

A: Avoid contact with prairie dogs or Gambian giant rats (search) that appear sick, especially if they are missing patches of fur, have rashes or have a discharge from their eyes or nose. Wash hands thoroughly after contact with these or any sick animals.

Q: What should I do with a sick prairie dog or Gambian giant rat?

A: Contact your local or state health department. Phone ahead first before taking animals to veterinarians so they can be prepared to receive them. Do not release the animals into the wild. The virus can persist in the environment, so thoroughly clean any place the animal has been, using bleach solution and latex gloves.