Monkeypox, a virus hailing from the rainforests of central and west Africa, recently crossed the Atlantic and appeared for the first time in the Western Hemisphere, infecting prairie dogs and people primarily in Illinois, Wisconsin, Ohio, and Indiana. Pet owners and veterinarians became infected after handling prairie dogs that had been in close contact with Gambian giant rats—believed to be the source of the outbreak—at an exotic pet distributor in Illinois.

“Since this is the first documented appearance of monkeypox in the United States, officials are not taking any chances. They’re treating this virus as though any mammal can get it,” says Dr. Gail Scherba, a veterinary virologist at the University of Illinois College of Veterinary Medicine in Urbana.

A monkeypox infection is similar to but often milder than smallpox. This disease can be fatal, although no deaths have been reported in the United States to date. Most people recover in 2 to 4 weeks.

The disease progresses similarly in animals and people. About 12 to 21 days after exposure to the virus, symptoms including fever, headache, swollen lymph nodes, aches, and fatigue develop. Several days after the fever ignites, a nodular rash (hard, painful pustules) breaks out, usually beginning on the extremities and trunk and spreading to other parts of the body. The rash eventually scabs and falls off, signaling the end of the illness.

“The virus is not extremely contagious, as human to human transmission is rare. It is spread through direct contact of broken skin with the lesions or scabs or from inhaled scabs,” explains Dr. Scherba.

There is no specific treatment available for monkeypox virus infections in animals. In Africa people who have had the smallpox vaccine experience a milder course of monkeypox. The Centers for Disease Control and Prevention recommends that people who have had direct contact with an individual or animal with a confirmed case of monkeypox get the vaccine. The virus appears to be susceptible to the anti-viral drug Cidofovir.

At this time people and animals are not considered in danger of contracting monkeypox unless they have been in contact with infected prairie dogs or humans. Exotic mammalian pets acquired on or after April 15, 2003, that are now sick should be examined for monkeypox virus infection. If you have a pet that has been exposed to monkeypox, closely watch for signs. Animals are considered in the clear if no signs have developed by 1 month after exposure.

If you think your animal has been exposed and is showing the signs associated with monkeypox, you should isolate the animal from other animals in the house and limit its exposure to people. One person should see to the care of the animal and should wear a mask and gloves when handling it. Contact your state or local health department for further instructions about quarantine, medical care, or sanitation procedures for the animal.

Euthanasia is currently recommended for all sick animals where monkeypox is the suspected cause to prevent further spread of the disease. Exposed animals that are not sick do not need to be euthanized, but quarantine is a necessary precaution.

If you have recently purchased a prairie dog, do not release it into the wild or take it to a shelter. It is important to prevent spread of the virus. If the virus enters the outside environment, it will be very hard to get rid of and the chance of people becoming infected will increase.

“This outbreak is a serious issue. Monkeypox virus is a very stable virus in scabs and can survive for years in the environment. We don’t want to get monkeypox established in our wildlife population,” warns Dr. Scherba.

Federal and local health agencies, veterinarians, and other medical professionals are working together to prevent the spread of monkeypox. For more information, contact your local veterinarian or visit the CDC Web site at www.cdc.gov/ncidod/monkeypox.