What Is Monkeypox And Could It Be A Threat In The U.S.?

The U.K. has recorded seven cases of monkeypox after a traveler returned from Nigeria with the virus. The World Health Organization said that exposed contacts were identified and that the risk of onward transmission was low. "However, as the source of infection in Nigeria is not known, there remains a risk of ongoing transmission in this country," it said in a statement.

What is monkeypox?

Monkeypox, a rare viral infection, is spread by wild animals and is generally found in forested areas of western and central Africa. It is spread via contact and droplet exposure via exhalation.

It is a zoonotic disease, meaning it spreads from animals to humans. The animal reservoir is unknown, WHO said, but it is thought to be from rodents. "Contact with live and dead animals through hunting and consumption of wild game or bush meat are known risk factors," WHO said.

The normal incubation period is between six and 13 days, but can be up to 21 days.

Initial symptoms of monkeypox include fever, headache, muscle aches, backache, body aches, chills and exhaustion. Patients can then develop a rash, which begins on the face before spreading to other parts of the body and later forming scabs.

For most people the virus is a "self-limited disease" and lasts two to four weeks. Most of those who are infected with monkeypox recover completely.

However, the virus poses a risk to children and getting monkeypox during pregnancy can lead to complications and stillbirth.

U.S. Officials Say Risk Is Small

U.S. public health officials said there is little cause for concern. The most recent cases of monkeypox in the U.S. occurred in 2021 and involved two travelers who had recently returned to the country from Nigeria, according to the Centers for Disease Control and Prevention (CDC), which emphasizes that the disease remains extremely rare in the country.

One of the biggest recent outbreaks, according to the CDC, came in 2003, when 47 confirmed and probable cases of monkeypox were reported in six states—Illinois, Indiana, Kansas, Missouri, Ohio and Wisconsin.

A child with monkeypox
Monkeypox lesions on the arm and leg of a girl in Bondua, Liberia Getty

All of the cases were connected with a shipment of pet prairie dogs, which were infected after they were housed near imported small mammals from Ghana. The prairie dogs in turn infected the humans with which they came in contact. The outbreak was the first time that human monkeypox had been reported outside of Africa.

There is no specific vaccine or treatment for monkeypox, although first and second-generation smallpox vaccines have been used to treat some patients during the 2003 outbreak in the U.S., the ECDC says in its factsheet.