As if coronavirus hasn’t been enough, another virus — monkeypox — is making its presence felt overseas and in the United States.

Monkeypox (or mpox*), a virus that’s like smallpox but milder, doesn’t usually infect anyone in the U.S. However, in May 2022, a Massachusetts resident tested positive for mpox after a trip to Canada. Infections were also reported in Portugal, Spain and the United Kingdom in May 2022.

The mpox name came from its discovery in 1958, when colonies of research monkeys developed a pox-like illness. The first human case of mpox was reported in the Democratic Republic of Congo in 1970.

Subsequent human cases have been reported since, mainly in Africa.

Mpox symptoms include:

• Fever
• Headache
• Muscle aches
• Swollen lymph nodes
• Chills
• Exhaustion
• Sore throat

Within 1 to 3 days after the fever begins, people will develop a rash. It can take 14 days for the body to clear the mpox infection.

The virus mainly spreads through contact with infected animals but can also spread through contact with infected body fluids, mpox sores, or items such as clothing or bedding that have been contaminated with fluids or sores of a person or animal with mpox.

Mpox virus can also spread through respiratory droplets, but in a close setting, such as the same household or a healthcare setting.

There is some good news, however: mpox is rare, it’s not a new virus and is well understood by infectious disease experts.

“Monkeypox has not been known to transmit well from person to person,” says Jonathan Pinsky, M.D., medical director of infection control at Edward Hospital. “Most infections are linked to exposures with infected animals.”

In fact, in 2003 there was an outbreak of mpox in the Midwest, including Illinois, that resulted from human contact with infected prairie dogs that had been sold as pets. No human-to-human transmission was reported.

Because mpox is so similar to smallpox, the smallpox vaccine provides effective protection against both viruses. Mpox, like smallpox, spreads very slowly, making vaccination an effective way to stop outbreaks, Dr. Pinsky says. The smallpox vaccine can even prevent infection in people who receive it after exposure to an infected person.

The smallpox vaccine isn’t publicly available, as the World Health Organization declared smallpox eliminated in 1980. The United States has a supply of the vaccine in the unlikely case of an outbreak.

Dr. Pinsky says experts will likely determine the cause of the new mpox transmissions soon, which will help determine the public risk. At this point, no action is needed unless you suspect you have symptoms of mpox or think you may have been in contact with someone suspected of having mpox. In that case, contact your primary care physician’s office for guidance.

*Per the World Health Organization and the Centers for Disease Control and Prevention, we will begin using “mpox” as the new preferred term for “monkeypox.”