Monkeypox Is in the U.S.—Here’s What You Need to Know

Photo credit: ROGER HARRIS/SCIENCE PHOTO LIBRARY - Getty Images
Photo credit: ROGER HARRIS/SCIENCE PHOTO LIBRARY - Getty Images
  • The first case of monkeypox in the United States this year has just been reported in Massachusetts.

  • Two cases of the rare illness were reported in the U.S. last year.

  • Infectious disease experts are keeping an eye on larger clusters appearing around the world.


A case of monkeypox—a rare but potentially serious illness—has been detected in Massachusetts. The virus has shown up in unusual clusters in several parts of Europe and Canada over the past few weeks, raising eyebrows.

The U.K. has identified nine monkeypox cases, with only one patient recently traveling to Nigeria where the virus is commonly seen, The New York Times reports. The other patients didn’t travel and three of them live in the same home. It’s unclear how the others contracted the virus.

There are 23 suspected cases of monkeypox in Spain, 20 in Portugal, and at least 15 in Montreal, Canada. The Massachusetts man who contracted monkeypox recently traveled to Canada, according to the Massachusetts Department of Public Health.

The notice issued by the Massachusetts Department of Health included a warning to healthcare providers of what to be on the lookout for. “Based on findings of the Massachusetts case and the recent cases in the U.K., clinicians should consider a diagnosis of monkeypox in people who present with an otherwise unexplained rash and 1) traveled, in the last 30 days, to a country that has recently had confirmed or suspected cases of monkeypox 2) report contact with a person or people with confirmed or suspected monkeypox, or 3) is a man who reports sexual contact with other men,” the agency says.

This isn’t the first time monkeypox has shown up in the U.S. There were two cases reported in the country last year—one in a Maryland man who had recently returned from Nigeria, and the other in a Texas resident who had also recently returned from Nigeria. Those cases marked the first time the U.S. had seen monkeypox since 2003, per the Centers for Disease Control and Prevention (CDC).

While monkeypox is rare and isn’t considered to be a highly infectious virus that’s easily spread between people, infectious disease experts say that the latest string of cases is puzzling. “There’s a lot we don’t know at this point,” says Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York. “There may be some new epidemiology and new modes of transmission that we don’t understand. We need to sort that out.”

Monkeypox isn’t a virus most people in the United States are familiar with, so it might be unclear how to interpret this news. Should you be concerned? Are we at risk of a monkeypox outbreak? Here, infectious disease experts explain everything you need to know about the illness.

What is monkeypox?

Monkeypox is a rare disease caused by the monkeypox virus, according to the CDC. It was first discovered in 1958, when two outbreaks of a pox-like disease happened in colonies of monkeys that were kept for research.

The first human case of monkeypox was reported in 1970 in the Democratic Republic of Congo. Since then, other cases have been reported in people in other central and western African countries. The monkeypox virus is related to the variola virus, which causes smallpox.

Monkeypox cases are rare overall, but are most common in the Democratic Republic of Congo, which sees more than 1,000 recorded cases a year, per CDC data. The last documented cases of monkeypox in the U.S. were in 2003, when a small outbreak led to 47 cases linked to a shipment of animals imported from Ghana.

What are the symptoms of monkeypox?

The signs of monkeypox are similar to those of smallpox, but often milder. Overall, monkeypox lasts for two to four weeks. The illness starts with these symptoms, according to the CDC:

  • Fever

  • Headache

  • Muscle aches

  • Backache

  • Swollen lymph nodes

  • Chills

  • Exhaustion

Within a few days, an infected person will develop a rash that usually starts on the face and spreads to other parts of the body. The bumps then go through different stages before they fall off:

  • Macules (flat, discolored bumps)

  • Papules (raised area of skin)

  • Vesicles (blisters)

  • Pustules (small pumps that contain pus)

  • Scabs (dry, crusty bumps)

How do you get monkeypox?

A person can get monkeypox when they come into contact with the virus from an animal, a person, or materials contaminated with the virus, the CDC says. The virus can then enter the body through broken skin or the eyes, nose, or mouth.

You can also get the virus from an animal by being bitten or scratched, preparing bush meat, or by having direct or indirect contact with body fluids or lesions from infected people. The main disease carrier of monkeypox is unknown, although African rodents are suspected, says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security.

It’s not very contagious, but it can spread from person to person, says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. The CDC notes that human-to-human transmission is thought to mostly happen through large respiratory droplets. These can’t travel more than a few feet and people need to have “prolonged” face-to-face contact in order to spread the virus.

But the latest cluster of cases has experts wondering if the virus has mutated to be more contagious and easily spread between people. “The current cluster of cases in Europe, U.K., and Canada is a little different in that many cases are not linked to known travel-related cases, suggesting a chain of transmission exists that is not well known,” Dr. Adalja says. “Several of the cases are in men who have sex with men, suggesting sexual transmission and the involvement of sexual networks which is new.”

“Historically, monkeypox wasn't that infectious from humans to humans and it died out on its own,” Dr. Russo says. “But there’s no clear epidemiological link with many of these cases. That’s a little concerning.”

How is monkeypox treated?

There’s no “proven, safe” treatment for monkeypox virus, the CDC says online. However, the agency says, the smallpox vaccine and antivirals like cidofovir can be used to both prevent and treat infections.

Can you die from monkeypox?

Monkeypox can be serious and could kill as many as one in 10 people who become infected with it in Africa, the CDC says.

While Dr. Russo says that people “shouldn’t panic” over monkeypox, he does admit that there’s “some concern” over how this is spreading right now. “We’re getting this cryptic transmission somehow,” he says. “If it transmits a little better than it has in the past, the possibility exists that it could spread in the U.S.” He adds, “Let’s hope that’s not the case.”

Dr. Adalja says that there will “likely be more cases in the U.S.” but says that “threat to the general public is low.”

“The smallpox vaccine and antivirals are always the backstop if needed,” Dr. Adalja says.

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