Should we be worried about monkeypox?

With the COVID-19 threat subsiding, attention is shifting to monkeypox as the new contagion du jour. Already 1,000 cases have been reported across four continents—with more than 35 in the United States—in less than a month. The U.S. Centers for Disease Control and Prevention raised its health notice for monkeypox to level 2 and urged travelers to “practice enhanced precautions.” Four African countries where monkeypox is endemic have reported 63 deaths this year, although no deaths have been reported outside Africa in the current outbreak.

Here’s an explainer on the unusual disease.

What in the world is monkeypox?

The condition, caused by a virus similar to those behind smallpox and cowpox, was first discovered in a colony of monkeys. While not typically lethal, the disease is infectious, causes flu-like symptoms, and marks sufferers with tell-tale skin lesions—painful, raised red bumps filled with clear liquid.

Dr. Suraj Saggar, chief of infectious diseases at Holy Name Medical Center in New Jersey, said that before the current outbreak, the disease had rarely surfaced outside of Africa. “No one in the Western Hemisphere can say ‘I’m a monkeypox expert’ unless you’re working in a lab, because it’s not something you see on a regular basis,” he said.

But monkeypox has been around for decades. It’s endemic, or consistently present, in parts of Africa, where the first human case was identified in 1970. Scientists suspect the virus initially jumped to humans from African rodents, prairie dogs, or monkeys. But nobody knows its origins for sure, and how the current outbreak started is also unclear.

How does the monkeypox virus spread?

Unlike COVID-19, which is transmitted through airborne particles, monkeypox typically spreads through close contact with an infected person or contact with an infected animal.

The current monkeypox strain circling the globe afflicts sufferers with lesions primarily in their genital region. Monkeypox can spread through sexual contact, and initial reports have linked the most recent outbreak to male sexual activity at gay festivals and saunas in Europe. But doctors caution people not to jump to conclusions. “It is important to emphasize that the spread is not only via gay sex,” Dr. Peter Kasson, a virologist and biophysicist at the University of Virginia, said in an email. He noted some of the U.S. cases are connected to travel to Africa, contact with infected animals, or non-sexual contact with infected people.

Kasson and Saggar said monkeypox has a relatively long incubation period, so people could be infected for one to two weeks before showing symptoms. Doctors aren’t sure if and how transmissible the virus is during that period, according to Saggar. What is clear, though, is that once someone has symptoms, others can easily contract the virus by touching the lesions or an infected person’s items, such as clothing and bedding.

In the past, monkeypox occasionally left Africa through foreigners who interacted with local animals or traveled in the African bush. But the virus has only recently infected people who haven’t set foot on the continent. “Two weeks ago we were talking about [monkeypox infection] in Europe,” Saggar said, “Fast-forward a week and you have it in the U.S., person to person regardless of travel. Now we have it all over the world, except Asia and Antarctica.”

Prior to the current spate of cases, the last monkeypox outbreak in the United States was in 2003, when the CDC reported 47 confirmed and probable cases.

How are governments responding?

The global spread of monkeypox has been quick, but scientists and doctors have been just as quick to quell fears of another COVID-19-like pandemic. For one thing, there’s already an effective, time-tested vaccine: The smallpox vaccine is 85 percent effective against monkeypox, Kasson noted. Americans can’t order one from their local pharmacy, but Kasson said the U.S. government has been quietly stockpiling smallpox shots and delivering them to those who have been in close contact with confirmed monkeypox cases.

Rather than telling everyone to get vaccinated, Saggar said, experts are encouraging a “ring vaccination” strategy in which those at high risk for infection, as well as first and secondhand contacts, should seek a smallpox shot, avoid travel, and watch for symptoms.

“Where we are right now, I think monkeypox may be with us for a while, and it can be a serious disease,” Kasson said. “But I anticipate it will affect many fewer Americans than COVID.”