Claire Bugos is a New York City-based health and science reporter and writer.

Heather Mercer is native to Northwest Ohio (go Walleye!) and graduated from Loma Linda University with two doctorate degrees (psychology and public health). She is currently a professor at Owens Community College, as well as a fact-checker for Verywell Health. She has gained experience in a variety of settings, ranging from corporate wellness and preventive medicine, to mental health, chronic disease, and end-of-life care. 

Unusual cases of monkeypox are cropping up around the world. The World Health Organization (WHO) has documented more than 550 cases in 30 nations, including those where the disease does not usually appear.

The Centers for Disease Control and Prevention (CDC) is investigating 19 cases of monkeypox in U.S. patients. The disease remains rare and is much less severe than its cousin, smallpox.

Health officials are working to make sense of where and how the virus is spreading in the current outbreaks. They can turn to the research and experience of experts in Africa who have worked to minimize the spread of monkeypox for decades to better understand how the viral infection behaves.

Though monkeypox has been well-studied, many people in the U.S. are unfamiliar with the virus given its extreme rarity in the country.

Here are the signs to look out for if you suspect you might have been exposed to monkeypox.

According to the CDC, monkeypox begins with:

After one to three days, the patient develops a rash, often beginning on the face and then spreading to other parts of the body.

Monkeypox typically begins with flu-like symptoms, including fever, headache, muscle aches, and exhaustion. Different from smallpox, a key feature of monkeypox is that it also causes the lymph nodes to swell, according to the CDC.

Within one to three days, a rash will likely appear. It tends to start in the face and then spread to other parts of the body. Monkeypox causes skin abnormalities, called lesions, across the body, including on the soles of the feet and palms of the hands.

The lesions will progress through four stages—from flat spots to raised bumps to blisters and lesions filled with pus. The lesions will usually be the same size and stage of development on any given part of the body. As the body heals from the disease, the lesions will turn into scabs and eventually fall off.

In some cases, patients appear to have rashes that look like those from monkeypox, without first developing fever, Erica S. Shenoy, MD, PhD, a medical director at Massachusetts General Hospital and fellow at the Infectious Disease Society of America, said in a press call. As with all diseases, individuals can express symptoms in many ways.  

There are many common infections that could cause symptoms reminiscent of monkeypox. Lesions could form due to allergic reactions, for instance, and lymph nodes may swell in response to several infections. When assessing a patient with such symptoms, the CDC said health providers should rule out other causes first, but consider monkeypox as a potential diagnosis.

Symptoms may not emerge until five to 21 days after infection with monkeypox. People who are exposed to someone sick with monkeypox should isolate from others for the full 21 days to avoid spreading it to others, Shenoy said.

So far, there’s no evidence that the disease is sexually transmitted, and health officials emphasize that all people are vulnerable to monkeypox.

The illness typically lasts for two to four weeks. So far, there are no documented deaths due to monkeypox among people outside Africa.

If you suspect you may have been exposed to monkeypox, speak with a healthcare provider about how to track your symptoms and avoid spreading it to others.

“Contact tracing is essential at this time to be able to understand transmission networks and ensure that people get the care that they need, should they develop symptoms,” Shenoy said.

Anyone who has close contact with an infected person has a chance of getting sick with monkeypox. But it’s not as highly contagious as COVID-19, which spreads much more easily without direct contact with a sick individual.

Monkeypox is most often transmitted through skin-to-skin contact. It can also be passed through body fluids, respiratory droplets produced by coughing and sneezing, and contaminated materials like bedding.

In prior monkeypox outbreaks, researchers found that the likelihood of spreading monkeypox is higher for people living in the same household.

In the U.S. and other countries, there is a disproportionately high number of cases “in communities of gay, bisexual, and other men who have sex with men,” according to the WHO. Some of these cases were identified at sexual health clinics.

So far, there’s no evidence that the disease is sexually transmitted, and health officials emphasize that all people are vulnerable to monkeypox.

“What we know right now is that it's spread through close contact,” Shenoy said. “I don't think there's any reason to think that, at least at this point, there's anything different about that than just being a close contact.”

In an interview with STAT, Maria Van Kerkhove, PhD, an infectious disease expert at the WHO, said that there may be a higher number of cases emerging from “amplification events.” These are events—like social gatherings and sexual networks—where people are more likely to have skin-to-skin contact with others.

When talking about monkeypox, it’s important not to stigmatize the disease based on its current associations with the communities of men who have sex with men and its prevalence in certain parts of Africa, said Daniel Lucey, MD, MPH, FIDSA, FACP, a professor of medicine at Dartmouth Geisel School of Medicine and a fellow at the Infectious Diseases Society of America.

“We have lots of examples of how not to do it from the HIV pandemic and from the Ebola epidemic,” Lucey said. “It's very difficult, but it can and must be done.”

Monkeypox is a zoonotic virus, meaning it can pass from animals to humans. Scientists know that rodents and some other animals may carry the virus and pass it along to humans, but they’re not yet sure if the same is true for household animals.

“That would be a very big concern if dogs or cats were susceptible and actually infected and then if they could infect humans or other dogs or cats,” Lucey said. “But there's no evidence of that yet.”

Though the symptoms of monkeypox are relatively well defined, testing for the disease is limited to public health laboratories and the CDC. Shenoy emphasized the need to develop testing strategies to more quickly and effectively diagnose a monkeypox case.

“Not many people have diagnosed monkeypox in the United States and so we need rapid learning in terms of what to look for, what to ask the patient, and what to do in terms of next steps,” Shenoy said.

At a WHO meeting this week, a panel of experts from around the world outlined some of the outstanding questions about monkeypox, such as whether it’s possible to have an asymptomatic infection, how easily the virus spreads through respiratory droplets, and whether the disease can be transmitted through semen and vaginal fluids.

While scientists find the best ways to address the monkeypox outbreaks, some experts urged the scientific community to learn from the COVID-19 response and be sure that resources are shared with communities globally.  

“We can’t just solve the problem for high-income countries,” said Helen Rees, MB BChir, a medical researcher in South Africa who moderated the 2022 WHO conference. “We need to be sure that what we come up with in terms of solutions have an equitable impact.”

If you have been exposed to monkeypox or develop a rash or other signs of the disease, isolate yourself from others and speak with a healthcare provider about your symptoms.

You can also minimize your exposure by avoiding skin-to-skin contact, including sexual contact, practicing good hygiene, and wearing a face mask around sick individuals.

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World Health Organization. Monkeypox: Public health advice for gay, bisexual and other men who have sex with men.

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