What Is Monkeypox?

U.S. health officials are tracking clusters of infections in countries that don’t normally report monkeypox.

Published May 19, 2022

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A hospitalized-yet-healthy Massachusetts man marked the first confirmed U.S. case of monkeypox in 2022, and was just 1 of 3 such infections in the two decades prior. U.S. health officials announced the infection on May 18, maintaining that there is no immediate threat to the public. But as experts were said to be tracking several cases across Europe — including Italy, Sweden, the U.K., Spain, and Portugal — Snopes readers asked our editorial team to take a deeper look at the rare, lesion-causing virus.

Tracking Monkeypox in the U.S.

At the end of April, the unnamed man traveled to Canada where more than a dozen cases had been confirmed as of this writing, according to the Massachusetts Department of Public Health (DPH). The man traveled by private transportation.

While it’s the first known case of monkeypox in the U.S. in 2022, Texas and Maryland each reported one case in individuals who had recently traveled to Nigeria the year before, marking the first time in nearly two decades that human monkeypox was detected in a traveler to the U.S.

In 2003, the U.S. experienced its largest known outbreak when dozens of people became infected. It was linked to contact with pet prairie dogs that had been housed with African rodents and small mammals imported from Ghana that were infected with the virus, said the World Health Organization (WHO). This event was likely a spillover from a much larger outbreak in Nigeria that lasted from 2017 to 2019.

“Monkeypox reemerged in Nigeria in 2017 after more than 40 years with no reported cases. Since then, there have been more than 450 reported cases in Nigeria and at least eight known exported cases internationally,” wrote the Centers for Disease Control and Prevention (CDC).

Before that, human monkeypox in travelers from Nigeria had been documented on just seven occasions since 1978.

Understanding Infection and Symptoms

Like smallpox, monkeypox is a DNA virus that belongs to the poxvirus group, which is endemic to parts of Africa. Though infection is rare, it can be serious and begins with flu-like symptoms, like swelling of the lymph nodes, and progresses to a widespread rash on the face and body. (Smallpox is more easily transmitted and is fatal in nearly one-third of those infected. However, it was declared eradicated in 1980 after a global vaccination campaign.)

Monkeypox is mostly transmitted from infected wild animals to people and is mostly seen in parts of the world where humans interact with wild animals. Though not easily transmitted between people, human-to-human contact can occur and is spread through contact with bodily fluids, sores, or shared items, like clothing that has been contaminated. Infection can also spread through respiratory droplets.

It can take up to 21 days for symptoms to develop, with infection lasting up to a month. Because of its tell-tale skin lesions, monkeypox sometimes is confused with a sexually transmitted infection like syphilis or herpes, or with the virus that causes chickenpox.

“Milder cases of monkeypox may go undetected and represent a risk of person-to-person transmission. There is likely to be little immunity to the infection in those travelling or otherwise exposed, as endemic disease is normally geographically limited to parts of West and Central Africa,” wrote WHO in a May 18 statement.

Experts divide infection into two periods, the first being the “invasion period” (up to five days) characterized by fever, intense headache, swelling of the lymph nodes, back pain, muscle aches, and fatigue. The second phase typically begins within three days of fever onset, with skin eruptions. The associated rash is concentrated on the face and extremities, including palms of hands and soles of feet, but can also affect the mouth, genitals, and eyes. Lesions may have a flat base or be slightly raised and can sometimes be filled with clear or yellow fluid. Crusts of the lesions will dry up and eventually fall off.

Symptoms usually resolve on their own within two to three weeks.

No Readily Available Treatments in the U.S.

The CDC notes that there is no proven safe treatment available in the U.S. specifically for monkeypox, though doctors may prescribe rounds of antivirals of vaccinia immune globulin to combat the virus. The smallpox vaccine, vaccinia vaccine, is about 85% effective in preventing monkeypox infection, and those who were vaccinated as children may see milder symptoms if infected.

At a global level, WHO reports that a vaccine (MVA-BN) and a treatment of the antiviral tecovirimat were approved for monkeypox in 2019 and 2022, respectively, but neither countermeasure is widely available.

Diagnosis is made by collecting a sample or biopsy of a lesion and sending it to a laboratory for testing. Those who are sick or could be exposed are advised to self-isolate and track their symptoms, including the date of onset of fever and rash.

Is There Cause for Concern in the U.S.?

Monkeypox typically doesn’t occur in the U.S. and when it does, is generally associated with international travel to places where the virus is endemic. Even so, roughly 1 in 10 people may die, mostly those of a younger age.

“Many of these global reports of monkeypox cases are occurring within sexual networks. However, healthcare providers should be alert to any rash that has features typical of monkeypox. We’re asking the public to contact their healthcare provider if they have a new rash and are concerned about monkeypox,” said Dr. Inger Damon, a CDC poxvirus expert, in an agency statement.

The CDC urges healthcare providers in the U.S. to "be alert for patients who have rash illnesses consistent with monkeypox, regardless of whether they have travelled or have specific risk factors for monkeypox."

U.S. health officials contend that they do not believe there is a risk to the public. Aside from preventative hygienic practices to eliminate potential — and extremely unlikely — exposure, common household disinfectants can kill the virus responsible for monkeypox.


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Madison Dapcevich is a freelance contributor for Snopes.

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