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What is monkeypox, the rare disease now confirmed in Mass.?

An electron microscopy image of mature monkeypox virions, left, and immature virions, right, from a sample of human skin associated with the 2003 outbreak of monkeypox in the US.CDC/NYT

As if we didn’t have enough stressful news about viruses, health officials announced Wednesday that a rare disease has found its way into Massachusetts, and it’s called monkeypox.

A man who traveled to Canada was diagnosed with the monkeypox virus, the nation’s first confirmed case in 2022, and is being treated in isolation at Massachusetts General Hospital, state public health officials and the US Centers for Disease Control and Prevention said.

Here’s what to know about the disease.

What is monkeypox?

Monkeypox is a rare but potentially serious disease typically found in parts of central and west Africa where people have been exposed through “bites or scratches from rodents and small mammals, preparing wild game, or having contact with an infected animal or possibly animal products,” officials said.


It’s in the same family as smallpox, which was eradicated by vaccines in 1980, though monkeypox causes less serious illness.

Symptoms can be “flu-like” but also include “swelling of the lymph nodes” and “a rash on the face and body,” state public health officials said in a statement.

Most infections can last between two and four weeks, the statement said.

How is it spread?

State health officials said the virus does not easily spread among people but can be transmitted through contact with bodily fluids, monkeypox sores, respiratory droplets through face-to-face contact, or contaminated items, such as bed sheets or clothing. Common household disinfectants can kill the monkeypox virus, the CDC said in a statement.

Doctors said Wednesday that they believe people with the virus become infectious only after showing symptoms, and continue to be infectious until every single one of their lesions has scabbed over.

Where else has it been found?

Just one monkeypox case has been confirmed in the United States, but officials said they also are monitoring larger clusters of the virus reported in Europe.


Nine cases were identified in the United Kingdom this month, the first of which was detected in a man who had traveled to Nigeria, state public health officials said.

The other eight cases were confirmed in people who had not reported any recent travel. Other monkeypox cases have been confirmed in Portugal and Spain, the CDC said in a statement.

One MGH physician said the Massachusetts case is possibly an example of the rare virus spreading beyond its usual geographic borders.

Last year, Texas and Maryland each reported a case of monkeypox. According to the CDC, monkeypox reemerged in Nigeria in 2017 after no cases were reported for more than 40 years. Since then, more than 450 cases have been reported in Nigeria, the CDC said.

In 2003, there was a large outbreak in the United States that involved 47 confirmed and probable cases in six states. That outbreak was traced to the importation of small mammals from Ghana.

Why is it spreading now?

One expert told Reuters the recent outbreak of monkeypox could be due to increased travel after COVID restrictions dropped.

The vaccine used against smallpox was phased out when the disease was eradicated. But the shot also protects against monkeypox, and another researcher told Reuters that winding down the vaccine campaign could have led to a jump in cases in areas where monkeypox is endemic, or found regularly.

How worried should I be?

Officials on Wednesday said Massachusetts residents should be aware of the symptoms but not alarmed.


Sahar Fatima can be reached at sahar.fatima@globe.com Follow her on Twitter @sahar_fatima. Nick Stoico can be reached at nick.stoico@globe.com. Follow him on Twitter @NickStoico.