Monkeypox Symptoms Are Different From Previous Outbreaks, Doctors Warn

Topline

People infected with monkeypox during the ongoing global outbreak are displaying symptoms not typically associated with the viral infection, according to research published in the British Medical Journal on Thursday, meaning cases could be overlooked by clinicians as officials struggle to contain the escalating outbreak.

A health professional prepares a dose of a Monkeypox vaccine in Paris.

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Key Facts

Rectal pain and penile swelling, symptoms not generally associated with monkeypox infection, are commonly reported among people infected with monkeypox during the current outbreak, researchers at Guy’s and St Thomas’ NHS Foundation Trust in London found.

Of 197 participants with confirmed monkeypox infections between May and July—all were men and all bar one identified as gay, bisexual or other men who have sex with men—71 reported rectal pain and 31 reported penile swelling.

Twenty of these men were hospitalized for symptom management, the researchers said, most often for rectal pain or penile swelling.

Swollen tonsils and solitary lesions, also not typical symptoms of monkeypox, were reported in nine and 22 participants, respectively.

The researchers warned that these symptoms could be mistaken for other conditions like syphilis, ingrown hairs and tonsillitis and could help explain how the monkeypox outbreak had become so widespread by the time it was detected.

Big Number

14%. That’s the proportion of the cases studied that did not meet current U.K. Health Security Agency (UKHSA) definition for a probable monkeypox case, the researchers said. Almost half (47%) had symptoms and disease progressions that “contradict” the UKHSA definition for probable cases, notably by displaying systemic symptoms like fever, swollen lymph nodes and muscle aches after, rather than before, the onset of lesions.

What We Don’t Know

Experts are uncertain as to why monkeypox is causing new symptoms in some people. It’s possible the disease itself has changed and other infections among patients—32% screened in the study also had a sexually transmitted infection—mean the way in which it is transmitted could be playing a role. While monkeypox can be passed to anyone and spreads primarily by close physical contact, data suggests the current global outbreak is almost entirely fueled by transmission among gay, bisexual and other men who have sex with men. While the disease is not known to be sexually transmitted, the outbreak is being driven by sexual contact and the WHO recently shifted its stance and advised members of this group to consider reducing their number of sexual partners to curb the disease. Reports from the current outbreak point to much higher rates of skin lesions in genital and anal areas than expected from previous outbreaks, possibly a result of where the virus was transmitted.

Key Background

Monkeypox has been known for decades but has been ignored by most of the world as its spread was largely limited to some areas of Central and Western Africa. The virus is believed to be hosted in an unknown species of rodent. It can spread to and among humans from close contact and does not spread easily. Vaccines and treatments, mostly for a related virus, smallpox, are available for monkeypox but are in critically short supply. The World Health Organization has designated the outbreak a global public health emergency, its highest alert level, on account of the rapid worldwide spread. More than 21,000 confirmed monkeypox cases have been reported around the world this year, according to the Centers for Disease Control and Prevention, almost all in countries that have not historically reported monkeypox. Nearly 5,000 of these are in the United States. Testing is generally poor and these figures are likely to be much higher.

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Key Facts

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What We Don’t Know

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