Monkeypox causing penile swelling and rectal pain in ongoing outbreak

Penis swelling and rectal pain don’t normally occur with monkeypox, but a study of around 200 men in London suggests the symptoms may be common in the latest outbreak

By Jason Arunn Murugesu

Penile swelling and rectal pain are being reported by some people infected with monkeypox during the latest outbreak, symptoms that aren’t generally associated with the viral infection.

Julia Bilinska at Guy’s and St Thomas’ NHS Foundation Trust in London and her colleagues characterised the symptoms of 197 people, all male, who tested positive for monkeypox at an infectious disease centre in the city between May and July 2022.

Of these, 71 reported rectal pain and 31 reported penile swelling. Overall, 20 of the participants were hospitalised for symptom management, of which eight admissions were for anal or rectal pain and five for penile swelling.

All the participants had some form of lesion on their skin or mucous membranes, like those lining the mouth or genitals. Monkeypox is commonly associated with a widespread chickenpox-like rash that evolves into fluid-filled blisters that eventually scab. In 22 of the participants, however, there was a single lesion.

Nine of the participants also had swollen tonsils, another atypical monkeypox symptom.

As of 28 July, the NHS, US Centers for Disease Control and Prevention and World Health Organization did not recognise rectal pain, penile swelling, single lesions or swollen tonsils as monkeypox symptoms.

On 25 July, however, the UK Health Security Agency added a single lesion or lesions on the genitals, anus and surrounding area to its list of monkeypox symptoms, as well as proctitis – anal or rectal pain or bleeding.

Most (86 per cent) of the participants also reported more common monkeypox symptoms, including fever (62 per cent), swollen lymph nodes (58 per cent) and muscle aches and pain (32 per cent).

According to Bilinska, it is unclear why monkeypox is causing the new symptoms in some people. “It may suggest a change in the natural disease course, or it may be due to the mode of transmission,” she says. “It’s a question that deserves a lot more research.”

Although it takes time for new symptoms to be added to official lists, Bilinska says these signs of infection shouldn’t be overlooked. “If you know which signs and symptoms to look for, you are able to assess someone and test them early,” she says.

Of the 197 participants, 70 were HIV positive and 56 had a sexually transmitted infection. “It’s very possible that having two infections at the same time makes the symptoms worse,” says Bilinska. “That’s why it’s so important if a clinician is thinking ‘this could be monkeypox’, they should also be thinking ‘what other screening can [I] do for sexually transmitted infections?’”

The researchers also found that just 26.5 per cent of participants reported being in close contact with someone with a confirmed monkeypox infection or typical symptoms. “It’s definitely raised the possibility that someone could have no symptoms of monkeypox but still be able to pass it on,” says Bilinska.

What appears as asymptomatic transmission may be people having very mild or atypical monkeypox symptoms, she says.

In a study published on 21 July, Chloe Orkin at Queen Mary’s University of London and her colleagues similarly found that out of 528 monkeypox infections diagnosed between April and June across 16 countries, 54 people had a single genital lesion.

“It is possible that the penile, anal and oral lesions are occurring at the site of first contact with the virus either transmitted sexually or through close contact,” she says.

Journal reference: The BMJ, DOI: 10.1136/bmj-2022-072410