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Monkeypox Review Identifies Two Symptoms That Differ From Previous Outbreaks

Lesions appearing before systemic symptoms are among the differences identified compared to previous cases.


Rachael Funnell

Social Editor and Staff Writer

clockJul 28 2022, 22:30 UTC
Penile swelling and rectal pain should be considered possible symptoms of monkeypox, say researchers. Image credit: Dotted Yeti /

Penile swelling and rectal pain have been identified as two symptoms that are more common among a sample of monkeypox patients infected in the 2022 outbreak (recently declared a global health emergency) compared to patients from previous outbreaks. 

The news comes from a study published in the British Medical Journal that compared the symptoms of patients from London, UK, against previous outbreaks in endemic regions.


Nearly 200 confirmed monkeypox cases were included in the study, taken from an infectious disease center based in the capital and made up of patients who presented with symptoms between May and July 2022. Of those cases, 196 identified as gay, bisexual, or men who have sex with men.

Penile swelling (due to oedema, a condition in which excess fluid gathers in parts of the body) and rectal pain were common symptoms in this cohort. Curiously, these symptoms differ from the typical symptom profile seen among confirmed cases in previous outbreaks of monkeypox (soon to be renamed to prevent stigma).

The 197 patients all presented with lesions typical of monkeypox, which were mostly around the genitals and perineal area, which sits between the scrotum and anus in males and the vagina and anus in females.


Another difference between the London cohort of patients compared to previous outbreaks was that many of them reported developing lesions before feeling systemic illness (such as fever, swollen lymph nodes, muscle aches and pain). Existing case reports have indicated that systemic illness usually came first.

In light of the differences identified in the study, the authors suggest that monkeypox (which has undergone unprecedented mutations) be considered a potential diagnosis in patients presenting with penile swelling and rectal pain.

The study also highlighted that missed diagnosis may be occurring in patients who only develop a single lesion and swollen tonsils, or they may be mistaken for having other conditions. Before now, these were not considered typical symptoms of monkeypox, but they were present in 22 (solitary lesion) and nine (swollen tonsils) of the 197 confirmed cases.


Furthermore, just one of the 197 had recently traveled to an endemic region for monkeypox, and only a quarter were aware of having had contact with someone with a confirmed infection. This is significant because it could point towards silent transmission occurring between people with few or no symptoms, making contact tracing extremely difficult.

The study is limited in that it focuses on a small sample taken from a single center, but the researchers hope it can contribute towards better management of the ongoing monkeypox outbreak.

“Understanding these findings will have major implications for contact tracing, public health advice, and ongoing infection control and isolation measures,” they said.

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