Certain monkeypox symptoms seen now are slightly different from those reported during previous outbreaks in African regions, a latest study has found. Researchers are urging clinicians to pay attention to these symptoms as well.

For his or her paper, published Thursday in The British Medical Journal (BMJ), the researchers checked out 197 patients with confirmed monkeypox infections in London between May and July 2022. They were all men, with 196 of them identifying as gay, bisexual or other men who’ve sex with men. Their median age was 38.

All of them had lesions, typically within the genitals or the perianal area, while 86% also developed a systemic illness, with symptoms equivalent to fever, muscle aches and swollen lymph nodes, the BMJ noted in a news release.

Nonetheless, the researchers also noticed symptoms equivalent to penile swelling (penile oedema) and rectal pain – features that were different from those seen in previous outbreaks. The boys also displayed other symptoms equivalent to swollen tonsils and solitary lesions that weren’t known to be features of monkeypox. 

Among the symptoms were even severe enough to require hospital admissions. In comparison with current case reports, wherein the systemic symptoms typically precede the skin lesions, 38% of the patients developed the symptoms after the onset of the lesions.

“The characteristics of the cohort we describe differ from those of populations affected in previous outbreaks in endemic regions,” the researchers wrote.

Penile swelling and rectal pain, for example, were essentially the most common symptoms in patients who were admitted to hospitals. Nonetheless, these, in addition to the opposite “relatively common” symptoms, weren’t included in the general public health messages. Some 14% of the cases that the researchers checked out didn’t even meet the U.K. Health Security Agency’s guidance.

The agency’s definitions of possible and probable monkeypox infections include signs equivalent to an unexplained rash, fever, exhaustion, joint pain, intense headaches, backache and swollen lymph nodes.

The research team has urged clinicians to also consider the extra symptoms while diagnosing monkeypox in patients.

“These presentations must be included in public health messaging to help early diagnosis and reduce onward transmission,” they wrote, noting that their findings confirm the continuing “unprecedented community transmission” of the virus amongst gay, bisexual and other men who’ve sex with men.

Among the many patients, just one had recent travel links to a monkeypox endemic region.

“Disseminating awareness of atypical presentations is of important clinical importance as failure to acknowledge monkeypox infection as a possible differential could pose a serious risk to health care professionals and other contacts,” researchers said.