The monkeypox illness now spreading around the globe is showing some symptoms that are very different from those seen in previous outbreaks, a new study shows.
These unique symptoms include rectal pain, penile swelling, solitary lesions and swollen tonsils, researchers report in the July 28 issue of the BMJ.
"Understanding these findings will have major implications for contact tracing, public health advice, and ongoing infection control and isolation measures," the researchers explained in a journal news release.
For the study, researchers evaluated 197 confirmed monkeypox cases at an infectious disease center in London between May and July 2022.
All patients presented with monkeypox lesions, most commonly on their genitals or near their anus. All cases were men, and all but one were men who have sex with other men.
Most patients (86%) reported systemic symptoms like fever (62%), swollen lymph nodes (58%) and muscle aches and pain (32%).
In contrast with previous reports suggesting that such symptoms precede skin lesions, the British researchers found that 38% of patients developed lesions prior to systemic illness and 14% only developed lesions.
A total of 71 patients reported rectal pain, 33 had a sore throat, and 31 had a swollen penis, while 27 had oral lesions, 22 had a solitary lesion and nine had swollen tonsils.
Solitary lesions and swollen tonsils were not previously known to be typical symptoms of monkeypox, the researchers noted.
Overall, 10% of the study's patients were admitted to the hospital for management of symptoms, most commonly rectal pain and swelling of the penis, the researchers said.
More than one-third (36%) of participants also had HIV, while 32% of those screened for sexually transmitted diseases had one, the investigators found.