Intended for healthcare professionals


Monkeypox: Symptoms seen in London sexual health clinics differ from previous outbreaks, study finds

BMJ 2022; 378 doi: (Published 05 July 2022) Cite this as: BMJ 2022;378:o1659
  1. Melina Zachariou
  1. The BMJ

Monkeypox symptoms seen in patients attending four sexual health clinics in London appear to differ from those seen in previous outbreaks in Nigeria, Sudan, and the US, a study has found.1

Researchers from the Chelsea and Westminster Hospital NHS Foundation Trust and Imperial College London looked at the 54 cases diagnosed during a 12 day period in May 2022. They found that patients had a lower prevalence of tiredness and fever than seen in previously studied outbreaks. Skin lesions on genitals also appeared to be more common in this outbreak, while lesions on the face were less frequently seen.

Study co-author Ruth Byrne from the Chelsea and Westminster Hospital NHS Foundation Trust, said, “It is possible that at various stages of the infection monkeypox may mimic common sexually transmitted infections (STIs), such as herpes and syphilis, in its presentation. It’s important that sexual health clinicians and patients are aware of the symptoms of monkeypox as misdiagnosis of the infection may prevent the opportunity for appropriate intervention and prevention of onward transmission. Additional resources are urgently required to support services in managing this condition.”

As of 30 June, the total number of confirmed monkeypox cases in the UK has risen to 1235.2

The paper, published in Lancet Infectious Diseases, found that patients were all symptomatic and presented with skin lesions. A total of 49 (94%) had at least one skin lesion on the genital or perianal skin, and around nine out of 10 (37, 89%) had skin lesions affecting more than one anatomical site. Just over half of patients (30, 55%) had lymphadenopathy (swelling of lymph nodes), while one in four patients had a concurrent STI.

Patients mostly experienced a mild illness and recovered while isolating at home, however five people required hospital admission because of pain or infection of the skin lesions. All improved and were discharged, with an average of seven days spent in hospital.

All patients included in the study identified as men who have sex with men (MSM). The median age was 41 years and 70% (38 of 54) were white. All except two patients were not aware of having been in contact with a known case and none reported travel to sub-Saharan Africa, although many had recently visited other European countries.

Comparison with previous outbreaks

The researchers found the prevalence of fatigue, asthenia, or lethargy among patients (67%, 95% confidence interval, 54 to 79) was much lower than seen in previous outbreaks in Nigeria and the US (over 80%). Fewer patients also reported fever or febrile chills (57%, 95% CI 44 to 71), compared with outbreaks in Nigeria, Sudan, and the US (85% to 100%).

Skin lesions on the genital or perianal skin were more frequently seen in patients included in this study (94%), compared with two thirds in previous outbreaks, while the prevalence of lesions on the face and neck was much lower in this study, at around one fifth compared with 62% to 97% previously.

But, commenting on the paper, Boghuma Kabisen Titanji, assistant professor of medicine at Emory University, Atlanta, said the findings were consistent with the new cases now being reported around the world.

She said, “The findings are similar to those reported in cohorts from EU countries and the US. One in four people in this cohort had a concurrent STI which may reflect the study being conducted in sexual health clinics but could also reflect the overlap between how monkeypox is presenting in the ongoing outbreak and common STIs. It highlights the need to clarify the mechanisms of transmission in the current outbreak better to inform policies and approaches to contain it.”

The authors noted that their data was subject to selection biases as current guidance and health promotion materials are focused on promoting monkeypox testing in symptomatic people who self-define as MSM. They have stressed that it is important to remain alert to the possibility of spread to other groups while still balancing targeted health promotion to groups disproportionately affected by the current outbreak.