Finn A Filén (1), Catharina Missailidis (1), Victor EJ Westergren (1), Matias Garzón (1), Carl Johan Treutiger (1), Viktor Dahl, Anna Mia Ekström (1, 2)

Affiliates

(1) Venhälsan, Södersjukhuset, Stockholm, Sweden (2) Karolinska Institutet, Dept of Global Public Health

Abstract

Monkeypox is a zoonosis endemic to tropical Africa that started spreading among men who have sex with men (MSM) in Europe in early May 2022, predominantly through sexual or intimate contacts. The first case in Sweden was diagnosed at our outpatient clinic specializing on sexually transmitted infections among MSM, on May 16. This is the first summary of our observations from the first 3 months of the outbreak.

Methods

We defined a case as someone with typical symptoms and a positive PCR-test for monkeypox virus. For quality control, data for all cases was compiled including data on gender, sexual orientation, age, being on pre-exposure prophylaxis (PrEP) for HIV, being HIV positive, route of transmission for monkeypox, country of infection, other sexual transmitted infections (STI) or bacterial superinfections and any hospital admission between May 16 and August 26, 2022. We hereby present the most common characteristics among MSM diagnosed with Monkeypox in Sweden using median values and proportions.

Results
A total of 87 patients tested positive for monkeypox (86 MSM, one trans woman). The age range was 25-66 years (median 38). Out of the positive patients, 14/87 (16%) were born 1976 or earlier (e.g. the year when infant vaccination for smallpox ceased in Sweden). HIV positivity rate was 17/87 (20%), 53/87 (61%) were on PrEP. The mode of infection was assessed as sexual transmission in all cases. The proportion of patients infected outside of Sweden was 46/87 (53%). Concomitant STIs (gonorrhoea 12, chlamydia 8, syphilis 2, herpes 4) were diagnosed in 23/87 patients (26%). Bacterial superinfections with Streptococci (grp A, C/G), staphylococcus aureus (including one case of MRSA) were diagnosed in 12/87 cases (14%).
Inpatient care was needed for 8/87 patients (9%). Reasons for hospital admission were pain management, confirmed or suspected bacteremia, severe lymphadenopathy, surgical debridement of secondary infection, fever and fatigue. No deaths were reported.

Conclusions
Monkeypox has quickly established itself as an infection with possibility of sexual transmission across all continents including Sweden, where it so far predominantly has affected MSM and trans persons. There is a need for much more knowledge regarding infectiousness, immunity and those at most risk of serious illness. Infections were evenly spread over different age groups, which suggests that previous smallpox vaccination has little or no protective effect. A monkeypox diagnosis was strongly correlated with taking PrEP for HIV or already being HIV positive. There was a high coinfection rate with other STIs, thus STI screening is strongly recommended in suspected cases of monkeypox. Screening for herpes and bacterial superinfections is worthwhile to rule out concomitant treatable infections. Admission rate was much higher than for other STIs.