Due to the decrease in the number of mpox infections in the Netherlands, we were unable to include the desired number of study participants.

MonkeyPox Virus Infectious Disease (MPXVID) is a viral infection caused by the monkeypox virus (MPXV) which is an orthopoxvirus that is endemic in countries in West and Central Africa. The clinical course of the MPXVID is similar to smallpox (variola) but usually milder - with less severe disease symptoms seen in the West African subtype. Historically, the case fatality ratio of MPXVID ranged from 0 to 11% and fatality occurs more commonly among children. In Europe, human MPXVID only occurred as an imported disease with limited onward transmission. However, since May 2022 over 19.000 cases of MPXVID - mostly with the West African subtype - have been reported in Europe without a travel history to the endemic areas in Africa. The far large majority of patients with MPXVID in the current outbreak are gay, bisexual and other men who have sex with men (GBMSM). There is an urgent need to address essential knowledge gaps for optimal clinical care and public health management.

The aim of this study is to improve our understanding of clinical, virological, and psychosocial outcomes in patients with MPXVID. To get a better understanding of associated risk factors for MPXV infection, and to measure quality of life and stigma, the investigators will also include a control population of men without proctitis and MPXVID-related symptoms at day 0. In addition, the investigators want to assess the vaccine effectiveness against MPXVID of infant smallpox vaccination given before 1974, as well as vaccine effectiveness of the modified vaccinia Ankara (MVA) smallpox vaccine, when administered as pre- or post-exposure prophylaxis in high risk contacts of MPXVD patients.

Inclusion Criteria

Case:

- Individuals, with: I. Laboratory confirmed MPXVID, or II. A presumptive MPXVID case with pending laboratory confirmation

- Be able to provide informed consent by means of: I. Verbal or deferred informed consent, which will be complemented with a written informed consent during the subsequent outpatient study visit; II. Written informed consent during the baseline visit for presumptive cases

- Sufficient understanding of the Dutch or English language.

Control:

- Individuals without proctitis and MPXVID-related symptoms

Exclusion Criteria

Case:

• Presumptive cases with subsequent negative test for MPXV (can be included as control);
• Being under the age of 16 years old;
• Unlikely to comply with the study procedures, as deemed by the recruiting research doctor/nurse;
• Mental disorder that in the view of the investigator would interfere with adherence to the study procedures, or the decision to participate in the study;
• Investigators or otherwise dependent persons;
• Living in long term care facility.

Control:

• Positive test result for MPXV at baseline (day 0)
• Being under the age of 16 years old;
• Unlikely to comply with the study procedures, as deemed by the recruiting research doctor/nurse;
• Mental disorder that in the view of the investigator would interfere with adherence to the study procedures, or the decision to participate in the study;
• Investigators or otherwise dependent persons;
• Living in long term care facility.

The target population are all individuals visiting the STI-clinic of the Public Health Services of Amsterdam, irrespective of their gender, aged 16 years or older with a laboratory confirmed MPXV infection, or are suspected of MPXV while laboratory confirmation is pending. MPXV infection is diagnosed according to a routinely performed PCR test on lesion, anal-, pharyngeal and vaginal swabs in patients suspect of having MPXVID. The controls will be clients of the STI clinic who are individuals without proctitis and without MPXVID-related symptoms; they will only be matched on date of inclusion.