Study shows no undetected transmission of monkeypox virus before May 2022 in Rotterdam and Amsterdam

Study shows no undetected transmission of monkeypox virus before May 2022 in Rotterdam and Amsterdam

In a recently published study medRxiv * Preprint servers researchers investigated whether undetected transmission of human monkeypox virus (hMPXV) occurred before the first documented MPX case in Rotterdam and Amsterdam.

Lernen: Ausbruch des humanen Affenpockenvirus bei Männern, die Sex mit Männern haben, in Amsterdam und Rotterdam, Niederlande: keine Hinweise auf eine unentdeckte Übertragung vor Mai 2022 in einer retrospektiven Studie. Bildnachweis: Dotted Yeti/Shutterstock

background

The first hMPXV case was documented in Amsterdam on May 10, 2022 and in Rotterdam on May 19, 202222. Since then, several people around the world have been affected by MPX. However, the potential prior transmission of hMPXV among Dutch individuals is unknown. Analysis of ongoing unidentified hMPXV transmission could improve understanding of the dynamics of the ongoing MPXV outbreak in 2022 and guide policy making and intervention development to reduce the health burden of MPX.

About studying

In the present retrospective study, researchers investigated whether undetected transmission of human monkeypox virus (hMPXV) occurred before the originally documented case of hMPXV infection in Rotterdam and Amsterdam.

A total of 401 anorectal and ulcer samples from men who had sex with male (MSM) attending the Sexual Health Centers (CSH) in Rotterdam and Amsterdam, dated up to February 14, were analyzed. The CSH regularly receives the anorectal samples for Ct (Chlamydia trachomatis) and Ng (Neisseria gonorrhoeae) tests. In contrast, ulcer samples are obtained for VZV (varicella zoster virus), Tp (Treponema pallidum), and HSV (herpes simplex virus)-1, -2 testing. All specimens were preserved for four months.

Quantitative polymerase chain reaction (qPCR) analysis was performed between February 14 and February 9 to detect hMPXV in the samples. Participant data were unlinked from their electronic files before hMPXV test reports were available. The team retrospectively used the cut-off dates as the day before the first presentation of an identified MPX case in Rotterdam and Amsterdam, May 18th and May 9th, respectively.

At the Rotterdam CSH, anorectal samples from MSM individuals regularly collected for Ct or Ng testing and ulcer samples collected for VZV and HSV-1, -2 testing were subjected to hMPXV testing between April 1 and May 18, 2022. The team discovered hMPXV through quantitative pan-orthopoxvirus PCR analysis, followed by whole-genome sequencing or using an MPXV-specific target. Further, phylogenetic analysis was performed using available GenBank sequences and subsampling methods.

Results

In Amsterdam, 169 Ng/Ct-positive anorectal samples and 125 ulcer samples (regardless of VZV, Tp or HSV-1, -2 positivity) were tested for the presence of hMPXV. None of the samples were hMPXV positive. In Rotterdam, 93 Ct/Ng-positive anorectal samples were tested, of which 30 visitors reported complaints between April 1 and May 18, 18. Additionally, 12 ulcer samples were tested for the presence of hMPXV during the period. One resident of the ulcer sample group from Amsterdam and one resident of the anorectal sample group from Rotterdam were identified as hMPXV positive in the first week of May 2022.

The hMPXV-positive patient diagnosed in Amsterdam was between 50 and 54 years old, had multiple ulcers and an itchy rash on the upper areas of the legs, had not been reported with a sexually transmitted infection (STI) and had been diagnosed with genital herpes during the consultation, had not had anti-human PrEP (pre-exposure prophylaxis). Immunodeficiency virus (HIV) recipient, reported a history of occasional anal condom use with a sexual partner in the past six months, and had previously been diagnosed with HIV infection, Ct infection, Ng infection, and primary syphilis.

The hMPXV-positive patient, diagnosed in Rotterdam during a similar period, was between 20 and 24 years old, had proctitis, had been reported for an STI, was diagnosed during consultation with anorectal and pharyngeal Ct and Ng, had received PrEP for HIV, gave a history of occasional anal condom use at 30 sexual partners in the past six months, participated in group sex and recreational drug use, and had previously been diagnosed with a sexually transmitted disease.

Sequences from the hMPXV-positive Amsterdam MSM individual were identified as IIb (B.1) clade sequences and were closely related to global hMPXV strains. The hMPXV-positive Rotterdam resident sequences could not be analyzed due to insufficient deoxyribonucleic acid (DNA). The two hMPXV-positive cases were identified in a period (end of April 2022) coinciding with that of the first MPX case documentation in Spain (April 26), Portugal (April 29) and the United Kingdom (UK, April 21). . On average, hMPXV incubated for nine days in cases diagnosed in the Netherlands.

Before May 2022, no evidence of widespread hMPXV transmission was found in Dutch MSM sexual networks. It is very likely that the spread of the Dutch hMPXV outbreak across Europe occurred in a short time frame during the spring 2022 season among MSM individuals who were actively involved in sexual activity.

Overall, study results showed no evidence of extensive undetected hMPXV transmission among MSM individuals living in Rotterdam or Amsterdam before May 2022. The study results are consistent with those of other European cities and support a clonal global hMPXV outbreak in spring 2022.

*Important NOTE

medRxiv publishes preliminary scientific reports that have not been peer-reviewed and therefore should not be considered conclusive, guide clinical practice/health-related behavior, or treated as established information.

Reference:

• Henry J. de Vrieset al. (2022). Ausbruch des humanen Affenpockenvirus bei Männern, die Sex mit Männern haben, in Amsterdam und Rotterdam, Niederlande: keine Hinweise auf eine unentdeckte Übertragung vor Mai 2022 in einer retrospektiven Studie. medRxiv. doi: https://doi.org/10.1101/2022.11.19.22282179 https://www.medrxiv.org/content/10.1101/2022.11.19.22282179v1

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