Retrospective detection of asymptomatic monkeypox virus infections among male sexual health clinic attendees in Belgium de2022retrospective
Retrospective study at a Belgian sexual health clinic (Antwerp, Belgium) in May 2022 that screened stored specimens originally collected for gonorrhea/chlamydia testing for MPXV DNA. Leftover DNA extracts from 224 men were tested by MPXV PCR, identifying four MPXV-DNA-positive cases (three asymptomatic at sampling and one with a painful perianal rash). Follow-up anorectal swabs at days 21–37 were PCR negative for asymptomatic cases. Orthopox PCR, viral culture, and serology (orthopox IgG immunofluorescence) were used as confirmatory assays.
Analytes
mpxv_pooled_swab
MPXV real-time PCR (Ct values) performed on leftover DNA extract from a pooled sample (combination of first-void urine, oropharyngeal swab, and anorectal swab). PCR used primer sets targeting the MPXV-TNF receptor gene on an Applied Biosystems QuantStudio platform (DNA extraction for GC/CT testing via Abbott m2000sp; repeat extraction described with Maxwell Promega).
Measurements only — no shedding model is fitted to this analyte, usually because it is sampled once per participant, leaving no trajectory to fit, or because nothing was ever detected. Open triangles are non-detects, drawn at the assay's censoring limit. See the modelling methods for what these estimates do and do not support.
mpxv_anorectal_swab
MPXV real-time PCR (Ct values) on anorectal swab-derived material (leftover DNA extract and/or re-extracted original sample) using previously described primer sets targeting the MPXV-TNF receptor gene on an Applied Biosystems QuantStudio platform.
Measurements only — no shedding model is fitted to this analyte, usually because it is sampled once per participant, leaving no trajectory to fit, or because nothing was ever detected. Open triangles are non-detects, drawn at the assay's censoring limit. See the modelling methods for what these estimates do and do not support.
mpxv_oropharyngeal_swab
MPXV real-time PCR result (Ct/qualitative) on oropharyngeal swab-derived material using previously described primer sets targeting the MPXV-TNF receptor gene on an Applied Biosystems QuantStudio platform.
Measurements only — no shedding model is fitted to this analyte, usually because it is sampled once per participant, leaving no trajectory to fit, or because nothing was ever detected. Open triangles are non-detects, drawn at the assay's censoring limit. See the modelling methods for what these estimates do and do not support.
orthopox_pooled_swab
Pan-orthopoxvirus PCR (Ct values) on leftover DNA extract from a pooled sample (combination of first-void urine, oropharyngeal swab, and anorectal swab), performed as previously described in the cited method.
Measurements only — no shedding model is fitted to this analyte, usually because it is sampled once per participant, leaving no trajectory to fit, or because nothing was ever detected. Open triangles are non-detects, drawn at the assay's censoring limit. See the modelling methods for what these estimates do and do not support.
orthopox_anorectal_swab
Pan-orthopoxvirus PCR (Ct values) on anorectal swab-derived material, performed as previously described in the cited method.
Measurements only — no shedding model is fitted to this analyte, usually because it is sampled once per participant, leaving no trajectory to fit, or because nothing was ever detected. Open triangles are non-detects, drawn at the assay's censoring limit. See the modelling methods for what these estimates do and do not support.