Pepper Mild Mottle Virus (PMMoV) is widely used in wastewater-based surveillance (WBS) as a faecal indicator, population size marker and analytical process control. It is highly abundant in domestic wastewater and originates from consumption of products containing Capsicum species infected with PMMoV. However, despite its widespread use in WBS, data on the variability of PMMoV levels in wastewater are limited, and the main dietary sources are not fully investigated. In this study, we assessed the reliability of PMMoV as a faecal marker by analysing wastewater samples collected across multiple locations and timeframes in Sweden. We also analysed different foods to identify possible dietary sources. Our results showed consistently high PMMoV levels in wastewater, averaging 10.37 log10 genome copies per resident per day, with overall little variation between days, weeks, and years. Of 60 foods tested, 45 contained detectable levels of PMMoV, with particularly high concentrations, ranging from 5.70 to 12.21 log10 genome copies per serving, found in commonly consumed spices, including paprika powder, and various processed foods, including ready meals, sandwich spreads and snack products. These results highlight the dietary basis for the high and stable presence of PMMoV in domestic wastewater and emphasise its robustness as a faecal marker in the Swedish context.

The authors have declared no competing interest.

This study was funded by Carl Trygger Foundation for Scientific Research (CTS 22:2255) the SciLifeLab Pandemic Laboratory Preparedness Programme (grants C19RA:031, LPP1:008 and REPLP1:007) and governmental grants provided to the Public Health Agency of Sweden under assignment S2024/00187. 

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

All data produced in the present study are available upon reasonable request to the authors