Spanish wastewater reveals the current spread of Monkeypox virus

Besides nasopharyngeal swabs, monkeypox virus (MPXV) DNA has been detected in a variety of samples such as saliva, semen, urine and fecal samples. Using the environmental surveillance network previously developed in Spain for the routine wastewater surveillance of SARS-CoV-2 (VATar COVID-19), we have analyzed the presence of MPXV DNA in wastewater from different areas of Spain. Samples (n = 312) from 24 different wastewater treatment plants were obtained between May 9 (week 19 of 2022) and August 4 (week 31 of 2022). Following concentration of viral particles by a validated aluminum adsorption-precipitation method, a qPCR procedure allowed us to detect MPXV DNA in 56 wastewater samples collected from May 16 to August 4, 2022, with values ranging between 2.2 x 103 to 8.7 x 104 genome copies (gc)/L. This study shows that MPXV DNA can be reproducibly detected by qPCR in longitudinal samples collected from different Spanish wastewater treatment plants. According to data from the National Epidemiological Surveillance Network (RENAVE) in Spain a total of 6,119 cases have been confirmed as of August 19, 2022. However, and based on the wastewater data, the re-ported clinical cases seem to be underestimated and asymptomatic infections may be more frequent than expected.

Automated summary

Monkeypox virus (MPXV) DNA was detected in various samples including saliva, semen, urine, and fecal samples besides nasopharyngeal swabs. The study analyzed the presence of MPXV DNA in wastewater collected from different areas of Spain using a surveillance network. The results showed that MPXV DNA could be consistently detected in longitudinal wastewater samples from different treatment plants, indicating the possibility of underestimated cases and frequent asymptomatic infections.