Leuven sewage flagged a parvovirus wave a year before the official alert, thanks to a broad virus scan
KU Leuven researchers found 339 virus species in two and a half years of wastewater with a single technique, and now want to test it at other treatment plants.
Researchers at KU Leuven's Rega Institute have developed a technique for detecting hundreds of viruses in sewage at once. Until now, wastewater monitoring has searched specifically for a limited number of viruses already suspected to be circulating, virologist Jelle Matthijnssens explained to VRT NWS. The new approach first selectively extracts viral genetic material from a sample, so that viruses at low concentrations and even variants of the same virus become visible, the university says. The research was published in the journal Nature Water.
For more than two and a half years, the team examined wastewater every week from an Aquafin treatment plant in Leuven that handles water from some 120,000 residents. According to the paper, that amounted to 127 samples over 31 months. In them the researchers found a combined 339 virus species and 715 virus strains, including rotaviruses, noroviruses and adenoviruses, as well as viruses that are not routinely tested for. Some viruses peak in winter and spring, others in summer. For rotavirus, the signal in sewage typically ran about a week ahead of clinical figures.
The most striking example is parvovirus B19. As early as April 2023, the team saw a clear rise in Leuven's wastewater, while Belgian health authorities only raised the alarm officially more than a year later. In young children the virus often causes a rash, but it can be dangerous for pregnant women, Matthijnssens told VRT NWS. In the summer of 2024, many pregnant women were admitted to hospital with complications. In his view, the method would probably also have given an earlier signal at the start of the coronavirus pandemic.
Residents need not worry about the large numbers of viruses: people are regularly infected with viruses that do not make them ill but do show up in wastewater, the virologist stresses. The technique is meant to complement existing disease surveillance, not replace it, and any signal always needs clinical follow-up, KU Leuven writes. The study relies on one treatment plant in one city. The team now wants to test the method at other plants and see whether near real-time monitoring at several sites across Belgium is feasible.