CDC's wastewater page says A(H5) detections can signal that animals or humans may be infected, but cannot say whether the virus came from animals, an animal product such as milk, or humans, which is the whole point when a surveillance signal starts traveling faster than its caveat [1].

The paper's May 18 piece on why bird-flu wastewater needed a milk-versus-human warning label argued that surveillance without source discipline becomes public-risk theater, especially when the same technical finding can point toward dairy, poultry, wastewater handling, or clinical infection.

CDC updates the data every Friday and says detections do not necessarily mean humans in the community are infected [1], while its bird-flu situation summary still describes sporadic United States human cases in dairy and poultry workers, low current public-health risk, and no identified human-to-human spread in the United States [2].

The interesting science is humble: wastewater can see what clinical testing misses, but it is a sewershed signal rather than a diagnosis, and the gap between X and CDC is whether a plus sign in wastewater is allowed to outrun the source caveat that public-health and agriculture teams still have to investigate before communities infer human spread.

That caveat is not bureaucratic cowardice; it is the difference between a surveillance alarm that directs testing and a rumor that tells the public the wrong species, product, or exposure route caused the signal.

-- KENJI NAKAMURA, Tokyo