Wastewater Surveillance of Aichi Virus in Baltimore.

This study established long-term wastewater surveillance of Aichi virus (AiV) in Maryland. AiV, a member of the Kobuvirus genus associated with acute gastroenteritis, has established itself as an integral marker for wastewater-based monitoring; however, two key research questions remain unaddressed for the Baltimore metropolitan area: (1) whether AiV is consistently detectable in municipal wastewater throughout the year, and (2) whether its concentrations exhibit a measurable seasonal pattern. To address these hypotheses, influent samples were collected on a weekly basis from WWTP-A and WWTP-B from January to December 2023 (with grab sampling conducted at WWTP-A and automated collection deployed for the influent sampling of the water treatment plant B). All samples (n = 51) were subjected to PEG 8000 concentration, RNA extraction, cDNA synthesis, and RT-qPCR quantification. We observed AiV RNA in 94.12% of the samples from both facilities (25/51 at WWTP-A and 23/51 at WWTP-B) with concentrations that ranged from 2.5 to 3.63 log10 gc/L and a seasonal pattern showing consistent declines: loads for WWTP-A declining from winter (3.58 log10 gc/L) to fall (2.56) and for WWTP-B from winter (3.28 log10 gc/L) to fall (2.31). The year-round constant AiV presence provides a strong basis for its use as a stable viral marker within wastewater-based epidemiology efforts.