# Human norovirus persists longer than Escherichia coli in sandy soil, independent of plant decaying materials

## TL;DR

Human norovirus lasts longer in sandy soil than E. coli, regardless of decaying plant material, which is important for food safety in agriculture.

## Contribution

This study provides new data on the persistence of human norovirus and its surrogate in agricultural soils under controlled conditions.

## Key findings

- Human norovirus GII genome copies persisted longest in soil with a T1D of 28 weeks.
- Decaying plant material did not significantly affect microbial inactivation rates.
- Tulane virus showed strong correlation with HuNoV GII, supporting its use as a surrogate.

## Abstract

Human norovirus (HuNoV) is the leading cause of foodborne illnesses in the U.S. Fresh produce, often consumed raw, can serve as a vehicle for HuNoV transmission; however, limited data exist on its persistence in agricultural environments. This study evaluated the persistence of HuNoV GII, its cultivable surrogate Tulane virus, and Escherichia coli TVS 353 in sandy Florida agricultural soil. Soil samples with or without additional cilantro leaves (to simulate decaying plant debris) were incubated at 12 °C and tested for microbial concentrations at regular intervals over 29 weeks, using RNase RT-qPCR (both viruses), TCID50 (Tulane virus), and plate count (E. coli). Inactivation kinetics were fitted to log-linear and non-linear models to estimate the weeks required for the first 1-log10 reduction (T1D). Decaying cilantro leaves did not substantially impact microbial inactivation (p > 0.05). E. coli declined most rapidly (T1D = 2.2), followed by infectious Tulane virus (T1D = 5.63), Tulane virus genome copies (T1D = 11.8), and HuNoV GII genome copies (T1D = 28). A strong correlation of Tulane virus infectivity with HuNoV GII RNase RT-qPCR (r = 0.82) supported its suitability as a surrogate. Under the tested conditions, HuNoV’s prolonged persistence should be accounted for in risk assessments for preharvest fresh produce production.

The online version contains supplementary material available at 10.1038/s41598-025-31728-1.