Purpose : To evaluate the presence of Norwalk virus (NV) RNA on the hands of volunteers orally challenged with NV-seeded oysters.
Methods : This study was incorporated into a clinical trial that evaluated NV inactivation in oysters by high hydrostatic pressure processing (HPP). Forty-four adults were orally challenged with NV in artificially seeded oysters with or without HPP treatment, and 13 subjects became infected. During the acute phase of follow-up, 159 handrinse samples were collected from 6 infected and 6 uninfected subjects on days 3-5 post-NV challenge. Viruses were precipitated with polyethylene glycol followed by viral RNA extraction with the EasyMAG method. NV RNA was quantified using a NV-specific real-time RT-PCR assay with an internal PCR amplification control and RNA standards.
Results : A total of 40.8% (29/71) of the handrinse samples collected from 6 infected volunteers screened presumptively positive for NV, with an average of 3.56-log genomic equivalent copies (GEC) of NV detected per positive hand rinse sample. The NV detection rates and geometric mean titers showed no significant differences (P > 0.05) between samples collected immediately after bathroom use and during routine vital sign measurements. In addition, NV titers in handrinse samples and fecal samples collected on the same day showed no clear correlation. Efforts are currently underway to confirm presumptively positive samples.
Significance: These findings provide further evidence that NoV contamination on human hands is important, but does challenge current paradigms that huge quantities are omnipresent on the hands of those infected. Developing effective hand hygiene strategies to prevent NoV transmission and infection is critical in work places. This research was approved by an Institutional Review Board.