Norovirus Contamination on Hands of Infected Individuals during Norovirus Outbreaks in Long-term Care Facilities

Introduction: The majority of the norovirus outbreaks in the U.S. are reported in long-term care facilities (LTCFs).  Although direct person-to-person transmission is regarded as the primary transmission route for norovirus, outbreak investigations suggest that the hands of infected individuals play an important role in norovirus transmission.

Purpose: The aim of the study was to collect and test hand rinse samples from infected individuals for norovirus.

Methods: As part of a prospective study on norovirus outbreaks in LTCF, hand rinse samples and stool samples were collected from 22 infected residents and staff between days 0 - 4 after onset of norovirus symptoms. Hand rinse samples (25 ml) were collected using a glove juice method and concentrated using for 18 h and norovirus was lysed by guanidinium isothiocyanate. Viral RNA was then purified and further concentrated using Qiagen midi-columns Zymo-spin columns. Norovirus was extracted from stool using guanidinium isothiocyanate-silica based extraction kit on an automatic magnetic bead-beating platform. GI and GII norovirus was detected and quantified by real time RT-PCR and further positive samples were further typed by conventional RT-PCR and sequencing of the positive products.

Results: Of the 22 hand rinse samples, 10 (45.5%) tested positive for norovirus with viral loads ranging from 3.4 to 7.9 log RNA copy numbers per hand rinse sample. Genotypes of viruses detected in hand rinse samples were identical to the genotypes detected in the stool samples from the individuals.

Significance: These findings demonstrate that almost half of the symptomatic people from which a hand sample was collected tested positive for norovirus with significant higher viral loads than was reported previously in controlled human volunteer studies. These data support the need for better hand hygiene strategies to prevent norovirus transmission.