Management of Norovirus gastroenteritis in the community

In vivo comparison of two human norovirus surrogates for testing ethanol-based handrubs: the mouse chasing the cat!

Human noroviruses (HuNoV), a major cause of acute gastroenteritis worldwide, cannot be readily cultured in the lab. Therefore, a feline calicivirus (FCV) is often used as its surrogate to, among other things, test alcohol-based handrubs (ABHR). The more recent laboratory culture of a mouse norovirus (MNV) provides an alternative. While MNV is closer to HuNoV in several respects, to date, no comparative testing of FCV and MNV survival and inactivation on human hands has been performed. This study was designed to address the knowledge gap. The rates of loss in viability during drying on hands were -1.91 and -1.65% per minute for FCV and MNV, respectively. When the contaminated skin was exposed for 20 s to either a commercial ABHR with 62% (v/v) ethanol or to 75% (v/v) ethanol in water, FCV infectivity was reduced by <1 log₁₀ while that of MNV by nearly 2.8 log₁₀. Extending the contact time to 30 s reduced the FCV titer by almost 2 log₁₀ by both test substances and that of MNV by >3.5 log₁₀ by the commercial ABHR while 75% ethanol did not show any noticeable improvement in activity as compared to the 20 s contact. An 80% (v/v) aqueous solution of ethanol gave only a 1.75 log₁₀ reduction in MNV activity after 20 s. The results show significant differences in the ethanol susceptibility of FCV and MNV in contact times relevant to field use of ABHR and also that 62% ethanol was a more effective virucide than either 75% or 80% ethanol. These findings indicate the need for a review of the continuing use of FCV as a surrogate for HuNoV.

Viral gastroenteritis in Charleston, West Virginia, in 2007: from birth to 99 years of age

OBJECTIVE

To describe factors associated with a rectal swab or stool sample positive for norovirus, rotavirus, or adenovirus.

DESIGN

Retrospective study.

SETTING

Charleston Area Medical Center, a regional academic medical center in Charleston, West Virginia.

METHODS

Rectal swab or stool samples were obtained from patients suspected of having viral gastroenteritis. These samples were sent to the Charleston Area Medical Center virology laboratory for testing in 2007. Viral antigen in rectal swab and stool samples is detected by use of commercially available immunoassay kits for each virus. Data were extracted from the virology laboratory database for the following 1-year time period: January 1, 2007, through December 31, 2007. When necessary, additional information was obtained from electronic administrative data on patients.

RESULTS

There were 2,867 rectal swab and stool samples available for viral testing. Of these samples, 1,261 (44%) were positive for a virus. Of these positive samples, 972 (77%) were positive for norovirus, 182 (14%) were positive for rotavirus, and 110 (9%) were positive for adenovirus. The patients in the youngest age group had the highest number of test results positive for all 3 viruses. When the test results for the youngest age group (0-9 years) were compared with those for all the other age groups combined (10-99 years), the proportion of positive cases was highest for the youngest age group (P<.001). There were significant seasonal trends for all 3 viruses. Multivariate analysis of norovirus showed that season, source, sex, and age were significant predictors of a positive test result. Multivariate analysis of rotavirus showed that season and source were significant predictors of a positive test result. Multivariate analysis of adenovirus showed that season and age were significant predictors of a positive test result.

CONCLUSIONS

We conclude (1) that these 3 viruses are common causes of gastroenteritis in Charleston, West Virginia; (2) that infants and young children are more likely to test positive for these viruses than are older individuals; (3) that norovirus was the most common cause of gastroenteritis; and (4) that there are seasonal trends for all 3 viruses.