Norovirus Lawyer & Attorney : Marler Clark : Norovirus Blog

American Society for Microbiology
Sascha Mormann, Mareike Dabisch, and Barbara Becker

Abstract

Contaminated food is a significant vehicle of human norovirus transmission. The present study determined the effect of physicochemical treatments on the tenacity of infective human norovirus genogroup II in selected foods. Artificially contaminated produce was subjected to a selection of processes used by the food industry for preservation and by the consumer for storage and preparation. Virus recovery was carried out by ultrafiltration and monitored with bacteriophage MS2 as an internal process control. Norovirus was quantified with monoplex one-step TaqMan real-time RT-PCR and an external standard curve based on recombinant RNA standards. A RNase pretreatment step was introduced to avoid false-positive PCR results caused by accessible RNA allowing the detection of intact virus particles. Significant titer reductions were obtained with heat treatments usually applied by the consumer for food preparation (baking, cooking, roasting). Generally, processes for preservation and storage, such as cooling, freezing, acidification ( pH 4.5) and moderate heat treatments (pasteurization) appear to be insufficient to inactivate norovirus within a food matrix or on the surface. Beside the persistence in processed food, this study provides comparable data about individual matrix-specific protective effects, recovery rates and inhibitory influences on the PCR reactions. The established workflow might be applied to other non-cultivable enteric RNA viruses which are connected to foodborne diseases. The obtained data of this project may also benefit the process optimization for norovirus inactivation in food by adjusting food processing technologies and promote the development of risk assessment systems in order to improve the consumer protection.

• Email This
• Print
• Comments
• Trackbacks
• Share Link

A study suggests one possible culprit: dirty restrooms.  Most restrooms on these ships are not being properly cleaned, the authors say, and a sanitation program run by the Centers for Disease Control and Prevention does not detect the dirty ones.

According to researchers writing in the Nov. 1 issue of Clinical Infectious Diseases, the C.D.C. identified contamination with norovirus as the problem in almost all of these infections. But the ships generally had high passing scores on the inspection closest to their outbreaks. In fact, their scores were on average higher than those of ships with passengers who had no episodes of diarrheal disease.

Norovirus can survive for weeks on surfaces at room temperature, and it is difficult to kill. “It’s a tough virus,” said the lead author of the study, Dr. Philip C. Carling. “It isn’t killed by alcohol hand rubs. Chlorine bleach is the only thing that works.”

There were 19 outbreaks of intestinal illness during the 3-year study period. Although the survey was not designed to detect norovirus or establish the cause of any illness, the restroom cleanliness scores were slightly lower on ships that had outbreaks than on those that had none.

The difference was not statistically significant, but the authors said the findings were consistent with the possibility that restroom contamination contributed to norovirus epidemics.

“We’re not saying that poor cleaning causes norovirus outbreaks,” Dr. Carling said, adding, “I believe that one or more people with norovirus who handle food, or possibly a passenger, comes down with norovirus, and substandard hygiene serves as a facilitator of the spread in a closed population.”

• Email This
• Print
• Comments (1)
• Trackbacks
• Share Link