[A norovirus-borne outbreak caused by contaminated bottled spring water in a school, Zhejiang province]

OBJECTIVE

To study a local hospital reported acute gastroenteritis in a boarding school on its source of infection, mode of transmission and risk factors of the infection.

METHODS

A suspected case was defined as who had developed diarrhea (≥ 3 times/day) or vomiting among teachers or students of the school, during April 19 - 30, 2010. A confirmed case was from a probable case plus tested positive for norovirus in stool specimens by using RT-PCR. Stool specimens of cases and environmental specimens were collected for laboratory diagnosis. In a case-control study, we compared exposures to sources of bottled water, consumption of bottled water, and hygienic habits of 220 probable or confirmed cases from April 21 - 23 in the peak of the outbreak, together with another 220 controls, with frequency-matched by school grade.

RESULTS

20.3% of the 1536 students but none of the teachers developed the disease. 98.6% of the cases (n = 217) and 85.5% (n = 188) of the controls had drunk bottled water in the classroom (OR(M-H) = 12.3, 95%CI: 3.7 - 40.9). 47.9% (n = 104) of the cases and 41.5% (n = 78) of the controls had drunk unboiled bottled water in classroom (OR(M-H) = 3.8, 95%CI: 1.5 - 9.6). 47.9% (n = 104) of the cases and 48.4% (n = 91) of the controls had drunk bottled mixed water (boiled and unboiled) in the classroom (OR(M-H) = 2.8, 95%CI: 1.1 - 7.0). Stool specimens from 3 cases and one bottle of uncovered bottled water in classroom showed positive of having norovirus genotype II. Coliforms was cultured much higher rates than standard deviations in the bottled water. The factory making the bottled water was not licensed or having strict disinfection facilities.

CONCLUSION

Bottled spring water contaminated by norovirus was responsible for this outbreak.

[Research development on disinfection technology for viruses in drinking water]

With the deterioration of water source pollution, the quality requirements for drinking water of countries will become stricter and stricter, and the microbe index has been one of the important aspects. The introduction of the virus index and the development of disinfection technology focusing on virus have significant importance for the improvement of the drinking water standards and for the protection of people health in every country. To be familiar with the domestic and abroad research development of the disinfection control technology focusing on virus provides certain theory guidance and technological support for continuously improving drinking water standard in our country and for establishing safer drinking water processing technologies. So, this article will comprehensively describes 4 aspects: resistance comparison of virus over every disinfection technology, influential factors of disinfection, research development of new technology, and the mechanisms.