Norovirus how to prevent norovirus infection
Norovirus (Nov) is an important pathogen causing the outbreak of non bacterial acute gastroenteritis worldwide. It is also the pathogen of the most serious food borne diseases. About 90% of non bacterial diarrhea is caused by this kind of virus.
People of all ages are generally susceptible to Nov, and children, the elderly, people with immune deficiency and patients with organ transplantation are highly vulnerable. In 2006, the U.S. Centers for Disease Control and prevention listed Nov as a bioterrorism class B factor. In developed countries, there are about 900000 children under 5 years old who seek medical treatment for diarrhea caused by Nov infection every year, of which more than 60000 need to be hospitalized; In developing countries, 11 million children are hospitalized due to Nov infection every year, and 218000 people die. Among the diarrhea cases of children under 5 years old hospitalized in the viral diarrhea monitoring sentinel hospital from 2006 to 2013, the detection rate of Nov increased from 11.2% in 2007 to 20.3% in 2011, suggesting that the epidemic trend of Nov among children in China has increased in recent years, which should be paid attention to by medical and health organizations.
Prevention and control
Outbreaks caused by norovirus often occur in closed or semi closed environments. The control measures mainly include isolation and control of infectious sources, strengthening environmental disinfection and hand hygiene. Patients, suspected patients and asymptomatic carriers should be isolated. Students should avoid continuing to live in school after they get sick. Food processors should start working 2 ~ 3 days after recovery. Vomit should be quickly cleaned and disinfected with bleach, and contaminated food should be discarded. When textiles (including clothes, towels, tablecloths and napkins) are contaminated with vomit or feces, they should be cleaned at high temperature quickly. Existing data have proved that hand hygiene plays an important role in blocking the transmission of norovirus, and it is strongly recommended to wash hands with soap (hand sanitizer) and running water for more than 20s. Its effect has been confirmed by research that it may be better than ethanol.
In order to complete the infection process, three factors need to exist at the same time, including the source of infection, the route of transmission and the susceptible population.
The main sources of Nov infection are patients with Nov virus infectious diarrhea, recessive infections and healthy carriers. From the onset to 2 weeks after recovery, the virus was excreted from vomit and feces. Nov can infect people with less than 100 virus particles. The amount of virus in the feces of patients 1 ~ 3 days after onset is large, up to 105 ~ 1011 virus particles per gram of feces, which has a high risk of transmission.
Route of transmission
Nov can be transmitted through food source, water source and direct contact between people. Human to human transmission can be divided into fecal to oral transmission and aerosol transmission of vomit. These characteristics make the outbreak of Nov infected diarrhea easy to occur in closed or semi closed places, such as hospitals, nursing homes, troops, schools, restaurants, kindergartens, families and other places. Among the 348 Nov outbreaks released by the Centers for Disease Control and prevention in the United States, the spread of virus caused by food pollution, human to human transmission and drinking water pollution accounted for 39%, 12% and 3% respectively, indicating that food pollution is the main way of Nov transmission.