[KoK! Health] How to Prevent the Winter Unwelcome Guest 'Norovirus'

Transmission through food and human contact
No vaccine available, maintain strict hygiene and cook food thoroughly

Norovirus structure image (Photo by Korea Disease Control and Prevention Agency)

[Asia Economy Reporter Chunhee Lee] Food poisoning is commonly thought to occur only in summer, but winter is not safe either. This is because food poisoning caused by norovirus is rampant in winter. According to the Ministry of Food and Drug Safety on the 31st, among the 54 cases of norovirus food poisoning (4,990 patients) occurring annually on average from 2017 to 2021, as many as 40% were concentrated in winter. This is why caution is needed even in winter.

Norovirus is a very small virus that causes inflammation in the human stomach and intestines. It is commonly transmitted between people and can also be infected through contaminated food. Once infected with the virus, the body produces antibodies through an immune response, but the antibody maintenance period is short, lasting only a few months, so even if one has had food poisoning once, re-exposure can lead to reinfection.

After infection with norovirus, there is an incubation period of one to two days. Then nausea, vomiting, diarrhea, fever, and muscle pain occur, and in severe cases, dehydration symptoms accompany. Most cases heal naturally within 2 to 3 days, but overseas, elderly patients with underlying diseases have died. Conservative treatment to supply fluids and prevent dehydration is necessary, and intravenous fluid supply may be required if dehydration is severe.

(Photo by Himchan Hospital)

Norovirus is transmitted not only through consumption of contaminated food but also through person-to-person contact, and it is highly contagious. However, there is no special vaccine, so thorough personal hygiene and careful handling of food are essential. Avoid eating raw seafood or food that is not fresh, and be cautious when eating seasonal raw oysters or Gwamegi (half-dried Pacific saury). Seafood like oysters should be cooked at a core temperature of 85℃ for more than one minute to kill norovirus, so it is better to eat them cooked whenever possible. Untreated groundwater is easily contaminated with norovirus, so it should be boiled before use. Fruits and vegetables should be soaked in clean water sufficiently and then washed under running water. Cooking utensils should be sterilized by boiling or using disinfectants.

Norovirus particles are small and strongly adhere to surfaces, so thorough handwashing is fundamental for prevention. Use soap or detergents and wash hands under running water for more than 30 seconds, scrubbing fingers, backs of hands, and palms carefully. Since infection often occurs through patients’ feces, vomit, saliva, or contaminated hands, toilets, door handles, and areas inside and outside bathrooms should be frequently wiped with alcohol disinfectants.

Dr. Hyomoon Son, Deputy Director of the Gastroenterology Department at Incheon Himchan General Hospital, advised, “Norovirus remains active even at minus 20℃ and, unlike bacteria, its survival period lengthens as temperatures drop in winter, so vigilance is necessary.” He added, “In places where people gather densely, such as daycare centers, schools, military units, and nursing facilities, it is especially important to maintain strict personal hygiene.”