The disaster of norovirus outbreaks
Google ‘norovirus school’, and you will find countless cases of entire schools abroad being shut down because a majority of their student population is incapacitated by norovirus-associated diarrhoea. The virus can survive for up to three weeks outside the human body, is shed in large doses by infected patients, and ingestion of even a small number of virus particles is enough to cause the disease. Now, think of schoolchildren, how much attention they pay to hand-washing, how freely they mingle with one another, and how someone or the other in the student population is always sick with AGE: a school environment is almost an incubator for noroviruses.
Not only is the virus potent, it is also shed by kids before they even begin to exhibit symptoms; this continues long after the child is asymptomatic. Hence, even an apparently healthy child, or one who seems to have recovered from his illness, is a potential source of infection.
Parents of children who are infected are advised to keep their child home from school for 2-3 days even after the symptoms disappear. In an increasingly competitive, overloaded education system where teachers struggle to complete teaching the syllabus, and multiple exams and extracurricular activities are scheduled throughout the week, this advisory is unlikely to be heeded. On the flip side, missing an entire week of school can upset a child’s life.
Elderly people are also extremely susceptible to norovirus. In the US, norovirus cases are most frequently seen in old-age homes. Noroviruses are also responsible for a majority of diarrhoea outbreaks in healthcare settings. Cruise ships on long voyages are an isolated environment where improper hygiene by a single food-handler can infect an entire ship, as is often reported by the western media.
How to prevent the spread of norovirus
The US Center for Disease Control advocates the following methods:
• Wash hands with soap and warm running water for a minimum of 20 seconds before and after contact with patients, after using the lavatory, and/ or before and after eating. Alcohol-based hand sanitisers alone won’t do.
• Wash your fruits and vegetables. Cook seafood thoroughly.
• If you’re sick, don’t cook or care for others for at least 2 to 3 days after you recover.
• Clean contaminated surfaces first, then disinfect them. Use a chlorine bleach solution with a concentration of 1,000 to 5,000 ppm (5 to 25 tablespoons of household bleach (5.25%) per gallon of water) or other disinfectant registered as effective against norovirus by the Environmental Protection Agency. In areas with high levels of soiling and resistant surfaces, up to 5000 ppm chlorine bleach may be used.
• Clean carpets with detergent and warm water, and follow this with steam cleaning.
• Steam-clean all soft furnishings that may be damaged by bleach
• Discard all disposable cloths in biohazard bags
• Launder all non-disposable cloths, i.e. linens, blankets, towels, and clothing
What’s the catch?
Many disinfectants and hand sanitisers used in their present formulations are ineffective against noroviruses. For example, certain chemicals present in the gel of ethanol-based hand-rubs may protect the virus against the alcohol, necessitating a higher concentration of ethanol in the formulation for it to be effective.
Chlorine-based disinfectants are among the most effective virucidal disinfectants. However, noroviruses are relatively resistant to hypochlorite. Some strains of the virus have been found to require ≥500 ppm of hypochlorite to achieve statistically significant reduction in virus concentration. Noroviruses are also resistant to inactivation using quaternary ammonium compound formulations at all concentrations.
A majority of food-borne norovirus illnesses is a result of contamination by infected food-handlers during preparation. Ready-to-eat foods, and foods handled after cooking are the most frequently identified products associated with outbreaks. The virus cannot be completely degraded despite heating to 72 degrees, and can persist on the surface of refrigerated foods for at least 10 days, and in mineral and tap water for over two months.
With home-cooked food sent in tiffin boxes being increasingly replaced by catering provided by facility management companies in schools, it is critical that the latter employ a combination of regular disinfection and use of personal protective equipment by foodhandlers to prevent a potential outbreak that is always on the horizon. Schools need to support them by teaching and supervising proper hand-washing done by each and every student; then, and only then, will schools become the safe, healthy temples of education they are intended to be.
