By Dr. Mercola
Norovirus is the leading cause of food-borne outbreaks in the US, with fresh produce (especially leafy vegetables and fruits) among the most common culprits.1
While you can be infected with norovirus through direct contact with someone who's infected, this virus is often spread through the fecal-oral route, when you consume food or water that's contaminated.
According to the US Centers for Disease Control and Prevention (CDC), sick food handlers are the main source of food-borne norovirus outbreaks and caused about half of such cases from 2001 to 2008.2
This makes sense, since norovirus outbreaks are commonly associated with contaminated foods from restaurants and long-term care facilities. It turns out there may be an additional culprit, however, an insidious one that to date has received very little attention.
Dirty Water Used to Dilute Pesticides May Spread Norovirus
Contaminated water has long been recognized as a potential introduction source of norovirus to fresh produce, but typically this has centered on water used to irrigate crops.
Researchers from the Netherlands decided to look into the water used to reconstitute pesticides to determine if that could be a relevant source of infectious norovirus, and their results revealed a strong possibility that it could.3
They tested four fungicides and four insecticides commonly used on lettuce and raspberries (two foods associated with norovirus outbreaks), diluted with water that had been spiked with norovirus.
In seven of the eight pesticides tested, norovirus persisted even two hours later. As reported by Environmental Health Perspectives:4
"Farmers mix pesticides with water from sources including wells, irrigation ditches, rivers, and lakes. All these water sources have been known to harbor norovirus. Until recently, no one had tested whether norovirus in contaminated water remains infectious after pesticides are added."
The study suggests that if farmers use contaminated water to reconstitute their pesticides, the virus is likely to still be active when it's sprayed onto crops. The researchers concluded:
"The application of pesticides may therefore not only be a chemical hazard, but also a microbiological hazard for public health. The inclusion of antiviral substances in reconstituted pesticides may be appropriate to reduce the virological health risk posed by the application of pesticides."
Though the researchers recommended adding antiviral substances to water, a much simpler, and healthier, option is to buy organic produce as much as possible, since this eliminates the use of chemical pesticides.
Signs and Symptoms of Norovirus
Noroviruses are the leading cause of gastroenteritis in the US, responsible for up to 21 million illnesses, 71,000 hospitalizations, and 800 deaths each year.5 They generally cause a nasty infection that leads to diarrhea, abdominal pain, and vomiting within 24-48 hours of exposure. Norovirus infection is often referred to as the "stomach flu," although it shouldn't be confused with influenza, which is a respiratory infection.
The symptoms of norovirus infection can be quite debilitating, but most people recover on their own within a few days. Those most at risk of complications (typically dehydration) are infants, the elderly, and those with compromised immune systems.
The elderly living in nursing homes and children in day care facilities are often among those hardest hit, due to their close proximity with others and the highly contagious nature of these viruses. This is also the reason why cruise ships are sometimes associated with norovirus outbreaks. To get an idea of just how contagious this group of viruses is, a person with norovirus infection may shed billions of norovirus particles, but it takes just 18 of these particles to infect someone else.6
How Norovirus Is Spread Via Your Food
As far as food poisonings go, noroviruses are strongly associated with restaurant-prepared or store-bought "complex foods" – foods that contain a number of ingredients so that the specific culprit cannot be pinpointed. Ready-to-eat foods, including salads, sandwiches, ice, cookies, and fruit, are also risks, although eating any food that is contaminated with vomit or feces from an infected person could lead to infection.7
Not only can the virus be spread before a person starts feeling sick, but it also remains in a person's stool for two weeks – or more – after the symptoms resolve. So if a food handler is not careful, he could continue to spread the virus to others for some time.
Even heating a food may not be enough to get rid of this resilient virus. Noroviruses can survive heating up to 140°F as well as quick-steaming methods often used to prepare shellfish.8 It can also survive being frozen. Of course, if the featured study is correct it's possible that your food could be contaminated before it's even harvested while it's sprayed with pesticides in the field.
The Keys to Lowering Your Risk of Stomach Flu
As mentioned, buying organic produce may be one of the best ways to lower your risk, as it will reduce your exposure to pesticides and the potentially contaminated water used to reconstitute them. Washing your vegetables and fruits before use may also help to reduce your risk (although probably won't get rid of norovirus completely).
Because many norovirus outbreaks are tied to restaurant or ready-made foods, the more you prepare your own food at home, the lower your risk of contracting this food-borne infection is likely to become.
Finally, washing your hands remains one of the best strategies for preventing the stomach flu. Washing your hands (and your children's hands) with soap and water if you've been in a public place and before eating is essential. Be careful not to over-wash your hands, however, as this can create tiny cuts in your hands where a virus can enter. Other common sense measures for preventing the stomach flu include:
- Trying not to touch your eyes, mouth, or nose (which is how the virus enters), especially if your hands are not clean
- Avoiding sharing utensils, drinking cups, hand towels, etc. with others
- Try oil of oregano. Carvacrol, an active substance in oregano oil, may be effective against norovirus, as it has been found to break down the virus’ tough outer layer. The study found oregano oil may inactivate norovirus within one hour of exposure. Not only can you try adding oregano oil to your natural cleaners to use as a surface disinfectant, but oregano oil can also be taken internally. When choosing an oregano oil, generally the higher the carvacrol concentration, the more effective it will be.
Along with the practical precautions mentioned above, preventing the stomach flu also involves keeping your immune system healthy by following these five steps to boost your immune system health.
What to Do if You're Infected with Norovirus
Most people will become infected with the stomach flu at some point during their lives. If this happens, make sure the vomiting and diarrhea does not cause you to become dehydrated, as dehydration can be life threatening. So if you begin to become dehydrated, it is vital that you go to an emergency room for evaluation and treatment.
Initially, however, the following simple protocol is often very effective in clearing up the stomach flu long before you get to this point. If you have thrown up, put your stomach at complete rest for at least three hours. Avoid water, crackers, soda… everything for at least three hours after the last time you throw up.
Once three hours have passed and no further vomiting has occurred, then try sipping small amounts of water slowly. If that is tolerated and you have not vomited further, you can gradually increase the water. Do this for one to two hours and if that is tolerated then you are ready for the final phase: large doses of a high-quality probiotic, taken every 30 to 60 minutes until your symptoms go away.
Small amounts of fresh crushed ginger root, which is available in nearly every grocery produce section, finely cut up and swallowed whole can be enormously helpful for the nausea. But remember, it should not be taken for at least three hours after the last time you throw up.