Norovirus: Another Virus to Investigate


Risk factors for norovirus include eating foods in non-sanitary places and attending childcare centers or preschools.

Norovirus is a virus that belonging to the Caliciviridae family,which includes a group of single-stranded RNA viruses that may cause problems such as inflammation of the stomach or intestines or acute gastroenteritis. The virus has been previously called the Norwalk or Norwalk-like virus, which was named after the original Norwalk strain that caused the 1968 outbreak of gastroenteritis in a school in Norwalk, Ohio. Norovirus is now classified into 10 different genogroups and 48 genotypes. ¹

Risk factors for norovirus include eating foods in non-sanitary places and attending childcare centers or preschools. It can also include living in proximity with high-risk patient population, such as patients in nursing homes. It can also become a risk in environments in which many individuals congregate in confined spaces, such as in hotels, resorts, cruise ships, and other destination places. This risk escalates if the person comes into contact with another person with such a virus. ²

When it comes to testing specimens for norovirus, whole stool seems to be the preferred option for the best diagnosis. When there is an outbreak, it is recommended to collect samples from at least 5 people with symptoms, especially at the acute phase of the disease. This is when the virus is most active and can be best illustrated via the specimen. Patient vomitus can also be collected in addition to stool specimens during an outbreak. Besides the acute phase specimens, the convalescent phase specimens can also be collected during thethird or fourth week from when the symptoms started.

Norovirus can cause a great deal of vomiting and diarrhea for infected patients and it can easily spread from one person to another. This is due to the fact that patients with norovirus can shed millions of norovirus particles in the environment, making others sick as well. Other ways the virus can spread is through eating foods and drinking liquids that may be contaminated with the virus, touching contaminated surfaces, or sharing food or utensils with a person who is infected with the norovirus.

Even in patients who recover from norovirus, the virus can spread for up to 2 or 3 weeks, so caution should still be taken. Notably, if water for agriculture is contaminated with the virus, then whatever food is grown in the water will also be affected. This could cause outbreaks in places such as restaurants or stores selling food and poultry. ¹

It is possible to contract norovirus many times, although it is also possible to develop immunity. Such immunity may be presented when outbreaks happen. However, researchers do not know how long immunity against norovirus may last.

The most common symptoms associated with norovirus include diarrhea, vomiting, nausea, stomach problems, and pain. Some patients may experience fever, headache, and body aches. As norovirus impacts stomach lining, it may also cause acute gastroenteritis, impacting the intestines.

Patients can develop symptoms 12 to 48 hours after being exposed to the virus and most patients see symptom improvement 2 to 3 days after exposure. Due to the severity of the symptoms in the first few days of the virus, many patients may experience symptoms such as extreme vomiting and diarrhea, many times a day, which may lead to dehydration. Symptoms of such dehydration can include decreased urination, dry mouth and throat, dizziness when standing, and similar symptoms.

Preventive measures can be taken to avoid contracting the virus. Thorough handwashing with soap and water is essential, especially after using the toilet or changing diapers and before eating, handling food, or taking other medications. Using alcohol-based hand sanitizers in addition to hand washing is another way to protect oneself against norovirus. Additionally, cooking foods thoroughly— including both meats and vegetables—may prevent the virus spread. The virus can survive in temperatures as high as 145 degrees Fahrenheit.¹

Patients with the virus should not prepare food, attend classes or meetings, and should stay away from public places, such as restaurants, schools, daycares, and nursing homes. Cleaning surfaces thoroughly with disinfectant can also help prevent spread of the virus in the homes of both infected and not-infected people. Using chlorine bleach solutions with water is proven to be effective against norovirus, according to the Environmental Protection Agency.

There is no specific medicine to treat norovirus, although drinking plenty of liquids and staying hydrated may prove to be very beneficial when it comes to recovery. Plenty of rest can help as well. If the symptoms do not improve or if they worsen, patients should visit their primary care physician for further evaluation and assessment.³


  1. CDC. Reporting and Surveillance for Norovirus. Updated March 5, 2021.
  2. Mayo Clinic; Norovirus infection. February 5, 2020; Accessed March 31, 2021.
  3. NHS Inform; Norovirus. December 18, 2020;,of%20fluids%20to%20avoid%20dehydration.. Accessed March 31, 2021.
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