Family name(s): Caliciviridae



What is Norwalk Virus?

Norwalk virus is an extremely common cause of food-borne illnesses especially in Japan. It greatly affects the human gastrointestinal system. The viruses are commonly associated with shellfishes harvested from sewage-contaminated waters. The norovirus occurs occasionally on many places of the world mainly cruise ships, schools, daycares, restaurants, and summer camps.

What are the Symptoms of Norovirus Infection?

Norwalk virus symptoms occur in all age groups and may include :

1. Stomach cramping

2. Nausea

3. Vomiting (profuse, nonbloody, nonbilious)

4. Watery diarrhea

5. Low-grade fever

6. Head or muscle aches

The symptoms usually show within 1 to 3 days after exposure to the virus, and can persist up to two days to several weeks.

How do Noroviruses Spread?

Norwalk viruses are transmitted via the fecal-oral route. These viruses only spread from person-to-person, and can’t be spread by animals.

Other common routes of infection include:

1. Shellfishes harvested from waters contaminated with sewage.

2. Having contact with objects or surfaces contaminated with norovirus, and then placing their hand in their mouth.

3. Infected people who don't wash their hands regularly especially before preparing or touching food that another person might eat.

4. Ice or water that is contaminated with sewage.

Recurrent infections can occur through lifetime because norovirus has many different strains, which makes a person’s body difficult to develop long-term immunity.

How to Diagnose Norwalk Virus?

Several tests have became available that can detect norovirus. Laboratory techniques like ELISA (Enzyme-Linked ImmunoSorbent Assay) method and the RT-PCR (reverse transcription polymerase chain reaction) method are used for diagnosis.

How to Prevent the Spread of Norwalk Virus?

The best way to prevent the spread of Norwalk viruses is by thorough handwashing after toilet use and before preparing or serving foods for at least 15 seconds. In addition, have plenty of rest and stay home until your Norwalk virus symptoms are gone.

Other preventive measures are:

1. People who already have a Norwalk virus infection should never prepare food for others.

2. Those who are sick with diarrhea or vomiting should not work in daycare centers or health care facilities until these symptoms have stopped.

3. Dispose or clean and disinfect infected materials or contaminated surfaces immediately after an incident of Norwalk virus infection in your home.

4. Eat only thoroughly cooked shellfish. Avoid food or water that might be prepared in an unsanitary way such as party foods and raw or uncooked foods.

5. Immediately wash clothing that may be contaminated with Norwalk virus after an illness incident.

6. Avoid handshaking when it’s not necessary.

Treatment for Norwalk Virus Infection

There is no antibiotic (Norwalk virus is not bacterial) and antiviral agents that can kill or treat Norwalk viruses. There is also no vaccine yet to prevent infection. Never use any antibiotics, as they tend to make the illness worse. Getting rest and drinking plenty of water to avoid dehydration is the most recommended for this type of illness. Dehydration has the most harmful effect that can result from norovirus infection. Doctors suggest drinking juices that gives additional nutrients to the body rather than drinking just plain water. Avoid drinking milk as it contains sugars that are hard to break down making it harder to digest. Milk may bring you other gastrointestinal problems like stomach cramps and diarrhea.

Some doctors suggest the following recipe for an oral rehydration drink that you can buy at most convenience stores and it is inexpensive to prepare:

To one liter of water, add

- 8 teaspoons of table sugar

- 1/2 teaspoon of table salt

- 1/3 teaspoon of Lite salt (potassium chloride) and

- 1/2 teaspoon of baking soda

Contracting Norwalk-type viruses or noroviruses can indeed be very dangerous and deadly if you don’t follow the preventive measures. Remember to use proper sanitation procedures and utmost cares as soon as an illness episode occurs. Still, the best-known treatment in the medical community is to drink plenty of liquid or electrolyte replacement.