Types of Food Poisoning: Norovirus

Noroviruses are a group of viruses that cause the "stomachflu," or gastroenteritis. Norovirus was recently approved as the official namefor the group of viruses sometimes described as "Norwalk-like viruses" (NLV). Other names that have been used includecaliciviruses (Caliciviridae) andsmall round structured viruses.

Viruses are different from bacteria and parasites, some ofwhich can cause illnesses similar to norovirus infection. Like all viral infections, noroviruses arenot affected by treatment with antibiotics, and cannot grow outside of aperson's body.

Symptoms of IllnessCaused by Norovirus

Symptoms of norovirus illness include:

• Nausea
• Vomiting
• Diarrhea
• Some stomach cramping

Sometimes, people experience:

• Low-grade fever
• Chills
• Headache
• Muscle aches
• General sense of tiredness (fatigue)

Norovirus illness often begins suddenly, and the infectedperson may feel very sick. Symptomsusually begin about 24 to 48 hours after ingestion of the virus, but can appearas early as 12 hours after exposure. Symptomsusually last for about 1 or 2 days, with vomiting many times a day.In general, children experience more vomiting than adults.

People who get ill from norovirus have no long-term healtheffects related to their illness.

However, sometimes infected persons are unable to drinkenough liquids and experience dehydration that may need special medicalattention. This is usually a problemseen among the very young, the elderly, and the persons with weakened immunesystems.

How Do People BecomeInfected with Noroviruses?

Noroviruses are found in the stool or vomit of infectedpeople. People can become infected invarious ways, including:

• Eating food or drinking liquids that are contaminated with norovirus
• Touching surfaces or objects contaminated with norovirus, and then placing their hand in their mouth
• Having direct contact with another person who is infected and showing symptoms

People working in daycare centers or nursing homes shouldpay special attention to children and residents who have norovirusillness. Norovirus is very contagiousand can spread rapidly throughout such environments.

Norovirus can spread easily from person to person. People infected with norovirus are contagiousfrom the moment they begin feeling ill to at least 3 days after recovery. Some people may be contagious for as long as2 weeks after recovery. It isparticularly important to maintain good hand-washing and other hygienicpractices, even after they have recently recovered from norovirus illness. Particular care should be taken with youngchildren in diapers who may have diarrhea.

Who can get anorovirus infection?

Anyone can become infected with norovirus and its manystrains. Because there are many strainsof the virus, it is difficult for a person's body to develop long-lastingimmunity, meaning that the norovirus illness can recur throughout a person'slifetime. Genetic factors can also makepeople more or less susceptible to being infected and developing a more severeform of the illness.

Treating NorovirusInfection

Currently, there is no antiviral medication that worksagainst norovirus and there is no vaccine to prevent infection. Norovirus infection cannot be treated withantibiotics, since antibiotics fight against bacteria and not viruses.

Norovirus illness is usually brief in healthyindividuals. When people are ill withvomiting and diarrhea, they should drink plenty of fluids, such as oralrehydration fluids (ORF), juice, or water to prevent dehydration. Sports drinks do not replace the nutrientsand minerals lost during norovirus illness.

Preventing Norovirus

The following guidelines are recommended for preventingNorovirus:

• Frequently wash your hands, especially after toilet visits and changing diapers and before eating or preparing food
• Carefully wash fruits and vegetables, and steam oysters before eating them
• Thoroughly clean and disinfect contaminated surfaces immediately after an episode of illness by using a bleach-based household cleaner
• Immediately remove and, using hot water and soap, wash clothing or linens that may be contaminated with norovirus after an episode of illness
• Flush or discard any vomit and/or stool in the toilet and make sure that the surrounding area is kept clean

Persons who are infected with norovirus should not preparefood while they have symptoms and for three days after they recover from theirillness. Food that may have beencontaminated by an ill person should be disposed of properly.