The remaining 47% of noroviruses were the result of “10 different GI and GII genotypes, including GII.4 New Orleans”, GII.4 Sydney’s predecessor. 51% of the GII.4 Sydney cases were attributed to direct person-to-person transmission as opposed to food contamination. (1)
Noroviruses spread very rapidly and mutate almost as quickly. As a result, there are several variants of the virus and the virus is constantly in a state of change.
The complexity of noroviruses can be best understood when you realize that out of the five genogroups (groups of related viruses within a genus or origin) (2) there are a minimum of 34 genotypes (sub-groups) that are currently known. Most of the time when you contract a stomach virus, it’s the result of one of the norovirus genogroups.
Its ability to mutate makes this virus genus challenging to anticipate, track and much less develop a vaccine against it. As a complex viral strain, the norovirus mutations are ongoing. In fact, the CDC has tracked four new strains every two to three years over the last 10 years.
It’s important to understand that not all new virus strains result in epidemic outbreaks. Many times when people learn of a new virus strain, they suffer unnecessary panic.
Noroviruses aren’t new. They just went unidentified up until 1968, when they were then identified thanks to better diagnostic methods and technology. Many people believe incorrectly that a norovirus is the same as stomach flu. While it may have some of the same stomach flu symptoms–severe diarrhea and vomiting–it’s a different strain completely.
Norovirus Statistics Can Be Misleading
Out of 70,000 people hospitalized annually, 800 die from the virus. (3)
If taken without explanation, these statistics alarm most people who believe the average person might fall victim and become one of the 800 death statistics. This isn’t true.
First of all, these statistics are of known cases, meaning people who have been hospitalized and treated specifically for norovirus. Most people who contract a norovirus recover and don’t require hospitalization, therefore, those cases aren’t reported.
Stool or vomitus must be analyzed in order to diagnose norovirus. This type of diagnostic tool is only used for severe cases that require hospitalization or whenever a group of people become ill.
According to the CDC (Center for Disease and Control), the people at greatest risk of hospitalization and death as a result of a norovirus are “elderly persons, young children, and immunocompromised patients”. (1)
The norovirus is transmitted 51% of the time through personal contact. 20% of those who contract the virus do so through the transference of the virus through food preparation.
The common place where the virus breeds and is easily transmitted is in large crowds. These can be any educational institute or school. Cruise ships are notorious for outbreaks as are nursing homes and military installations. (3)
It’s understandable then, that the higher mortality rate falls within the three specific groups of patients. Any place where people are congregated or live together has a higher risk factor than individuals living in their homes.
The elderly typically have a weaker immune system due to age and other debilitating diseases. Children are weaker simply because their immune systems aren’t fully developed and body mass is considerably less than an adult. Patients with compromised immune systems are more susceptible to disease and have little reserve for fending off a vicious viral attack.
Precaution against Contracting a Norovirus
Currently, there is no cure or treatment for norovirus. Avoidance in catching the virus is the best line of defense. The way to accomplish this is through the practice of good hygiene.
The CDC advises:
“Proper hand hygiene, environmental disinfection, and isolation of ill persons remain the mainstays of norovirus prevention and control.”
You should wash your hands frequently, using soap and running water for a period of no less than 20 seconds, especially before eating. It’s also advised that you keep your hands out of your mouth and nose as good hygiene practices.(1)
The CDC determined that “ alcohol-based hand sanitizers did not demonstrate any appreciable reduction of viral RNA (ribonucleic acid in genetic material)”. (4)
The CDC also states that:
“Hand sanitizers might serve as an effective adjunct in between proper handwashings but should not be considered a substitute for soap and water handwashing.”
Sodium hypochlorite (chlorine bleach) is recommended as an “excellent disinfectant that kills the virus” and should be used on surfaces, especially toilets, doorknobs and handrails. (4)
The agency endorses the FDA food code of “no bare-hand contact with ready-to-eat foods (foods edible without washing, cooking, or additional preparation to achieve food safety)”. (5)
Since a Norovirus is highly contagious, the CDC recommends that all infected people be isolated to prevent spreading the disease. This is a simple yet very effective way to interrupt the spread of the virus and allow it to end with the infected patient(s).
The virus may be contagious for longer periods than suspected. Typically the incubation period is 12 to 48 hours. Once the person becomes sick, he will “shed” the virus within two to five days.
However, stool samples of patients reveal that the virus is still present as many as four weeks after the patient has recovered. Scientists don’t know if the virus is still contagious during this stage of the patient’s recovery, so it’s best to continue with precautions and assume the virus is still active and contagious to others. (4)
Outlook for Seasonal Cases of Norovirus
The CDC reports that January is the peak month for norovirus season. (4) That doesn’t mean outbreaks can’t happen during other times of the year. In fact, each year the United States reports nearly 21 million stomach illnesses as noroviruses. (4)
Just because you’ve had a norovirus doesn’t mean you become immune to the same virus or its variant. For some reason, this virus doesn’t allow for this type of immunity through contraction.
The best way to protect yourself and your family is through good hand-hygiene and surface cleaning. Should a member of your family contract the virus, isolation, regular hand-washing and chlorine bleach cleaning of surface areas may reduce the risk of all family members contracting the virus, too.