The San Luis Obispo Tribune reports that an outbreak of norovirus stemming from a North County restaurant has sickened close to 100 people, according to the San Luis Obispo County Public Health Department. SLO County Public Health Epidemiologist Jessie Burmester said 97 people have been reported sick as part of a confirmed norovirus outbreak earlier this month. “When we perform our investigations, we’re really looking for a common source or exposure point,” she said. “Individuals have provided the name of the restaurant consistently for all the individuals that have reported on behalf of the 97 people so far.”
If I owned a restaurant in Paso Robles that was not the link in the Norovirus outbreak, I think I would be pissed.
Well, for whatever the reason the SLO County Public Heath authorities are remaining quiet as is the local media. So, here is what you need to know during an outbreak.
The Centers for Disease Control and Prevention (CDC) estimates that noroviruses cause nearly 21 million cases of acute gastroenteritis annually, making noroviruses the leading cause of gastroenteritis in adults in the United States.
Nature has created an ingenious bug in norovirus. The round blue ball structure of norovirus is a protein surrounding the virus’s genetic material. The virus attaches to the outside of cells lining the intestine, and then transfers its genetic material into those cells. Once the genetic material has been transferred, norovirus reproduces, finally killing the human cells and releasing new copies of itself that attach to more cells of the intestine’s lining.
Humans are the only host of norovirus, and norovirus has several mechanisms that allow it to spread quickly and easily. Norovirus infects humans in a pathway like the influenza virus’ mode of infection. In addition to their similar infective pathways, norovirus and influenza also evolve to avoid the immune system in a similar way. Both viruses are driven by heavy immune selection pressure and antigenic drift, allowing evasion of the immune system, which results in outbreaks. Norovirus can survive a wide range of temperatures and in many different environments. Moreover, the viruses can spread quickly, especially in places where people are in proximity, such as cruise ships and airline flights, even those of short duration.
Norovirus causes nearly 60% of all foodborne illness outbreaks. Norovirus is transmitted primarily through the fecal-oral route, with fewer than 100 norovirus particles needed to cause infection. Transmission occurs either person-to-person or through contamination of food or water. CDC statistics show that food is the most common vehicle of transmission for noroviruses; of 232 outbreaks of norovirus between July 1997 and June 2000, 57% were foodborne, 16% were spread from person-to-person, and 3% were waterborne. When food is the vehicle of transmission, contamination occurs most often through a food handler improperly handling a food directly before it is eaten.
Infected individuals shed the virus in large numbers in their vomit and stool, shedding the highest number of viral particles while they are ill. Aerosolized vomit has also been implicated as a mode of norovirus transmission. Previously, it was thought that viral shedding ceased approximately 100 hours after infection; however, some individuals continue to shed norovirus long after they have recovered from it, in some cases up to 28 days after experiencing symptoms. Viral shedding can also precede symptoms, which occurs in approximately 30% of cases. Often, an infected food handler may not even show symptoms. In these cases, people can carry the same viral load as those who do experience symptoms.
Norovirus illness usually develops 24 to 48 hours after ingestion of contaminated food or water. Symptoms typically last a relatively short amount of time, approximately 24 to 48 hours. These symptoms include nausea, vomiting, diarrhea, and abdominal pain. Headache and low-grade fever may also accompany this illness. People infected with norovirus usually recover in two to three days without serious or long-term health effects.
Although symptoms usually only last one to two days in healthy individuals, norovirus infection can become quite serious in children, the elderly, and immune-compromised individuals. In some cases, severe dehydration, malnutrition, and even death can result from norovirus infection, especially among children and among older and immune-compromised adults in hospitals and nursing homes. Recently, there have been reports of some long-term effects associated with norovirus, including necrotizing entercolitis, chronic diarrhea, and post-infectious irritable bowel syndrome, but more data is needed to support these claims.
Proper hand washing is the best way to prevent the spread of norovirus.
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