20200521h Santa Cruz, CA: When I investigated what was going on back on Dec. 18, 2019, the first thing I ran across was a New York Times article by Jessica Grose on a Norovirus outbreak at an elementary school. Some points made in the article:
- There are multiple strains of norovirus migrating around the world. Catching one strain does not prevent you from catching a different strain;
- Noroviruses are seasonal and most active during Nov-Apr in the Northern Hemisphere and May-Oct in the Southern Hemisphere;
- Noroviruses are highly contagious stomach viruses that cause nausea, vomiting and diarrhea;
- Noroviruses are able to live on surfaces for days;
- Infected people can shed billions of virus particles for two weeks or more;
- As few as 10 virus particles are needed to cause an infection;
- If there is an outbreak at a school, then kids should change our of their clothes as soon as they get home and leave their clothes and backpack at the front door;
- Infected people should self-quarantine;
- Active infections normally last 1 to 3 days; and
- Avoid going to the E.R. if you are infected.
From wikipedia, the following additional facts:
- Noroviruses are the most common cause of gastroenteritis, responsible for about 18% of all cases worldwide;
- There is no vaccine or specific treatment;
- There are an estimated 685 million cases of disease and 200,000 deaths worldwide associated with norovirus infections, 25% of which are children under the age of five;
- Noroviruses are named after the city of Norwalk, Ohio, after an outbreak in 1968;
- Like coronaviruses, noroviruses are single-stranded positive-sense RNA viruses;
- Unlike coronaviruses, noroviruses are non-enveloped (naked capsid) viruses;
- The norovirus genome is linear and non-segmented, with a length of about 7500 bases;
- The norovirus capsid varies in size from 23-40nm in diameter. The smallest 23nm capsids are composed of 60 VP1 proteins and the largest 40nm capsids are composed of 180 VP1 proteins;
- The estimated mutation rate is 12-14 substitutions per 1000 sites per year, which is considered high for RNA viruses;
- Diagnosis of norovirus infection is made via PCR assays within a few hours, with detection ability of as few as 10 virus particles;
- Infection by one strain of norovirus generally provides immunity against reinfection by the same strain for 6-24 months;
- Noroviruses can survive for weeks on hard and soft surfaces, and for months to years in still water; and
- Individuals with different ABO(H) histo-blood group phenotypes are infected by noroviruses in a genotype-specific manner.
Regarding blood-type, I found an article by Prof. Patricia L. Foster on livescience: Your Blood Type Might Influence Your Risk of Getting the Stomach Flu. Some interesting facts from the article:
- Noroviruses can survive in temperatures from 32 to 145 degrees Fahrenheit; and
- As naked-capsid viruses, noroviruses are resistant to alcohol-based hand sanitizer.
Here is a interesting quote from the article regarding blood type specific infections:
When norovirus is ingested, it initially infects the cells that line the small intestine. Researchers don’t know exactly how this infection then causes the symptoms of the disease. But a fascinating aspect of norovirus is that, after exposure, blood type determines, in a large part, whether a person gets sick.
Your blood type — A, B, AB or O — is dictated by genes that determine which kinds of molecules, called oligosaccharides, are found on the surface of your red blood cells. Oligosaccharides are made from different types of sugars linked together in complex ways.
The same oligosaccharides on red blood cells also appear on the surface of cells that line the small intestine. Norovirus and a few other viruses use these oligosaccharides to grab onto and infect the intestinal cells. It’s the specific structure of these oligosaccharides that determines whether a given strain of virus can attach and invade.https://www.livescience.com/blood-type-stomach-flu-norovirus-risk.html