Norwalk virus can you get more than once

Anyone can get infected with norovirus, and you can get it more than once. It is estimated that a person will get norovirus about five times during their lifetime. Norovirus outbreaks occur throughout the year, however, more than 80 percent of reported outbreaks occur from November to April.

Norovirus spreads quickly, as it is found in the vomit and feces of infected people. You can get it by:. People with norovirus illness are most contagious from the moment they begin feeling ill and for the first few days after they recover. Some people may be contagious for even longer. There is currently no vaccine available to prevent norovirus infection or drug to treat sick people. Learn how to protect yourself and others by following a few simple steps:.

Practice proper hand hygiene. Wash your hands carefully with soap and water, especially after using the toilet and changing diapers, and always before eating or preparing food. These alcohol-based products can help reduce the number of germs on your hands, but they are not a substitute for washing with soap and water. Handle and prepare food safely.

Globally, norovirus kills , people a year. At least one study has shown that about 20 percent of people of European origin have a genetic mutation that protects them from common norovirus strains, something that might help in development of better vaccines.

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When norovirus is ingested, it initially infects the cells that line the small intestine. 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.

The presence of one oligosaccharide, called the H1-antigen, is required for attachment by many norovirus strains. Norovirus evolves rapidly. There are 29 different strains currently known to infect humans, and each strain has different variants. Each one has different abilities to bind to the variously shaped sugar molecules on the intestinal cell surface. These sugars are determined by blood type. But, if the same group of people is exposed to a different strain of norovirus, different people may be resistant or susceptible.

In general, those who do not make the H1-antigen and people with B blood type will tend to be resistant, whereas people with A, AB, or O blood types will tend to get sick , but the pattern will depend on the specific strain of norovirus. This difference in susceptibility has an interesting consequence.

When an outbreak occurs, for example, on a cruise ship, roughly a third of the people may escape infection. A norovirus infection provokes a robust immune response that eliminates the virus in a few days.