Is It Possible to Catch the Stomach Flu Again
In the last few [winter] months, schools all over the country have airtight because of outbreaks of norovirus. Also known as stomach flu, norovirus infections cause watery diarrhea, depression-grade fever and, most alarming of all, projectile vomiting, which is an extremely effective manner of spreading the virus.
Norovirus is very infectious and spreads chop-chop through a confined population, such as at a schoolhouse or on a prowl ship. Although most sufferers recover in 24 to 48 hours, norovirus is a leading cause of babyhood disease and, in developing countries, results in about 50,000 child deaths each twelvemonth.
Interestingly, not everyone is every bit vulnerable to the virus, and whether yous go sick or not may depend on your blood type.
Norovirus is hard to get rid of
I am a microbiologist, and I got interested in norovirus because, while norovirus symptoms are lamentable under any circumstances, my encounter with the virus was particularly inconvenient. During a seven-twenty-four hours rafting trip down the Grand Canyon, the affliction passed through the rafters and crew, one past 1. Obviously, the wilderness sanitary facilities were not the best to cope with this outbreak. Luckily, everyone, including me, recovered quickly. It turns out that norovirus outbreaks on Colorado River rafting trips are common.
As debilitating as the disease it causes tin can be, the norovirus particle is visually beautiful. It is a type of virus known every bit "non-enveloped" or "naked," which means that it never acquires the membrane coating typical of other viruses, such equally the flu virus. The norovirus surface is a protein coat, called the "capsid." The capsid protects the norovirus' genetic material.
The naked capsid coat is one factor that makes norovirus so difficult to command. Viruses with membrane coatings are susceptible to booze and detergents, simply non so norovirus. Norovirus can survive temperatures from freezing to 145 degrees Fahrenheit (virtually the maximum water temperature in a home dishwasher), lather and mild solutions of bleach. Norovirus tin persist on homo hands for hours and on solid surfaces and food for days and is as well resistant to alcohol-based hand sanitizers.
To make things worse, only a tiny dose of the virus—as few as ten viral particles—is needed to cause disease. Given that an infected person can excrete many billions of viral particles, it's very hard to prevent the virus from spreading.
Susceptibility to norovirus depends on blood type
Your claret type—A, B, AB, or O—is dictated past genes that make up one's mind which kinds of molecules, chosen oligosaccharides, are found on the surface of your red claret cells. Oligosaccharides are fabricated from different types of sugars linked together in complex means.
The same oligosaccharides on red blood cells besides 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 construction of these oligosaccharides that determines whether a given strain of virus tin can adhere and invade.
The presence of 1 oligosaccharide, chosen the H1-antigen, is required for attachment by many norovirus strains.
People who do not make H1-antigen in their intestinal cells make up 20% of the European-derived population and are resistant to many strains of norovirus.
More than sugars tin can be attached to the H1-antigen to give the A, B or AB blood types. People who can't make the A and B modifications have the O blood type.
Unlike strains of norovirus infect dissimilar people
Norovirus evolves rapidly. In that location are 29 dissimilar strains currently known to infect humans, and each strain has different variants. Each one has different abilities to demark to the variously shaped sugar molecules on the intestinal cell surface. These sugars are adamant past blood blazon.
If a group of people is exposed to a strain of norovirus, who gets sick will depend on each person'southward blood type. But, if the same grouping of people is exposed to a different strain of norovirus, different people may exist resistant or susceptible. In general, those who practice not brand the H1-antigen and people with B blood type volition tend to exist resistant, whereas people with A, AB, or O claret types will tend get ill, simply the pattern will depend on the specific strain of norovirus.
This divergence in susceptibility has an interesting consequence. When an outbreak occurs, for instance, on a cruise send, roughly a third of the people may escape infection. Because they do not know the underlying reason for their resistance, I think spared people engage in magical thinking—for example, "I didn't get ill because I drank a lot of grape juice." Of course, these mythical evasive techniques volition not work if the next outbreak is a strain to which the private is susceptible.
Immunity to norovirus is curt-lived
A norovirus infection provokes a robust immune response that eliminates the virus in a few days. However, the response appears to be curt-lived. Most studies accept found that immunity guarding against reinfection with the aforementioned norovirus strain lasts less than half dozen months. Likewise, infection with 1 strain of norovirus offers little protection against infection from some other. Thus, yous can accept repeated bouts with norovirus.
The diverseness of norovirus strains and the impermanence of the allowed response complicates development of an effective vaccine. Currently, clinical trials are testing the effects of vaccines made from the capsid proteins of the 2 most prevalent norovirus strains.
In general, these experimental vaccines produce skilful allowed responses; the longevity of the immune response is at present under study. The next stage of clinical trials volition examination if the vaccines really prevent or reduce the symptoms of norovirus infection.
Source: https://biology.indiana.edu/news-events/newsletters/2020-spr-newsletter/norovirus.html