Norovirus is a common, highly contagious illness affecting the stomach and intestines, often called the “stomach flu.” It causes symptoms like nausea, vomiting, diarrhea, stomach pain, fever, headache, and body aches. This virus spreads rapidly, leading many to wonder about re-infection after experiencing it.
Immunity After Norovirus Infection
The human body does develop some immunity following a norovirus infection, yet this protection is generally not long-lasting and is often limited. While some studies suggest immunity to a specific strain might last from six months to two years, other models indicate a longer duration. This means that even after recovery, the body may only be protected against the exact strain of norovirus that caused the initial illness.
There are numerous different strains or genotypes of norovirus, which complicates the immune response. An infection with one strain typically offers minimal protection against others. Consequently, individuals can experience repeat infections with norovirus throughout their lives.
Factors Affecting Re-infection
Re-infection with norovirus is common due to the virus’s genetic diversity and high transmissibility. Noroviruses are classified into several genogroups, with Genogroup I (GI) and Genogroup II (GII) being the primary ones that infect humans. Within these genogroups, there are many distinct genotypes and variants, such as GII.4, which is globally recognized as the most prevalent and often associated with more severe illness.
Norovirus is highly contagious, requiring only a small number of viral particles, sometimes as few as 10, to cause disease. Furthermore, infected individuals can continue to shed billions of viral particles in their stool for up to two to three weeks after their symptoms have resolved, contributing to the ease of spread.
Reducing Your Risk of Getting Norovirus Again
Practicing rigorous hygiene measures is important for preventing future norovirus infections. Thorough handwashing with soap and water for at least 20 seconds is a primary defense, as alcohol-based hand sanitizers are less effective against norovirus.
Diligent cleaning and disinfection of contaminated surfaces are also important steps. After someone has been sick, surfaces should first be cleaned with soap and water, then disinfected using a bleach solution, such as 5 to 25 tablespoons of household bleach per gallon of water.
Careful food handling practices include washing fruits and vegetables, thoroughly cooking shellfish like oysters, and avoiding preparing food for others if you are unwell. Staying home from work or school when sick and avoiding close contact with others helps limit transmission.
What to Do if Symptoms Return
Should norovirus-like symptoms reappear, focusing on hydration is important to prevent complications. Drinking plenty of fluids, such as water, sports drinks, or oral rehydration solutions, helps to replace fluids lost from vomiting and diarrhea. It is advisable to take small, frequent sips rather than large amounts at once, especially if nausea is present.
Rest is also beneficial, and individuals should isolate themselves to prevent further spread of the virus. While most people recover at home, seeking medical attention is recommended if symptoms of severe dehydration develop, such as decreased urination, a dry mouth and throat, or dizziness when standing. Persistent symptoms, like diarrhea lasting more than seven days or vomiting for over two days, or the presence of severe abdominal pain or bloody stools, also warrant a medical consultation.