Old virus seeks new public health action

Norovirus–3D rendering

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Norovirus was first identified in 1972 by Albert Kapikian and colleagues in Norwalk, Ohio, and more than 50 years later it continues to cause epidemics of infection and disease in the United States.¹ It is the most common cause of epidemic gastroenteritis, causing 19 to 21 million infections annually, resulting in 2.27 million outpatient visits, 465,000 emergency department visits, 109,000 hospitalizations, and 900 It is the cause of human death.² This virus is especially dangerous to children under 5 years of age, adults over 85 years of age, and immunocompromised people. These groups are at high risk for severe disease and are responsible for most outpatient and emergency room visits.²

Outbreak potential, transmission, and symptoms

Without definitive public health measures such as widely available vaccines, norovirus outbreaks are likely to become more common. “Increased travel by people is facilitating the spread of the virus to new areas. The genetic diversity and rapid evolution of norovirus means new strains may emerge and cause further outbreaks. Climate change may also be impacting outbreak patterns and locations,” says Raj Raj, FACP, FCCP, FAASM, board certified in internal medicine, critical care, pulmonology, and sleep medicine, and chief medical advisor. Dr. Dasgupta says. At Sleep Advisor.

Norovirus has many other names, including gastroenteritis, gastroenteritis, winter vomiting virus, and cruise ship virus. However, it is not related to the common flu, which is caused by the influenza virus. There are several strains of norovirus, but they all belong to the norovirus family. Caliciviridae A family of nonenveloped, positive-sense, single-stranded RNA viruses. It is highly contagious and only 10 virus particles can cause an infection. The main way the virus spreads is through food-related infections. Food contaminated during preparation by food service workers is a common source of infection. Infection from eating contaminated fruits and vegetables is also common, as is fish and oysters. Person-to-person transmission is also possible when droplets from an infected person's vomit or stool infect others. Surface contamination is also part of the spread.³

The virus is mutating rapidly, and the CDC has announced a 50% increase in infections due to new strains.² “Norovirus is a very shape-shifting virus,” Dasgupta says. “This constant evolution means new strains emerge from time to time, which can affect how outbreaks occur and the effectiveness of preventive measures,” he added.

Two people who tested positive for norovirus are considered an outbreak. There are 2,000 outbreaks a year in the United States, most occurring between November and April. 2 Outbreaks have occurred in several locations, including medical facilities, cruise ships, barracks, schools, nursing homes, and resorts. The incubation period for norovirus is 12 to 48 hours, with a median of 33 hours.

The most common symptoms are nausea, vomiting, and diarrhea. However, some people also report body aches, headaches, abdominal pain or cramps, and chills. Fever is also reported as a less common symptom. Symptoms last for 1 to 3 days, but may resolve on their own. People with weakened immune systems, those who have recently received a transplant, the elderly, and newborns are at higher risk of developing the deadly disease and should take special care.³

Prevention and control, reliable methods, and new options

The basis of prevention is proper hand washing. Research shows that washing your hands with soap and water for 20 seconds is the most effective hand hygiene method to remove viruses.³ Alcohol-based disinfectants are less effective. Although it is effective in reducing the number of viruses on your hands, it is most effective when used in conjunction with proper hand washing.

Surface decontamination also plays an important role in infection control. When symptoms of diarrhea or vomiting occur, the virus is accidentally dispersed into the air and onto surfaces. Sinks, toilets, beds, chairs, counters, doors, faucet handles, and floors are all potential sources of infection. All potentially contaminated surfaces must be decontaminated, and items that cannot be decontaminated must be disposed of.³ Pathogens can survive on surfaces for two weeks. They can tolerate sub-zero temperatures and warm water, but will die if exposed to temperatures of 145 degrees Fahrenheit (62.7 degrees Celsius).

Bleach kills viruses. 5 to 25 tablespoons of chlorine bleach per gallon of water creates an effective disinfectant solution that can be used to disinfect surfaces and bedding.^Four Bipolar ionization is a new technology that is also being used to reduce infectivity and kill viruses.

“Additionally, norovirus can be present on touchable surfaces such as doorknobs, phones, computer keyboards, handrails, or other surfaces recently touched by an infected person, making it a bipolar virus in home and office air conditioning systems. Adding ionization helps eliminate surface contamination in public spaces by continuously disinfecting surfaces, protecting spaces and reducing the risk of infection,'' says New York University Grossman School of Medicine and New York “We're thrilled to be working with the University of Langone Medical Center,” said Philip M. Tierno, Jr., Ph.D., professor of microbiology and pathology at University Langone Medical Center.

Tierno added that people infected with norovirus need to be exempted from work to curb transmission. Most people stop shedding virus within three days, but people with weakened immune systems may continue shedding virus in their stool for months.^Five Allowing sick people to work puts the public at risk. The virus is highly contagious, so one sick person can infect hundreds of people. However, many food handlers do not receive paid sick leave, which is often difficult to enforce. Lawmakers need to do more to pass laws that require paid sick leave for workers in the interest of public health.

What's next for norovirus prevention?

For many years, noroviruses could not be grown in the lab, but recent advances have allowed scientists to grow them in bacteria-rich tissues like the intestines. They are difficult to cultivate in the laboratory, hindering research on insecticidal, control, and detection. It is disturbing to consider that this disease costs the United States 7.6 million yen in direct costs and 165.3 million yen in lost productivity annually.⁶

There is still no cure for norovirus. In most people, this is a self-limiting illness that resolves after about three days. The focus of care is to maintain adequate hydration and treat symptoms. Probiotics may help control diarrhea, but this is still being researched. Extreme fluid loss can occur, leading to complications such as dehydration, hypokalemia, hyponatremia, metabolic acidosis, hemolytic uremic syndrome, and renal failure.³

This year, scientists reported clinical improvement in four immunocompromised patients infected with chronic norovirus following treatment with favipiravir, including in combination with nitazoxanide. Although these drugs reduced infectivity, more extensive studies are needed to confirm their safety and usefulness in larger populations.⁷

There is no widely available vaccine for norovirus, but several vaccine candidates are undergoing clinical trials. One of the most promising candidates was created by researchers at the University of Washington School of Medicine, who fused a recombinant norovirus with an existing rotavirus vaccine and elicited an immune response from mice against both viruses.⁸ It remains to be seen whether this result can be safely and effectively replicated in humans.

Perhaps because most people recover without incident and the annual death toll remains below 1000, norovirus does not receive as much attention as it should. But concerted efforts to speed up vaccine development and identify drugs that reduce transmissibility could save lives for vulnerable groups and help reduce the enormous annual costs of norovirus outbreaks.

References

1. Lucero Y, Matson DO, Ashkenazi S, George S, Orian M. Norovirus: past, present, and future facts and considerations. virus. 2021;13(12):2399. Published November 30, 2021. doi:10.3390/v13122399
2. Norovirus burden and trends | CDC. https://www.cdc.gov/norovirus/burden.html
3. Cape G, Gignac E. Norovirus. [Updated 2023 Aug 14]. In: StatPearls [Internet]. Treasure Island, Florida: StatPearls Publishing; from January 2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513265/
4. Prevention of norovirus. Centers for Disease Control and Prevention. Published on May 10, 2023. https://www.cdc.gov/norovirus/about/prevention.html
5. Norovirus. National Collaboration Center for Infectious Diseases. Published on January 25, 2023. norovirus.
6. Birch SM, O'Shea KJ, Lee BY. Correction: Clinical and economic burden of norovirus gastroenteritis in the United States. infectious disease journal (Online University of Chicago Press)/Journal of Infectious Diseases. 2021;224(4):741. doi:10.1093/infdis/jiab197
7. Kreins A, Roux E, Pang J, et al. Favipiravir induces HuNoV virus mutagenesis and loss of infectivity and improves clinical symptoms in immunocompromised patients. clinical immunology. 2024;259:109901. doi:10.1016/j.clim.2024.109901
8. Toru Kawagishi, Sánchez-Tacuba L, Feng N, et al Mucosal and systemic neutralizing antibodies against norovirus were induced in infant mice orally inoculated with recombinant rotavirus. National Graduate School of Science U.S. A. 2023;120(9):e2214421120. doi:10.1073/pnas.2214421120