Norovirus

Norovirus is a highly contagious virus that causes acute gastroenteritis in people of all ages. It belongs to the Caliciviridae family and includes several genogroups (I–VII); genogroup II, especially GII.4, is most often associated with human outbreaks. Norovirus is a leading cause of gastroenteritis worldwide, with outbreaks common in schools, restaurants, long-term care facilities, and cruise ships. Illness typically involves vomiting, diarrhea, nausea, abdominal cramps, and sometimes fever, lasting one to three days.

Transmission occurs mainly by the fecal-oral route, through contaminated food or water, contact with contaminated surfaces, or close person-to-person contact. The infectious dose is very low, and viral shedding can occur before and after symptoms. The incubation period is typically 12–48 hours.

Diagnosis is clinical, supported by RT-PCR testing of stool in outbreak investigations. There is no specific antiviral treatment; care is supportive, focusing on hydration and electrolyte replacement. Most people recover without complications, though dehydration can be serious in young children and older adults.

Prevention emphasizes hand hygiene with soap and water, proper food handling, and environmental cleaning. Alcohol-based sanitizers are less effective against non-enveloped viruses; contaminated surfaces should be disinfected with bleach or other effective agents. Infected individuals should stay home from work or school until symptoms have subsided for 24–48 hours.

Immunity to norovirus is incomplete and short-lived, and reinfection with different strains is common. No licensed vaccine is available, though several candidates have reached clinical trials. Ongoing vaccination research and infection-control measures remain central to reducing outbreaks.