Norovirus & Viral Gastroenteritis

One vomiting passenger on a cruise ship. Forty-eight hours later, 300 people are sick. That's not bad luck — that's 18 viral particles doing exactly what they evolved to do.

Norovirus is the leading cause of acute gastroenteritis outbreaks worldwide, responsible for approximately 50% of all foodborne disease outbreaks. It thrives in closed or semi-closed settings: cruise ships, nursing homes, hospitals, daycare centers, schools, and military barracks. The virus is extraordinarily contagious — the infectious dose is as low as 18 viral particles, and a single vomiting episode can aerosolize billions. Transmission routes: fecal-oral (primary), contaminated food or water (food handlers are the #1 source), direct contact with contaminated surfaces (virus survives on surfaces for days to weeks), and aerosolized vomit particles. Presentation: sudden onset of projectile vomiting, profuse watery (non-bloody) diarrhea, abdominal cramps, nausea, low-grade fever, and myalgia. Symptoms are typically self-limiting within 24–72 hours. Diagnosis: usually clinical during known outbreaks; RT-PCR of stool is available but rarely needed for individual management. Treatment: supportive care with focus on rehydration — oral rehydration solution (ORS) is first-line, IV isotonic fluids for severe dehydration or inability to tolerate oral intake. No antiviral or vaccine is currently available. Infection control: contact precautions with gown and gloves, hand hygiene with SOAP AND WATER (alcohol-based hand sanitizer has limited effectiveness against norovirus — same principle as C. diff), bleach-based environmental disinfection (1000–5000 ppm sodium hypochlorite), prompt isolation of symptomatic patients, and staff exclusion for 48 hours after symptom resolution. During outbreaks: cohort symptomatic patients, restrict new admissions if possible, enhance environmental cleaning frequency, and suspend communal dining in facilities.

Key Distinctions

Like C. difficile, norovirus requires soap and water for hand hygiene — alcohol-based sanitizer is inadequate. Students often default to 'hand sanitizer' as sufficient for all infectious disease; this is a repeated testing pattern. Do not confuse norovirus (self-limiting 24–72 hours, vomiting-predominant) with bacterial gastroenteritis (may be bloody, often longer duration, may require antibiotics). Staff must stay out for 48 hours after symptom resolution, not just until symptoms improve — viral shedding continues after clinical improvement.

Clinical Pearl

Norovirus and C. diff share the same hand hygiene rule: soap beats sanitizer. If it can survive on surfaces for weeks, alcohol isn't killing it on your hands.