Recommend proper food safety practices, hand hygiene, and oral rehydration for afflicted patients.
Norovirus is a highly contagious virus that can lead to gastroenteritis and is the most common cause of foodborne diarrhea and vomiting.1 It causes about 19 million to 21 million illnesses each year, according to the CDC.1 The virus also leads to about 56,000 to 71,000 hospitalizations and 570 to 800 deaths annually, which occur mostly in elderly individuals and young children.1 Norovirus was once thought of as only a cruise ship illness; indeed, the Royal Caribbean Oasis of the Seas cruise ship made headlines in January 2019 when it was affected by a norovirus outbreak among 475 passengers.2 However, norovirus outbreaks can occur in any setting, including hospitals and restaurants.
Individuals can contract norovirus through contaminated food or water or by touching contaminated surfaces.3 In fact, as few as 18 viral particles can cause an infection.1,4 Norovirus can also be transmitted through feces and vomit. Unfortunately, individuals can contract norovirus more than once and are most likely to become infected in cooler months, especially between November and April.4
SYMPTOMS AND RISK FACTORS
Norovirus can cause gastroenteritis, which leads to inflammation of the intestines and the stomach. The most common symptoms include abdominal pain, diarrhea, nausea, and vomiting (figure).1 The diarrhea and vomiting can lead to dehydration, with symptoms including decreased urination, dizziness, and dry mouth and throat.1 Children and infants experiencing dehydration may cry with few or no tears and have dry diapers.4
Symptoms typically develop 12 to 48 hours after an individual is exposed to norovirus and usually last 1 to 3 days.1 Advise patients to contact their physician if they develop diarrhea that persists or experience abdominal pain, bloody stools, dehydration, and severe vomiting.
Pharmacists should counsel patients about the following risk factors for developing norovirus: being immunocompromised; consuming food handled with unsanitary practices; living in close quarters, such as nursing homes; living with a child attending day care or preschool; and staying on cruise ships or in hotels, resorts, or other destinations with other individuals in close quarters.4
Because the symptoms of norovirus are similar to those of other stomach viruses, diagnosing the condition may be difficult unless patients provide a stool sample within the acute illness phase, 48 to 72 hours after symptom onset, which is when the greatest amount of virus is shed.1,5 Clinicians can sometimes detect norovirus in stool samples 7 to 10 days after symptoms begin.1 Stool and vomit samples are usually collected when a norovirus outbreak is suspected. Additionally, food and water samples can be collected to identify the source of an outbreak.
Unfortunately, no recommended medications are available for the treatment of norovirus. Because norovirus is a viral infection, clinicians and patients cannot use antibiotics. Pharmacists should advise patients infected with norovirus to drink plenty of fluids to prevent dehydration.4 Sports drinks and other beverages without alcohol or caffeine can help with mild dehydration.4 Recommend oral rehydration fluids, such as Pedialyte, to replace important electrolytes lost from diarrhea and vomiting. Severe dehydration may require hospitalization with intravenous fluids. Investigators are evaluating a norovirus vaccine, but no immunization is available for prevention or treatment.4 One new study analyzed 3747 norovirus outbreaks in the United States from a national outbreak reporting system and laboratory surveillance database and found that the specific genogroup II type 4 strain caused worse outcomes.6 These results could help in the development of a norovirus vaccine.
Pharmacists play a key role in educating patients about norovirus prevention. One important tip is washing hands carefully with soap and water for at least 20 seconds, especially after changing diapers or using the bathroom and before eating or preparing food.4 If soap and water are not available, individuals should use an alcohol-based hand sanitizer that contains at least 60% alcohol.1 Instruct individuals to carefully rinse fruits and vegetables and thoroughly cook shellfish before eating. Patients with norovirus should not prepare food for others while they have symptoms and for at least 2 days after they recover.1,4 Advise patients to clean and disinfect contaminated surfaces using a bleach-based household cleaner and to machine wash and thoroughly dry laundry that may be contaminated with stool or vomit. Individuals should handle soiled items carefully with disposable gloves and wash their hands afterward to prevent the spread of norovirus. Pharmacists should recommend that patients take oral rehydration products with them while traveling. Pedialyte products include powder formulations that dissolve in drinks, making them ideal for travel.
During cruise shore excursions, especially in developing countries, patients should avoid ice and drink beverages from only sealed containers and eat food that is cooked and served hot.1 Pharmacists can direct patients to the CDC’s Vessel Sanitation Program website to search for cruise ship inspection scores.7 The programs inspect vessels twice a year, and a score of 86 or higher is considered satisfactory, whereas 85 or lower is failing.7
Jennifer Gershman, PharmD, CPh, is a drug information pharmacist and Pharmacy Times® contributor who resides in South Florida.