Norovirus: The Stomach Flu

Most people expect to have a great time when they book a cruise. Some viral infections, however, have cast a shadow on those vacation plans even though they’re not  pandemic diseases.  The first was hantavirus, but 0there’s another, just as unlikely to cause a pandemic,  but still a major pain in the…stomach. That’s norovirus, otherwise known as the stomach flu. Recently, over 100 people were sickened on the Carnival Princess and 50 more on a French cruise ship.

We personally had an experience with the virus a few years ago when my wife sampled “The World’s Best Hot Dog” at a street stand in New York City while visiting our daughter. Believe me, it’s no fun. Considering that food contaminated with norovirus can be found everywhere from the Big Apple to the Grand Canyon to the high seas, the family medic should know about it.

ABOUT NOROVIRUSES

Hantavirus has gotten the press, but norovirus is the leading cause of foodborne illness in the U.S. The U.S. reports 19 million to 21 million cases a year. Humans are, apparently,  the only hosts of the virus, affecting people of all ages. It’s particularly dangerous in the elderly, the very young, and those with weakened immune systems. November to April is the most common time for outbreaks.

Norovirus is very contagious (just 5-20 viral particles can cause illness) and is easily transmitted through contaminated food or water, close personal contact, and even by air droplets from vomit, contaminated kitchen counters, and even toilet flushes. Infection can be passed from person to person for a time even after apparent recovery.

Here’s how contagious the norovirus is: In one outbreak reported in 1998, 126 people were dining at a restaurant when one person vomited onto the floor. Despite a rapid cleanup, 52 customers fell ill within 72 hours. More than 90% of the people who later dined at the same table reported symptoms. 70% of diners at nearby tables got sick.

Norovirus is a hardy microbe, known to survive for long periods outside a human host. It can live for weeks on countertops and up to twelve days on clothes. It can survive for months in still water. Disinfectants containing chlorine, however, like bleach will quickly eliminate it, as will sufficient heat.

SYMPTOMS OF “STOMACH FLU”

The symptoms of the stomach flu include nausea and vomiting, watery diarrhea, and (sometimes severe) abdominal pain, usually within 12 to 48 hours of exposure. Additionally, muscle aches, headache, and fever are common. Luckily, life-threatening illness is rare, with dehydration being the main danger in those infected with the virus. Symptoms may last several days before eventually subsiding.

Unlike some viruses, immunity after recovery from norovirus is only temporary. Antibodies against the virus at thought to last not much longer than, say, six months. Also, there are various strains of noroviruses; getting one doesn’t protect you against others.

Outbreaks of norovirus infection often occur in closed spaces such as nursing homes, schools, camps, prisons and, surprise, cruise ships. Shellfish, such as oysters, and salad ingredients are the foods most often implicated in norovirus outbreaks (except, of course, “the World’s Best Hot Dog”).

TREATING NOROVIRUS

As is the case with most viruses, there is no known cure for norovirus infection. Antibiotics aren’t effective, as they’re meant to kill bacteria, not viruses. Treatment involves staying well-hydrated. Suspect dehydration if you see these signs and symptoms:

• Dry mouth
• Decrease in quantity or dark color of urine
• Dizziness when standing up
• Decreased elasticity of skin (it “tents” when pulled)
• No tears when crying or unusual irritability in infants

Using antidiarrheal meds like loperamide (Imodium) and anti-vomiting drugs like Ondansetron (Zofran) may also help.

PREVENTING NOROVIRUS

A cure may not be available, but prevention is another issue. To decrease the chance of norovirus infection:

• Wash your hands frequently, especially after using the restroom or handling food. Be especially sure to do this for two weeks after becoming infected (yes, you can be contagious for that long). Interestingly, norovirus can survive the use of hand sanitizers, so stick with good old soap and water.
• Wash food before cooking; cook shellfish thoroughly.
• Frequently disinfect contaminated surfaces with a bleach solution (the EPA recommends 5-25 drops of bleach per gallon).
• Keep sick individuals away from food preparation areas.
• Avoid close contact with others when you are sick, and don’t share utensils or other items.
• Wear disposable gloves while handling soiled items.
• Immediately remove and wash clothes that may be contaminated with vomit or feces. Machine dry if possible.

If you’re planning a cruise, you might consider taking Vitamins C and Zinc about two weeks before your trip to boost your immune system.

Once you’re on the ship:

• Avoid using shared serving utensils if possible, and opt for food cooked to order rather than buffets.
• Avoid touching handrails on stairs.
• Use tis0sues or your elbow to push elevator buttons. In fact, stay out of elevators and use the stairs, without handrails, if you physically can.
• Avoid sick people: If you hear people coughing or notice someone vomiting, leave the area.
• Pack a Medical Kit: Bring essential items, including antiseptic wipes, OTC medications (Pepto-Bismol, Imodium, cold medicine, Ibuprofen), and prescription meds.

It may be difficult to completely eliminate the risk of norovirus infection, but careful attention to hand and food hygiene will go a long way towards avoiding the stomach flu and making a trip a memorable one (in a good way).

Joe Alton MD