Tips to Protect Yourself and Your Shipmates from Noroviruses

By Allen Wright, staff epidemiologist, Navy and Marine Corps Public Health Center

Here at the Navy and Marine Corps Public Health Center (NMCPHC), the Navy’s hub for health surveillance, we are supporting you by continuously monitoring the health of our Navy so that we may advocate for and recommend improved force health protection guidance to you and your leadership.  

One of my tasks toward that end is to monitor the incidence of disease and non-battle injury as it is reported from our Navy’s afloat units. This team effort between us and Navy Medicines’ fleet reporters has provided us a clearer understanding of the major sources/types of illness that you are likely to experience while serving aboard our Navy’s ships, and now we can say with more certainty that acute gastroenteritis, most likely from a norovirus, is the source of most sudden onset vomiting and diarrhea occurring aboard our ships. This is not a surprising finding, because noroviruses are infectious at extremely low doses, and they are easily spread from person to person.  Their hardiness enables them to survive extended periods (a few days) in the environment, enabling their transfer between people via commonly handled objects.

Norovirus is a leading cause of disease from contaminated foods in the United States. Foods that are most commonly involved in foodborne norovirus outbreaks include leafy greens (such as lettuce), fresh fruits, and shellfish (such as oysters). However, any food item that is served raw or handled after being cooked can become contaminated with noroviruses. (Photo from the CDC)

The following are actions you can take to protect yourself, your shipmates, and your family. First, know that it is most important that you maintain good habits of always washing your hands after using the toilet, changing diapers, eating, or preparing/handling food.  Do this vigorously for at least 20 seconds with soap and water. Do this because outbreaks of disease from these viruses often begin when an infected food handler who contaminates ready-to-eat foods or utensils, and once out in a population, the virus spreads quickly from person-to-person especially among those in crowded-living quarters aboard ship. This happens because the virus is shed in high amounts in feces and vomit; and it is infectious at very low doses. Therefore, if you have leadership responsibilities, take time to talk to your new shipmates about the special importance of good hygiene and frequent hand washing while serving aboard our Navy’s ships. 

I am occasionally asked about the effectiveness of hand sanitizers.  Do they help?  For noroviruses we are not sure.  It’s believed that certain alcohol based hand sanitizers can be helpful in slowing the spread of some diseases, but it’s not clear how effective they are against noroviruses, so I advise that you do not substitute them for hand washing with soap and water.  If they are all you have, still use them when you would normally wash your hands.  They will help reduce the threat from other disease causing organisms, and it’s better than doing nothing. 

Finally, I want emphasize that noroviruses are very hardy organisms that cannot be killed by the use of typical sanitizing agents.  For that reason, it is very important that you notify your “Doc” if you or your shipmates experience or become aware of vomiting or fecal accidents in a head aboard your ship.  Do not attempt to clean it up yourself, unless instructed by your medical personnel to do so, and limit access to the area.  Know that clean up in these situations requires special procedures and sanitizers to be effective if a norovirus is believed to be the cause of the illnesses. 

While I’ve touched on the basics, there is more to know.  I encourage you to visit the U.S. Centers for Disease Control’s Preventing Norovirus Infection website at http://cdc.gov/features/norovirus to learn more.  If you are a “Doc” in the fleet, I encourage you to see specific guidance that we (NMCPHC) have developed for you.  Use it to support your commander and your shipmates.  It is available in our technical guide at http://www.med.navy.mil/sites/nmcphc/diseases-and-condtioins /Pages/dafault.aspx under the link titled “Norovirus illness Prevention and Control: Guidance for the US Fleet.”