Jonel Aleccia of NBC News took on a rather unpleasant subject norovirus (aka the stomach flu or the winter vomiting bug) in his recent article.
Although it is an intriguing topic, and dispels some myths, the overall message that if you simply avoid eating at restaurants (especially the salad bars) you will dodge this hideous infection is misleading.
ACSH s Dr. Josh Bloom, who spent many years in antiviral research while he was employed in the pharmaceutical industry, explains: Norovirus is essentially the perfect pathogen. It is generally regarded as the most contagious germ in the world. As few as ten viral particles are sufficient to infect a person. It is also difficult to kill, since it resists many disinfectant methods that would deactivate other viruses. Maybe even worse is that being infected confers very little immunity against reinfection. I believe it was created by Satan himself.
The NBC piece debunks the idea that this is mainly a disease associated with cruise ships. While these outbreaks are not uncommon, they represents a miniscule fraction of the number of cases per year.
But the article also seems to suggest that improper food handling is the primary cause of transmission of the virus. This is incorrect.
Dr. Bloom explains, Improper food handling is the cause of the majority of outbreaks. But does this mean it is the primary cause of infection? It does not, and this is made clear if look beyond the headline.
Why is this? The CDC study examined the number of outbreaks between 2009 and 2012, and concluded that 520 of these were directly attributable to contamination by food workers. They also concluded that these outbreaks were responsible for one quarter of the 20 million annual infections in the US.
Dr. Bloom is a bit puzzled: This seems like an awfully large number of infections per outbreak, but let s assume the numbers are right. This still leaves 15 million cases that are not related to food handling. This is why the headline is misleading. It implies that if you simply avoid restaurants or improved food handling procedures are implemented that you will dodge this thing. This is not correct.
Why is this? The stability and infectivity of the virus make it transmissible in many ways, including airborne particles, infection from surfaces, and the always popular fecal-oral route typically from improper hand washing. People can transmit the infection anywhere from one day before symptoms occur, to two days (and sometimes as long as two weeks) after they subside. This is why it goes around families like wildfire.
CDC Director Tom Frieden, describing policies (such as making sick employees stay home) said yesterday, "We do know how to stop norovirus from contaminating our food.
Dr. Bloom respectfully disagrees: If you were able to prevent all food borne transmission of norovirus, which will never happen, there would still be 15 million infections per year. And there will always be workers whose symptoms have yet to appear, or have subsided, and they will still be infective.
He adds, Fortunately, there is a vaccine that is doing well in clinical trials, and could be available in about two years if all goes right. You do not want to get between me and the pharmacy that is giving this vaccine.
For additional reading on this subject, we recommend you read Dr. Bloom s 2011 Medical Progress Today blog piece entitled New Vaccine May Give Norovirus the Heave Ho.