Transcript of interview with Aron Hall, DVM, MSPH, DACVPM, an epidemiologist with the viral gastroenteritis team of the Centers for Disease Control and Prevention
Interview conducted by Natalie McGill, reporter for The Nation’s Health newspaper.
Listen to this interview as a recording on our podcast page.
Okay. The first question I have is what is norovirus?
Norovirus is actually a group of highly contagious viruses that commonly cause acute gastroenteritis, which is diarrhea or vomiting. There is wide diversity of noroviruses, several different strains and genotypes, but all cause kind of the same clinical syndrome.
What are the most common causes of norovirus, and how does it spread? What are some common scenarios where this virus can really do some damage?
Noroviruses are spread in a variety of different ways, which makes them so challenging to control. They can be spread directly between people through what we call the fecal-oral route. So basically when people get fecal matter on their hands and don’t wash them properly, they put their hands in their mouth and make other people sick. It can also spread through food and through water. It can also persist on surfaces for long periods of time. When people touch those surfaces and put their hands in their mouth, they can get sick. And then finally, people when they vomit and have norovirus, the virus can become aerosolized and can spread through the air over short distances and potentially infect other people.
What are some of the signs and symptoms of norovirus?
The clinical symptoms of norovirus are pretty nonspecific. It’s characterized mostly by diarrhea or vomiting. It can also be accompanied by fever, body aches, headache, nausea, stomach pain, a variety of nonspecific symptoms. It’s actually because of these nonspecific symptoms, we sometimes refer to it as the stomach flu — although it has no relationship with influenza, which is the virus that causes the flu.
If someone believes they have the signs and symptoms of norovirus, what are some of the first steps they should take? What steps should friends and family members who have come into contact with them take?
If you’re infected with norovirus, the biggest concern is dehydration. You want to make sure that you’re drinking plenty of fluids and maintaining proper hydration. Dehydration can be the most severe complication of norovirus infection. Then there are also concerns about spreading it to others, particularly family members or people providing care for you. For that, you really want to focus on hand hygiene. Make sure you’re washing your hands very well, removing any fecal or vomitus material that might be on your hands. Clean off surfaces, washing countertops and such — all of that can go a long way. Finally, if you’re sick, you really want to try to self-isolate as much as you can — so staying home from work while you’re sick, using a dedicated bathroom in your home if possible can certainly help prevent spreading to others.
What are the consequences of not monitoring norovirus or not seeking treatment right away for symptoms?
Well one of the biggest concerns in terms of infection and not taking appropriate care is dehydration. Indeed we see this is as the most common complication, and what ultimately leads to hospitalization — even death — associated with norovirus. So staying properly hydrated by drinking fluids. Or if you do have to seek care, sometimes you have to get rehydration either orally or intravenously.
As far as not monitoring for norovirus, from a public health standpoint it’s very important that we kind of track norovirus activity, as it can rise and fall at different times of the year. Some years we can have big increases in norovirus activity. We want to track transmission within the community so we can provide appropriate education and prevention messages to keep people safe.
That leads me to one question that I had, which was that the Centers for Disease Control and Prevention says that outbreaks are most common between November and April in the United States. Are there any particular reasons why there are so many in this timeframe?
Well norovirus does show a pronounced winter seasonality. We do see year after year an increase in both outbreaks, as well as sporadic cases of the disease every winter — typically beginning December, January, and February, sometime in there. We don’t know for certain why this happens, but you see the same patterns with lots of viruses — influenza, RSV, and other viruses that cause the common cold. We think a lot of this has to do with human behaviors. People just gather more indoors when it’s cold outside, and they have more opportunities to spread infection to one another. There may also be some issues with the virus itself. It actually persists longer when it’s colder, so it can survive on surfaces for longer periods of time when the temperatures are lower. All of that may contribute to this winter seasonality.
What are some examples of steps a person can take to prevent the occurrence of norovirus in the first place?
Certainly maintaining good hygiene is probably the most important thing you can do to keep yourself safe from norovirus. Washing your hands after using the bathroom, before eating food, before caring for others, after changing diapers really can go a very very long way to preventing not just the norovirus infection, but a variety of other infections. There is also environmental disinfection and sanitation that can go a long way – cleaning up any vomitus accidents that may happen. Really just standard infection control is the best way to prevent the spread of norovirus.
Is norovirus more common in children, adults? Is there a certain may be age frame where it’s more apt to spread?
The highest rates of norovirus infection are in young children. Kids under the age of five seem to have the highest per capita rates. However, the most severe outcomes or the highest rates of death occur in the elderly who are aged over 65 years. They get infected less frequently than kids, but they are more likely to have severe consequences of infection. And then in the middle age ranges, we see lower rates of infection and lower rates of complication. It’s really the extremes of the age spectrum that are most often impacted and most severely impacted by noroviruses.
I guess I would just highlight really that this is a tremendous disease burden that’s imposed by norovirus. I think it often gets dismissed as a relatively mild, transient infection; but it occurs so often. We estimate about 20 million cases of norovirus every year in the United States and it can cause a lot of severe disease also — upwards of 70,000 hospitalizations and nearly 800 deaths every year in the U.S. So it really does cause a substantial amount of morbidity.
Alrighty. Dr. Hall, thank you so much for taking out the time to talk. I really appreciate it.
My pleasure.