Stomach flu breakthrough?
BACKGROUND: Norovirus is a highly contagious virus. It is also called “food poisoning” or “stomach flu,” but is not related to the flu (influenza). The virus can be caught from an infected person, contaminated water or food, or by touching contaminated surfaces. However, there is some evidence for spreading airborne(probably when viruses become airborne from projective vomiting and then land on). It is the most common cause of foodborne-diseases in the United States. Anyone can become infected with norovirus and can have it many times in their life. It can become dangerous for young children and older adults. The virus causes the stomach, intestines, or both to become inflamed, also known as acute gastroenteritis. Norovirus is the most common cause of acute gastroenteritis. It is responsible for 21 million illnesses, contributes to 70 thousand hospitalizations, and 800 deaths. (Source: www.cdc.gov).
SYMPTOMS: Norovirus causes diarrhea, nausea, stomach pain, throwing up, fever, headache, and body aches. The virus often causes patients to throw up or have diarrhea many times a day, putting them at risk for dehydration. Symptoms of dehydration include: dry mouth and throat, decrease in urination, and feeling dizzy when standing. Children who are dehydrated may cry without producing tears and can be unusually sleep or fussy. To prevent dehydration, patients should drink plenty of liquids to replace fluids that have been lost. Sports drinks can help with mild dehydration, but they cannot replace important nutrients and minerals. Oral rehydration fluids are available over the counter and are found to be most helpful for mild dehydration. (Source: www.cdc.gov).
NEW TECHNOLOGY: There is no specific medicine to treat people with the norovirus. The norovirus infection cannot be treated with antibiotics because it is a viral infection, not a bacterial infection. Last year, a nasal spray vaccine was tested on 90 volunteers. One third of those who got the vaccine developed symptoms related to the norovirus. Researchers believe the nasal vaccine only worked against one of the genetic strains of norovirus instead of multiple strains. The new injectable vaccine works against two, resulting in a cross-reaction that provides added protection. In the new study, participants received two injections in their arm of vaccine or placebo four weeks apart. There were no serious side effects related to the use of the vaccine. Researchers used blood tests to check for evidence of virus-fighting antibodies. Compared to placebo, participants of all ages mounted a rapid antibody response. Researchers believe that the new vaccine will result in patients having fewer symptoms than those getting a placebo. (Source: www.webmd.com)
John Treanor, MD, Professor of Medicine, Microbiology, and Immunology, and Chief of Infectious Diseases Division at the University of Rochester Medical Center, talks about a possible vaccine for Norovirus.
What is Norovirus?
Dr. Treanor: Noroviruses are probably the most common infectious cause of acute gastroenteritis in the United States. They are very common and they cause a typical illness characterized mostly by vomiting. When you have Norovirus, you know it. You will have very intense vomiting for about 24 hours and sometimes it is accompanied by diarrhea. However, not always and its associated with some fever and some muscle aches. Most people will recovery completely over the next day or two.
How common is it?
Dr. Treanor: It is clearly the most common cause of gastroenteritis. Most people will have an episode or two every year. It seems like perhaps it is more common in people who are living in close circumstances with lots of other people, but everybody is going to get Norovirus or one of the related viruses at some point through their life.
Is it an umbrella term for lots of viruses?
Dr. Treanor: One of the things about this virus is it is very infectious. When you have it, although you recover quickly, you continue to shed it from your body for many days afterwards. It only takes the tiniest dose to infect the next person. So the characteristic of Norovirus is lots of other people get sick; what they call the secondary attack rate is very high because it is so contagious.
Is that why cruise ships have such a problem with it?
Dr. Treanor: Absolutely; any situation where you have people living in close proximity to each other. When a Norovirus outbreak gets started, it is very tough to stop.
How serious is it or how serious can it get?
Dr. Treanor: For most people it is going to be a very self-limited illness, but we have recognized that in older adults, there can even be deaths associated with Norovirus. The CDC estimates, it’s not a large number, but something like 700 deaths associated with Norovirus every year, mostly in older people or people with compromised immune systems.
Does it affect infants and toddlers the same? Is it like the flu where it is worse for infants and older people or is Norovirus not as dangerous for infants?
Dr. Treanor: It is really not dangerous for toddlers and infants. However, it does generate a lot of illness and emergency room visits for gastroenteritis, but it usually is resolved by itself eventually.
Since for most people it resolves itself by itself fairly quickly, what is the need for a vaccine? Why were you studying that?
Dr. Treanor: It is a very common illness. When you have it, you are very disabled. It is really tough to get up and go to work or do anything else while you are having Norovirus because you are throwing up every hour. So, although a vaccine would not be designed to prevent deaths due to Norovirus, you could prevent a tremendous amount of disability in this country with a vaccine that was effective. For example, the Department of Defense is very interested in trying to find vaccines or other ways to prevent Norovirus because there have been some major outbreaks of Norovirus in military camps and bases which actually compromises readiness and so this is an important problem for them to control.
Are there lots of different Noroviruses where a vaccine might be similar to a flu, where you might get one every year? Is that the idea?
Dr. Treanor: There are some amazing parallels between the Noroviruses and the flu. One of them is that there does appear to be a form of antigenic change over time with the Noroviruses where the predominant strain is eventually replaced by another strain. So, it is possible that if we were using an effective Norovirus vaccine we might have to update it from time to time.
What has your research shown? What have you studied?
Dr. Treanor: I am involved in a project that involves a lot of investigators in many centers and it is all designed to try and evaluate one particular candidate “virus-like particle” vaccine for Norovirus; which means that the protein is there, but the RNA isn’t and so it does not replicate or cause disease. It has been given to people via muscle and also nasally. It can stimulate antibody which in theory should be protective against Norovirus.
Is it effective yet against it or you are not quite sure?
Dr. Treanor: What we have shown is that it generates an immune response. Now, does it work? To test that, we are doing studies where some volunteers are coming into a special facility that we have to be intentionally exposed to Norovirus to see whether people who have received the vaccine will be protected against an artificially induced illness as the fastest and most sure way to demonstrate protectiveness of the vaccine. If it works in those studies then we will go forward with larger studies in the field to prove that it works in people who acquired Norovirus naturally.
Have you seen early results at all from those studies?
Dr. Treanor: Yes, there was a study that was published last year in which people received the vaccine by nose, nasally, and those individuals did have some protection against artificial challenge. What we would like to do now is find ways to improve the efficacy of the vaccine.
So, not all of them are protected, but a number of them are?
Dr. Treanor: Protection meaning that the proportion of people who developed illness in the placebo group, the ones who were not vaccinated, was higher than the proportion in the vaccine group.
Do you think that an injectable like a flu vaccine may be more effective than the nasal?
Dr. Treanor: Yes. What we have seen with the injectable vaccine is that the antibody levels that are generated are much higher than we are seeing with a nasal vaccine. There is a good reason to believe that this will even be more effective in preventing Norovirus.
How would this help people?
Dr. Treanor: We are still trying to figure out what would be the real role of a Norovirus vaccine and it depends a little bit on how effective it is and, importantly, how long the protection lasts. If it was a very effective vaccine and the protection lasted for many years, you might see this incorporated into the regular schedule of vaccines that we give to children and adults. If it is something which ultimately is a shorter lived vaccine, you might end up using it in specific situations like if you were going on a cruise; you might want to get the vaccine before you left or the military might want to use it before deployments. Where it ends up being used, will depend on how these studies ultimately turn out, both in terms of how broad the protection is against many strains and how long the protection lasts.
There will be a lot of applications then?
Dr. Treanor: Yes. There could be a lot of ways to use this vaccine and I think there will be.
Do you think that this will make it that far? Will it be a common vaccine to get?
Dr. Treanor: I am very hopeful. I think there is every reason to believe that it will be protective. The big unanswered question is how long will the protection last and that would be a major factor in determining how we use the vaccine.
Can you see this being not just for going on a cruise ship or for military personnel; could you see this as a yearly vaccine?
Dr. Treanor: Yes. I think if the vaccine is effective enough and we are convinced that the protection is durable, then you could see this incorporated into the regular schedule of vaccines that are given to children and adults. Maybe you get your Norovirus vaccine at the same time you got your flu shot or something like that. That is very possible.
Would the impact be huge?
Dr. Treanor: Absolutely. The Norovirus is a very disabling illness. So, the impact would be in reducing that disabling feature of the virus and allowing people to go on with their normal lives.
Have you had Norovirus before?
Dr. Treanor: Yes, many times.
Can you tell me a little bit about it?
Dr. Treanor: I work in the lab with Norovirus and I’m handling samples and processing things and many years ago had the occasion to get Norovirus that way by accident. I have also just acquired it like everybody else does. Who knows where it came from? I had the typical illness, vomiting for a day or two and feeling very uncomfortable. As I mentioned, one time I managed to get this while working in the lab, which was when I was a Fellow and my mentor at the time thought it would be a great idea to present me as an example of Norovirus at Grand Rounds.
How popular do you think this would be, certainly among parents, but just in general for people?
Dr. Treanor: I think because it is so common. It would be a very popular vaccine under the assumption that it works. It is certainly going to be very well tolerated. When people leave with the vaccine, they have not really had any substantial side effects. I think it would be a very popular vaccine.
How is it currently treated?
Dr. Treanor: You really can’t do anything. There is some evidence that Pepto-Bismol may reduce the diarrhea slightly, but there really isn’t anything you can do except trying to stay well hydrated.
FOR MORE INFORMATION, PLEASE CONTACT:
John Treanor, MD
Professor of Medicine, Microbiology, and Immunology
Chief of Infectious Diseases Division
University of Rochester Medical Center
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