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Q's and A's on Pandemic Influenza with BGen Hilary Jaeger, CF Surgeon General
By Capt Cindy Tessier, Communications and public affairs advisor with the CF Health Services Group
What is the difference between influenza, pandemic influenza and avian influenza?
Lots of people are having difficulty keeping these three things separate in their minds, and that confusion tends to make people more worried than they need to be.
Influenza is.a generic term for respiratory tract illnesses caused by a certain family of viruses and transmitted from one infected host to another. Some of these viruses have a preference for infecting humans, some for birds or other animals. People tend to use the term 'flu' for any respiratory illness that seems worse to them than a cold, even if it's not caused by an influenza virus. Medical professionals may use the term 'flu-like illness' in this way, but will not diagnose influenza without laboratory tests. Every year there is a peak in human influenza over the late fall and winter months, when people spend more time indoors in close quarters, which makes the person-to-person spread much more efficient.
Avian Influenza is. Avian describes something related to birds and avian influenza is a fairly general term describing influenza that originated in, and is usually confined to birds. As with human influenza, there are often several strains of avian influenza going around in different places in the world; these strains can vary in their severity, how far they spread, and whether they can or cannot infect humans. Scientists label the strains with letters and numbers that are shorthand for describing the proteins on the surface of the virus. The avian influenza currently attracting all the attention is the H5N1 strain. This H5N1 strain is indeed a catastrophe-if you are a bird, or if your livelihood depends on raising birds. It is not at present a human health emergency.
Pandemic Influenza is.Pandemic describes a disease that occurs over a whole country or the world, so pandemic influenza is a form of influenza that effects a large number of people throughout a country or the world, much more than the usual yearly influenza. It occurs when a strain of influenza virus emerges that has three characteristics that combine to make it much more powerful than the types of influenza that happen every year. First, the virus must be capable of causing disease in humans. Some influenza viruses do not readily infect people, and some viruses can infect people without causing illness. Second, it must be a strain of virus that has not circulated in humans for a very long time, so that nobody has even partial immunity to it. That is, their immune system has never been exposed to it before so it cannot readily fight the virus. Third, it must be able to be transmitted directly from person to person without any intermediate steps. There were three influenza pandemics in the 20th century: 1918-1919, 1957-58, and 1968-1969. Most public health experts agree the world is 'overdue' for another one.
Will an annual "Flu Shot" provide protection against a potential mutated strain of avian influenza?
No, the annual flu shot is designed to protect against the strains of viruses that public health experts believe will cause that winter's cases of the usual type of influenza. The influenza vaccine in most years combines the strains that circulated last year, because strains often circulate for more than one cycle, and the best estimate of which strains found early in the year will go on to cause illness. If a pandemic breaks out, it will be caused by a strain that has not been encountered in humans for a very long time, if ever. Until that strain of virus is identified, a specific vaccine against it cannot be developed. But it is still important to get your annual flu shot. Most people don't realize that influenza causes over 30,000 deaths every year in North America, and many times more get sick and lose time from work. Much of this could be prevented if more people got their annual "flu shot" and followed good hand washing practices when in contact with people who are sick.
Does the CF have a stockpile of 'flu shots' and other inoculations to protect our members from unknown influenzas?
If an influenza virus strain is unknown, there can be no vaccine ('shot') for it. Vaccines work by teaching our immune systems to quickly recognize specific viruses by the shape and size of the proteins on the surface of the virus. Influenza has the ability to intermittently alter the shape and size of these proteins, so a vaccine that protects against one strain probably won't work against others. Until the strain is identified so that the shape and size of the proteins can be identified, an effective vaccine cannot be made. From identification of a new strain to the production of the first vial of vaccine usually takes up to 6 months, and another month or so is usually required to develop immunity. In the meantime, antiviral medications, either to prevent illness or as treatment after a person becomes ill, can lessen the severity of the pandemic for both individuals and the population as a whole. The CF has enough antivirals to allow the critical operational tasks of the CF to continue until the vaccine becomes available.
Do you have any specific health advice or information for members serving in locations overseas-particularly in locations such as Turkey where avian flu is known to be present?
The first advice is not to overreact. Don't lose sleep or buy antiviral medications at any price. So far all of the human infections with H5N1 viruses have been in people who had close contact with birds, specifically poultry. Therefore it makes sense, if you are concerned, to avoid such contact. And close contact means just that - it does not mean having birds fly over your head, or nest in a tree in your back yard; it means raising them, commercially or for your own consumption, in some cases keeping them as pets, including letting ducks and chickens roam inside the home. The activities that seem to carry the most risk of human infection are the direct slaughter of birds, and their rendering and plucking. So I would advise you not to buy live fowl at markets in affected areas and prepare them yourself. Influenza viruses are killed completely by heat, so there is no need to exclude chickens or other poultry from your diet, so long as it is thoroughly cooked. And there is no need to get rid of your pet parrot or budgerigar so long as they have no contact with poultry or wild waterfowl. The Public Health Agency of Canada has good advice for travelers on their website www.phac-aspc.gc.ca
In your professional opinion what is the risk of avian influenza mutating to humans and causing a pandemic influenza?
The current H5N1 avian influenza outbreak deserves to be carefully watched. This virus has two of the three characteristics necessary for a pandemic to develop: First, we know for sure it can cause disease in humans. Over the past two years, there have been 121 documented cases of human illness caused by this virus, with 62 deaths. While these numbers may seem alarming, remember that at least 30,000 people will die in North America this year from the usual yearly influenza. And second, it is a type of influenza virus that has not previously been encountered by humans (or at least not since we have had the ability to keep track of this kind of thing). But it cannot move easily, if at all, from human to human, and therefore at the moment cannot cause a pandemic. Nobody can say for sure when, or if, this particular virus will develop that ability. It may happen next week, next year, or it may never happen; and while we are busy watching H5N1 it is possible for a pandemic strain to originate from another source entirely.
What role will the CF Health Services play in the event of a nationwide influenza pandemic?
CF Health Services will contribute to Health Canada's overall surveillance of the status situation, and will work to ensure that the health of CF personnel and impact on CF operations is minimized.
