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Influenza
The influenza virus is a highly mutable, infectious respiratory disease. Many subtypes exist, and their crossing with each other may result in the emerging of new viruses. Birds and mammals as well can be affected by the virus besides humans, which can further accelerate the rate of spreading. When two different types of viruses cross, a virus with a brand new structure evolves, which resembles the preceding ones only slightly. If a virus gets into our system, with which we have been infected before, our immune system recognizes it, and defeats it before it could spread. The intensity of the immune reaction depends on how much the virus in our system resembles the earlier ones. In case of a shift, however, a type of influenza evolves, against which nobody is protected, because at the time of the infection nobody is immune to it. After a couple of days our immune system becomes active, and can cope with the formerly unknown viruses as well, therefore when it gets into our system again, it cannot spread any more. A shift is a fairly rare phenomenon, but smaller structural changes (drifts) occur regularly.
The influenza virus might be referred to by a number of denominations. The different virus strains can be classified according to their basic types (H1N1, H3N2), their carrier (ex. pig, bird, human), or their capacity to cause illness.
H1N1:
In case of the virus that has been spreading since April, 2009, the shift most likely occurred in the system of pigs, hence the name ‘swine flu’. More than 10 000 new influenza cases have been recorded in 40 countries since the first appearance of the virus. The swine flu is believed to spread just like the typical influenza virus, and the symptoms are not significantly different either. The reason for the world-wide spread of the disease is that our immune system has to face a formerly unknown virus, and cannot protect itself from it.
Seasonal influenza:
The seasonal influenza virus causes the largest number of illnesses throughout the world. In the last fifty years there were 35 influenza epidemics in Hungary. Between 1950 and 2000 at least 1 million people got infected in 10 out of all the influenza epidemics, and in 3 of those epidemics the number of registered influenza patients exceeded 2 million. Because of the mutable nature of the influenza virus, there are smaller and smaller structural changes in the virus strains each year. The WHO continually monitors the influenza viruses circulating around the world. Which virus strains are the most suitable to provide optimal protections as vaccine viruses in the next influenza season is decided on the basis of detailed virological research. This variability creates the necessity to repeat the seasonal influenza vaccination year after year.
Symptoms of influenza:
There are no typical symptoms only characteristic of influenza. The different virus strains cause similar complaints. They are mostly accompanied with high fever, muscular pain, and sleepiness. The infection is often followed by sore throat, cold, and cough. The complaints usually ease after a couple of days, and they soon end. The biggest threat is not the influenza itself, but the possible superinfections caused by the virus. Aggressive subtypes of the influenza virus may wreck the mucous membrane of the lungs, which could even lead to pneumonia.
Who are at the highest risk?
Complications rarely occur among healthy people, because their immune system can react quickly to the pathogens getting into their systems. According to CDC, the American institute controlling the spread of epidemics, people at high risk are babies, children, expectant mothers, the elderly, and those suffering from some kind of chronic illness. In their cases the course of the illness might be more severe, because of the occurrence of different possible complications.
Prevention
All influenza viruses spread by droplet infection. They are present in the exhaled air, adhere to the objects in our surroundings, on public transportation vehicles, at school, or at the workplace. The spread of the virus cannot be stopped, but we can do quite a lot in order that the least people get infected. The most important prevention method is the vaccination that provides protection against the known virus types; this is especially important in case of the new type of influenza. A facemask should be worn, and kisses and handshakes should be avoided when greeting others, for the sake of prevention. It is important to wash hands often, and to clean surfaces that are often touched, ex. telephones, door handles, tables, and elevator buttons.
Vaccination
The most effective means to prevent influenza is vaccination. The seasonal flu vaccination is not efficacious against A(H1N1)v influenza, therefore a new vaccine had to be developed against the new virus. In the autumn of 2009 the opportunity has presented itself to start not only seasonal vaccination, but also vaccination against the pandemic influenza A(H1N1)v in Hungary. Protection can be attained by two different influenza vaccines applied together. The first one is the seasonal flu vaccine called Fluval AB, the second vaccine is Fluval P for the prevention of pandemic influenza. Hungarian doctors are by law prohibited to use any other types of vaccines currently used abroad against pandemic influenza (lack of registrations certificate). Immunity develops in two weeks following the vaccination, and lasts several months. The H1N1 vaccination is already in commercial circulation, and is thus available to the patients of Dr. Rose Medical Center as well.