Influenza comes from the Italian words for “influence.” It goes back to the 1500s when people did not know what caused these epidemics of coughing, headache, muscle ache and even death. So people believed their health was being “influenced” by the stars.
Today, science and technology has become so advanced that we know that the flu is not due to the influence of the stars, but something even stranger called viruses.
All influenza viruses that we know about, came originally from wild bird viruses. Not just any wild birds, but birds that are considered to be waterfowl like chickens, ducks and geese or shore birds.
These birds are what we call the reservoirs of influenza. There are billions and billions of these birds in the world. Many of them migrate and influenza viruses circulate in them on and ongoing basis. By and large, the virus does not harm these birds, but because of their ability to migrate from temperate zones to tropical zones and vice versa, it allows the virus to spread globally.
One may ask: how did the bird flu or influenza start affecting humans?
Since ancient times the water fowl formed a part of the diet and eventually became domesticated livestock reared for their meat and eggs. Transmission of the flu virus to humans might have been as early as then. However, with meat and egg consumption and the explosion of human population in this modern time, we see the development of industrial scale chicken facilities which creates a perfect environment for origins and spread of so-called super strains of the influenza virus.
There is data that supports association of an increased demand for poultry products and the emergence of virulent strains of this virus capable of bird to human and human to human transmission.
In 2009 we saw a further evolution of this via the pandemic of swine flu or H1N1 strain of the influenza virus. This strain is thought to be a mutation of four known strains of the influenza. The process of the emergence of this new strain seems to have started with human and birds transmitting different strains of influenza to an intermediate porcine hosts, namely pigs. During co-infection, different segments of each virus recombined to form a new viral strain, H1N1, that is even more virulent than the original parent viral strains. This new strain spreads from pigs to human through direct contact.
Normally, the virus is able to mutate in such a way because of its inefficient replication and reproducing its genetic material as well as combining genetic material from its bird, pig and human hosts. Thus, its genetic material, which determines its surface structure changes, and the immune system has to relearn the surface of the virus before it launches an immune response.
As a result, humans can never become immune to the influenza virus because of how it rapidly mutates. This is a key feature in ability to infect, cause disease and even cause death.
Unlike other types of commonly known viruses that infect humans, like measles or yellow fever that stay exactly the same through years and decades, influenza is characterised by the ability to mutate or drift. In a world like today when there are serious diseases like Tuberculosis and Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS), why is there so much concern about the influenza?
Looking further back, we see in 1918 an influenza pandemic triggered by the virus became the worst plague in human history. This influenza virus, which originating from birds, killed more people in 25 weeks than AIDS have killed in 25 years. Thus, influenza is the only virus on the planet capable of infecting billions. This has further increased with the pandemics such as swine flu in modern times. These pandemics results from the virus’ ability to drift.
Every 10 years a so, a brand new form of the virus emerges that is not seasonal or have infected humans before. An influenza pandemic is the emergence of an influenza virus that is totally new. Thus, the impact of the virus can be much more severe and can result in a huge number of deaths.
The influenza virus affects the human respiratory tract. When someone has contracted influenza virus, the common symptoms are; fever, muscle aches, joint pains, cough, sore throat, chest pain and generally feeling unwell. There is no cure, so patients are advised to treat the symptoms conservatively with bed rest, increase fluids and medication for the pain and fever, until the immune system rids the body of the virus.
There is, however, the influenza vaccine which is recommended annually. As the virus mutates, new vaccines are produced every year to combat against new strains. The shot confers some protection, however, if one contracts the virus after getting the shot, they may suffer less complications than if they did not have the shot. These may include serious complications, even death.
There is the anti-vaccination movement that advocate against getting the vaccine and other sceptics about the vaccine. There is currently no significant data to support their claims. What is clear is that influenza causes serious morbidity and mortality annually as supported by local data by the Ministry of Health. Individuals who get the vaccine have a better chance of avoiding the flu and its complications, even death. Get vaccinated now!
Dr Visham Bhimull
MBBS (UWI) Diploma in
Family Medicine (UWI)