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The word Influenza was coined from the Italian word for Influence. Influenza is a viral, infectious disease, occurring in mammals and birds. It is transmitted by air and through contact with bodily fluids.
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The Influenza Virus:
Influenza is caused by RNA viruses of the Orthomyxoviridae family. Here are some of characteristics of the influenza viron-
- Size of the influenza viron is around 80 to 120 nanometers in diameter.
- Spherical shape usually, but also occurs in filamentous forms.
- Outer surface has a lipid covering with projecting glycoprotein spikes.
- Two types of spikes - haemagglutinin (HA) or neuraminidase (NA)
- A matrix protein lines the inside of the lipid covering.
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There are three main types of influenza viruses:
- Type A influenza virus is the one that causes pandemics or worldwide epidemics. It infects humans, animals and birds. Type A strains are the most varied and adaptable of the influenza viruses. At present, researchers know of 15 HA serotypes and 9 NA serotypes. However, there are many subtypes arising from frequent protein changes and combinations.
- Types B affects only mammals, but it is less severe than Type A and has no distinguishable serotypes.
- Type C also infects only mammals, causes disease rarely and has no distinguishable serotypes.
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So Who Discovered the Influenza Virus?
Several researchers working over a long span of time. The first recorded instance of the symptoms of influenza was by Herodotus some 2400 years ago. But its secrets were not revealed until much later in history.
In 1918, a veterinarian called J.S. Koen noted similarities between influenza symptoms in the pigs he was treating and the symptoms of the then raging Spanish Flu epidemic in humans.
Researchers N. McBryde and Robert Shope, working independently, carried out influenza-transmitting experiments on pigs in 1928. Taking mucus from infected pigs and using bacterial filters, they inserted the viral loaded mucus into the nostrils of healthy pigs in order to infect them. McBryde failed in his experiments, but Robert Shope succeeded in reproducing the disease. His experiments proved finally that influenza was indeed caused by a virus.
The first identification of the human influenza virus came about in 1933, through the works of researchers Wilson Smith, Christopher Andrews and Patrick Laidrow.
In 1944, Thomas Francis Jr. and his team of researchers at the University of Michigan, with the assistance of the U.S. Army, developed a killed-virus vaccine for influenza. This was based on the earlier work of Frank Macfarlane Burnet who showed that the virus lost virulence when it was cultured in fertilized hen's eggs.
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History of Influenza:
Influenza probably first occurred after humans began domesticating animals and fowls, and transmitted from the animals to humans. However, given the similarity of its symptoms to other diseases like dengue, diphtheria, typhoid and pneumatic plague, it's tough for researchers to trace the exact history of influenza.
We find a description of flu symptoms in Hippocrates' writings more than 2400 years ago. The first recorded European Influenza epidemic happened in the 1580s. It is thought to have begun in Russia and then it spread fast to Continental Europe and Africa, wiping out populations on a massive scale.
There was another severe flu epidemic in 1743 in Europe. More severe epidemics followed in 1830-1833 and in 1918-1919. The latter, which started during the closing stages of the First World War, was dubbed the Spanish Flu and spread worldwide, killing an estimated 20 to 40 million people.
Flu epidemics in more modern times have been sporadic and less severe, in part due to better control and medical know-how. The notable ones were Asian Flu of 1957-1958, the Hong Kong Flu of 1968-1969, the Swine Flu in New Jersey in 1976, the worldwide Russian Flu in 1977 and the H5N1 avian influenza in Hong Kong and Asian countries in 1997. However, the emergence of new and hardier strains remains a matter of concern of public health programs around the world.