Before the H1N1 Pandemic: A Brief History of H1N1

June 11, 2009 marked the beginning of a global A (H1N1) Pandemic. World Health Organization declared alert level 6 first global Pandemic since the 1968 Hong Kong Flu. This global pandemic has trampled on and challenged the medical world and the people in general. What is H1N1? When did the first outbreak happen? These are the questions that need to shed some light on so that we could arm ourselves with proper knowledge on how to combat this disease.

What is A (H1N1)?

Basic Health Screening

H1N1 virus is the most common type of influenza in human. It’s a subtype of Influenza Virus. Some strains are endemic in humans like the A(H1N1) and the seasonal flu. Some are endemic in pigs (swine influenza) and some are in birds (avian influenza).

H1N1 can be subdivided according to the two proteins found on the surface of the virus: H (hemagglutinin) and N (neuruminidase). All of the influenza strains contain these two protein structure, however, they vary from strain to strain in terms of the structure of the proteins.

Each strain is assigned an H and an N numbers based on how many protein structures they contain. For example, common strains in birds contain 16 H and 9 N proteins while only 1-3 H and 1-2 N are common strains found in human.

When did the first outbreak happen?

History has it that the first known outbreak of H1N1 was that of Avian Influenza. It happened sometime around 1918-1919. The pandemic was phenomenally called as Spanish Flu not because it originated in Spain but because Spain is the only European country that printed reports about it. The Spanish Flu killed about 50-100 million people worldwide.

The Spanish Flu, which is similar to the recent Avian Flu, killed so many people because of its cytokine storm on the body. The virus attacks the lung cells. Then it causes hyperactivity of the immune system that releases the cytokines into the lung tissue. Because of this, there will be extensive leukocyte migration towards the lungs that will cause damage to the lung tissue and secretion of liquid into the organ. The patient will have difficulty breathing and dies.

Fifty years later, sometime around 1978-1979 there was a “Russian Flu” pandemic—which was caused by a strain of Influenza A virus. It infected mostly children and young adults under the age of 23. The virus was similar to the Flu on 1947-57. It mostly affected children that’s why it was not really considered a true pandemic.

2009 Flu Pandemic

Studies on H1N1 genetic characterization show that the 2009 Flu virus was similar to the swine flu viruses present in U.S. Pigs. However, European strains were found in the structure of matrix proteins and neurominadase (NA). So, the American Swine flu is actually a mixture of different strains of swine flu, bird flu, and human flu.

Looking Forward

We can see how this virus has evolved from a simpler Avian Flu to Swine Flu and eventually to a mixture of different strains. Nonetheless, we’re looking forward and counting on the medical people to come up with a way to totally eradicate and put a stop to this pandemic.

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