The Spanish Flu

Here's about the Spanish Flu cause by the H1N1.

The Spanish Flu, also known as La Grippe, or La Pesadilla, was an unusually severe and deadly strain of avian influenza, a viral infectious disease, that killed some 50 million to 100 million people worldwide over about a year in 1918 and 1919. It is thought to have been one of the most deadly pandemics so far in human history. It was caused by the H1N1 type of influenza virus, which is similar to bird flu of today, mainly H5N1 and H5N2.

The Spanish flu caused an unusual number of deaths because it, like H5N1, caused a cytokine storm in the body. The virus infected lung cells, leading to overstimulation of the immune system via release of cytokine bursts into the lung tissue. This leads to extensive leukocyte migration towards the lungs, causing destruction of lung tissue and secretion of liquid into the lung, and making it difficult for the patient to breathe. Due to the nature of the infection, people with a normal healthy immune system were more susceptible to the disease, such as young adults compared to young children and the elderly.