Part of the human condition is to wake up one day feeling slightly nauseous and feverish. Then as the day progresses, you may start to experience a myriad of symptoms including chills, muscle aches, vomiting and diarrhea. You have the flu and best thing to do is to take to your bed until the illness has run its course.
Fortunately, you will probably recover, for the most part, within a week after having lost some strength, stamina and a few kilos, particularly if you were relatively healthy to begin with. However, this benign scenario is not always how it is with the flu. A dramatic case in point is the Spanish flu. Though history books have, up until recently, largely ignored the Spanish flu, it swept throughout the world and left fear, death and grief on an almost incomprehensible scale in its wake.
The Spanish flu was a global influenza pandemic that struck suddenly in 1918 but had faded away by 1920. This flu was caused by an influenza A virus strain of subtype H1N1. This strain was unusually severe and deadly, particularly among an unlikely group. Typically those who die from the flu are the very young, the very old or those with compromised immune systems. The victims of the Spanish flu were noteworthy not only because most were healthy young adults in the prime of their lives but also because of their sheer numbers.
The time from the appearance of the first symptoms until death was often frighteningly swift, a perfectly healthy individual could be struck down and dead within a day. Another notable aspect of the Spanish flu was that it occurred during the summer and autumn in many areas whereas most influenza outbreaks are normally limited to the winter months.
No one knows exactly how many people died of the Spanish flu, but estimates range from 20 million to a staggering 100 million worldwide over the two-year period from 1918 to 1920. An extremely high rate of infection of 50% combined with a mortality rate of 2% to 20% compared to the normal 0.1% mortality rate of the flu was responsible for the enormous number of deaths.
But why was the Spanish flu so deadly? The currently held theory is that this strain of the flu triggered what is known as a "cytokine storm." Cytokines are cellular messengers in the immune system. A cytokine storm occurs when the immune system overreacts to a pathogen and causes serious tissue and organ damage. Thus, those individuals with a healthy immune system are at more of a disadvantage when a pathogen triggers a cytokine storm.
One of the greatest fears among public health officials every flu season is that this year will be the year that an influenza virus similar to the Spanish flu will come onto the scene. Humankind has so far dodged the bullet, but some experts feel that the appearance of an influenza virus of the same virulence as that of the Spanish flu is only a matter of time.