Influenza

Influenza

The word influenza comes from the medieval Italian meaning influence, and is a reminder that some doctors believed it was caused by the unfavourable influence of the planets. The flu is, in fact, a viral disease, which means that it can mutate. Therefore a flu vaccine is only effective for a few years at the most.

The most serious pandemic was the Spanish Flu of 1918–20. Beginning just as World War I was ending, this deadly flu virus claimed 50 to 100 million lives (between 3 and 5 per cent of the world's population), making it one of the deadliest diseases in human history. Unusually it was also most dangerous for 20 to 40 year-olds.

In most years a strain of influenza spreads across the globe, resulting in about 250,000 to 500,000 deaths worldwide.

Viral diseases remain a challenge…