We have all heard of bird and swine flu, however there are a number of subtypes of flu with even greater danger to human health. Usually the infection spreads in the cold season. Flu is dangerous for its complications and bacterial infection. Hundreds of thousands of people worldwide die from this disease.
The most dangerous type of flu is considered "Asian". He strikes the elderly and often leads to deaths.
Equally perilous is the "Hong Kong" flu. This is a mutation of the Asian virus. The epidemic in 1969-1969 years had claimed nearly one million lives. As "Asian" influenza, "Hong Kong" affects most frequently the elderly.
Avian influenza has its own characteristics. He quickly passed from birds to humans and causes severe complications in the struggle with which doctors are sometimes powerless. Pleases only one thing: person-to-person avian flu.