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Five of the world's deadliest diseases !?

·        Smallpox

Before being eradicated in the 20th century, smallpox was one of the deadliest diseases in human history.

The last known natural case was in Somalia in 1977, according to WHO.

The only known cases since then were caused by an accident in a Birmingham laboratory in 1978, which killed one person and created a limited outbreak.

WHO has a small stockpile of smallpox vaccine, as do other countries and organisations, but there has been concern in recent years that terrorists could get hold of the virus to use as a biological weapon.

·        Influenza

Seasonal influenza is thought by WHO to have annual global attack rate estimated at 5%-10% in adults and 20%-30% in children.

This means an there are an estimated three to five million cases of severe illness, and about 250,000 to 500,000 deaths each year.

The most notorious outbreak in modern history was the Spanish Flu epidemic of 1918, which is said to have killed more people than World War One - about a third of the world's population, or 500m people were infected and estimates suggest 50m died.

A strain of avian influenza or bird flu has been spreading mainly through Asia since 2003, with 650 deaths confirmed by WHO.

·        Plague

During the 14th and 17th centuries the Black Death ravaged Europe and Asia.

Infection was spread from large numbers of rats to man through bites from fleas, causing deadly bubonic plague and a highly contagious strain of pneumonia.

In 2010, 17 people were found to have plague in Peru - four were pneumonic plague, 12 were bubonic plague and one was septicemic plague.

Other outbreaks of plague, which can have symptoms including a cough, swollen lymph glands and high fever, have occurred in China, Algeria and the Democratic Republic of Congo in recent years.

·        Sars

In 2003 doctors from WHO became aware of the virus Sars, or severe acute respiratory syndrome.

The virus, first spotted in China, went on to infect more than 8,000 people and kill more than 750.

Sars causes sufferers to run a fever, have flu-like symptoms and have difficulty breathing. There is currently no known cure or vaccine.

·        Malaria

Everyone despises being eaten alive by pesky mosquitoes in the summer, but you would be surprised how many of those annoying bugs could actually lead to our demise! Malaria is caused by a parasite that is transmitted from one human to another through the bite of an infected mosquito. In humans, the parasites travel to the liver, where they mature. Once matured, they release another parasite that then enters the bloodstream and infects the red blood cells. The parasites multiply at a rapid speed, but symptoms could take up to one year to show. The disease is a major health problem in much of the tropics and subtropics. It is estimated that there are 300-500 million cases of malaria each year, and more than 1 million people die from the disease. It presents a major health hazard for travelers to warm climates — something definitely to be weary of when planning that once-in-a-lifetime trip to the rain forest.

Reference: 

http://www.bbc.co.uk/