7.Catchy Coughs
They cause outbreaks, epidemics, even pandemics that spread from continent to continent. Modern medicine and hygiene have given us some control over devastating infectious diseases, even eradicating smallpox, but, for the most part they remain with us, often preying upon the poorest and most vulnerable.
6.Smallpox
A photo taken in 1975 shows the village cemetery in the Bangladesh countryside where smallpox victims were buried. The disease was believed to have killed 46 percent of its victims at a hospital in the Dacca, Bangladesh and to have ravaged the country for centuries. A disease marked by lesions on the skin, smallpox is believed to have emerged about 3,000 years ago in India or Egypt before sweeping across continents. The variola virus, which causes smallpox, killed as many as third of those it infected and left others scarred and blinded, according to the World Health Organization. In 1980, the WHO declared the disease officially eradicated, after a decade-long vaccination campaign. The last known remaining samples of the virus are being held in facilities in the U.S. and Russia.
5.Plague
Unlike smallpox, this ancient killer is still with us. Plague, which is caused by a bacterium carried by fleas — like the one shown above — has been blamed for decimating societies including 14th century Europe during the Black Death, when it wiped out roughly a third of the population. The disease comes in three forms, but the best known isbubonic plague, which is marked by buboes, or painfully swollen lymph nodes. Plague is now found in animals throughout the world, particularly in the western U.S. and Africa. In 2009, the World Health Organization reported 958 cases worldwide.
4.Malaria
Although it is preventable and curable, malaria has a devastating effect in Africa, where the disease accounts for 20 percent of all childhood deaths, according to the World Health Organization. It is present on other continents as well. A parasite carried by blood-sucking mosquitoes causes the disease, which is first characterized by fever, chills and flu-like symptoms before progressing on to more serious complications. By 1951, the disease was eliminated from the U.S. with the help of the pesticide DDT. A subsequent WHO campaign to eradicate malaria was successful only in some places, and the goal was downgraded to reducing transmission of disease, according to the U.S. Centers for Disease Control and Prevention.
3.Influenza