According to scientists, the world population will reach 11 billion by the year 2100 and one of the consequences of this would be the complexity of the control epidemics.
Population growth also accelerates the growth of emerging infectious disease caused by the emergence of new drug-resistant bacteria and viruses - this trend we have seen for the past several decades. Scientists are closely watching the new viruses that can cause the next pandemic, and try to find new drugs against pathogens, which have long been known to mankind, but have developed resistance to existing antibiotics.
Here are five such diseases, which caused the worst pandemic of the last century, and which never leave the field of view of modern scholars:
Flu
From severe 1918 pandemic that killed between 50 and 100 million people, to the swine flu in 2009, took several thousand different strains of influenza viruses have caused some of the most terrible epidemics of the past century. This group of pathogens is under constant control of most of its incredible pandemic alert.
During seasonal epidemics, the virus infects up to 15 percent of the population, which influences. Annual epidemics result in around 3 to 5 million cases of severe illness and between 250 and 500 thousand deaths every year around the earth, according to World Health Organization.
This ever-changing virus has undergone some serious mutations in the past century and repeatedly re-infected humanity through pets. Significant outbreaks included the Asian flu of 1957 and the Hong Kong Flu of 1968, each of which has led to several million deaths.
SARS (SARS)
SARS is caused by SARS corona virus. It first appeared in China in 2002, and through the airport in a matter of weeks has spread to 37 countries. The virus has infected about 8,000 people across the globe, 800 of whom died.
The majority of patients infected with SARS corona virus, develop pneumonia. The virus is spread by close contact between people, especially rapidly - while sneezing and coughing. The disease can also be obtained by touching surfaces or objects contaminated with infected saliva droplets.
Scientists were able to trace the SARS virus to bats. It is assumed that this virus could find its way into the human population through livestock markets in China.
AIDS
Since its introduction in the 1980s, AIDS has infected 60 million people and claimed the lives of about 30 million.
Scientists believe that the AIDS virus is spread to the mankind from chimpanzees somewhere in the middle of the 20th century. Hacking and virus destroys the immune system, leading to a condition known as Acquired Immunodeficiency Syndrome. Without proper functioning of the immune system, people with AIDS can easily become a victim of other diseases - often fatal.
The virus is transmitted through blood, semen and other bodily fluids. Most infections occur through sex with infected people or sharing needles for injecting drugs.
Across the globe in 2011 recorded 2.5 million new cases of AIDS. To date, this diagnosis is approximately 34.2 million people.
Malaria
Although the disease is close to humanity, probably since the days of antiquity, it continues to pose a global threat to this day. From it there is no vaccine, and according to the WHO, in many parts of the world causing its parasites have developed resistance to many antimalarial drugs.
In 2010, approximately 219 million people worldwide have been infected with malaria, and 660,000 of them died. The disease is widespread in tropical regions - Africa, Asia and the Americas, although about 90 percent of disease falls on Africa.
Plasmodium - the parasite that causes malaria - gets into a person's blood through a mosquito bite, and paves the way to the liver, which multiplies unnoticed for days. At some point the parasites lurking in the membranes of liver cells, leave them and go into the bloodstream, affecting the red blood cells and disrupting the blood supply to the internal organs.
Tuberculosis
Tuberculosis (TB) was traced to 17 thousand years ago, but it is not under full kontrolёm to this day. Caused by the bacterium Mycobacterium tuberculosis, TB - this is the second greatest killer in the world, second only palm AIDS.
Over the past two decades, mortality from TB fell by almost half. In 2012, 8.6 million people became ill with TB and 1.3 million died. More than 95 percent of deaths from the disease occur in low-and middle-wealth.
Although TB is curable and its problematic forms that are resistant to the most effective and affordable medicines, according to the WHO, there are in almost all countries.
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