10. Bubonic Plague
Bubonic plague or also known as Black Death which is mainly a disease in rodents and fleas (Xenopsylla cheopsis) which killed 30-60% of Europe Population and estimated to have killed 75-200 millions of People at 1348-1350. Infection in a human occurs when a person is bitten by a flea that has been infected by biting a rodent that itself has been infected by the bite of a flea carrying the disease. The bacteria multiply inside the flea, sticking together to form a plug that blocks its stomach and causes it to begin to starve. The flea then voraciously bites a host and continues to feed, even though it can not quell its hunger, and consequently the flea vomits blood tainted with the bacteria back into the bite wound. The bubonic plague bacterium then infects a new victim, and the flea eventually dies from starvation. Any serious outbreak of plague is usually started by other disease outbreaks in rodents, or a rise in the rodent population.It is caused by a bacterium called Yersinia pestis which is today successfully treated with antibiotics. Bubonic plague is extremely rare but occasional outbreaks still occur.
9. Polio
Poliomyelitis, often called polio or infantile paralysis, is an acute viral infectious disease spread from person to person, primarily via the fecal-oral route. Although roughly 90% of polio infections are asymptomatic, affected individuals can exhibit a range of symptoms if the virus enters the blood stream. In less than 1% of polio cases the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis. It is said to have killed 10 thousands people since 1916.
8.Smallpox
Smallpox (also known by the Latin names Variola or Variola vera) is a contagious disease unique to humans. Smallpox is caused by either of two virus variants named Variola major and Variola minor. The deadlier form, V. major, has a mortality rate of 30–35%, while V. minor causes a milder form of disease called alastrim and kills ~1% of its victims. Long-term side-effects for survivors include the characteristic skin scars. Occasional side effects include blindness due to corneal ulcerations and infertility in male survivors. Smallpox killed an estimated 60 million Europeans, including five reigning European monarchs, in the 18th century alone. Up to 30% of those infected, including 80% of the children under 5 years of age, died from the disease, and one third of the survivors became blind. To this day, smallpox is the only human infectious disease to have been completely eradicated from nature.
7. Spanish Flu
The deadliest flu pandemic in recorded history that spread throughout the world at the end of World War I in 1918 and estimated to have infected about 50-100 millions of people.The Spanish flu pandemic lasted from 1918 to 1919, spreading even to the Arctic and remote Pacific islands.the first symptoms of spanish flu are extreme fatigue, fever, headache, victims would start turning blue. Sometimes the blue colour become so pronounced that it was difficult to determine a patients original skin colour. some patients would cough with such force that some even tore their abdomen's muscle. Foamy blood comes out from their nose and mouth, a few bled from their ears or even vomiting. Spanish flu comes so suddenly and severely that many of the victims died within of hours of coming down of their first symptom. Some died a day or two after realizing they were sick. Spanish flu completely opposed the mortality rate of normal flu epidemic which has a mortality rate of 0,1% while spanish flu has a mortality rate of nearly 100%.
6. Cholera
Cholera (or Asiatic cholera or epidemic cholera) is an extreme diarrheal disease caused by the bacterium Vibrio cholerae. Transmission to humans is by ingesting contaminated water or food. The major reservoir for cholera was long assumed to be humans, but some evidence suggests that it is the aquatic environment. In its most severe forms, cholera is one of the most rapidly fatal illnesses known—a healthy person may become hypotensive within an hour of the onset of symptoms and may die within 2-3 hours if no treatment is provided. More commonly, the disease progresses from the first liquid stool to shock in 4-12 hours, with death following in 18 hours to several days without rehydration treatment. It is said to have killed 12 thousands of people since 1991.
5. Ebola virus
The Ebola virus first emerged in 1976 in simultaneous outbreaks in Sudan and Zaire. It is known to be a zoonotic virus as it is currently devastating the populations of lowland gorillas in Central Africa. Despite considerable effort by the World Health Organization, no animal reservoir capable of sustaining the virus between outbreaks has been identified. However, it has been hypothesized that the most likely candidate is the fruit bat. Ebola hemorrhagic fever is potentially lethal and encompasses a range of symptoms including fever, vomiting, diarrhea, generalized pain or malaise, and sometimes internal and external bleeding. Mortality rates are generally very high, in the region of 80% – 90%, with the cause of death usually due to hypovolemic shock or organ failure.
4. Malaria
Malaria is a vector-borne infectious disease caused by protozoan parasites. It is widespread in tropical and subtropical regions, including parts of the Americas, Asia, and Africa. Each year, it causes disease in approximately 515 million people and kills between one and three million, most of them young children in Sub-Saharan Africa. Malaria is commonly associated with poverty, but is also a cause of poverty and a major hindrance to economic development. Malaria is one of the most common infectious diseases and an enormous public-health problem. The disease is caused by protozoan parasites of the genus Plasmodium. The most serious forms of the disease are caused by Plasmodium falciparum and Plasmodium vivax, but other related species can also infect humans.
3. Influenza
Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses). In humans, common symptoms of influenza infection are fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort. In more serious cases, influenza causes pneumonia, which can be fatal, particularly in young children and the elderly. Sometimes confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus. Although nausea and vomiting can be produced, especially in children, these symptoms are more characteristic of the unrelated gastroenteritis, which is sometimes called “stomach flu” or “24-hour flu.” Typically, influenza is transmitted from infected mammals through the air by coughs or sneezes, creating aerosols containing the virus, and from infected birds through their droppings. Influenza can also be transmitted by saliva, nasal secretions, feces and blood. Infections also occur through contact with these body fluids or with contaminated surfaces. Influenza is estimated to have killed 36 thousands people per year.
2. HIV/AIDS
Acquired immunodeficiency virus or AIDS is a collection of symptoms and infections resulting from the specific damage to the immune system caused by the human immunodeficiency virus (HIV) in humans, and similar viruses in other species (SIV, FIV, etc.). The late stage of the condition leaves individuals susceptible to opportunistic infections and tumors. Although treatments for AIDS and HIV exist to decelerate the virus’ progression, there is currently no known cure. HIV are transmitted through direct contact from body fluid such as blood that contains HIV. this transmission can come from blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding.Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century; it is now a pandemic, with an estimated 38.6 million people now living with the disease worldwide.It is said that HIV has killed more than 25 millions people since 1981.
1. Cancer
The disease which meets all the criteria of pandemic except that it is not contagious is currently the most deadly disease in the world. According to the WHO, as many as 7.6 million people died from cancer worldwide in 2008. It can often be cured if discovered and treated early but unfortunately, many types of cancer do not cause any signs or symptoms until the disease has progressed. According to some experts, every third person will develop cancer at some point of life.
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