10 Piores Epidemias do Mundo

10 Worst Epidemics of the World
An epidemic occurs when a disease affects disproportionately, a lot of people within a given population, such as a city or a geographic region. If it reaches even greater numbers and a wider area, these outbreaks become pandemics.

Before the explorers, conquistadors and European settlers began to fill the New World at the beginning of 1500, the Americas were home to about 100 million native speakers. During the centuries that followed, epidemic diseases have reduced that number to somewhere between 5 and 10 million [source: Yount]. Although these people, like the Incas and the Aztecs (in English), have built cities, they did not live long enough to propagate them the kind of diseases that Europeans had or had domesticated many animals. When Europeans came to the Americas, they took a lot of diseases for which the natives had no defense or immunity.

This painting represents the conquest of the Aztec capital Tenochtitlan by the Spanish explorer Hernando Cortez, on 13 August 1521. What ensured his victory was no modern firearms, but smallpox that the conquistadors led accidentally to the mainland.

Chief among these was smallpox disease caused by the variola virus. This virus began affecting humans for thousands of years, with the most common form of the disease was responsible for a mortality rate of 30% [source: CDC]. Smallpox causes high fever, body aches and a rash which soon pass from bumps and crusts filled with fluid to permanent scarring. The disease is spread primarily by direct contact with the skin or body fluids of an infected person, but can also spread through the air indoors.

Despite the creation of a vaccine in 1796, a smallpox epidemic continued to spread. In 1967, the virus has killed two million people and scared thousands more worldwide [source: Choo]. That same year, the World Health Organization led a campaign to eradicate the virus through mass vaccinations. As a result, 1977 marked the last case of smallpox occurred naturally. Effectively eliminated from the natural world, the disease exists only in laboratories.

1918 Flu
In 1918, the world watched the end of the First World War. Later that year, the estimated number of deaths reach 37 million worldwide and millions of soldiers trying to return home. Then, a new disease. Some called Spanish flu, other than the great flu or flu of 1918. Independent addition, the disease killed approximately 20 million people in a matter of months [source: Yount]. In one year, the flu would, but only after inflicting a staggering death toll. Global estimates range between 50 and 100 million fatalities [source: NPR]. Many consider this the worst epidemic (pandemic later) recorded in human history.

gripe espanhola
Nurses caring for victims of the Spanish flu epidemic of 1918 in canvas tents in Massachusetts

The 1918 flu virus was not caused by typical flu we see every year. It was a new strain of flu microbe, the virus of avian influenza A H1N1. Scientists suspect that the disease has been transmitted from birds to humans in the Midwest shortly before the outbreak. It was later dubbed the Spanish flu after an outbreak in Spain killed 8 million people [source: NPR].
Worldwide, the immune system of people was totally unprepared for the new virus - like the Aztecs did not expect the arrival of smallpox in the 1500s. The transport troops and supply lines at the end of World War I allowed the virus to quickly reach pandemic proportions, spreading to other continents and countries.

Resurrection of a killer
In 2005, researchers recreated the avian influenza A virus H1N1 from genetic material found in the lungs of victims of the 1918 flu. Scientists hope that by studying the deadly virus, they can better prepare for future outbreaks of new influenza viruses.
The 1918 flu symptoms typical of a normal flu, including fever, nausea, aches and diarrhea. In addition, patients often develop black spots on the cheeks. When his lungs filled with liquid, they ran the risk of death from lack of oxygen. Those who died were drowned in their own mucus.

The epidemic subsided in a year when the virus mutated into other less fatal. Most people today have some degree of immunity to this H1N1 virus family, inherited from those who survived the pandemic.

Black Death
Cartloads of corpses, dying isolated families, kings and peasants begging release - when it comes to epidemic diseases, few images are as terrible as the Black Death.

peste negra
This painting from 1656 is a doctor wearing mask and clothing proteçãoCarroças full of corpses, dying isolated families, kings and peasants begging release - when it comes to epidemic diseases, few images are as terrible as the Black Death.

Considered the first true pandemic disease, the plague killed half the population of Europe in 1348 and decimated parts of China and India. This "great dying" followed paths of trade and war, wiping out towns and forever changing the structure of classes, global politics, commerce and society.
For too long, the Black Death was an epidemic of plague, bubonic form traveling in the rat fleas, and the air in its pneumonic form. Recent studies have called this into question. Some scientists claim that the Black Death may have been a virus similar to Ebola hemorrhagic. This form of the disease results in heavy bleeding. Scientists are still studying genetic material from alleged victims of the plague in the hope of finding genetic evidence to confirm their theories.
Caused by the bacterium Yersinia pestis, the disease can still pose a problem in poor areas and infested by rats. Modern medicine allows for easy treatment of the disease in its early stages, making it a far less lethal threat. Symptoms include swollen lymph glands, fever, cough, bloody sputum and difficulty breathing.

Malaria is not new to the world of epidemic diseases. There are records of its impact on human populations of more than 4000 years ago, when Greek writers noted their destructive effects. The description of the mosquito-borne disease emerged in ancient medical texts from India and China. Until then, scientists have associated the disease with standing water where mosquitoes proliferate.

Malaria is caused by protozoa of the genus Plasmodium that are common to both species: humans and mosquitoes. When infected mosquitoes feed on human blood, they carry these protozoa. Once in the blood, they grow within red blood cells, destroying them. Symptoms range from mild to fatal, but usually include fever, chills, sweating, headache and muscle aches.

Organizers prepare the world's largest net for the African Summit on Roll Back Malaria (African Conference on the Reduction of Malaria) in 2000. The disease continues to kill, annually, more than one million people in sub-Saharan Africa.

There is a great difficulty in obtaining specific numbers related to the old malaria epidemics. You can better see the effects of the disease earlier if we analyze the major developments in malaria-infested regions. In 1906, the United States employed more than 26,000 workers to build the Panama Canal. Organizers hospitalized more than 21 thousand of them on account of the disease [source: CDC].
Only in the American Civil War, 1,316,000 men supposedly had the disease and 10,000 died. During the First World War, British forces pinned malaria, French and German for three years. Approximately 60,000 American soldiers died of the disease in Africa and the South Pacific during the Second World War [source: website of malaria].

At the end of World War II, the United States tried to prevent the epidemic of malaria. Earlier, the country has made good progress using the insecticide DDT (Dichloro-diphenyl-trichloroethane), now banned, and then took preventive measures to keep down the mosquito populations. After the CDC (Center for Disease Control) declararou that malaria had been eradicated in the United States, the World Health Organization began to eradicate it worldwide. However, the results were heterogeneous and costs, war, politics, and the emergence of mosquitoes resistant to insecticides and strains of drug-resistant malaria, finally led to the abandonment of the project.

Currently, malaria continues to pose a problem in much of the world, especially in sub-Saharan Africa, an area that was excluded from the WHO eradication campaign. Annually, between 350 and 500 million cases of malaria occur in the region [source: CDC]. Of these cases, over 1 million result in death. Even in the United States, occurring over a thousand cases and several deaths each year, despite earlier statements eradication.

Tuberculosis caused great impact on humanity and destroyed populations. Ancient texts detailing how victims of the disease were affected. There was even DNA evidence of disease in Egyptian mummies discovered.

Caused by the bacterium Mycobacterium tuberculosis, TB is spread from person to person through the air. The bacteria usually reaches the lungs, causing chest pain, weakness, weight loss, fever, night sweats and bouts of coughing up blood. In some cases, bacteria also affects the brain, the kidneys or the spine.
Mother and son expect attendance at a public hospital in the outskirts of Kolkata, India, where tuberculosis is a major public health problem

In the early 17th century, the TB epidemic in Europe, known as the great white plague, killed about one in every seven people infected. Tuberculosis was a common problem in colonial America. Even in the late 19th century, 10% of all deaths in the U.S. were attributed to tuberculosis [source: Department of Health and Public Services of Nebraska].

In 1944, doctors developed the antibiotic streptomycin used in fighting the disease. We made further progress in the following years and, after 5000 years of suffering, humanity finally had a cure for the ancient Greeks called phthisis, "a devastating disease."

Despite modern treatments and cures, tuberculosis continues to infect about 8 million people annually, killing consequently, about 2 million [source: Department of Health and Public Services of Nebraska]. The disease reappeared in force in the 90's due to a lack of prevention programs and treatment, global poverty and the emergence of new antibiotic-resistant strains. In addition, patients with HIV / AIDS are left with compromised immune systems, making them more susceptible to disease. As the AIDS virus is spread worldwide, tuberculosis also reappeared.

The people of India have always lived with the dangers of cholera, but only after the 19th century the rest of the world knew this disease. During this period, the merchant ships accidentally exporting the deadly bacteria to cities in China, Japan, North Africa, the Middle East and Europe. There followed six cholera pandemics that killed millions of people.
A father carries his son sick during the cholera outbreak in 1994. This outbreak took thousands of lives in Goma, Zaire, after a million people have fled the war in Rwanda.

Cholera is caused by a bacterium called intestinal Vibrio cholerae. The infections are usually mild. About 5% of people who contract the disease have vomiting, diarrhea and cramps strong legs - symptoms that quickly lead to severe dehydration and a drop in blood pressure. You can contract the bacteria through direct physical contact with infected person, but cholera is spread mainly by contaminated water and food.

Due to the cramped and squalid conditions of the main cities of Europe during the industrial revolution in the early 19th century, cholera spread again. The doctors were demanding better living conditions and more sanitary sewage systems, finding that the "bad air" was responsible for the epidemic. This measure helped a lot, but it was only after the disease has been linked to contaminated water that the number of cases has decreased considerably.

For decades, the anger was forgotten - seemed to be just a disease of the 17th century, defeated by improvements in sanitation and medicine. However, a new strain of cholera emerged in 1961, in Indonesia, having spread to much of the world. The resulting pandemic continues today. In 1991, cholera has weakened about 300 thousand people and killed 4000 [source: Yount].

The emergence of AIDS in the '80s led to a global pandemic, killing about 25 million people since 1981. According to recent statistics, 33.2 million people are HIV-positive and 2.1 million people died of AIDS in 2007 alone [source: Avert].

A banner against AIDS in the city of Gaborone, in Botswana, in October 1999. At the time, more than one in four adults in Botswana, were infected with HIV / AIDS.

AIDS (acquired immunodeficiency syndrome) is caused by HIV (human immunodeficiency virus). The virus is transmitted by contact with blood, semen and other body fluids, and affects the human immune system. With weakened immune systems opens up avenues for infection, called opportunistic infections, which otherwise would not represent a problem. The HIV infection becomes AIDS when the immune system is severely affected.

Scientists believe that HIV was transmitted to humans by certain species of monkeys and apes in the mid 20th century. During the 70s, the population of Africa grew and war, poverty and unemployment plagued urban areas. Prostitution and drug abuse injectable arrived to chaos, and HIV was being transmitted through sex without a condom and reuse of contaminated needles and syringes. Even in hospitals, the reuse of syringes and needles, and blood transfusions contributed to the epidemic.

There is still no cure for AIDS, although certain drugs can prevent HIV developing into the disease. Other medications can help fight opportunistic infections. Several organizations have promoted treatment campaigns, knowledge and prevention of AIDS. HIV is usually transmitted through sexual intercourse and the use of shared needles. The doctors are still recommending the use of condoms and needles.

Yellow fever
When Europeans began importing African slaves to the Americas, they also brought a number of new diseases such as yellow fever. The disease devastated the colonies, decimating farms and even large cities.

febre amarela
A resident of Aguas Lindas, in Goiás, Brazil is vaccinated against yellow fever during an epidemic in 2008

When the emperor of France, Napoleon Bonaparte sent an army of 33,000 men to land in French North America, yellow fever killed 29 thousand of them. Napoleon was so shocked by the amount of dead who decided that the territory was not worth the risk of further losses. France sold these lands to the United States in 1803 - an event known in history as the Louisiana Purchase [source: Yount].

Yellow fever, like malaria is transmitted from person to person by the bite of gnats. Symptoms include fever, chills, headache, muscle pain, back pain and vomiting. The severity of symptoms varies from mild to fatal and serious infections can lead to bleeding, shock and kidney and liver failure. Liver failure causes jaundice, ie the yellowing of the skin, which gives the disease its name.

Despite vaccination, treatment procedures and improved mosquito control epidemics of disease persist today in South America and Africa.

Epidemic typhus
Crowd a certain amount of people in poor hygiene conditions and you will probably need a lice infestation. Cities and miserable troops camped, throughout history, have endured threats of devastating parasites and bacteria. The tiny microbe Rickettsia prowazekii causes one of the most devastating infectious diseases that the world has ever seen: the epidemic typhus.

This photo from 1945 shows a British soldier spraying a prisoner recently released from filthy conditions in the concentration camp of Bergen-Belsen - necessary measure to combat the epidemic typhus.

The disease plagued humanity for centuries, causing thousands of deaths. Given their frequency among the troops encamped, was usually called "camp fever" or "war fever." During the Thirty Years' War [1618-1648], in Europe, typhus, plague and starvation claimed an estimated 10 million people. Sometimes, outbreaks of typhus determined the outcome of entire wars [source: Conlon].

When the Spanish forces laid siege to the Moorish stronghold of Granada, in 1489, an outbreak of typhus caused pass 25 thousand to 8 thousand soldiers in a single month [source: Conlon]. Due to the ravages of typhus, it would be another century before the Spanish could drive the Moors from Spain. As recently as World War I, the disease caused millions of deaths in Russia, Poland and Romania.

Symptoms of epidemic typhus typically include headache, loss of appetite, malaise, and a rapid increase in temperature, which soon turns into a fever, accompanied by chills and nausea. If untreated, the disease affects blood circulation, resulting in spots of gangrene, pneumonia and renal failure. A high fever can develop into a delirium, coma and heart failure.

Better methods of treatment and sanitary conditions greatly reduced the impact of epidemic typhus in modern times. The emergence of a vaccine against typhus during World War II and the widespread use of DDT on lice populations helped effectively eliminate the disease in the developed world. Outbreaks still occur in parts of South America, Africa and Asia.

The researchers suspect that polio was an epidemic in humans for millennia, paralyzing and killing thousands of children. By 1952, it is estimated that there were 58,000 cases of polio in the United States - one third of the patients were paralyzed. Of these, more than 3000 died.

A worker in 1956, the Glaxo Laboratories, mixing three distinct strains of poliovirus vaccine for preparing dead end.

The cause is polio poliovirus, which affects the nervous system of man. It spreads by fecal material, usually being transmitted through contaminated water and food. Initial symptoms are fever, fatigue, headache, vomiting, stiffness and pain in the limbs. With this, approximately 1 in 200 cases leads to paralysis [source: WHO]. Although it usually affects the legs, the disease sometimes affects the respiratory muscles usually with fatal results.

Poliomyelitis occurs most often in children, but also adults can achieve. It all depends on when the person finds the virus first and develops its first infection. The immune system is better prepared to fight the disease in children, so the older the person at primary infection, the greater the risk of paralysis and death.

Polio is a disease for the old man and circulates around the world for centuries. With increased exposure to the virus, immunity grew louder, especially in children. In the 18th century, improved methods of sanitation in many countries. This limited the spread of disease, natural immunity and decreased the chances of exposure in childhood. Consequently, an increasing number of older people contracted the virus and the number of cases of paralysis in developed nations has skyrocketed.

There is no effective cure for polio, but doctors have perfected a vaccine against the disease in the early 50s. Since then, cases in the United States and other developed countries have fallen dramatically, and only a few developing nations still have the disease at epidemic levels. Because humans are the only known carriers of the virus, the vaccination almost guarantees the extinction of polio. In 1988, the World Health Organization Initiative organized the Global Polio Eradication to achieve this goal.


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