Top 10 Deadliest Outbreaks

Top 10 Deadliest Outbreaks

10. The Smallpox Epidemic of the 1500s

During the 1500s, conquerors and colonists invaded the Americas, making it the home of almost 100 million people. The natives, such as the Incas and Aztecs, did not have immune systems that were able to defeat new diseases. These new diseases reduced the population to between 5 and 10 million.

Smallpox was caused by the variola virus. The disease caused fevers, body aches and a rash that turns from fluid-filled bumps and scabs into permanent, deep scars. The disease spread through direct contact with infected people's skin or bodily fluids, but could also be contracted through the air in small, confined spaces.

Even though the smallpox epidemic during the 1500s was not intentional, there have been instances where the spread of the disease has been a conscious effort to wipe out a population. In 1763, during the French and Indian War, British Commander Sir Jeffrey Amherst instructed the infection of the Ottawa tribes by sending infected blankets to the people.

Since smallpox has been removed from the population throughout the world due to a vaccine, concerns have emerged that the disease could be used as a terrorist attack when exposed to the unvaccinated public.

9. The Polio Outbreak of 1952

Polio is the result of the poliovirus poliomyelitis which targets the human nervous system, and researchers believe this disease has plagued human populations back to ancient times. In 1952, there were 58,000 cases in the United States which resulted in 1/3 of the patients becoming paralyzed.

The disease spreads through fecal matter, traveling through contaminated food and water. Symptoms include fever, fatigue, headache, vomiting, stiffness and limb pain and approximately one in every 200 cases leads to paralysis.

The disease mostly affects children but can affect adults as well and severity depends on if the person has encountered the disease before. Children's immune systems are more prepared to fight off the virus, so if an adult encounters the disease for the first time they have a greater risk of paralysis and death.

Even though there is no real cure for polio, doctors in the 1950s created a polio vaccine. As a result, cases in the Unites States and other developed countries decreased substantially. Humans are the only known carriers of polio, so the widespread use of the vaccine can lead to complete extinction of the disease.

8. Typhus Outbreaks

Ricksettsia prowazekii, a tiny microbe, is responsible for typhus, one of the most deadly diseases in the world's history. Outbreaks are the result of crowds of people trapped in dirty conditions, often during wartime. Hence, the disease has been called "camp fever" or "war fever."

When Spanish troops entered Grenada in 1489, typhus decreased the forces from 25,000 to 8,000 in one month. During Europe's Thirty Years War (1618-1648), the disease killed approximately 10 million people. Even during World War I (1914-1919), typhus outbreaks killed millions of people in Russia, Poland and Romania.

Typical symptoms for the disease include headache, loss of appetite and a fast rise in temperature. Fever, chills and nausea normally follow. If typhus continues untreated, however, it can lead to illnesses affecting blood circulation, gangrene, pneumonia and even kidney failure.

Modern science and technology have improved the potential for typhus outbreaks. The typhus vaccine implemented during World War II in addition to the use of DDT on lice populations has also helped. However, outbreaks still occur in parts of the world such as Africa, Asia and South America.

7. The Great White Plague

Cases of tuberculosis can be traced by to ancient Egypt, where DNA evidence proves its presence in Egyptian mummies. During the 1600s, the disease plagued the population of Europe for over 200 years. Known as the Great White Plague, it killed roughly one out of every seven people it infected.

Tuberculosis continued to be a problem in colonial America and during the late 19th century, with estimates that 10 percent of all deaths in the United States were the result of the disease. In 1944, however, doctors came up with a preventative aid, known as antibiotic streptomycin and more improvements were made in later years.

Even with these new treatments, tuberculosis still continues to infect an estimated 8 million people and kill 2 million per year. During the 1990s, the disease made a comeback due to drops in treatment programs, increase global poverty and the introduction of new, anti-biotic resistant strains of the disease.

6. The First Cholera Pandemic

India's population has endured cholera's wrath since ancient times, but it wasn't until the 19th century when it became global after traders unintentionally carried the disease back to China, Japan, North Africa, Europe and the Middle East. Since then, six outbreaks have occurred resulting in millions of deaths.

Cholera is caused by the intestinal bacteria, Vibrio cholerae. Infections are relatively mild (only a small percentage of those infected suffer from severe vomiting and leg cramps, leading to dehydration and shock) but only those immune systems who stay hydrated long enough can easily defeat the disease.

The first cholera pandemic struck the European cities during the industrial revolution of the 1800s. As a result, doctors called for cleaner and more sanitary living conditions, believing that "bad air" was the root of the disease. Even though this helped, the connection was finally made to bad drinking water.

After the 1800s, people believed cholera was in the past. However, new outbreaks occurred in 1961 in Indonesia and 1991 and pandemics continue to this day.

5. The Plague of Justinian

The Emperor Justinian spread his empire during the 6th century around the rim of the Mediterranean and throughout Europe, hoping to create a long-lived dynasty. However, his dreams came to a sudden halt when disease-infected mice from lower Egypt reached the harbor town of Pelusium in 540 A.D. During this time, the disease spread to Alexandria and Constantinople, Justinian's capital, and eventually ravaged the population of his empire.

By the time the disease ended in 590 A.D., more than 100 million lives were lost, bringing trade to a stand-still and arguably bringing on the Dark Ages.

Modern-day efforts have been made to study DNA and answer some of the questions about the Plague of Justinian. Since only minimal research has been conducted on the plague, scientists and historians believe that further exploration will contribute by shedding light on other types of disasters, both man-made and natural.

4. Malaria Outbreaks

Malaria has been around for over 4,000 years, dating back to the Greek writers and ancient Indian and Chinese medical texts. Scientists back then recognized the connection between mosquitoes and the waters where they breed.

Malaria is caused by four different species of Plasmodium microbes common to two species: mosquitoes and humans. The disease is passed to humans when an infected mosquito feeds on human blood and the microbes grow inside the red blood cells, destroying them along the way.

Typical symptoms (which can vary in intensity) include fever, chills, sweating, headache and muscle pains. One major outbreak occurred in 1906 while the United States employed over 26,000 workers to help build the Panama Canal. During this time, more than 21,000 of these workers were hospitalized for malaria.

Wars are also a breeding ground for malaria outbreaks; 1,316,000 men reportedly suffered from the disease during the American Civil War, and 10,000 died. After other outbreaks during World War I and II, efforts were made to curb the epidemic. Today, malaria still poses a threat to human populations in sub-Saharan Africa, infecting between 250 and 500 million lives and resulting in more than 1 million deaths each year.

3. The Black Death

Between Hollywood movies and countless history textbooks, the Black Death is one of the most well-known outbreaks in history. It is considered the first true pandemic disease, and completely obliterated Europe's population (by half, to be exact) in 1348 in addition to parts of China and India.

The Black Death traveled from its bubonic form on fleas and rats and through the air into its pneumonic form. The massive population decrease caused tremendous effects in Europe, destroying whole cities and altering trade, society, class structure and global politics.

Symptoms of the Black Death were normally terrible and appeared extremely fast. Victims experienced painful swelling on the lymph nodes which would appear on the armpits, legs, neck and groin. These swellings would turn from red eventually into a dark purple or black color. Other symptoms included a high fever, delirium, bleeding in the lungs, and vomiting, and victims usually died after two to four days of being infected.

2. The Spanish Flu of 1918

As World War I came to a close in 1918 (with an estimated death toll of 37 million worldwide), a new strain of flu ravaged the human population. Called the Spanish Flu, the Great Influenza and the Flu of 1918, it killed as many as 20 million people in a matter of months. Within one year, the flu ran its course but left a startling death toll.

This new strain of flu microbe, known as the H1N1 avian influenza A virus, was suspected of moving from birds to humans in the U.S. Midwest right before its outbreak. It got its name, the Spanish Flu after an epidemic killed 8 million people in Spain.

The virus was so deadly because people's immune systems simply weren't prepared for the new strain. Patients carried the same symptoms of the normal flu: fever, nausea, aches and diarrhea. The large troop transports in addition to close quarters in military barracks at the end of World War 1 exacerbated the outbreak and helped it reach pandemic proportions.

Back in 2005, research scientists rebuilt the H1N1 avian influenza A virus with material gathered from the lungs of the 1918 victims in order to better prepare for future outbreaks.

1: AIDS

In 1981, the world witnessed the emergence of AIDS. Since the breakout of this global pandemic, it is estimated to have killed more than 25 million people. Currently, there are 33.2 million people that are HIV-positive and 2.1 million people died in 2007 alone.

AIDS, an acquired immune deficiency system, is caused by HIV, the human immunodeficiency virus. The virus is able to spread through contact with blood, semen and various other bodily fluids and damages the human immune system. After the virus damages the immune system, the body is susceptible to infections, called opportunistic infections, which in other situations would not be dangerous.

So how did HIV become a human pandemic? Scientists believe that the virus was transferred from a certain species of monkey and ape to humans in the mid-20th century. As Africa's population grew in the 1970s, during a time of intense war and poverty, the virus spread via unprotected sex and contaminated needles.

Unfortunately, there is currently no cure for AIDS. Numerous drugs have developed which can keep HIV from developing in AIDS, along with additional medications to help fight opportunistic infections. Because there is no cure, the battle to help prevent AIDS from spreading has become a worldwide issue. Education about prevention includes not sharing needles and using one of the various modes of protection during intercourse.

(Author Deepak Kumar)