Despite several epidemics through the centuries and around the world, many recurrent and devastating, we’re still here. Of course we can’t let our guard down to the possibility of the advent for new plagues. Thanks to what we learned from these maladies, we are now more prepared and adapted than never. Not completely safe, though. Here are some of the most lethal infectious diseases known to man.

#5 Influenza

Also known as the Avian Flu, its pandemic was very intense, but also very fast. The most recent one involve the H1N1, or the swine flu, which killed hundreds of thousands of people between the years 2009 and 2010. It caused more than 50 million deaths worldwide, which is far more than Ebola, and there is an estimate between 200.000 and 500.000 of deaths every year.

For many, it is considered even greater than the Black Death. The symptoms are very similar to a normal flu, but can easily evolve to a severe nose, mouth and ear bleeding. The worst thing happens when there is too much fluid in the lungs, leading to death. Despite its low mortality rate, it is important to stay aware of the flu seasons and the possibilities of new pandemics.

[Wikipedia] [LiveScience] [Popular Science]

#4 Measles

Also known as Rubeola, Measles is identified by its characteristics red rashes on the skin. Other common symptoms involve sore throat, fever and runny nose, but it becomes truly serious and devastating when it leads to brain infection. Since its first occurrences in the 19th century, it is estimated that this disease caused the death of about 200 million people around the globe.

Since it is so contagious, it is really easy to spread on dense urban areas and a reason for great concern. Although much less common nowadays, some eventual outbreaks still happen in a few countries. It is transmitted by a close contact with infected people, usually through coughing and sneezing. Thanks to the vaccine developed in the 60s, occurrences have drastically declined over the years.

[LiveScience] [Wikipedia] [WebMD]

#3 Ebola

This one got a lot of attention of the media not long ago, but it emerged in 1976 in Sudan and Zaire outbreaks. They still occur in Africa, particularly in Guinea and Sierra Leone. Recently there have been a few isolated cases in the US, thankfully under proper treatment and control. It causes a very high fever, followed by extreme internal and external bleeding. Other symptoms are also very similar to a simple flu, including fever, headaches and muscle pain. On a more severe state, diarrhea and vomiting may happen, followed by an extreme fatigue.

The infection occurs by contact through blood and body fluids mostly, and it can be diagnose with blood and tissues tests. Those who present the symptoms must be isolated immediately and lead to a proper hospital care, so further treatment and evaluation could take place. The mortality rate is very high and those who survive take months to fully recover, but the chances of survival have improved just recently, thanks to novel researches and experimental treatments. Its name came from the Ebola river, where the disease first appeared.

[NHS Choices] [Everyday Health] [Healthline] [Wikipedia]

#2 Smallpox

This disease, also known as Variola, caused the death of millions of Europeans during the 18th century. From them, it would spread through the Americas, reaching the native population and killing more than 300 million by the 20th century, including some of the Aztec population. This malady inflicts only humans, and characterizes for the skin lesions and bumps it causes, along with intense and lasting fever and hemorrhaging, eventually leading to death.

The mortality rate can be as high as 30% on its deadliest form. After recovery, some effects and complications could remain indefinitely. Fortunately, the development of a vaccine along with prevention programs helped mitigate most of the cases, and it was considered officially eradicated in 1980. The last registered case was from Somalia in 1977.

[Wikipedia] [Oddee] [BBC]

#1 Rabies

Rabies is transmitted to humans through bitten of infected animals, mostly bats and dogs. It is extremely important to seek help after such incidents, since a simple and preventive vaccine may eventually save your life. The symptoms manifest themselves a few months after the infection, which range from anxiety and agitation to the most well known salivation and hydrophobia. What makes it truly lethal is the serious and irreversible affliction in the nervous system.

This disease may not have killed millions like those previously mentioned, but it is definitely the most lethal, which makes it no less deadly. Thanks to health treatment and public prevention campaigns, incidences have shown a remarkable declined over the years. There are still many occurrences, particularly in Africa and Asia, causing the death of thousands of people every year.

[Nature World News] [Wikipedia] [NPR] [The Telegraph]

What is most important is to be more attentive and don’t use the media as a single source of information. Many references, especially the medical ones, can give you a better idea of many aspects for such plagues, like causes, prevention, contagion and the true chances and consequences of a pandemic. Not only you will learn more about the subject, but also become well aware that there is no reason for panic or emotional distress, like the Ebola case in USA seemed to be.

photo credit: Ebola virus via flickr