LISTS OF DEADLIEST VIRUSES

Deadliest and scariest viruses

According to Microbe World

Nature sure has created some tiny monsters when it comes to microbes—bugs that make us throw up, ooze pus, bleed out of our eyes and cough up blood. But which take top honors (or dishonors) for being the most lethal of all?

HIV/AIDS, the Global Tragedy

The Human Immunodeficiency Virus or HIV causes the disease we know as AIDS. AIDS is a pandemic—a disease outbreak that is happening all over the world. In 2000 alone, 3,000,000 people died of AIDS. Since the AIDS pandemic began around 1985, almost 22,000,000 people have died from the disease. Right now, HIV infects more than 36,000,000 people across the world, so that death toll will definitely get a lot bigger over the next several years.

HIV doesn’t kill people itself. Instead, the virus shuts down a person’s immune defenses—the tools used to fight off invading germs—by infecting and destroying important immune cells called T cells. Once a person loses too many T cells, his or her body can no longer deal with other microbes that cause infections. HIV merely opens the floodgates. Eventually HIV-infected people become overrun by germs and die of lung infections, skin infections or other diseases.

We now have several drugs that fight HIV. They cannot cure the infection, but they can keep it in check. Unfortunately, victims of HIV have to take several of these drugs every day for life and the drugs are very expensive. In Africa and other developing parts of the world where HIV is spreading most rapidly, most people don’t have enough money to buy these drugs. That’s why we can expect the death toll from HIV/AIDS to get a lot bigger over the next several years.

The Flu Virus—Even Deadlier than HIV?

Oh come on now, I’m sure you’re saying. The flu virus here in a list of the most lethal microbes?

Sure, every year during what’s called "the flu season" tens of thousands of people get the flu. Despite feeling all achy and lousy for several days, most people eventually beat the virus and recover just fine.

But that’s not how it went during the 1918 flu season. That year, World War I was raging so the effects of the flu virus sort of got overshadowed by the bigger, more obvious effects of bullets and bombs.

However, in 1918 the flu virus killed at least 675,000 American people. Worldwide, it killed at least 21,000,000 people. These are low estimates. Some research now suggests that the flu may have killed 40,000,000 to 50,000,000 people around the world that year.

Researchers still aren’t sure why the 1918 flu virus was so deadly. Victims of the flu that year died in a gruesome way, the virus causing so much fluid to build up in their lungs so rapidly that it was like drowning.

If higher estimates of how many people died from the 1918 flu are true, then the 1918 flu is the deadliest microbe ever in a single year. Thank goodness we haven’t seen a flu bug that deadly again—but will we someday?

The Plague

The 1918 flu virus and HIV are the biggest killers of modern times. But back in the 14th century, the bacterium that causes bubonic plague, or the Black Death as it was also known, was the baddest bug of all.

In just a few years, from 1347 to 1351, the plague killed off about 75,000,000 people worldwide, including one-third of the entire population of Europe at that time. It spread through Asia, Italy, North Africa, Spain, Normandy, Switzerland, and eastward into Hungary. After a brief break, it crossed into England, Scotland, and then to Norway, Sweden, Denmark, Iceland and Greenland.

The plague bacterium is called Yersinia <yer-sin-ee-uh> pestis. There are two main forms of the disease. In the bubonic <boo-bah-nick> form, the bacteria cause painful swellings as large as an orange to form in the armpits, neck and groin. These swellings, or buboes, often burst open, oozing blood and pus. Blood vessels leak blood that puddles under the skin, giving the skin a blackened look. That’s why the disease became known as the Black Death. At least half of its victims die within a week. The pneumonic <new-mon-ick> form of plague causes victims to sweat heavily and cough up blood that starts filling their lungs. Almost no one survived it during the plague years.

Yersinia pestis is the deadliest microbe we’ve ever known, although HIV might catch up to it. Yersinia pestis is still around in the world. Fortunately, with bacteria-killing antibiotics and measures to control the pests—rats and mice—that spread the bacteria, we’ve managed to conquer this killer.

Ebola, the Bloody Virus

Some of you at the beginning of this page might have thought of the Ebola virus as the scariest, deadliest microbe you’ve ever heard of. Those of you who did so have probably seen the movie Outbreak or read The Hot Zone, which spotlighted this grisly virus.

Ebola is definitely a nasty killer. It is part of a group of viruses that, among other effects on the body, cause the blood to stop clotting. Victims begin oozing blood from their mouths, noses, internal organs, even their eyes. It kills up to almost 90% of those who get infected.

With that kind of death rate, Ebola would be the deadliest microbe of all if it was more common. Fortunately, infections by this virus are pretty rare. There have only been seven outbreaks in humans. It has killed just over 800 people since the first outbreak in the Democratic Republic of the Congo (formerly called Zaire) in 1976.

While outbreaks of this virus are rare and relatively small, Ebola is still one mean microbe that I wouldn’t ever want to tangle with. If you want to meet someone who has tackled Ebola, visit the interview with Dr. Ali Kahn in the Careers section

http://archives.microbeworld.org/know/deadliest.aspx

8 Historically Terrifying Viruses

– by Jessica Bloustein Marshall 5/16/13

It seems like a new virus that's trying to kill us pops up somewhere in the world every other day. The World Health Organization recently announced that it is monitoring a new contagious,respiratory-infection-inducing coronavirus (suggested codename: Middle East respiratory syndrome coronavirus or MERS-Cov) that is responsible for dozens of illnesses and several deaths in the Middle East and Europe in the last few months.

While a handful of deaths does not a pandemic make, there is much to fear from tiny imperialistic pathogens—invisible to all but the most powerful microscopes—that invade our cells to replicate, messing them up like a coke-fueled rock band destroys a hotel room after a concert.

All the hand-sanitizer in the world can’t save us from some of history’s nastiest viruses and the horrifying diseases they cause in humans—and we know you’re just itching to know all about them. Here are eight of the deadliest viruses the world has ever seen.

1. EBOLA

Its melodic moniker may roll off the tongue, but if you contract the virus (below), that's not the only thing that will roll off one of your body parts (a disturbing amount of blood coming out of your eyes, for instance). Four of the five known Ebola viral strains cause Ebola hemorrhagic fever (EHF), which has killed thousands of people in sub-Saharan African nations since its discovery in 1976.

The deadly virus is named after the Ebola River in the Democratic Republic of the Congo where it was first reported, and is classified as a CDC Biosafety Level 4, a.k.a. BSL-4, making it one of the most dangerous pathogens on the planet. It is thought to spread through close contact with bodily secretions. EHF has a 50 to 90 percent mortality rate, with a rapid onset of symptoms that start with a headache and sore throat and progress to major internal and external bleeding and multiple organ failure. There’s no known cure, and the most recent cases were reported at the end of 2012 in Uganda.

2. MARBURG

In 1967, a group of lab workers in Germany (Marburg and Frankfurt) and Serbia (then Yugoslavia) contracted a new type of hemorrhagic fever from some virus-carrying African green monkeys that had been imported for research and development of polio vaccines. TheMarburg virus is also BSL-4, and Marburg hemorrhagic fever has a 23 to 90 percent fatality rate. Spread through close human-to-human contact, symptoms start with a headache, fever, and a rash on the trunk, and progress to multiple organ failure and massive internal bleeding. There is no cure, and the latest cases were reported out of Uganda at the end of 2012. An American tourist who had explored a Ugandan cave full of fruit bats known to be reservoirs of the virus contracted it and survived in 2008. (But not before bringing his sick self back to the U.S.)

3. HANTAVIRUS

There are many strains of hantavirus floating around (yep, it’s airborne) in the wake of rodents that carry the virus. Different strains, carried by different rodent species, are known to cause different types of illnesses in humans, most notably hemorrhagic fever with renal syndrome (HFRS)—first discovered during the Korean War—and hantavirus pulmonary syndrome (HPS), which reared its ugly head with a 1993 outbreak in the Southwestern United States. Severe HFRS causes acute kidney failure, while HPS gets you by filling your lungs with fluid (edema). HFRS has a mortality rate of 1 to 15 percent, while HPS is 38 percent. The U.S. saw its most recent outbreak of hantavirus—of the HPS variety—at Yosemite National Park in late 2012.

4. LASSA

This BSL-4 virus gives us yet another reason to avoid rodents. Lassa is carried by a species of rat in West Africa called Mastomys. It’s airborne…at least when you’re hanging around the rat's fecal matter. Humans, however, can only spread it through direct contact with bodily secretions. Lassa fever, which has a 15 to 20 percent mortality rate, causes about 5000 deaths a year in West Africa, particularly in Sierra Leone and Liberia. It starts with a fever and some retrosternal pain (behind the chest) and can progress to facial swelling, encephalitis, mucosal bleeding and deafness. Fortunately, researchers and medical professionals have found some success in treating Lassa fever with an antiviral drug in the early stages of the disease.

5. RABIES

Rabies has a long and storied history dating back to 2300 B.C., with records of Babylonians who went mad and died after being bitten by dogs. While this virus itself is a beast, the sickness it causes is now is wholly preventable if treated immediately with a series of vaccinations (sometimes delivered with a terrifyingly huge needle in the abdomen). We have vaccine inventor Louis Pasteur to thank for that.

Exposure to rabies these days, while rare in the U.S., still occurs as it did thousands of years ago—through bites from infected animals. If left untreated after exposure, the virus attacks the central nervous system and death usually results. The symptoms of an advanced infection include delirium, hallucinations and raging, violent behavior in some cases, which some have argued makes rabies eerily similar to zombification. If rabies ever became airborne, we might actually have to prepare for that zombie apocalypse after all.

6. SMALLPOX

The virus that causes smallpox wiped out hundreds of millions of people worldwide over thousands of years. We can’t even blame it on animals either, as the virus is only carried by and contagious for humans. There are several different types of smallpox disease that result from an infection ranging from mild to fatal, but it is generally marked by a fever, rash, and blistering, oozing pustules that develop on the skin. Fortunately, smallpox was declared eradicated in 1979, as the result of successful worldwide implementation of the vaccine.

7. DENGUE

The leading cause of death in the tropics and subtropics is the infection brought on by the dengue virus, which causes a high fever, severe headache, and, in the worst cases, hemorrhaging. The good news is that it's treatable and not contagious. The bad news is there's no vaccine, and you can get it easily from the bite of an infected mosquito—which puts at least a third of the world's human population at risk. The CDC estimates that there are over 100 million cases of dengue fever each year. It's a great marketing tool for bug spray.

8. INFLUENZA

No virus can claim credit for more worldwide pandemics and scares than influenza. The outbreak of the Spanish flu in 1918 is generally considered to be one of the worst pandemics in human history, infecting 20 to 40 percent of the world's population and killing 50 million in the span of just two years. (A reconstruction of that virus is above.) The swine flu was its most recent newsmaker, when a 2009 pandemic may have seen as many as 89 million people infected worldwide.

Effective influenza vaccines exist, and most people easily survive infections. But the highly infectious respiratory illness is cunning—the virus is constantly mutating and creating new strains. Thousands of strains exist at any given time, many of them harmless, and vaccines available in the U.S. cover only about 40 percent of the strains at large each year.

http://mentalfloss.com/article/50625/8-historically-terrifying-viruses