World's Deadliest Viruses

World's Deadliest Viruses  

  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.

1. The most dangerous virus is the Marburg virus. It is named after a small and idyllic town on the river Lahn - but that has nothing to do with the disease itself. The Marburg virus is a hemorrhagic fever virus. As with Ebola, the Marburg virus causes convulsions and bleeding of mucous membranes, skin and organs. It has a fatality rate of 90 percent.

2. There are five strains of the Ebola virus, each named after countries and regions in Africa: Zaire, Sudan, Tai Forest, Bundibugyo and Reston. The Zaire Ebola virus is the deadliest, with a mortality rate of 90 percent. It is the strain currently spreading through Guinea, Sierra Leone and Liberia, and beyond. Scientists say flying foxes probably brought the Zaire Ebola virus into cities.

3. The Hantavirus describes several types of viruses. It is named after a river where American soldiers were first thought to have been infected with the Hantavirus, during the Korean War in 1950. Symptoms include lung disease, fever and kidney failure.

4. The various strains of bird flu regularly cause panic - which is perhaps justified because the mortality rate is 70 percent. But in fact the risk of contracting the H5N1 strain - one of the best known - is quite low. You can only be infected through direct contact with poultry. It is said this explains why most cases appear in Asia, where people often live close to chickens.

5. A nurse in Nigeria was the first person to be infected with the Lassa virus. The virus is transmitted by rodents. Cases can be endemic - which means the virus occurs in a specific region, such as in western Africa, and can reoccur there at any time. Scientists assume that 15 percent of rodents in western Africa carry the virus.

                                   

   
                                                            Marburg virus

                          

                                                                     Ebola virus                     

Hanata Virus

                                          

                                                 H5N1  Virus                             

Scientists identified Marburg virus in 1967, when small outbreaks occurred among lab workers in Germany who were exposed to infected monkeys imported from Uganda. Marburg virus is similar to Ebola in that both can cause hemorrhagic fever, meaning that infected people develop high fevers and bleeding throughout the body that can lead to shock, organ failure and death.

The mortality rate in the first outbreak was 25 percent, but it was more than 80 percent in the 1998-2000 outbreaks in the Democratic Republic of Congo, as well as in the 2005 outbreak in Angola, according to the World Health Organization (WHO).

                                                                

Ebola virus

The first known Ebola outbreaks in humans struck simultaneously in the Sudan and the Democratic Republic of Congo in 1976. Ebola is spread through contact with blood or other body fluids, or tissue from infected people or animals. The known strains vary dramatically in their deadliness. One strain, Ebola Reston, doesn't even make people sick. But for the Bundibugyo strain, the fatality rate is up to 50 percent, and it is up to 71 percent for the Sudan strain, according to WHO.

The outbreak underway in West Africa began in early 2014, and is the largest and most complex outbreak of the disease to date, according to WHO.

                                                        

Rabies

Although rabies vaccines for pets, which were introduced in the 1920s, have helped make the disease exceedingly rare in the developed world, this condition remains a serious problem in India and parts of Africa."It destroys the brain, it's a really, really bad disease," .We have a vaccine against rabies, and we have antibodies that work against rabies, so if someone gets bitten by a rabies animal we can treat this person”. However, "If you don't get treatment, there's a 100 percent possibility you will die."

                
HIV

  An estimated 36 million people have died from HIV since the disease was first recognized in the early 1980s. "The infectious disease that takes the biggest toll on mankind right now is HIV". Powerful antiviral drugs have made it possible for people to live for years with HIV. But the disease continues to devastate many low- and middle-income countries, where 95 percent of new HIV infections occur. Nearly 1 in every 20 adults in Sub-Saharan Africa is HIV-positive, according to WHO.

                                         
Smallpox

Smallpox is a highly contagious and sometimes fatal disease. There is no specific treatment for people with smallpox, and the only prevention is vaccination.

In 1980, the World Health Assembly declared the world free of smallpox. But before that, humans battled smallpox for thousands of years, and the disease killed about 1 in 3 of those it infected. It left survivors with deep, permanent scars and, often, blindness.

Mortality rates were far higher in populations outside of Europe, where people had little contact with the virus before visitors brought it to their regions.  For example, historians estimate 90 percent of the native population of the Americas died from smallpox introduced by European explorers. In the 20th century alone, smallpox killed 300 million people.

"It was something that had a huge burden on the planet, not just death but also blindness, and that's what spurred the campaign to eradicate from the Earth.

Hantavirus
 Hantavirus pulmonary syndrome (HPS) first gained wide attention in the U.S. in 1993, when a healthy, young Navajo man and his fiancée living in the Four Corners area of the United States died within days of developing shortness of breath. A few months later, health authorities isolated Hantavirus from a deer mouse living in the home of one of the infected people. More than 600 people in the U.S. have now contracted HPS, and 36 percent have died from the disease, according to the Centers for Disease Control and Prevention.

The virus is not transmitted from one person to another; rather, people contract the disease from exposure to the droppings of infected mice.

Previously, a different Hantavirus caused an outbreak in the early 1950s, during the Korean War, according to a 2010 paper in the journal Clinical Microbiology Reviews. More than 3,000 troops became infected, and about 12 percent of them died.

While the virus was new to Western medicine when it was discovered in the U.S., researchers realized later that Navajo medical traditions describe a similar illness, and linked the disease to mice.

Influenza

 In 2009, this virus (then called the swine flu) caused a pandemic, and is thought to have killed 200,000 people worldwide.

During a typical flu season, up to 500,000 people worldwide will die from the illness, according to WHO. But occasionally, when a new flu strain emerges, a pandemic results with a faster spread of disease and, often, higher mortality rates.

The most deadly flu pandemic, sometimes called the Spanish flu, began in 1918 and sickened up to 40 percent of the world's population, killing an estimated 50 million people.

"I think that it is possible that something like the 1918 flu outbreak could occur again". If a new influenza strain found its way in the human population, and could be transmitted easily between humans, and caused severe illness, we would have a big problem."

Dengue

Dengue viruses are transmitted to humans by the bite of an infected mosquito. Dengue viruses are transmitted to humans by the bite of an infected mosquito.

Dengue virus first appeared in the 1950s in the Philippines and Thailand, and has since spread throughout the tropical and subtropical regions of the globe. Up to 40 percent of the world's population now lives in areas where dengue is endemic, and the disease — with the mosquitoes that carry it — is likely to spread farther as the world warms.

Dengue sickens 50 to 100 million people a year, according to WHO. Although the mortality rate for dengue fever is lower than some other viruses, at 2.5 percent, the virus can cause an Ebola-like disease called dengue hemorrhagic fever, and that condition has a mortality rate of 20 percent if left untreated.

We really need to think more about dengue virus because it is a real threat to us. There is no current vaccine against dengue, but large clinical trials of an experimental vaccine developed by French drug maker Sanofi have had promising results.

Rotavirus

Two vaccines are now available to protect children from rotavirus, the leading cause of severe diarrhea illness among babies and young children. The virus can spread rapidly, through what researchers call the fecal-oral route (meaning that small particles of feces end up being consumed).

Although children in the developed world rarely die from rotavirus infection, the disease is a killer in the developing world, where rehydration treatments are not widely available.

The WHO estimates that worldwide, 453,000 children younger than age 5 died from rotavirus infection in 2008. But countries that have introduced the vaccine have reported sharp declines in rotavirus hospitalizations and deaths.