Viruses have been around since before man even existed. As long as their were animals and plants there will have no doubt been viruses.
Today these viruses have become almost impossible to contain or control as they seem to mutate around everything that we throw at them in our attempts to defeat them.
Every human being has come into contact with a human virus in some form whether it is the common cold or something more severe. By the way, the Black Death was NOT a virus, it was bacterial.
This list is in no particular order and is certainly not THE 5 deadliest viruses in the world but they are 5 viruses that should not be taken lightly. We will have a separate post detailing a further 5 viruses that you should be aware of.
Ebola was originally discovered back in 1976 in what is now known as DR Congo and is spread through contact with bodily fluids or blood of those infected.
In 2014, Ebola killed more than 11,000 people throughout Liberia, Guinea and Sierra Leone in West Africa. Fatality rates vary depending on the strain: the Zaire strain has a fatality rate of 90 per cent, according to the World Health Organisation, while the Reston strain does not even make people ill.
Once a person becomes infected, the disease has an incubation period of between 2-21 days. The initial symptoms start off as sudden malaise, headache, and muscle pain which then progresses to high fever, vomiting, severe hemorrhaging and in 50%-90% of patients, death usually occurs within days. The scariest thing about Ebola is that there is currently no vaccine or cure.
If left untreated, Rabies has a 100% mortality rate which means that if we had no vaccine available, Rabies would be THE most deadly virus on this list.
It is zoonotic which means that it is transmitted through the bite of an animal and then works its way through the peripheral nerves to the brain.
The incubation period can take up to several months, depending on how far it has to go to reach the central nervous system. Initial symptoms start off as acute pain, violent movements, depression, uncontrollable excitement, and inability to swallow water. This then progresses to periods of mania followed by coma and then death.
Even with vaccines available, there are around 55,000 people that die every year to this virus with most cases being reported in Asia and Africa.
Smallpox is an extremely contagious disease that is caused by the variola virus. In the 20th century alone, smallpox killed over 300 million people worldwide. Thankfully, WHO declared that the Smallpox virus had been eradicated in 1980 but as anybody should know, this only gives it chance to mutate into something much more severe. The last known natural case was in Somalia, East Africa, in 1977.
The initial symptoms start off as a high fever, a bumpy rash, pus-filled blisters, vomiting and body aches. Survivors are often left blind and with deep, permanent scars.
HIV (Human Immunodeficiency Virus) has killed more than 25 million people since 1981. It gets to the immune system by infecting important cells, including helper cells called CD4+ T cells, plus macrophanges and dendritic cells. It then goes on to kill these cells, damaging the infected person’s immunity and leaving them more at risk from infections.
In many cases, the infected person will go on to develop AIDS. Once a patient has AIDS common infections and tumours normally controlled by the CD4+ T cells start to affect the person.
In the latter stages of the disease, pneumonia and various types of herpes can infect the patient and cause death.
HIV can be transmitted via the bodily fluids of infected individuals, such as blood, breast milk, semen and vaginal secretions.
There is no known cure for the HIV virus. However, effective antiretroviral drugs can control the virus and help prevent transmission.
Influenza has been claiming lives for centuries with pandemics occurring on an average of three times per century causing millions of deaths.
The most fatal pandemic on record was the Spanish flu outbreak in 1918, which caused between 20 million and 100 million deaths.
In order to invade a host, the virus shell includes proteins that bind themselves to receptors on the outside of cells in the lungs and air passages of the victim. Once the virus has latched itself onto the cell it takes over so much of its machinery that the cell dies.
Vaccinations against the flu are common in developed countries. The problem though is that just because a vaccine may be effective one year, it doesn’t necessarily mean that it will work the next time round.
The Influenza A virus H5N1, more commonly known as the bird flu, is a viral infection spread from bird to bird. While it would normally only affect birds, in Hong Kong in 1997, humans were also infected which at the time, 18 people were infected with 6 people dying. Since the deadly virus first infected humans in 1997, it has killed 60 per cent of infected patients.