DANGER BUGS
The 12 deadliest viruses in history revealed – and some of them are circulating right now
Including one dubbed 'break-bone fever' and another with a 100% kill rate
FROM Ebola to rabies - history is full of terrifying viruses that have killed millions upon millions of people.
Some have been eradicated with effective vaccines, but not all of these deadly illnesses are things of the past.
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Many continue to lurk deep in our forests and below the Earth's surface.
Numerous factors are playing a part in their spread - from climate change and population growth, to humans encroaching into never-before-explored jungles.
And they are infecting and killing thousands, and in some cases millions, of people every year.
Based on mortality rates, here are the 12 of the most deadly viruses ever to have infected humans, and which ones are still circulating today.
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1. Marburg virus
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One of the world's most deadly viruses is Marburg.
The highly contagious bug comes from the same family as Ebola and spreads incredibly quickly from person to person.
It has a fatality rate of up to 88 per cent, according to the World Health Organization (WHO), and there is no known cure or treatment.
It was first identified in 1967 in both Marburg and Frankfurt in Germany and in Belgrade, Serbia.
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The outbreak was linked to labs using African green monkeys imported from Uganda.
Marburg is transmitted via fruit bats and spreads between humans through bodily fluids.
Model, 24, hospitalised after getting attacked by two monkeys while in bikini photoshoot & left needing five rabies jabs
Symptoms usually come on fast and severely and include a fever, headache, diarrhoea, nausea, chest pain, and malaise.
Patients are often described as "ghost-like", with extreme fatigue and drawn features.
Most sufferers go on to develop haemorrhaging within a week, with fatal cases bleeding from multiple areas - such as the nose, gums and vagina.
Death usually happens between eight and nine days after onset - largely due to severe blood loss and shock.
Cases have been reported in South Africa, Angola, Kenya, Tanzania, Uganda, Congo, Ghana, and Equatorial Guinea in recent years.
The USA, Netherlands, Russia and Germany have also reported infections linked to travel or laboratory contamination.
Marburg is listed by the WHO as a top 10 priority disease, meaning it poses "the greatest public health risk".
2. Ebola virus
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The Ebola virus disease - previously called Ebola haemorrhagic fever - is a viral infection that occurs in humans and primates.
It is rare but incredibly serious and often fatal.
Ebola begins with symptoms including a fever, intense fatigue, muscle pain and a sore throat, before progressing to vomiting and diarrhoea.
It can also cause internal and external bleeding, as well as vision problems, trouble sleeping, hearing loss, memory loss and depression.
On average, 50 per cent of people who contract Ebola will die.
But fatality rates have varied between 25 and 90 per cent in past outbreaks.
People can catch Ebola by touching infected animals when preparing, cooking or eating them, infected fluids (like saliva, urine, faeces or semen), or things that have the bodily fluids of an infected person on, such as clothes or sheets.
The virus enters the body through cuts on the skin or when touching the eyes, nose or mouth, according to WHO experts.
Ebola first appeared in 1976 in two simultaneous outbreaks in what is now Nzara, South Sudan, and Yambuku, the Democratic Republic of Congo.
Since then, it has been found in large numbers in countries including Guinea, Uganda, Gabon, South Africa, and the Ivory Coast.
3. Rabies
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Rabies is a rare but serious infection, usually caught from a bite or scratch from an infected animal.
This is typically a dog, bat, coyote, fox, skunk or raccoon.
Once symptoms appear, rabies is fatal in 100 per cent of cases, WHO warns.
The infection is common worldwide but is predominantly found in , , and Central and
After a bite or other rabies exposure, the virus can take weeks or months to start causing symptoms.
These will usually begin as flu-like, such as fever, and get more aggressive as time passes.
Sufferers often go on to experience numbness or tingling, hallucinations, anxiety, bursts of energy, difficulty swallowing, problems breathing, fear of fresh air, and paralysis, according to the NHS and WHO.
Rabies kills an estimated 59,000 people across 150 countries every year.
Thankfully, there is an effective vaccine against rabies, which you should get if you visit an area where the condition is common.
4. HIV/AIDS
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Almost 40million people globally were living with HIV at the end of 2022, WHO data shows.
If left untreated, this can weaken the immune system and cause AIDS, which kills about one million people a year.
AIDS, which stands for acquired immune deficiency syndrome, is several potentially life-threatening infections and illnesses that happen when the immune system has been severely damaged by HIV.
AIDS cannot be transmitted between people, but HIV can. There is currently no cure for either.
However, powerful antiviral drugs have made it possible for people to live for years with HIV, so that it doesn't turn into AIDS.
An estimated 40million people have died from AIDS since it was first recognised in the early 1980s.
In the US alone, there are 1.5 deaths per 100,000 population, the Centers for Disease Control and Prevention estimates.
Most people with HIV will notice a short illness, similar to flu, two to six weeks after getting the virus.
This includes a high temperature, sore throat, body rash, tiredness, joint pain, muscle pain and swollen glands.
Once the immune system becomes severely damaged, symptoms can include weight loss, chronic diarrhoea, night sweats, skin problems, recurrent infections, and serious life-threatening illnesses.
In the UK, most HIV cases are caused by having sex with someone with it without using a condom.
It is generally considered the deadliest virus of the modern world.
"The infectious disease that takes the biggest toll on mankind right now is HIV," Dr Amesh Adalja, an infectious disease specialist, told .
5. Smallpox
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Smallpox was once a common global disease.
It caused small blood vessels of the skin, mouth, and throat to become infected before the virus spread across the body.
"It was one of the most devastating diseases known to humanity and caused millions of deaths," the WHO says.
Estimates suggest smallpox, which is believed to have existed for about 3,000 years, killed about 30 per cent of those it infected.
It left survivors with deep, permanent scars and, often, blindness.
In the 20th century alone, smallpox killed 300million people, according to National Geographic.
Fortunately, after various vaccination campaigns during the 19th and 20th centuries, it was considered globally eradicated in 1979.
"This remains among the most notable and profound public health successes in history," the WHO says.
6. Hantavirus
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Hantavirus pulmonary syndrome (HPS) is a very deadly disease for those who catch it, but it has killed relatively few people.
The virus is found in rodents and only passes to humans if someone ingests their bodily fluids - such as urine, faeces or saliva.
Those who are unlucky enough to catch the virus have a 60 per cent chance of dying.
People infected with hantavirus will show symptoms including a fever, bleeding and kidney damage, according to experts from the Chinese Center for Disease Control and Prevention.
In China, vaccines for hantavirus have been available for nearly 20 years.
Getting jabbed is seen as the most effective way to prevent infection.
Hantavirus has been reported in rodents in Europe, the Balkans, Asia, North America and Argentina, government data shows.
7. Influenza
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You may be surprised to learn that influenza, or flu, is one of the deadliest viruses worldwide.
Many people think of it as a slightly more severe version of the common cold, but it can be very serious.
Flu affects around five to 20 per cent of the UK population each year.
During a particularly bad flu season, around 30,000 Brits will die after contracting the virus.
Globally, there are around one billion seasonal flu cases, including three to five million cases of severe illness.
WHO data shows it causes up to 650,000 respiratory deaths annually.
It might only kill 1.8 in 100,000, but it infects so many it's one of the leading killers.
However, there are vaccines to combat the disease.
Each year, the flu virus changes, and jabs are adjusted to deal with this.
Overall, flu vaccines appear to be effective at preventing the virus in around 40 to 60 per cent of cases.
The symptoms of flu are very similar to those of a very bad cold.
The NHS says this includes suffering from a high temperature of 38C or more, as well as body aches and a dry cough.
You may also have difficulty sleeping, loss of appetite and feeling or being sick.
8. Dengue
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Dengue fever is a viral infection caused by the dengue virus.
It is spread by mosquitoes and is generally found in the tropical and subtropical regions of the globe.
However, it is becoming increasingly common elsewhere.
According to the WHO, dengue infects 100 to 400million people a year.
Although it has a lower mortality rate than some other viruses - at around one per cent- the virus can cause an Ebola-like disease called dengue hemorrhagic fever.
This version has a mortality rate of 20 per cent if left untreated.
A vaccine is available to children living in areas where dengue is common.
But there is no vaccine available to protect against dengue fever, also called break-bone fever because it causes severe joint pain, for travellers.
Other symptoms of dengue include a fever, headache, pain behind the eyes, nausea, vomiting, swollen glands, bleeding gums, and a rash.
9. Rotavirus
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Rotavirus is a diarrhoeal disease that kills about 527,000 people every year.
It spreads quickly through the faecal-oral route (when small particles of faeces are eaten).
Thanks to vaccines, children in the Western world are protected against the virus.
However, the disease is a killer in the developing world, where rehydration treatments are not widely available.
As well as vomiting and diarrhoea, which can be watery and bloody, rotavirus can also cause stomach pain and a mild fever.
Illness can last between three and nine days, according to the NHS.
10. SARS
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SARS was first identified in 2003 during an outbreak in China, according to the WHO.
It is a deadly virus that causes severe acute respiratory syndrome.
It likely emerged in bats then hopped to other mammals before making the leap to humans.
The disease is known to cause flu-like symptoms, like a fever, chills and body aches.
It often progresses to pneumonia - a severe condition in which the lungs become inflamed and fill with pus.
SARS kills around 9.6 per cent of those it infects.
However, no new cases of SARS have been reported since the early 2000s, according to the US Centers for Disease Control and Prevention.
11. Covid
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Covid is caused by the SARS-CoV-2 virus.
As you likely know, it is a respiratory illness that emerged in China in 2019.
It doesn't kill a huge proportion of those who it infects, but it has caused more than 7million deaths worldwide - and counting.
There have been more than 760million recorded cases since December 2019, though the true number is likely much higher.
The virus poses a higher risk to people who have underlying health conditions such as diabetes, high blood pressure or obesity.
Common symptoms include a fever, cough, loss of taste or smell and shortness of breath.
More serious signs include breathing difficulties, chest pain and loss of mobility.
Covid is constantly evolving, with new variants continuously cropping up.
This, plus vaccinations, mean the mortality rate also changes.
Over 13billion vaccine doses have been administered as of June 2023.
12. MERS
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Finally, to round out the 12, is Middle East respiratory syndrome, or MERS.
It first sparked an outbreak in Saudi Arabia in 2012 and another in South Korea in 2015.
The illness has a high mortality rate, killing about 35 per cent of people diagnosed with it.
However, the virus has taken the lives of only 858 people as of 2021 because it is easily contained and does not spread easily between humans.
MERS belongs to the same family of viruses as SARS and Covid.
It is so lethal because it often progresses to severe pneumonia, and there is no vaccine to prevent it.
The risk of infection with MERS to people in the UK is very low, according to the NHS.
There have been only five cases here since 2012, with the most recent identified in August 2018.
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There is evidence that camels in the Middle East are the main source of MERS, but it can be passed from person to person through coughing.
Symptoms include a fever, cough, difficulty breathing, diarrhoea and vomiting.
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