The diseases with 100% fatality rates – from ‘laughing sickness’ to an inhereted ‘brain folding’ bug

SOME diseases are so devastating that survival is virtually impossible – with fatality rates hitting 100 per cent.

Thankfully, due to modern medicine, they’re incredibly rare.

The few that do exist are mostly genetic, such as a brain-wasting disease passed down through families.

Others, however, have more bizarre origins, with one even stemming from cannibalistic practices.

And yes, here in the UK, a few of these diseases have left their mark.

So, let’s take a closer look at these rare but devastating illnesses – and specifically, why they’ve earned their reputation as some of the deadliest diseases known to humankind.

Creutzfeldt–Jakob Disease (CJD)

Creutzfeldt–Jakob disease (CJD), is described by the US Centre for Disease Control (CDC) as “always fatal”.

It causes proteins in the brain – called prions – to fold abnormally, hence why it is called a prion disease.

The folds ultimately cause brain damage and death.

In most cases, it develops “sporadically”.

But the killer condition can also be inherited if one parent carries a mutation that causes prions to form in their brain during adulthood.

The inherited form of the disease only affects about one in every nine million people in the UK, according to the NHS.

And in the US, about one in a million people are diagnosed annually.

Most people die within a year of the first symptoms, which include memory loss, impaired thinking, personality changes, and sudden, jerky movements.

The Mayo Clinic likens it to Alzheimer’s but at high speed, with additional symptoms like blindness, speech problems, and severe coordination issues.

Fatal familial insomnia (FFI)

Imagine a genetic condition that not only steals your sleep but ultimately your life – that’s fatal familial insomnia (FFI) in a nutshell.

This rare disease – also in the piron family – affects the brain and central nervous system.

It causes sleepless nights, memory loss, and worsening muscle twitching, according to the National Organization of Rare Disorders (NORD).

It’s a degenerative condition which means it gets progressively worse, and there’s no cure.

Treatment focuses on easing symptoms and keeping patients comfortable.

Globally, it affects between between 50 and 70 families worldwide.

But only one or two people out of one million end up testing positive.

In the UK and the US, cases are extremely rare, with only a handful reported.

Rabies

If you thought rabies was just a problem for your pet, think again.

This is one of the deadliest diseases known to humanity, with fewer than 20 reported human survivors worldwide, according to the CDC.

It starts deceptively mild with flu-like symptoms and an odd itching sensation near the bite, the NHS says.

But when it progresses, it’s terrifying triggering anxiety, hallucinations, a fear of water (hydrophobia), and full-on cerebral dysfunction.

Without immediate treatment after exposure, rabies is almost always fatal.

In the UK, rabies is extremely rare, largely due to strict animal control and vaccination programs.

The last recorded case of classical rabies contracted in the UK was in 1902.

However, there have been isolated cases associated with animal bites abroad.

For example, in 2012, a UK resident died from rabies after being bitten by a dog in South Asia.

The US sees three cases on average each year.

Kuru

Kuru, a fatal brain disorder, has one of the most bizarre histories.

It was rampant in the 1950s and ’60s among the Fore people of New Guinea due to ritualistic cannibalism.

They would eat the infected brains of diseased individuals, who were carrying kuru.

Like CJD and FFI, kuru was caused by an infectious protein, or prion, according to Healthline.

The name kuru means “to shiver” or “trembling in fear,” as tremors were one of the earliest symptoms.

People would go on to develop slurred speech, followed by mood changes and an inability to eat or stand.

Death usually occured within six months to a year.

Before they died, victims would frequently burst into fits of laughter, which is why it is sometimes called the “laughing sickness”.

Fortunately, as cannibalism declined, so did kuru – it’s now almost extinct.

There have been no reported cases of kuru in the UK or the US, as the disease was confined to specific cultural practices in New Guinea.

Gerstmann–Sträussler–Scheinker Syndrome (GSS)

Another brain-folding disease, gerstmann–sträussler–scheinker syndrome (GSS), is so rare it’s been identified in only a handful of families worldwide.

Most people develop symptoms between 35 and 55, starting with coordination problems and progressing to dementia, slurred speech, and even blindness.

Symptoms can slowly progress for two to 10 years before resulting in severe disability and death.

No treatments exist to halt its progression – instead, therapies are focused on managing symptoms.

In the UK, GSS is extremely rare, with only a few recorded cases.

The National CJD Research & Surveillance Unit monitors such cases as part of their surveillance of prion diseases.

In the United States, GSS is equally rare, with fewer than 50 documented cases.