TedEd-14

Why is Meningitis so Dangerous?

In 1987, tens of thousands of people gathered in Saudi Arabia for the annual Hajj pilgrimage. But
what started out as a celebration led to a health crisis: just a few days after the pilgrimage, morethan 2,000 cases of meningitis broke out spreading across Saudi Arabia and the rest of the world.
The outbreak was so fierce that it was believed to have sparked a wave of deadly meningitis
epidemics that ultimately infected tens of thousands of people worldwide. Meningitis is theinflammation of the meninges, three tissue layers responsible for protecting the brain and spinalcord. What makes meningitis so dangerous compared to other diseases is the sheer speed withwhich it invades a person’s body. In the worst cases, it causes death within a day. Fortunately,
that’s rare for patients who receive early medical treatment.

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Why is Meningitis so Dangerous?

The disease primarily comes in three forms: fungal, viral, and bacterial – the last being the mostdeadly by far, and what we’ll focus on. People usually contract bacterial meningitis by breathing intiny particles of mucus and saliva that spray into the air when an infected person sneezes orcoughs. It can also be transmitted through kissing, or sharing cigarettes, toothbrushes or utensils.
Some people can be infected and carry the disease without showing symptoms or getting sick,which helps the disease spread quickly to others. Once the bacteria enter the nose, mouth, andthroat, they cross the surrounding membranes and enter the bloodstream. From there, bacteria
have rapid access to the body’s tissues – including a membrane called the blood-brain barrier. Thisis made of a tight mesh of cells which separate blood vessels from the brain, and block everything
except for a specific set of particles, including water molecules and some gases.
But in ways that scientists are still trying to understand, meningitis bacteria can trick the barrier into
letting them through. Inside the brain, the bacteria swiftly infect the meninges. This triggers
inflammation as the body’s immune response kicks into overdrive, bringing on fever and intense
headaches. As swelling in the meninges worsens, the neck begins to stiffen. Swelling in the brain
disrupts its normal function – causing symptoms like hearing loss and extreme light sensitivity. As
pressure increases in the cranium, it may also make the person confused – one of the hallmarks ofthe disease. A few hours in, the rapidly multiplying bacteria start to release toxins, leading tosepticemia, also known as blood poisoning. This breaks down blood vessels, letting blood seepout and form what starts out looking like a rash, and evolves into big discoloured blots beneath theskin. At the same time, these toxins burn through oxygen in the blood, reducing the amount thatgets to major organs like the lungs and kidneys. That increases the chance of organ shut down –and alongside spreading septicemia, threatens death.

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Why is Meningitis so Dangerous?

That all sounds scary, but doctors are so good at treating meningitis that a visit to the hospital candrastically reduce an adult’s risk of dying from it. The longer it’s left untreated, though, the more
likely it will lead to lasting damage. If declining oxygen levels cause cell death in extreme parts ofthe body – like fingers, toes, arms and legs – the risk of amputation goes up. And if bacterial toxins
accumulate in the brain and trigger cell death, meningitis could also cause long-term brain damage
and memory loss. So fast treatment, or better yet, prevention, is critical. That's why most countries
have vaccines that defend against the disease in its deadliest forms. Those are usually given to thepeople who are most at risk – like young children, people with weak immune systems, or people
who gather in large groups where an outbreak of meningitis could potentially happen.
In addition to those gatherings, meningitis is most common in a region called the meningitis beltthat stretches across Africa, though cases do happen all over the world. If you’re concerned thatyou or someone you know may have meningitis, get to the doctor as soon as possible; quick action
could save your life.