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  • 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, more than 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 the inflammation of the meninges, three tissue layers responsible

  • for protecting the brain and spinal cord. What makes meningitis so dangerous compared

  • to other diseases is the sheer speed with which 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.

  • The disease primarily comes in three forms:

  • fungal, viral, and bacterial-- the last being the most deadly by far,

  • and what we'll focus on.

  • People usually contract bacterial meningitis by breathing in tiny particles

  • of mucus and saliva that spray into the air when an infected person sneezes or coughs.

  • 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, and

  • throat, 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. This is 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 gasses. 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 of the disease.

  • A few hours in, the rapidly multiplying bacteria start to release toxins,

  • leading to septicemia,

  • also known as blood poisoning. This breaks down blood vessels,

  • letting blood seep out and form what starts out looking like a rash, and

  • evolves into big discoloured blots beneath the skin. At the same time, those toxins

  • burn through oxygen in the blood, reducing the amount that gets to major organs like

  • the lungs and kidneys. That increases the chance of organ shut down--and alongside

  • spreading septicemia, threatens death.

  • That all sounds scary, but doctors are so

  • good at treating meningitis that a visit to the hospital can drastically 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 of the 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 the people 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 belt that stretches

  • across Africa, though cases do happen all over the world. If you're concerned that

  • you or someone you know may have meningitis, get to the doctor as soon as

  • possible; quick action could save your life.

In 1987, tens of thousands of people gathered in Saudi Arabia for the annual Hajj pilgrimage.

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B2 US TED-Ed bacteria brain blood disease bacterial

Why is meningitis so dangerous? - Melvin Sanicas

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    黃齡萱 posted on 2018/11/20
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