Recently there has been
a lot of talk about measles. What does measles actually do,
and should you vaccinate against it? Or is this just hysteria? Measles is a virus: a hull of proteins, RNA, plus some more proteins for reproduction. It cannot reproduce by itself;
it needs a host cell to do so. To understand measles, we have to
understand the immune system. You might already have seen the visual system we developed
to help here. Now, let’s focus on the parts of
the immune system relevant to measles. The measles virus enters humans
through the nose, mouth, or eyes. The measles infection starts in the lungs. Measles is especially good at infecting
the body’s first line of defence: macrophages, powerful guard cells
that protect the lungs from intruders. They enter a cell and take it over. The virus reprograms the cell and transforms it into a dangerous
virus production center. Once a cell is filled with viruses, they leave the crippled cell
and begin the cycle over again. But the immune system has
powerful weapons against virus infections: natural killer cells. These cells basically patrol the body
and check other cells for infections. If they find an infected cell,
they order it to commit suicide. This is so effective that for
the first 10 days or so, you will not even notice that
you’re infected with measles. And now, the reason why measles
is so powerful. After a period of fighting and dying, macrophages alert the brain of the
immune system: the dendritic cells. The job of the dendritic cells is
to collect samples of intruders, travel to the lymph nodes, and then activate the heavy weapons that eradicate the infection very fast
in a team effort. But the measles virus uses
a dreadful tactic. It infects the dendritic cells and uses them as a Trojan horse
to enter deeper into the body. The infected cells travel to the next
lymph node to alert other immune cells. Once it arrives, the measles virus spreads around the
virgin T and B cells and infects them. It attacks the very system that
evolved to fight it. Now, things happen very fast. The lymph system spreads the virus
everywhere and it enters the bloodstream, infecting cells while traveling. Measles infects organs like the spleen, the liver, the intestines,
and, most importantly, the lungs. The symptoms range from a very high fever, headache, sickness,
bronchitis, and, of course, a rash. In the lungs, the immune system was
doing pretty okay. But now, millions of viruses
attack a second time and kill countless cells, wiping out
the defense systems. In this phase, you start coughing out
millions of measles viruses. Measles is so contagious at this stage, that if you meet someone
who isn’t vaccinated, there’s about a 90% chance
you’ll infect them. Without the protective army in the lungs,
other bacteria or viruses that would usually not stand a chance can
now enter the lungs and develop into harmful parallel infections that
can cause pneumonia, the most common way to
die from measles. Your body’s immune system is now
seriously wounded. Various protective systems are hurt
and disrupted. The virus spreads everywhere, infecting
the skin all over the body. The typical measles rash now
becomes visible. And in some cases, the measles virus reaches the brain and causes
a brain infection. If it does so, the chances of dying
are between 20 to 40 percent, and there may be long-term damage. But your body is far from giving
up at this stage, and it fights back agressively. Some dendritic cells survive
long enough to activate the anti-virus forces of the body. Plasma cells in the lymph nodes
start producing billions of antibodies, tiny proteins that mark infected cells
for destruction or clump the virus together. Killer T cells flood the body
and kill infected cells left and right. After 2 to 3 weeks, the body usually gets the upper hand and overwhelms
the infection. But the immune system is now
seriously weakened, and may take weeks or months to recover, leaving the body vulnerable
to other diseases. But, if you make it, you are now immune: the immune system remembers
the virus forever. Measles is no joke. Although 84% of all humans are
vaccinated against measles, 122,000 people died because
of the infection in 2014. Some people cannot get vaccinations, either because they’re too young,
because of chemotherapy or HIV, or because they’re allergic
to the vaccine. They need the rest of us to
stop the disease for them. The measles vaccination is
safe, cheap, and available. There are no benifits from having
measles at all. You don’t strengthen your immune
system and it’s not more natural. Most people who don’t vaccinate
only want the best for their children, which is honorable. But if you ask yourself, “Am I putting the life of my child
and other children at risk by not vaccinating against measles?” The sad answer is yes. Yes, you are. Let’s not play the blame game, though. Let’s work together and
eradicate this virus. Together, we can get rid of these
dreadful monsters and consign them to their rightful place:
the history books. Subtitles by the Amara.org community