Curbing the spread of disease Part 1

 

        

Once people came to understand that germs cause many diseases,
they started identifying and blocking the paths along which
the germs travel. In many cases, doing this was possible before
anyone had any detailed knowledge of the actual germs involved.

One strategy for blocking the spread of infectious disease is
quarantine, which involves identifying the people who have a contagious
disease and separating them from healthy people so that
the disease doesn’t spread. Quarantines have been used for
thousands of years. More recently quarantines have helped control
diseases like the supercontagious and deadly Ebola virus, which
has devastated several villages in Africa over the past few decades,
and SARS (severe acute respiratory syndrome).

Quarantines can be effective in controlling some contagious diseases.
But there are several big drawbacks. For one thing, it can
be hard to identify all the sick people. In many cases, a person
might be infected and still be able to spread the disease for quite a
while before developing any symptoms of the disease.
Second, some infected people never get sick at all. But in either
case, a person who looks healthy.





might still be able to pass on his or her germs to others. Quarantines
also can’t always block other ways that germs might spread—
for example, through infected water, food, animals, or insects.
Finally, quarantines can mean separating sick people from their jobs,
friends, and family, and that can be very hard to do. Today, big
quarantines involving lots of people are rare and are used
mainly in emergencies.

Another way to control the spread of disease is by controlling the
vectors that help it spread. A vector is a kind of middleman: a creature
which carries a germ that infects people. For example, mosquitoes
are the main vectors for malaria (a deadly disease common
in the tropics). For centuries, European explorers assumed that
the disease was caused by something in the tropical air (in fact,
the word “malaria” translates to (bad air”). But in 1895, the British
biologist Ronald Ross discovered that a tiny parasite (an organism
that lives off another organism) really causes the disease. Three
years later, a team of Italian scientists figured out that the parasite
was carried by mosquitoes and was spread through their bites.
Once people understood this, people in tropical cities were able to
reduce the threat of malaria by draining nearby swamps where
mosquitoes bred.