One major worry around the world right now is a brand-new
deadly disease called SARS—Severe Acute Respiratory Syndrome.
A virus, which experts believe jumped from farm animals to
humans in China, causes SARS. The disease spreads easily and
researchers are working hard to develop vaccines and treatments.
For updates, visit the World Health Organization .
Throughout human history, people have unknowingly
carried disease-causing microbes
from place to place, often with disastrous results. In the centuries
after Christopher Columbus first landed in the Americas, Europeans
brought infectious diseases that killed tens of millions of
people—80 to 90 percent of the native population.
MORE AND MORE ON THE MOVE
Globalization and growing international
trade also contribute to disease. Some major roadways in India,
for example, are known as "AIDS
highways" because the long-distance truck drivers who use
these highways carry the virus. Experts estimate that a half-million
truck drivers in India are HIV-positive.
As international travel becomes more affordable
and a whole lot easier, more than 600 million people worldwide
take airplane trips each year. Those who travel by car, bus,
ship, train—and by foot—are just too numerous too
count.
Plane travel especially fuels the spread of disease. One of
the strangest phenomena is called "airport
malaria"—which strikes people who live near airports
in countries that have no malaria (until an infected mosquito
or person gets off the plane). In Paris, France, for example,
neighbors of the international airport who have never traveled
to malaria-risk countries have come down with falciparum malaria—the
most serious form of the disease.
Click to see how quickly the mosquito-borne West
Nile virus, which first appeared in the U.S. in 1999, is
spreading.
Most immigrants to the U.S.
now come from Latin America and Asia Source: Population Reference Bureau |
People flow from poor economic areas
to places that offer jobs and opportunity. Mexicans go to the
United States, Turks, to Germany, and Indonesians, to Malaysia.
Some even move from one part of their own country to another.
More than 100 million workers in China, for example, have migrated
to the economically prosperous provinces along China's coasts.
When migrant farmworkers
clear rainforests and do other kinds of work that bring them
into contact with mosquito-borne diseases such as yellow
fever. These workers sometimes get more than they bargained
for, bringing home both the diseases and the mosquitoes that
carry the diseases. Learn more about yellow
fever, which hits about 200,000 people each year—in
cities and in rural areas.
WAR, REFUGEES, AND DISEASE
All of the countries in this
chart have recently experienced major wars
Source: UNHCR |
Movement of people caused by war contributes
most to disease. In Central Africa, for example, decades of
almost continuous wars have produced at least 15 million refugees—people
who must live year after year without homes or even the most
basic sanitary facilities. It is no coincidence, then, that
some of the world's worst and most threatening disease epidemics—including
meningitis,
cholera,
and Ebola—start
in Central Africa.
HITCHING A RIDE TO THE MOON
Some bacteria can thrive in
extreme environments-
from boiling hot springs to polar ice
Source: MicroAngela |
One of the reasons the situation
is so serious is that microbes are such good travelers. Here
is one experience that caused scientists to be super cautious
when the astronauts returned from the moon in 1970:
- A surprising thing happened in 1969.
When astronauts from Apollo
12 landed on the moon—they found bacteria from
Earth! How did that happen?
- The bacteria sat inside a camera that
had been on the moon since 1967, when an unmanned NASA spacecraft
had landed.
- Scientists had not sterilized the camera
before sending it to the moon, because they were sure that
microbes could not survive the journey.
- But plenty of microbes had survived
the vacuum of outer space, exposure to deadly space radiation,
extremely low temperatures, and lack of food for more than
three years!
This shows just how tough microbes can
be, and how difficult it can be to keep them from tagging
along. Click here
to get the bigger picture about bacteria and other small parts
of our world.
Get more fun facts about microbes and space from NASA.
