Knowing how disease spreads is a crucial starting point for thinking about global warming and human health. The more we understand about disease, the better chance we have
at preventing or minimizing outbreaks
related to climate
change. Diseases basically have two simple—but all
too effective—techniques for transmission,
or spreading.
Direct Transmission: That's when disease-causing microbes
(alias "germs") travel straight from one person to another.
Let's say, for instance, that your kid brother catches a cold.
He unintentionally sneezes in your face while you're wrestling
for the remote. Vicious little viruses
land right on your skin. Before long, Bro' has the remote,
and you have the cold.
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In extreme cases, health officials may quarantine, or block off, places where a contagious disease has appeared.
Source: Center for Disease Control and Prevention
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Indirect Transmission: Even little brothers eventually
learn how to use tissues, so diseases have other ways to get
around too. Some bacteria
and viruses hang out in water or soil. When people drink the
water that's contaminated with microbes, they get sick. Many
diseases hitch rides aboard vectors—science
lingo for insects and other living things that carry bacteria,
viruses, or parasites.
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This map
shows outbreaks of microbe-caused diseases during the
1990s.
Source: Center for Disease Control and Prevention |
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Biotic Factors: These relate to living
things. If the rat population in a city grows,
diseases carried by rats have a better chance
of spreading.
