Most infectious diseases are impacted by changes in the environment. Malaria, dengue, and viral encephalitis infections, for example, are highly sensitive to environmental changes.

The clearing and settlement of tropical rainforests has exposed woodcutters, farmers, and ecotourists to new vector-borne diseases.

The 2009 “swine flu” pandemic starkly illustrated the impact of globalization and air travel on the movement of infectious diseases—with the infection spreading to 30 countries within six weeks and to more than 190 countries and territories within months.

The 2009 “swine flu” pandemic starkly illustrated the impact of globalization and air travel on the movement of infectious diseases—with the infection spreading to 30 countries within six weeks and to more than 190 countries and territories within months.

The above describes how vaccines work. Antibiotics work by either killing bacteria or stopping them from reproducing, allowing the body's natural defenses to eliminate the pathogens.

The 1918 influenza pandemic is estimated to have killed between 50 million and 100 million people worldwide. Many of those deaths were due to the effects of pneumococcal pneumonia, a secondary complication of flu for which no antibiotics existed in 1918.

The 1918 influenza pandemic is estimated to have killed between 50 million and 100 million people worldwide. Many of those deaths were due to the effects of pneumococcal pneumonia, a secondary complication of flu for which no antibiotics existed in 1918.

Influenza is not a vector-borne disease, meaning it is not transmitted to humans indirectly via an insect, an arthropod, or another animal. Malaria and yellow fever are transmitted by mosquitoes. Lyme disease is transmitted by deer ticks.

Influenza is not a vector-borne disease, meaning it is not transmitted to humans indirectly via an insect, an arthropod, or another animal. Malaria and yellow fever are transmitted by mosquitoes. Lyme disease is transmitted by deer ticks.

Influenza is not a vector-borne disease, meaning it is not transmitted to humans indirectly via an insect, an arthropod, or another animal. Malaria and yellow fever are transmitted by mosquitoes. Lyme disease is transmitted by deer ticks.

Because strep throat is caused by a bacterium called Streptococcus pyogenes, it is treatable with antibiotics but not antivirals. Currently there is no vaccine available to prevent strep throat.

Because strep throat is caused by a bacterium called Streptococcus pyogenes, it is treatable with antibiotics but not antivirals. Currently there is no vaccine available to prevent strep throat.

Because strep throat is caused by a bacterium called Streptococcus pyogenes, it is treatable with antibiotics but not antivirals. Currently there is no vaccine available to prevent strep throat.

Scientists believe that hot weather may speed up both the breeding cycle of mosquitoes and replication of the virus in insects’ guts.

Growing evidence does suggest that infections are behind many chronic diseases once thought to be caused by genetic, environmental, or lifestyle factors, including peptic ulcers and cervical, liver, and gastric cancers.