Infectious Diseases
Infectious diseases kill more people worldwide than any other single cause. Infectious diseases are caused by germs. Germs are tiny living things that are found everywhere - in air, soil and water. Though some infectious diseases are not contagious, others may be transmitted from animal to person (bird flu and cat scratch disease) or from person to person (MRSA, HIV, and other STDs). You can get infected by touching, eating, drinking or breathing something that contains a germ. Germs can also spread through animal and insect bites, kissing and sexual contact. Vaccines, proper hand washing and medicines can help prevent infections.
There are four main kinds of germs:- Bacteria - one-celled germs that multiply quickly and may release chemicals which can make you sick
- Viruses - capsules that contain genetic material, and use your own cells to multiply
- Fungi - primitive vegetables, like mushrooms or mildew
- Protozoa - one-celled animals that use other living things for food and a place to live