What are germs?

Germs

Men once believed that evil spirits made people sick.  Today we know that infectious diseases are caused by tiny organisms commonly called germs.

Three common kinds of germs are bacteria, viruses, and protozoa

Bacteria germs are one-celled plants that can be seen only through a microscope.  They cause many diseases, including pneumonia, scarlet fever and whooping cough.

Viruses are tiny organisms.  They are even smaller than bacteria.  Virus germs cause such diseases as mumps, measles, chicken pox and the common cold.

Protozoa are tiny one-celled animals.  Some kinds cause malaria and sleeping sickness.

The human body contains substances that germs can eat.  Germs invade the body through the nose, mouth, or a scratch in the skin.

Some germs causes an illness by destroying the tissue they live in.  Others produce poisons that can make us sick.

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