Many harmful microbes can pass from one person to another. Diseases caused by such microbes are said to be infectious diseases. Here are some ways that harmful microbes can be spread:

• in air

• through contact with animals

• through contaminated food

• through touch

• in water

Air

Droplets containing microbes fly into the air when people sneeze or cough. The microbes they contain get into other people if breathed in.

Chicken pox, colds, flu, measles and tuberculosis are spread like this.

Animals

Animals may carry harmful microbes. The microbes can get into a person who is scratched or bitten by such an animal. Malaria is a tropical disease spread by a tiny fly called a mosquito.

Food

Food can have harmful microbes in and on it. The microbes get into the body when the food is eaten, causing food poisoning. Thorough cooking kills most microbes, but they can survive under-cooking. Careless handling of food increases the risk from harmful microbes.

Touch

Microbes can be passed from one person to another when people touch each other, or when they touch something an infected person has handled. Athlete's food is spread like this.

Bacteria on the skin can be killed by antiseptics, and bacteria on surfaces can be killed by disinfectants. Washing your hands reduces the chance of spreading microbes.

Water

Water can have harmful microbes in it. The microbes get into the body when the water is swallowed. Cholera is a disease caused by a bacterium that spreads like this. Thorough boiling or adding chlorine to the water can reduce the chance of spreading microbes in this way.