Communicable Diseases

Disease are caused by pathogens. Pathogens are microorganisms that cause infectious disease. They can be:

- Viruses

- Bacteria

- Protists

- Fungi

Pathogens can infect plants or animals and can be spread by direct contact, water or by air.

Bacteria and viruses may reproduce rapidly inside the body.

Bacteria may produce poisons (toxins) that damage tissues and make us feel ill.

Viruses live and reproduce inside cells, causing cell damage.