What causes infection?
Microbes are living organisms such as bacteria, viruses, fungi, and parasites, which can multiply. Harmless, helpful, or harmful, bacteria are constantly adapting by mutating or acquiring genes from other strains or species in response to their environment.
A harmful microbe that has the potential to cause disease is called a pathogen. An infection occurs when pathogens invade and multiply within the body or spread among people. When they damage the body’s functions, they cause disease.
The causes of infectious disease:
Bacteria—single-cell organisms that cause strep throat, urinary tract infections and tuberculosis
Viruses—microbes that cause colds, chicken pox, and measles
Fungi—range from skin diseases to lung infections
Parasites—transmitted to humans, these can cause diseases like malaria