Infectious Disease Terms

Viral, bacterial, fungal, and parasitic infections. Browse definitions and meanings below.

230 terms

What is an infectious disease?

An infectious disease is an illness caused by an organism that entered the body from outside: a bacterium, virus, fungus, parasite or prion. What sets this group apart is that the cause can move between hosts, which is why the vocabulary includes words for transmission, incubation and containment.

Infection and disease are not the same thing, and the distinction does real work. Infection means the organism has established itself; disease means it is causing harm. A person can carry an organism for years without illness, and remain able to pass it on throughout.

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For learning, not diagnosis. This glossary provides general educational information and is not a substitute for advice from a qualified healthcare professional. If you may be experiencing a medical emergency, contact local emergency services.