n.
- An infection by a microorganism that normally does not cause disease but becomes pathogenic when the body’s immune system is impaired and unable to fight off infection, as in AIDS and certain other diseases.
- An infection by a microorganism that normally does not cause disease but does so when lowered resistance to infection is caused by the impairment of the body’s immune system.
An infection caused by a microorganism that under normal conditions would not bring about disease. Opportunistic infections occur when the body’s immune system is weakened by disease or malnutrition. (See AIDS.)