Opportunistic infection

What it means

An infection that is caused by a pathogen that would generally not be able to cause an infection in a host with a normal immune system. Such pathogens take advantage of the opportunity, so to speak, that is provided by a weakened immune system.

Opportunistic infection are infections that occur more often or are more severe in people with weakened immune systems than in those with normal immune system functioning.

Rare diseases that can present with this7

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category