Infection: There are over 100 species that are known to cause infection in humans. Three classifications of infection caused by fungi are systematic, opportunistic, and dermatophytic.
Toxicosis: Many fungi produce toxic metabolites called mycotoxins. The health effects from exposure to the levels of mycotoxins that may be encountered in contaminated indoor environments are not yet completely known. However, dramatic toxic and carcinogenic effects have been reported for animals and humans exposed to high levels of mycotoxins in laboratory studies. Generally mycotoxins are non-volatile and exposure usually occurs only after disturbance of a contaminated source. Symptoms of exposure may include headache, nosebleeds, dermatitis, and immune suppression.