Some fungi are persistent, defying curative treatment and leading to long term infection. In most cases, local trauma or damage is a key risk factor, including damage to the cornea of the eye (fungal keratitis) or skin inoculation of a particular fungus such as those causing mycetoma or sporotrichosis. Prior lung disease (particularly TB) is a major risk factor for chronic pulmonary aspergillosis, but it is not known if the same is true for chronic infection of the sinuses. In some cases, the fungus is a primary pathogen (e.g. Histoplasma capsulatum or Coccidioides immitis) and after initial infections fails to resolve properly leading to ongoing infection and inflammation.
The inclusion of fungal keratitis and fungus ball of the sinus together in this section is one of convenience, as not all patients in this category are immunocompromised, unlike those with invasive fungal infections. It is likely that important genetic factors determine the persistence of fungal infection leading to chronic disease.
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