Causes of Acute Sinusitis
Other Possible Acute Sinusitis CausesBesides a virus or bacteria, another possible acute sinusitis cause is an infection with fungus. This is known as fungal sinusitis (see Fungal Sinus Infection (Sinusitis)). Although fungi are abundant in the environment, they usually are harmless to healthy people because the human body has a natural resistance to fungus.
However, in people whose immune system is not functioning properly, fungus such as Aspergillus can cause acute sinusitis. Symptoms tend to be more severe than the typical sinus infection caused by a virus or bacteria.