Immuno-compromised patients such as transplantation, AIDS and steroid treatment patients are also frequently affected with life-threatening Aspergillus pneumonia and sinusitis. Fortunately, hospital pillows have plastic covers and so are unlikely to cause problems, but patients being discharged home - where pillows may be old and fungus-infected - could be at risk of infection.
Aspergillus can also worsen asthma, particularly in adults who have had asthma for many years, and cause allergic sinusitis in patients with allergic tendencies. Constant exposure to fungus in bed could be problematic. It can also get into the lung cavities created by tuberculosis which affects a third of the world's population, causing general ill-health and bleeding in the lung, as well as causing a range of plant and animal diseases.
Dr Geoffrey Scott, Chairman of the Fungal Research Trust which funded the study, said: "These new findings are potentially of major significance to people with allergic diseases of the lungs and damaged immune systems - especially those being sent home from hospital."
Professor Ashley Woodcock added: "Since patients spend a third of their life sleeping and breathing close to a potentially large and varied source of fungi, these findings certainly have important implications for patients with respiratory disease - especially asthma and sinusitis."