Aspergillosis

Aspergillus is a ubiquitous filamentous fungus that causes a spectrum of diseases ranging from allergic syndromes to life-threatening invasive infections. Although hundreds of species exist, fewer than 40 cause human disease, most commonly Aspergillus fumigatus, followed by Aspergillus terreus, Aspergillus flavus, and Aspergillus niger.

Illness occurs in cases of allergic reaction, immune suppression, or in previously damaged lung.

There are five main clinical syndromes caused by Aspergillus spp. gaining entry via the respiratory tract:

• Allergic bronchopulmonary aspergillosis (ABPA): this mainly affects patients with asthma, cystic fibrosis and bronchiectasis and is a hypersensitivity reaction to the colonisation of the airways/sinuses/lungs with Aspergillus
• Severe asthma with fungal sensitisation (SAFS): this is severe asthma with evidence of fungal sensitisation who do not meet the criteria for ABPA.
• Aspergilloma: the presence of a mycetoma (fungal ball) of aspergilli in a pre-existing pulmonary cavity
• Invasive aspergillosis: disseminated infection affecting the immunocompromised, which often starts in the lungs but may involve other organs and tissues through haematogenous spread.
• Chronic necrotising pulmonary aspergillosis (CNPA): subacute pulmonary infection affecting those with moderate immunosuppression and with or without pre-existing lung disease, causing a cavitating pulmonary infiltration.

Aspergillus species are also associated with causing otomycosis, extrinsic allergic alveolitis and cerebral infarctions or brain abscesses, endocarditis, and problems in the ears and sinuses.

Reference

1. Janssens I, Lambrecht BN, Van Braeckel E. Aspergillus and the Lung. Semin Respir Crit Care Med. 2024 Feb;45(1):3-20.