Air borne fungal diseases-Dr C R Meera

 Diseases transmitted through air and caused by fungus are called air borne  fungal diseases.  Air borne  fungal diseases Includes Cryptococcosis,  Blastomycosis, Coccidioidomycosis,  Histoplasmosis and Aspergillosis. 

1.  Cryptococcosis

Causative agent is a yeast, Cryptococcus neoformans. It is a soil saprophyte and inhalation of soil particles containing the causative agent will cause the disease.  Most of the infections are asymptomatic, but sometimes the infection may cause pulmonary cryptococcosis, leading to mild pneumonitis or inflammation of the lungs. 

2.  Blastomycosis

Causative agent is Blastomyces dermatitis.  This is also a soil borne fungus liberated to air by environmental or human activities. Inhalation of these soil particles containing the fungus will cause infection. Blastomycosis is a type of chronic infection. Suppurative (pus forming) and granulomatous lesions are formed in any part of the body. 

3. Coccidioidomycosis

Causative agent is soil fungus, Coccidioides immitis. Arthrospores of this fungus are liberated from soil into air by environmental and human activities. Inhalation of spores through the dust particles will lead to infection. Respiratory infection by Coccidioides immitis may be inpparent, benign, severe or even fatal. In most cases, respiratory infection is asymptomatic and gives lifetime immunity. Usually infection leads to self limited influenza  fever called “Valley fever” or “Desert rheumatism”. However, less than 1% of individuals develop chronic disease called “Coccidioidal  granuloma”,  which is fatal.

4. Histoplasmosis

Causative agent is Histoplasma capsulatum. This fungus is seen on rotting trees and in soil. Inhalation of spores liberated in air causes infection. Most of the infections are asymptomatic, but sometimes the fungus can cause intracellular infection of the reticuloendothelial system. This infection results in lymphadenopathy, hepatosplenomegaly, fever and anaemia which is highly fatal. Some people develop pulmonary disease resembling tuberculosis or TB.

5. Aspergillosis

Aspergillosis is caused by Aspergillus fumigatus. Aspergillus is an omnipresent fungus seen in organic matter, in soil, decomposing plants and animals, household dust, building materials, in some food and water.  Aspergillus is an opportunistic pathogen, meaning it is not a pathogen under normal conditions,  but when the conditions are favourable, it will cause infection in human beings. Major route of infection is the inhalation of conidiospores liberated in air from various sources containing this fungus. Inhalation of this fungus causes two types of Pulmonary aspergillosis. First type is called Allergic aspergillosis in which allergic response and asthma attacks are the results. Second type is called Bronchopulmonary aspergillosis. In this case, due to type 1 and type 2 hypersensitivity reactions, Bronchitis (inflammation of bronchi) is developed.  Also fungal growth in lungs will produce fungus balls called ‘aspergilloma’. Aspergilloma consists of tangled mass of fungus hyphae growing in the lungs which may spread to other organs and tissues.