There are several members of the genus Aspergillus causing infection among humans. However, the Aspergillus fumigatus is the most common. Transmission of the disease is associated with the aerial transfer of fungal spores and get entry into the human body through the breathing of these spores.
The allergic symptoms related to aspergillosis are coughing, wheezing beside several inflammatory pulmonary responses. Invasive aspergillosis further complicates these symptoms associated with chest pain, blood in a cough and shortness of breath. People suffering from immunodeficiency are the primary victim of invasive aspergillosis . However, allergic aspergillosis with bronchopulmonary symptoms is the common one estimated to infecting 4.8 million people worldwide .
Blastomyces dermatitidis and Blastomyces brasiliensis
Both Blastomyces dermatitidis and Blastomyces brasiliensis are responsible for causing a debilitating disease blastomycosis  the former in the North American region whereas the late in South Americas. This fungus is mainly found in moist soils with excessive organic matter like wood and leaves. Symptoms associated with blastomycosis are a cough, fever, night sweat, chest pain and severe lethargy. The microscopic spores of both these fungi enter into the human body through breathing and convert into yeast form lung as the body temperature environment is favorable for their growth. The blastomycosis in the North American region is mainly in Arkansas, Louisiana, Michigan, Minnesota, and Wisconsin states [4, 5].
The Candida albicans is an opportunistic pathogen causing several superficial and systemic diseases among immunocompromised humans. Disease caused by this fungus is mainly known as candidiasis. This fungus exists in two forms the yeast a circulate form and branched structure having several hyphae [6, 7]. Different types of candidiasis among human are oropharyngeal, genital and invasive.
Oral candidiasis is usually called as “thrush,” and vaginal infection mainly represented as yeast infections. Besides Candida albicans, there are several other species of this fungus including emerging Candida auris being considered as a global health threat in healthcare facilities like hospitals due it prominent resistance against antifungal agents . Efforts are ongoing to develop an antifungal that can prevent the morphological changes in fungi supposed to be involved in pathogenesis.
Hundreds of Cladosporium species are responsible for causing allergies among humans [9, 10]. Various species of this fungus can either grow inside or outdoor. Humidity and moisture support the growth of this fungus. This fungus is mainly present on the household items like carpets, wallpaper, fabrics, wood, and painted surfaces.
Risk factors for acquiring Cladosporium are a familial history of allergies, the presence of molds at work place and people with chronic skin problems and eczema. Cladosporium associated allergies and asthmatic conditions can be controlled by cleaning house with cleaning strategies. As such, there is a need to develop strategies for the identification of this fungus at home items.
The fungus Cryptococcus neoformans mainly infect the lungs and central nervous system (CNS). The lungs infection with this fungus leads to manifestations like a cough, severe chest pain and fever, whereas meningitis caused by this fungus is life threatning in the majority of the cases. The Cryptococcus neoformans is responsible for serious illnesses among individuals suffering from human immunodeficiency virus infections.
The highest global burden of cryptococcal meningitis is in Sub-Saharan Africa is >700,000 cases followed by East, South and Southeast Asia >133,000 with prevalence in the region like North and South Americas and Caribbean regions including Europe and Middle East regions .
The disease caused by this fungus is either called as mucormycosis or zygomycosis, and there are a variety of species causing disease . Like other fungi, spores are mainly involved in the transmission of disease. Mucormycosis is manifested in a variety of forms like rhino-cerebral, pulmonary, cutaneous, gastrointestinal and disseminated types.
Mucormycosis infections are not very common. However, few outbreaks have also been reported due to spore contamination of material supplied in hospitals . This situation demands, that hospitals supplies mainly linens have to be continuously monitored for the presence of this fungus spores. As unpredicted incidents can happen anytime thus precautionary measures are necessary.
This fungus is mainly present in soils having higher amounts of birds/bats droppings. In the USA Central Eastern States and globally this fungus has been reported in several parts of the world including Asia, Australia, Africa and several South American countries . Intriguingly in the US majority of people (60 - 90%) living in the valleys of Ohio and Mississippi river are exposed to this fungus.
The incidence of histoplasmosis is higher among elderly individuals who have weakened the immune system and immunocompromised individuals . Fungal transmission is through aerosols spores, and histoplasmosis is manifested as a cough, fever, fatigue, lethargy, headache an body aches. Long term lung infections have also been reported due to histoplasmas .
The Pneumocystis jirovecii fungus initially considered as the parasite is responsible for causing a life threatening infection among Pneumocystis pneumonia (PCP) among immunocompromised individuals particularly people suffering from acquired immunodeficiency syndrome (AIDS) . This fungus is transmitted among people through air and is usually present in healthy individuals’ lungs without causing symptoms and removed with the natural immunity mechanisms .
Major symptoms of this fungal infection are difficulty in breathing, fever, cough, chills, and fatigue. There is no effective antifungal agent for controlling this disease. However, a combination of trimethoprim/sulfamethoxazole has shown efficacy in controlling this opportunistic fungal infection. There is an unmet need to develop antifungal for controlling PCP among immunocompromised individuals.
The infections caused by the fungus Sporothrix schenckii are collectively known as sporotrichosis or rose gardener’s disease. This fungus is present universally in soils and plant matter mainly in rose bushes, and hay is the reason calling it rose gardener’s disease.
Cuts and bruises provide entry of this fungus into the human body, and the air is also considered as a conduit for transmitting this fungal infection and different type of sporotrichosis are cutaneous, pulmonary and disseminated based on the region this fungus is causing disease. The Sporotrichosis is considered as a rare fungal disease. However, outbreaks have been reported among the gardeners in countries like USA, Australia, Brazil, China and South Africa .
The Tinea pedis is a fungus causing a disease known as Athlete’s Foot. People acquire this fungus when they go out barefooted. Athletes mainly the swimmers and other athletes are prone to this fungal infection . The fungus spread all across the foot even to the toenails and hands.
Major symptoms associated with this fungal disease are itching and burning feeling between the toes associated with blisters. Cracking of the foot skin is also a manifestation of this fungal disease. This fungal infection is hard to cure even with available anti fungal products. A variety of antifungal and alternative treatments are used for the treatment of Athlete’s Foot.
Professor Dr. Muhammad Mukhtar
1. Rees, J.R., et al., The epidemiological features of invasive mycotic infections in the San Francisco Bay area, 1992-1993: results of population-based laboratory active surveillance. Clin Infect Dis, 1998. 27(5): p. 1138-47.
2. Denning, D.W., A. Pleuvry, and D.C. Cole, Global burden of allergic bronchopulmonary aspergillosis with asthma and its complication chronic pulmonary aspergillosis in adults. Med Mycol, 2013. 51(4): p. 361-70.
3. Castillo, C.G., C.A. Kauffman, and M.H. Miceli, Blastomycosis. Infect Dis Clin North Am, 2016. 30(1): p. 247-64.
4. Baumgardner, D.J., et al., Effects of season and weather on blastomycosis in dogs: Northern Wisconsin, USA. Med Mycol, 2011. 49(1): p. 49-55.
5. Baumgardner, D.J., et al., Geographic information system analysis of blastomycosis in northern Wisconsin, USA: waterways and soil. Med Mycol, 2005. 43(2): p. 117-25.
6. Lossinsky, A.S., et al., The histopathology of Candida albicans invasion in neonatal rat tissues and in the human blood-brain barrier in culture revealed by light, scanning, transmission and immunoelectron microscopy. Histol Histopathol, 2006. 21(10): p. 1029-41.
7. Mukhtar, M., D.A. Logan, and N.F. Kaufer, The carboxypeptidase Y-encoding gene from Candida albicans and its transcription during yeast-to-hyphae conversion. Gene, 1992. 121(1): p. 173-7.
8. Chowdhary, A., C. Sharma, and J.F. Meis, Candida auris: A rapidly emerging cause of hospital-acquired multidrug-resistant fungal infections globally. PLoS Pathog, 2017. 13(5): p. e1006290.
9. de Ana, S.G., et al., Seasonal distribution of Alternaria, Aspergillus, Cladosporium and Penicillium species isolated in homes of fungal allergic patients. J Investig Allergol Clin Immunol, 2006. 16(6): p. 357-63.
10. Katotomichelakis, M., et al., Alternaria and Cladosporium calendar of Western Thrace: Relationship with allergic rhinitis symptoms. Laryngoscope, 2016. 126(2): p. E51-6.
11. Park, B.J., et al., Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDS. AIDS, 2009. 23(4): p. 525-30.
12. Richardson, M., The ecology of the Zygomycetes and its impact on environmental exposure. Clin Microbiol Infect, 2009. 15 Suppl 5: p. 2-9.
13. Duffy, J., et al., Mucormycosis outbreak associated with hospital linens. Pediatr Infect Dis J, 2014. 33(5): p. 472-6.
14. Cano, M.V. and R.A. Hajjeh, The epidemiology of histoplasmosis: a review. Semin Respir Infect, 2001. 16(2): p. 109-18.
15. Woods, J.P., Revisiting old friends: Developments in understanding Histoplasma capsulatum pathogenesis. J Microbiol, 2016. 54(3): p. 265-76.
16. Wheat, L.J., et al., Pulmonary histoplasmosis syndromes: recognition, diagnosis, and management. Semin Respir Crit Care Med, 2004. 25(2): p. 129-44.
17. Catherinot, E., et al., Pneumocystis jirovecii Pneumonia. Infect Dis Clin North Am, 2010. 24(1): p. 107-38.
18. Medrano, F.J., et al., Pneumocystis jirovecii in general population. Emerg Infect Dis, 2005. 11(2): p. 245-50.
19. Acosta Soto, L., et al., Quantitative PCR and Digital PCR for Detection of Ascaris lumbricoides Eggs in Reclaimed Water. Biomed Res Int, 2017. 2017: p. 7515409.
20. Auger, P., et al., Epidemiology of tinea pedis in marathon runners: prevalence of occult athlete's foot. Mycoses, 1993. 36(1-2): p. 35-41.