Fungi

Fungi are unicellular or multicellular eukaryotic organisms found everywhere in nature. From large macroscopic species such as mushrooms and molds to microscopic yeasts, fungi exhibit remarkable morphological diversity.

While most fungi are harmless to humans, some can cause disease under specific conditions.

Image: “Hands of a woman with onychia mycosis” (watercolour, 1889) by Leonard Portal Mark. Courtesy of Barts Health NHS Trust Archives / Wellcome Images, original file “Hands_of_a_woman_with_onychia_mycosis_Wellcome_L0062076.jpg” on Wikimedia Commons (https://commons.wikimedia.org/wiki/File:Hands_of_a_woman_with_onychia_mycosis_Wellcome_L0062076.jpg). Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0, https://creativecommons.org/licenses/by/4.0/).

Public Health and Global Significance

Fungal infections kill over 1.5 million people each year and affect more than one billion globally [1][2]. Despite this, they remain a neglected public health issue, even though most deaths could be prevented with timely diagnosis and accessible treatment.

Severe fungal infections often occur as complications of underlying conditions such as:

• Asthma

• AIDS/HIV

• Cancer

• Organ transplantation

• Immunosuppressive therapy

Transmission and Pathogenesis

• Fungi reproduce through spores that spread via direct contact or inhalation.

• Infections most commonly affect the skin, nails, and lungs, but fungi can also penetrate the skin barrier, invade organs, and cause systemic infections [3].

• Many fungal infections are chronic and difficult to treat, with invasive mycoses often requiring months to years of therapy.

Unique Characteristics of Fungal Infections

• Often chronic and potentially fatal if untreated.

• Low contagion rate compared to bacterial or viral diseases, which contributes to limited public health awareness [4].

• Certain chronic infections, such as chromoblastomycosis and eumycetoma, can cause disfigurement, social isolation, and functional impairment [5].

Epidemiology

Fungal infections represent a major global disease burden:

• Chronic pulmonary aspergillosis: ~3 million cases annually

• Cryptococcal meningitis (HIV/AIDS-related): ~223,100 cases and 181,000 deaths per year, mainly in sub-Saharan Africa

• Invasive candidiasis: ~700,000 cases

• Invasive aspergillosis: ~250,000 cases

• Histoplasmosis: ~100,000 cases

• Fungal asthma: ~10 million cases worldwide [1]

• Pneumocystis pneumonia: >400,000 deaths yearly in untreated patients

Emerging Threats and Medical Context

Systemic fungal infections were rare before the 1950s, but modern medicine has created new opportunities for fungi to infect vulnerable hosts.Risk factors include:

• Antibiotic use

• Intensive care unit (ICU) treatment

• Immunosuppressive therapy

• Chemotherapy

Mortality rates for invasive fungal infections remain high — 30–90%, depending on the pathogen and patient group [6].

Superficial and Invasive Infections

Superficial infections:Affect skin, hair, and nails, impacting over 1 billion people worldwide.

Mucosal infections:Candida species causing oral or vaginal candidiasis.

Chronic subcutaneous infections:Include mycetoma and chromoblastomycosis, classified as neglected tropical diseases.

Chronic pulmonary fungal infections:Often develop as complications of tuberculosis or other chronic lung diseases.

Fungal allergies:Contribute to worsening of asthma, cystic fibrosis, and chronic sinusitis.

Invasive fungal infections:Life-threatening, requiring rapid diagnosis and targeted antifungal therapy.

Common Fungal Infections in Humans

• Aspergillosis: Severe lung infection in immunocompromised individuals.

• Blastomycosis: Primarily pulmonary, may spread to skin and bones.

• Candida albicans: Causes oral, vaginal, and systemic infections.

• Chromoblastomycosis: Chronic skin/subcutaneous infection, tropical or subtropical regions.

• Coccidioidomycosis: Pulmonary infection with fever and rash, common in the USA and Mexico.

• Cryptococcosis: Lung and CNS infection in AIDS patients.

• Tinea pedis (athlete’s foot): Common superficial fungal infection.

• Histoplasmosis: Acute flu-like or chronic, potentially fatal lung infection.

• Mucormycosis: Aggressive opportunistic infection.

• Onychomycosis: Nail fungus, common in elderly and diabetic individuals.

• Paracoccidioidomycosis: Endemic in South and Central America.

• Pneumocystis pneumonia: AIDS-related, fatal if untreated.

• Sporotrichosis: Chronic skin infection (“rose gardener’s disease”).

• Tinea versicolor/cruris: Superficial skin infections, common in tropical climates [7][8].

Conclusion

Fungal diseases represent a major yet underestimated global health challenge. Their chronic progression, complex pathogenesis, and high mortality rates in invasive cases demand greater attention from public health systems.Improved diagnostic tools, access to antifungal therapies, and vaccine development (where possible) are critical steps toward reducing global fungal disease burden.

References:

1. Bongomin F, Gago S, Oladele RO, Denning DW. Global and multi-national prevalence of fungal diseases—estimate precision. Journal of fungi. 2017 Dec;3(4):57.;https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5753159/

2. McKeny PT, Zito PM. Antifungal Antibiotics.2020 :https://www.ncbi.nlm.nih.gov/books/NBK538168/

3. Healthline Fungal Infections :https://www.healthline.com/health/fungal-infection#types

4. Casadevall A. Fungal diseases in the 21st century: the near and far horizons. Pathogens & immunity. 2018;3(2):183.:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6241320/

5. Rodrigues ML, Nosanchuk JD. Fungal diseases as neglected pathogens: A wake-up call to public health officials. PLoS neglected tropical diseases. 2020 Feb 20;14(2):e0007964 :.https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0007964

6. Fisher MC, Gurr SJ, Cuomo CA, Blehert DS, Jin H, Stukenbrock EH, Stajich JE, Kahmann R, Boone C, Denning DW, Gow NA. Threats posed by the Fungal Kingdom to humans, wildlife, and agriculture. mBio. 2020 Jun 30;11(3).:https://mbio.asm.org/content/11/3/e00449-20#sec-2

7. Gupta AK, Ricci MJ. Diagnosing onychomycosis. Dermatol Clin. 2006;24(3):365–9.

8. The free dictionary Available from:https://medical-dictionary.thefreedictionary.com/sporotrichosis