•         Fungi include yeast and mould

•         most are harmless, 50 species cause human diseases

•         incidence of serious fungal infection low

•         certain superficial fungal infection more common

Fungal Disease Mechanisms;

1. Some fungi cause immune reponse - may result in allergic ( hypersensitivity) reaction upon exposure to specific fungal antigen- eg. Aspergillus cause asthma & other allergic reaction
2. Production and action of mycotoxin (fungal exotoxin) eg. Aspergillus flavus grow on stored grains- aflatoxins highly toxic, induce tumors in some animals feeding on contaminated grains
3. Infection- growth of fungus on/in body + mycoses- range in severity - innocuous, superficial to life-threatening disease

Mycoses

3 categories:

I) Superficial Mycoses

•          colonisation of skin, hair/nails, infect only surface layers

•         disease is benign & self-limiting eg. Athlete’s foot (Tricophyton)

•         spread-personal contact with infected person, contaminated surfaces-bathtub, towels/bed linen

•         Treatment: topical application miconazole or griseofulvin

•         sometimes orally-drug enter bloodstream pass to skin inhibiting fungal growth

II) Subcutaneous Mycoses

•         involve deeper layers of skin

•         disease sporotrichosis - starts with infection of small wounds/abrasions forms ulcer and chancres

•         Treatment: oral potassium iodide or oral ketoconazole

III) Systemic Mycoses

•         fungal growth in internal organs -

classified as primary and secondary infections

-Primary- resulting in healthy individual due to fungal infection

-Secondary- due to individual who has impaired immunity - antibiotic therapy/immunosuppression

•         Histoplasmosis (Histoplasma capsulatum) and coccidiomycosis(Coccidioides immitis)both soil organisms, common & widespread  diseases in US.

•         Infection-airborne spores germinate an grow in lungs-respiratory disease

•         opportunistic fungal infection cauisng serious infections in individual with impaired immunity eg.AIDS patients

•         Effective fungal diseases difficult - lack of suitable fungus-specific antibiotic, most of these antibiotics also harm other eukaryotic organisms including human host

•         amphotericin B most effective, treatment of systemic infection inhuman- side effects kidney toxicity

•         elimination lf fungal pathogens from environment impractical-limitless reservoir

•         decontamination and air filteration in restricted environment possible