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Coccidioidomycosis |
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- Caused by Coccidioides immitis
- Endemic in Southwestern United States
- San Juaquin Valley -- "Valley fever"
- Phoenix -- "desert fever"
- Probably most virulent fungal pathogen
- Dimorphic
- Grows as hyphae, arthrospores in sandy soil
- Grows as spherules, endospores in tissue
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Historical Perspective |
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- First fungal pathogen recognized as dimorphic
- Posadas and Wernicke -- Protozoan?
- Riford & Gilchrist - isolated mold “contaminant”
- Ophuls & Moffitt -- worked out life cycle
- 1920’s and 1930’s -- recognized soil was reservoir, mild infection was common, severe disease uncommon
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Distribution of C. immitis |
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Primarily in Lower Sonoran Life Zone
- Semi-arid - alternating wet and dry seasons
- Hot summers, cool winters
Ecological Niche
- Sandy alkaline soil
- Inhabits rodent burrows
Endemic areas
- Parts of AZ, CA, TX
- Cases in Wisconsin - How?
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Coccidiodomycosis |
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Most common in dogs
- Breed susceptibility )Boxers, Dobermans)?
- Initial pulmonary infection - disseminates to long bones (legs) and elsewhere
Other animal species
Human disease
- Infection common in endemic areas - mild respiratory disease, rash, arthralgia, skin test +
- Associated with desert activity - excavation
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Pathogenesis |
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- Arthrospores inhaled
- Germinate into spherules in lung
- Spherules cleave internally into endospores
Granulomatous inflammation
- Macrophages, lymphocytes
- Can disseminate via lymphatic and bloodstream to other sites
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Diagnosis |
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- Try to visualize spherules and endospores in tracheal wash or lesion biopsy
Culture
- fluffy white mold - Biohazard!
- isolate as spherules - injection of animal
Serology
- coccidioidin is crude antigen
- Precipitins - early Abs
- C fixing Abs - prognostic, if elevated its a poor sign
- Skin test - many healthy individuals +
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