3 categories of primary systemic mycosis?
1) coccidioidomycosis
2) histoplasmosis
3) blastomycosis
What do all primary systemic mycoses have in common?
- Generalized throughout the body and typically subclinical
- Restricted to a particular geographical area
- Initiated in the LUNGS
- NOT transmissible
Geographical area for coccidioidomycosis?
Southwest- semiarid regions
aka. San Joaquin Fever, Valley Fever
What was inhaled to cause coccidioidomycosis?
Coccidioides immitis spores (from dried up soil/dust)
Describe coccidioides immitis dimorphism
Cool temps (25C) - branching, septate hyphae --> arthrospores Body temp - spherules containing ENDOSPORES in tissues
Two phases of coccidioides immitis: one in soil one in infected tissues
1) Mycelial arthrospore-soil:
Fungi live in dry desert conditions for years –> grow during rainy season (not infectious) –> hyphae develop arthropsores when dry summer months come along (disseminate as arthrocondia) –> become airborne
2) Spherule endospore-infected tissues:
Inhaled arthrospore turns into thick-walled spherule containing endospores–> spherules eventually open and release –> proliferation of infxn.
Primary Pulmonary Coccidioidomycosis
- 60% asymptomatic
- 95% recover from symptomatic (mild flu-like symptoms starting roughly 2 wks. after inhalation)
- 5-8% progress to chronic (cavities and nodules in lungs)- due to failed immune response
Disseminated Coccidioidomycosis (mostly in immunocompromised)
- Less than 1% affected –> rapid, and fatal
- Spread beyond lungs –> lymph –> blood spread
- Present with dramatic sweats, dyspnea at rest, fever, weight loss
- Often skin, bones, joints, and CNS (meningitis)
- Can take weeks to 2 years
Diagnosis for Coccidioidomycosis
Micro: Spherules in sputum, exudate, tissues in KOH
Serology: Coccidioidin Ag to detect antibody to mycelial-phase proteins; serum IgM Ab with primary infections; IgG later
Elevated IgG serum Ab is marker of disseminated (extrapulmonary)
Treatment for Coccidioidomycosis
Fluconazole, Itraconazole, or Amph B
What is the most prevalent mycotic infection in humans and animals?
Histoplasmosis
What are the two varieties of histoplasmosis causing agents?
1) Histo. Capsulatum capsulatum
2) Histo. Capsulatum duboisii
Dimorphism of Histo
Ambient/Cool temps (25C) - branching, septate hyphae –> microcondia and TUBERCULATE (round) macrocondia
Body temp- small, narrow-based, ovoid, budding yeast
Where is Histo normally found?
Soils contaminated with bird dung- chicken coops, roosts, caves, etc.
Who is at high risk for Histo infection?
- Construction; bulldozing decaying buildings
- Smokers
- Children
- Immunocompromised
Acute forms of histoplasmosis
1) Acute asymptomatic pulmonary
2) Acute symptomatic pulmonary: Chest pain while inhaling, fever, cough, chills
Chronic Pulmonary Histoplasmosis
- Fever- may resemble symptoms of pulmonary TB (cough up blood)
- Excessive sweating
- Shortness of breath
- Cough
- Chest Pain
Disseminated Histoplasmosis
- Mouth sores
- Skin Lesions
- Headache
- Fever
Other: can have joint pain, rashes, ERYTHEMA NODOSUM
What is the infectious/inhaled version of Histo?
Microconidia in soil containing bird droppings
Pathogenesis of Histoplasmosis
- 90% inhibited through CMI
Microconidia is inhaled –> develop into yeast and replicate in alveolar MQ –> acute pulm. histo (self-limiting; some nodules heal with calcification) –> chronic pulm. histo (especially in men with emphysema)
**After lung development can take disseminating route to reticuloendothelial tissues and become granulomatous –>DEATH
Geographical area for Histoplasmosis
Central and eastern states, Ohio River Valley, and Mississippi River Valley… Indiana area-ish. and more south.
Because yeast form survive and thrive in MQ like TB, infected individuals will have a similar response in a Histo skin test.
FYI
What percent of the population would likely test positive for Histo ‘round these parts?
90% COMFORTING
Diagnosing Histoplasmosis
- Presence of fungus in sputum, lung tissue, blood, CSF, BM
- Ag test: Capsular Ag in blood, urine, CSF
- X-rays show lung abnormalities- hilar calcifications
