247.1 🎓 醫孞生版

247.1.0.1 📌 䞀頁重點

247.1.0.1.1 Microbiology
  • Coccidioides immitis (California) + C. posadasii (other SW USA + Latin America)
  • Dimorphic fungus
  • Mycelial phase: in soil — arthroconidia (spores)
  • Tissue phase: spherules (10-100 µm) containing endospores — pathognomonic on histology
247.1.0.1.2 Geography
  • USA: Southwest (Arizona — Maricopa County, California — San Joaquin Valley, Nevada, New Mexico, Texas western, Utah southern)
  • Northern Mexico
  • Central + South America (Argentina, Brazil, Honduras, Venezuela)
  • Soil + arid + semi-arid climates
  • Dust storms + droughts → outbreaks (climate change expanding)
247.1.0.1.3 Transmission
  • Inhalation of arthroconidia from soil
  • Dust storms + construction + agricultural + earthquakes
  • Outdoor activities
  • NOT person-to-person (except rare organ transplant)
247.1.0.1.4 Burden
  • ~ 20,000 cases/yr USA (likely under-reported; possibly > 100,000)
  • 60-70% asymptomatic; 30-40% symptomatic
  • Increasing recognition + climate change
247.1.0.1.5 Clinical
247.1.0.1.5.1 Asymptomatic (~ 60%)
  • Most acquired infections
  • Lifelong immunity
247.1.0.1.5.2 Acute Pulmonary “Valley Fever” (30-40%)
  • 1-3 weeks post-exposure
  • Flu-like illness (fever, cough, fatigue, headache, myalgia)
  • Erythema nodosum + erythema multiforme (hypersensitivity reactions — classic)
  • Arthralgia (“desert rheumatism”)
  • Self-limited weeks-months
  • Eosinophilia common
247.1.0.1.5.3 Chronic Pulmonary
  • 5-10% of acute → chronic
  • Persistent cough, weight loss, fatigue
  • Nodules (often peripheral, solitary)
  • Cavities (sometimes complicated by mycetoma)
  • Months-years
247.1.0.1.5.4 Disseminated Coccidioidomycosis (Severe)
  • 0.5-5% of infections; higher in high-risk hosts
  • Risk Factors for Dissemination:
    • Filipino ancestry (highest risk; 100× general population)
    • African American ancestry (10× higher)
    • Pregnancy (especially 3rd trimester + postpartum)
    • HIV CD4 < 250
    • Solid organ + HSCT
    • Diabetes mellitus
    • Hispanic / Native American (intermediate risk)
  • Clinical:
    • Skin (#1 extrapulmonary): nodules, ulcers, granulomas
    • Bone + joint: lytic lesions, septic arthritis
    • Meningitis (most feared): persistent headache, altered mental status, cranial nerve palsies, hydrocephalus
    • Disseminated multi-organ
247.1.0.1.5.5 Coccidioidal Meningitis
  • Lifelong fluconazole (or itraconazole) — Tx of choice
  • 80%+ relapse if Tx discontinued
  • Mortality 10-30% with treatment
  • Hydrocephalus common (shunt often needed)
247.1.0.1.6 Diagnosis
  • Serology (anti-Coccidioides antibody): complement fixation (CF), immunodiffusion, EIA
    • IgM elevated acute; IgG later
    • CF titer correlates severity
  • Culture of sputum / BAL / tissue (BSL-3 — highly infectious!)
  • Histology: spherules with endospores in tissue (pathognomonic)
  • PCR emerging
247.1.0.1.7 Treatment
247.1.0.1.7.1 Asymptomatic / Mild Acute (Immunocompetent)
  • Observation (self-limited usually); no treatment
  • Symptom management
247.1.0.1.7.2 Symptomatic Acute (Immunocompetent)
  • Fluconazole 400 mg PO daily if severe symptoms, weight loss, long duration, persistent
  • 6-12 months
  • Many don’t require treatment if mild self-limited
247.1.0.1.7.3 Severe Pulmonary / Disseminated
  • Fluconazole 400-800 mg PO daily or itraconazole 200 mg bid
  • Continued for life in severe / immunocompromise (relapse common)
247.1.0.1.7.4 Coccidioidal Meningitis
  • Fluconazole 400-1200 mg/d PO LIFELONG (or itraconazole)
  • Intrathecal AmB if refractory
  • VP shunt for hydrocephalus
  • Relapse very common if Tx stopped
  • Mortality + morbidity high
247.1.0.1.7.5 Pregnancy
  • Avoid fluconazole 1st trimester (teratogenic)
  • Amphotericin B preferred during pregnancy if needed
  • Switch to fluconazole postpartum
247.1.0.1.7.6 Severe / Multi-Organ
  • Liposomal Amphotericin B induction → fluconazole maintenance