Coccidioidomycosis
๐ฆ Coccidioidomycosis is an infection caused by inhaling soil-based spores of the dimorphic fungus
Coccidioides immitis.
Endemic in dry desert regions of the Americas, it is also called "Valley Fever" or "San Joaquin Valley Fever".
๐ About
- Endemic to dry regions: central California, Arizona, parts of Texas, Mexico, Central & South America.
- Outbreaks often occur after dust storms or soil disruption.
๐ค Clinical Presentation
- Pulmonary disease (commonest): Fever, cough, chest pain, malaise, erythema nodosum ("desert bumps").
- Subacute meningitic syndrome: Headache, malaise, cranial nerve palsies, progressive over months.
- Disseminated disease: (rare, ~0.5%) can cause:
- Granulomatous meningitis
- Osteomyelitis, septic arthritis
- Pericardial effusion
- Sepsis / septic shock
โ ๏ธ Risk Factors for Dissemination
- Advanced HIV/AIDS (CD4 <250)
- Prolonged corticosteroid use
- Haematologic malignancy
- Solid organ transplantation
- TNF-ฮฑ antagonists (etanercept, infliximab)
๐งช Investigations
- CXR: Pulmonary infiltrates, cavitation.
- Sputum: Rule out TB (differential).
- HIV test: AIDS-defining illness.
- Serology: IgM & IgG titres for diagnosis and monitoring.
- Skin test: Coccidioidin (not widely used now).
- CSF (if meningitis suspected): โ Protein, โ Glucose, โ WCC with eosinophils, positive complement fixation tests.
๐ Management
- Mild pulmonary disease: Often self-limiting, may need no antifungal therapy.
- Moderate-severe / disseminated disease: Oral azoles (fluconazole, itraconazole, ketoconazole) for 3โ6 months. Posaconazole is an alternative.
- Severe / CNS disease: IV Amphotericin B.
- โ ๏ธ Long-term suppressive therapy may be required for meningitis.
๐ Key Teaching Points
- Think of it in travellers or migrants from endemic regions with unexplained pneumonia-like illness.
- Distinguish from TB (similar chest findings, chronic cough, cavitation).
- Important opportunistic infection in immunocompromised patients (HIV, transplant).
- Pregnant women are at increased risk of dissemination and require treatment.
Cases - Coccidioidomycosis
- Case 1 - Acute Pulmonary Disease:
A 32-year-old man returns from Arizona with fever, cough, chest pain, and erythema nodosum on his shins. Chest X-ray shows unilateral infiltrates. Serology for Coccidioides is positive.
Diagnosis: Primary pulmonary coccidioidomycosis (โValley feverโ).
Management: Usually self-limiting; if severe or immunocompromised โ oral fluconazole/itraconazole. Supportive care with rest and fluids.
- Case 2 - Disseminated Disease in Immunocompromised Host:
A 45-year-old man with advanced HIV presents with chronic cough, weight loss, fever, and worsening headaches. CT chest shows cavitary lung lesions; MRI brain shows enhancing lesions. CSF culture grows Coccidioides immitis.
Diagnosis: Disseminated coccidioidomycosis with CNS involvement.
Management: High-dose fluconazole (lifelong therapy for CNS disease), or amphotericin B in severe cases. Antiretroviral therapy optimisation.
Teaching Commentary ๐ต
Coccidioidomycosis is a fungal infection caused by Coccidioides immitis and C. posadasii, endemic to the Southwestern USA, Mexico, and parts of Central/South America. Infection follows inhalation of arthroconidia.
- Most infections are subclinical or mild โValley feverโ with flu-like illness, cough, chest pain, and erythema nodosum.
- Dissemination (skin, bone, meninges) occurs in <1%, but risk is higher in immunocompromised patients, pregnancy, and certain ethnicities (Filipino, African descent).
Diagnosis: serology, culture, or histology. Treatment: most mild pulmonary cases resolve spontaneously, but severe/disseminated disease needs azoles (fluconazole/itraconazole) or amphotericin B.
