Coccidioidomycosis
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Contents |
Introduction
- Disease is acquired via arthroconidia of the mold phase of Coccidioides immitis which disperse into the air. Epidemic infections may occur.
Etiology
- Risk factors for disseminated disease:
- Black
- Filipino
- Asians, Mexicans, Native Americans may be at increased risk
- Adult men develop disseminated disease more frequently than women
- pregnant
- debilitated
- immunocompromised
- severe primary infection
- complement fixation (CF) titers > 1:32
- persistent symptoms, > 6 weeks duration
- negative skin test
Pathology
- primary infection is in the lung:
- primary skin infection is rare
- tissue response is granulomatous with & without caseation
- developing spherules
- found in macrophages & multinucleated giant cells
- 10-80 um in size
- endospores within spherules: 2-5 um in size
- dimorphic pathogen
- arthroconidia in specimen are infective; disease may be contracted directly from laboratory specimen
Clinical-manifestations
- most frequently asymptomatic
- pulmonary signs/symptoms
-
- fever
- cough
- chest pain
- hemoptysis
- solitary pulmonary nodules (may persist)
- unilateral hilar adenopathy
-
- more frequent in adult women than in men
- may accompany primary infection
- are good prognostic signs
- papules
- ulcers
- draining sinuses
- subcutaneous abscesses
- disseminated disease most commonly affects:
- skin
- skeletal system: arthritis most commonly results from involvement of adjacent bone
- meninges:
- meningeal signs/symptoms
- may be acute
- most commonly indolent & chronic
Laboratory
- cytologic methods
- sensitivity only 50%
- wet preparations
- Calcofluor white staining
- 10-30% KOH may remove interfering tissue elements
- spherules may be demonstrated in:
- hyphae may be seen in cavitary lesions
- cultures are infective (use special precautions)
- organism grows rapidly (< 1 week)
- colonies are extremely variable in appearance
- alternating barrel-shaped arthroconidia with empty disjunctor cells
- Coccidioides serology with complement fixation (CF)
- useful for assessing extent & prognosis (in contrast to histoplasmosis & blastomycosis)
- antibodies detected 2-6 weeks after infection
- higher titers increase probability of disseminated disease
- rising titers suggest poor outcome
- rapid serologic tests may be useful for screening
- does not produce seroconversion as in histoplasmosis
- disseminated infection may be accompanied by anergy to skin testing
Complications
- pneumothorax
- empyema
- pericarditis
- atelectasis
- progressive pulmonary infection (resembles tuberculosis)
- dissemination (see clinical manifestations)
- chronic residual disease
Differential-diagnosis
- Blastomyces dermatitidis (non- budding form)
- Cryptococcus neoformans (non- budding form)
- adiaspiromycosis ( fungal form)
- rhinosporidiosis ( fungal form)
Management
- rapidly progressive or disseminated disease:
- amphotericin B: total dose 1-3 g
- lumbar puncture to assess meningeal involvement
- itraconazole
- fluconazole 400 mg PO QD
- mild to moderately severe disease
- drug of choice in coccidioidal meningitis
- ketoconazole [3]
- treatment should be continued for 1 year after resolution of signs & symptoms & indefinitely in patients with AIDS or coccidioidal meningitis
- the majority of primary infections resolve spontaneously without specific treatment
More General Terms
Additional Terms
References
- Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 324
- Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1234
- Medical Knowledge Self Assessment Program (MKSAP) 11, 15, American College of Physicians, Philadelphia 1998, 2009
