Coccidioidomycosis is an endemic systemic mycosis resulting in both asymptomatic and life-threatening disseminated infections.
- Coccidioides spp. are dimorphic fungi that live in the soil.
- Endemic to the southwestern United States (southern California, Arizona, western and southern Texas, New Mexico), northern Mexico, and parts of South and Central America
- Infection is acquired from exposure to aerosolized spores (arthroconidia) usually during recreational or occupational activities; clusters of cases may involve dust storms and earthquakes.
- The average incubation period is 10 to 16 days (range 1 to 4 weeks) for primary infection.
- There is no person-to-person spread except in rare instances of draining lesions or donor derived transmission through organ donation.
- 60% of acute infections are subclinical (asymptomatic).
- Rising incidence reported in the United States over the past 2 decades
- Annual incidence in 2011 was 42.6 per 100,000 population.
- Highest rate of infection in the summer and early fall
Seropositivity rates in children living in endemic area for 1 year approach 20%, whereas rates in children living in endemic area for 10 or more years approach 80%.
- The course of illness is highly variable and depend on host immune response and amount of exposure.
- Risk factors for disseminated infection:
- Immunosuppression (especially organ transplant recipients, those receiving immunosuppressive therapies and immunomodulators, and those with HIV infection)
- Male gender (adult)
- Neonates, infants, and the elderly
- Filipino, African American, Native American, Hispanic ethnicity
- Risk of dissemination is less in children than in adults.
- No special isolation or precautions for the hospitalized patient
- Contaminated dressings from skin lesions should be handled and discarded with care.
- Inhalation of aerosolized spores from culture can be hazardous to laboratory personnel.
- Preventive efforts are aimed at dust control and trials to eliminate organisms from soil.
- Immunocompromised people should be counseled to avoid activities that may expose them to aerosolized spores in endemic areas.
- Spores (arthroconidia) are the infectious forms of Coccidioides organisms; they are released from the mold and propagate the mold in the soil.
- Inhalation of arthroconidia from disturbed, arid soil is the major route of infection.
- In tissues, arthroconidia enlarge to form spherules. Mature spherules release endospores that propagate in the host and continue the tissue cycle.
- Primary infection occurs in the lungs.
- Most patients have infection limited to a localized area of lung and hilar lymph nodes after mounting an intense inflammatory response with granuloma formation.
- Extrapulmonary dissemination occurs via lymphatic or hematologic spread and usually involves the skin, bones and joints, and central nervous system but can spread to virtually any organ system.
- Coccidioides immitis and Coccidioides posadasii are the etiologic agents of coccidioidomycosis.
- Asymptomatic infection is the most common outcome, occurring in 60% of infected individuals.
- Primary pulmonary infection accounts for most symptomatic cases; nonspecific illness most common feature (cough, malaise, chest pain, fever); self-limited in most cases; may be accompanied by reactive rashes such as erythema multiforme or erythema nodosum
- Disseminated disease occurs in <1% of infected individuals and may manifest with
- Subacute or chronic and frequently involves more than one bone (40%)
- Common sites are the hands, feet, ribs, skull, and vertebrae.
- Develops within 6 months of initial infection
- Hydrocephalus is a common complication.
- Central nervous system vasculitis and intracerebral abscesses are rare.
- Cutaneous disease:
- Papules or pustular lesions that ulcerate are most common.
- Most commonly seen on the face but can occur anywhere
- Regional adenitis is common.
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