Coccidioidomycosis : Diagnosis, Pathophysiology And Treatmet
Coccidioidomycosis is caused by infection with Coccidioides immitis. The endemic regions encompass the semi-arid regions of the southwestern United States from California to Texas, known as the Lower Sonoran Zone.
- Most of those infected are asymptomatic or have nonspecific symptoms that are often indistinguishable from those of ordinary upper respiratory infections, including fever, cough, headache, sore throat, myalgias, and fatigue. A fine, diffuse rash may be appear during the first few days of illness.
- â€œValley feverâ€ is a syndrome characterized by erythema nodosum and erythema multiforme of the upper trunk and extremities in association with diffuse joint aches or fever. Valley fever occurs in approximately 25% of infected persons, although, more commonly, a diffuse mild erythroderma or maculopapular rash is observed.
- Pulmonary coccidioidomycosis can also present as acute pneumonia or develop into a chronic, persistent pneumonia complicated by hemoptysis, pulmonary scarring, and the formation of cavities of bronchopleural fistulas.
- Disseminated infection occurs in less than 1% of infected patients. Dissemination may occur to the skin, lymph nodes, bone, meninges, spleen, liver, kidney, and adrenal gland.
Diagnosis of Coccidioidomycosis
- Most patients develop a positive skin test within 3 weeks of the onset of symptoms.
- Infection is characterized by the development of IgM to C. immitis, which peaks within 2 to 3 weeks of infection and then declines rapidly, and IgG, which peaks in 4 to 12 weeks and declines over months to years.
- Recovery of C. immitis from infected tissues or secretions for direct examination and culture provides an accurate and rapid method of diagnosis
Treatment of Coccidioidomycosis :
- Only 5% of infected persons require therapy. Candidates for therapy include those with severe primary pulmonary infection or concurrent risk factors (e.g., HIV infection, organ transplant, or high doses of glucocorticoids), particularly patients with high complement fixation antibody titers in whom dissemination is likely.
- Specific antifungals (and their usual dosages) for the treatment of coccidioidomycosis include amphotericin B IV (0.5 to 0.7 mg/kg/day), ketoconazole (400 mg orally daily), IV or oral fluconazole (usually 400 to 800 mg daily, although dosages as high as 1200 mg/day have been utilized without complications), and itraconazole (200 to 300 mg orally twice daily as either capsules or solution). If itraconazole is used, measurement of serum concentrations may be helpful to ascertain whether oral bioavailability is adequate. Amphotericin B is generally preferred as initial therapy in patients with rapidly progressive disease, whereas azoles are generally preferred in patients with subacute or chronic presentations. Treatments for primary respiratory disease (mainly symptomatic patients) are 3- to 6-month courses of therapy.