From the Guidelines
Treatment for chronic Coccidioides infection detected by EIA with positive IgG and negative IgM antibodies should be initiated for symptomatic patients, those with progressive disease, immunocompromised individuals, pregnant women, and patients with disseminated infection. First-line treatment is fluconazole 400-800 mg daily for at least 3-6 months, with some cases requiring 12 months or longer depending on clinical response, as suggested by the 2016 IDSA clinical practice guideline for the treatment of coccidioidomycosis 1. Alternative options include itraconazole 200 mg twice daily, which may be preferred for skeletal infections. Severe cases might require amphotericin B (lipid formulation 3-5 mg/kg/day or deoxycholate 0.7-1.0 mg/kg/day). Treatment decisions should be individualized based on disease severity, location of infection, and patient factors, considering the clinical response and potential side effects of antifungal treatment 1. Regular monitoring of clinical symptoms, radiographic findings, and serologic titers is essential to assess treatment response. The absence of IgM with positive IgG indicates a non-acute, established infection, which often requires longer treatment courses than acute disease. Some patients with mild, stable disease and normal immune function may be monitored without antifungal therapy if they remain clinically stable, as indicated by the lack of effective antifungal treatment for uncomplicated coccidioidal pneumonia in the past 1. However, for patients with concurrent diabetes or who are otherwise frail because of age or comorbidities, initiating antifungal treatment is recommended, with treatment courses continued for at least 1 year and, in some cases, longer 1. It is also important to note that some experts recommend higher doses of fluconazole, but there is no evidence that higher doses are more effective, and treatment should be tailored to the individual patient's response 1.
From the Research
Treatment of Coccidioides Infection
- The decision to treat Coccidioides infection is based on various factors, including the severity of symptoms, the presence of underlying medical conditions, and the results of serologic tests 2, 3.
- A positive enzyme immunoassay (EIA) result for IgG antibodies, as in the case of EIA 2, indicates a likely chronic infection 4, 2.
- The absence of IgM antibodies suggests that the infection is not in the acute phase, as IgM antibodies are typically present in early coccidioidomycosis 2, 5.
- Treatment with antifungals, such as fluconazole, may be considered for patients with chronic coccidioidomycosis, especially if they have underlying medical conditions or are immunocompromised 6, 3.
- However, early treatment with antifungals may abrogate the development of IgG antibodies, which can complicate serodiagnosis and epidemiologic studies 6.
Serologic Tests for Coccidioidomycosis
- Serologic tests, such as EIA, immunodiffusion, and complement fixation, are useful for diagnosing and monitoring coccidioidomycosis 4, 2, 3.
- The sensitivity and specificity of these tests vary, with EIA having a sensitivity of 88.3% and a specificity of 90% 4.
- Isolated positive IgM serologic results by EIA should prompt further follow-up and diagnostic testing, as they may indicate early coccidioidomycosis 5.
- Quantitation of coccidioidal IgG antibodies can provide an indicator of disease progression or regression 2, 3.