Coccidioidomycosis

Credit: www.life-worldwide.org

Coccidioidomycosis is a pulmonary or hematogenously spread disseminated disease caused by the fungi Coccidioides immitisand C. posadasii; it usually occurs as an acute benign asymptomatic or self-limited respiratory infection. The organism occasionally disseminates to cause focal lesions in other tissues. Symptoms, if present, are those of lower respiratory infection or low-grade nonspecific disseminated disease. Diagnosis is suspected based on clinical and epidemiologic characteristics and confirmed by chest x-ray, culture, and serologic testing. Treatment, if needed, is usually withfluconazole, itraconazole, newer triazoles, or amphotericin B.

(See also the Infectious Diseases Society of America’s Coccidioidomycosis .)

In North America, the endemic area for coccidioidomycosis includes

• The southwestern US
• Northern Mexico

The affected areas of the southwestern US include Arizona, the central valley of California, parts of New Mexico, and Texas west of El Paso. The area extends into northern Mexico, and foci occur in parts of Central America and Argentina. About 30 to 60% of people who live in an endemic region are exposed to the fungus at some point during their life. In the US, about 150,000 infections develop annually; over half of them are subclinical.

Pathophysiology

Infections are acquired by inhaling spore-laden dust. Thus, certain occupations (eg, farming, construction) and outdoor recreational activities increase risk. Epidemics can occur when heavy rains, which promote the growth of mycelia, are followed by drought and winds. Because of travel and delayed onset of clinical manifestations, infections can become evident outside endemic areas.

Once inhaled, C. immitis spores convert to large tissue-invasive spherules. As spherules enlarge and then rupture, each releases thousands of small endospores, which may form new spherules. Pulmonary disease is characterized by an acute, subacute, or chronic granulomatous reaction with varying degrees of fibrosis. Lesions may cavitate or form nodular-like coin lesions.

Sometimes disease progresses, with widespread lung involvement, systemic dissemination, or both; focal lesions may form in almost any tissue, most commonly in skin, subcutaneous tissues, bones (osteomyelitis), and meninges (meningitis).

Progressive coccidioidomycosis is uncommon in otherwise healthy people and more likely to occur in the following contexts:

• HIV infection
• Use of immunosuppressants
• Advanced age
• 2nd half of pregnancy or postpartum
• Certain ethnic backgrounds (Filipino, African American, Native American, Hispanic, and Asian, in decreasing order of relative risk)

Symptoms and Signs

Primary coccidioidomycosis

Most patients are asymptomatic, but nonspecific respiratory symptoms resembling those of influenza, acute bronchitis, or, less often, acute pneumonia or pleural effusion sometimes occur. Symptoms, in decreasing order of frequency, include fever, cough, chest pain, chills, sputum production, sore throat, and hemoptysis.

Physical signs may be absent or limited to scattered rales with or without areas of dullness to percussion over lung fields. Some patients develop hypersensitivity to the localized respiratory infection, manifested by arthritis, conjunctivitis, erythema nodosum, or erythema multiforme. Read more >>

Source: https://www.merckmanuals.com/professional/infectious-diseases/fungi/coccidioidomycosis