Microbiology
Summary
Coccidioides immitis, or cocci, is a dimorphic fungus commonly found in California and the Southwestern United States. The fungal spores are inhaled from dust, creating a higher risk of infection during activities that disperse large amounts of dust such as dust storms and post-earthquake scenarios. This results in increased cases of coccidioidomycosis, or San Joaquin Valley fever. In tissue sample, Coccidioides immitis can be seen as large, yeast-like spherules containing endospores. The spherules are larger than red blood cells and upon rupturing, release endospores that spread through the lungs and possibly the rest of the body.
When it comes to clinical features of coccidioidomycosis, the majority of immunocompetent people are asymptomatic or subclinical. However, there can be instances of acute pneumonia presenting with fever, sweats, and arthralgias. Radiographic images can show cavities or nodules, or both, in the lungs of some patients. Another symptom is erythema nodosum, an inflammatory condition that causes red, extremely tender nodules which usually form on the shins. In immunocompromised patients, cocci can disseminate into the skin, bones and, in serious cases, cause meningitis. The treatment for local lung infections includes azole drugs, while systemic infections are treated with the drug amphotericin B.
Lesson Outline
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FAQs
Coccidioides immitis is a type of fungi known as dimorphic fungi. It's mainly found in soil and can cause a disease called coccidioidomycosis, or San Joaquin Valley fever, when humans inhale spore forms. This fungus is prevalent in the San Joaquin Valley, hence the disease's nickname.
Initial infection by Coccidioides immitis often passes unnoticed as it may cause mild symptoms resembling the common cold or flu: fever, cough, headaches, rash, and muscle aches. However, in some severe and rare instances, it may progress to more serious conditions like pneumonia. Some patients may develop erythema nodosum, a condition marked by tender, red bumps on the shins.
Coccidioides immitis is dust-borne and primarily found in the soil. It's transmitted when the fungi's spores, which are present in the soil, are disturbed and become airborne. These spores are small enough to be inhaled into the lungs, infecting people who have been exposed to them. This commonly occurs during activities that stir up soil, like construction or farming.
People who are immunocompromised, such as those with HIV/AIDs or patients undergoing chemotherapy, are more susceptible to contracting San Joaquin Valley fever. This is because their immune system's ability to fight off infections and diseases is compromised. If these individuals inhale Coccidioides immitis spores, they are less able to prevent the spores from growing and causing infection, leading to severe or disseminated disease.
Coccidioides immitis is primarily found in the soil of arid regions in the southwestern United States, especially in parts of California and Arizona. It's also present in parts of Mexico, Central America, and South America. People can get infected by inhaling the airborne spores when the soil containing the fungus is disturbed.
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