Mary Anne Jackson, MD | Interim Dean - UMKC School of Medicine | Medical Editor, The Link Newsletter
Infection with Coccidioides species, so-called Valley Fever, occurs by inhalation of this dimorphic fungus and cases are most common in endemic regions, mostly in the southwestern United States. Present in the top 4-12 inches of soil and associated with decaying vegetation, dissemination of the fungus is facilitated by rains in semi-arid regions, and then carriage of the fungus by winds as the soil dries.
Cases have occurred after occupational or avocational exposures (e.g., archeologists, construction workers) and an increase in disease has followed national disasters associated with soil disruption, such as earthquakes. Most commonly reported in those residing in California, Arizona, New Mexico, south Texas, southern Nevada and Utah, disease in California is usually associated with infection caused by C. immitis. Cases in those residing in desert regions of the southwestern U.S., Mexico and Central and South America are generally caused by C. posadasii.
Between 1998 and 2011, the incidence of disease in endemic regions increased from 5.3 per 100,000 to 42.6 per 100,000; 66% of cases were reported in California, 31% in Arizona, 1% in other endemic states and <1% in non-endemic areas. Increased awareness is necessary as cases have recently been reported in non-endemic regions; Missouri reported 93 cases between 2004-2013, 45 in travelers to endemic areas; and 48 in those without confirmed travel. Cases in other non-endemic regions, such as south-central Washington state, have been reported and Coccidioides soil contamination has been confirmed.
Clinicians should be aware that coccidioidomycosis cases are increasing, including those practicing in non-endemic regions. The CDC suggests the acronym COCCI which recommends you CONSIDER the diagnosis, ORDER appropriate testing, CHECK for risk factors, CHECK for complications and INITIATE treatment when appropriate.
Consider the diagnosis
Respiratory symptoms are most common. It is estimated that 24% of those with community-acquired pneumonia (CAP) in at-risk regions are infected with Coccidioides species, with most presenting with fever, and cough with shortness of breath. The illness may mimic influenza and tuberculosis, complicated pulmonary disease with empyema and mediastinal involvement is well recognized. A unique feature of coccidioidomycosis is the association of CAP with dermatologic and rheumatologic manifestations. Erythema nodosum is especially notable. Non-pulmonary disease may occur by contamination of traumatic wounds. Cutaneous lesions may be associated with regional lymph node infection.
If CAP is recognized in those residing in endemic regions, or if pulmonary disease is associated with travel, symptoms and signs usually occur after a one-to-four-week incubation period. Not every patient in endemic regions requires diagnostic testing, but those with severe symptoms and risk factors for complications should be tested. IgM and IgG serology is appropriate first-line testing.
Check for risk factors
The vast majority of infected patients, approximately 65%, with primary pulmonary disease have self-limited disease. Higher risk of severe disease is noted in males and those of African or Filipino descent. Bone marrow and solid organ transplant recipients, those receiving chronic steroids or biologic modifiers, HIV infected, women in the third trimester, those with diabetes and a subset of those with gene mutations of interferon-gamma or IL-12 have the highest risk for complicated/disseminated disease.
Check for complications
Extrapulmonary dissemination to soft tissues, bone and/or meninges occurs typically within weeks to months of primary infection. In a review of cases occurring between 1990 and 2008, 3,089 deaths occurred with mortality rates higher in those >65 years of age. Deaths were more commonly reported in Native Americans, Hispanics, Asians and Blacks than for whites and in those with chronic diseases associated with immunosuppression.
The vast majority of patients recover without treatment, although some experts consider therapy in hopes of speeding recovery. For those with severe symptomatic disease, extrapulmonary disease and for those at risk of dissemination, fluconazole is the drug of choice, except in pregnant women and in cases of meningitis associated with basilar involvement where amphotericin is preferred.
Coccidioidomycosis Acquired in Washington State. Marsden-Haug N, et al. Clin Infect Dis, 56(6); 847-850, 2013.
Coccidioidomycosis in a State Where It Is Not Known To Be Endemic — Missouri, 2004–2013. Turabelidze G, et al. MMWR, June 19, 2015 / 64(23);636-639.
Coccidioidomycosis-associated Deaths, United States, 1990–2008. Huang JY, Bristow B, Shafir S, Sorvillo F. Emerg Infect Dis. 2012;18(11):1723-1728. https://dx.doi.org/10.3201/eid1811.120752.