Surveillance for Coccidioidomycosis - United States, 2011-2017

Coccidioidomycosis (Valley fever) is an infection caused by the environmental fungus Coccidioides spp., which typically causes respiratory illness but also can lead to disseminated disease. This fungus typically lives in soils in warm, arid regions, including the southwestern United States.

2011-2017.

Coccidioidomycosis has been nationally notifiable since 1995 and is reportable in 26 states and the District of Columbia (DC), where laboratories and physicians notify local and state public health departments about possible coccidioidomycosis cases. Health department staff determine which cases qualify as confirmed cases according to the definition established by Council of State and Territorial Epidemiologists and voluntarily submit basic case information to CDC through the National Notifiable Diseases Surveillance System.

During 2011-2017, a total of 95,371 coccidioidomycosis cases from 26 states and DC were reported to CDC. The number of cases decreased from 2011 (22,634 cases) to 2014 (8,232 cases) and subsequently increased to 14,364 cases in 2017; >95% of cases were reported from Arizona and California. Reported incidence in Arizona decreased from 261 per 100,000 persons in 2011 to 101 in 2017, whereas California incidence increased from 15.7 to 18.2, and other state incidence rates stayed relatively constant. Patient demographic characteristics were largely consistent with previous years, with an overall predominance among males and among adults aged >60 years in Arizona and adults aged 40-59 years in California.

Coccidioidomycosis remains an important national public health problem with a well-established geographic focus. The reasons for the changing trends in reported cases are unclear but might include environmental factors (e.g., temperature and precipitation), surveillance artifacts, land use changes, and changes in the population at risk for the infection.

Health care providers should consider a diagnosis of coccidioidomycosis in patients who live or work in or have traveled to areas with known geographic risk for Coccidioides and be aware that those areas might be broader than previously recognized. Coccidioidomycosis surveillance provides important information about the epidemiology of the disease but is incomplete both in terms of geographic coverage and data availability. Expanding surveillance to additional states could help identify emerging areas that pose a risk for locally acquired infections. In Arizona and California, where most cases occur, collecting systematic enhanced data, such as more detailed patient characteristics and disease severity, could help clarify the reasons behind the recent changes in incidence and identify additional opportunities for focused prevention and educational efforts.