Estimated Burden of Coccidioidomycosis.

Importance: Coccidioidomycosis is an underrecognized fungal infection that can cause serious illness and constitutes a considerable public health burden. The number of cases is likely substantially higher than the nationally reported total, as surveillance does not capture patients who do not seek medical care or who are undiagnosed or misdiagnosed. Coccidioidomycosis is not reportable in all states, and cases not reported to public health entities are likewise missed. A systematic estimate of coccidioidomycosis burden is needed to raise awareness and inform public health interventions and policy.

Objective: To assess the annual burden of symptomatic coccidioidomycosis in the US.

Design, setting, and participants: This cross-sectional study developed models incorporating coccidioidomycosis cases reported to the National Notifiable Diseases Surveillance System from January 1 to December 31, 2019, as model inputs. Multipliers from US public health surveillance accounted for factors including health care-seeking behavior, underdiagnosis, underreporting, and in-hospital mortality. Multiplier values were sourced from a combination of literature review and expert opinion. Regional estimates were generated using endemicity levels categorized as high (Arizona and California), low (Nevada, New Mexico, Texas, Utah, and Washington), or unknown (all other states and Washington, DC). Data were accrued from January 1, 2022, to July 1, 2024, and analyzed from October 1, 2022, to September 1, 2024.

Exposure: Coccidioidomycosis reported to public health surveillance entities.

Main outcomes and measures: Models estimated annual incident symptomatic coccidioidomycosis cases, hospitalizations, and deaths nationally and regionally in the US.

Results: A nationwide total of 273 000 (95% credible interval [CrI], 206 000-360 000) incident symptomatic coccidioidomycosis cases were estimated in 2019. High-endemic states accounted for the highest burden (125 000 [95% CrI, 94 000-165 000] cases), followed by states of unknown endemicity (103 000 [95% CrI, 66 000-155 000] cases) and low-endemic states (46 000 [95% CrI, 31 000-65 000] cases). Nationally, models estimated 23 000 annual hospitalizations (95% CrI, 18 000-28 000) and 900 annual deaths (95% CrI, 700-1100) associated with coccidioidomycosis.

Conclusions and relevance: In this cross-sectional study, the estimated national burden of symptomatic coccidioidomycosis in 2019 was 10 to 18 times higher than the number of cases reported through national surveillance. Better awareness, diagnostic testing practices, and reporting are needed to improve patient outcomes and enhance our understanding of coccidioidomycosis epidemiology.