Background: The incidence of coccidioidomycosis-an emerging fungal infection-is high within California state prisons. In 2015, California began offering a Methods: We fit catalytic models to skin test data from 154,450 males aged 18 to 64 years incarcerated in California state prisons between January 11, 2015, and September 15, 2024. Findings: Estimated test sensitivity was 48.8% (95% confidence interval (CI): 45.1-52.6%). Low sensitivity was attributed to waning reactivity, estimated at 5.3% (95% credible interval (CrI): 4.3, 6.3%) loss in reactivity per year since infection. We estimated a prevalence of prior infection among males from the hyperendemic Kern County of 17.9% (95% CrI: 12.1, 26.0) at 18 years and 94.7% (95% CrI: 89.8, 97.4) by 65 years, and an annual average FOI in Kern County of 54.8 new infections per 1000 susceptible males (95% CrI: 41.6, 70.0). Regions outside the highly endemic area demonstrated lower, but non-negligible, prevalences of prior infection; prior infection prevalence among San Francisco Bay Area male residents reached 16.9% (95% CrI: 13.3, 21.2) by age 65. Interpretation: These findings update our understanding of population immunity to coccidioidomycosis among California males entering prison and inform disease risk in this high-risk population. Funding: NIHNIAID K01AI173529.