Introduction: Southern California is one of the endemic areas of coccidioidomycosis and patients receiving immunosuppression including kidney transplant recipients are at higher risk for dissemination and severe disease. Screening Coccidioides serology should have benefit in asymptomatic immunocompromised patients who live in endemic areas.
Objective: To evaluate the prevalence of Coccidioides serology and living area by zip code in kidney transplant recipients at UCLA for early detection of coccidioidomycosis.
Methods: We used data from UCLA Kidney Transplant Program. We examined 2,961 patients who underwent kidney transplantation between January 1, 2007 and December 31, 2016. Coccidioides serology testing by ELISA was done before or within 14 days after kidney transplantation. We used the five-digit zip code for mapping the location of the approximate endemic areas. Patients with incomplete zip code or Coccidioides serology were excluded from this study.
Results: Prevalence of positive Coccidioides IgG and IgM were 1.37% and 2.95%, respectively. (figure) A total of 116 patients had positive results of either IgG or IgM, or both, among these, 32 (27.59%) had isolated IgG positivity and 77 (66.38%) had isolated IgM positivity. Patients who live in highly endemic areas were more likely to have positive Coccidioides serology. (p<0.01) (table) Almost patients with positive and indeterminate serology results were in suspected, established, or highly endemic area. Patients, who were not from endemic areas, were less likely to have positive test results. 
Conclusions: Screening Coccidioides serology is a useful testing in kidney transplant candidates who live in endemic areas. Clinical correlation and confirmation test should be helpful for laboratory interpretation especially in patients with either isolated IgG or IgM positivity. Future directions would include following patients post-transplant to determine whether prophylaxis is successful in prevention reactivation as well as how serology testing results change over time.