Predictors of Fatal Outcomes among Pediatric Patients Hospitalized for Rocky Mountain Spotted Fever, Sonora, Mexico, 2004-20241.

The tickborne disease Rocky Mountain spotted fever (RMSF) remains life-threatening among children in northern Mexico. We retrospectively investigated 500 pediatric RMSF patients hospitalized in Sonora during 2004-2024. We analyzed clinical, laboratory, and sociodemographic data to identify predictors of fatality by using descriptive statistics and multivariable logistic regression. We found that the overall case-fatality rate was 19.8%, decreasing over time from 31.4% (2004-2013) to 14.5% (2014-2024). Fatal outcomes were associated with delayed doxycycline treatment (>5 days after symptom onset), older age, Indigenous background, and abnormal laboratory markers. Among survivors, 16% had life-altering sequelae, including amputations and neurologic deficits. Cases occurred year-round, predominantly in urban settings. Timely doxycycline administration remains a critical factor in reducing mortality rates. Vulnerable populations, including persons living in poverty, children >10 years of age, and Indigenous communities, require targeted interventions. Strengthening early diagnosis and understanding mechanisms underlying severe disease and death could improve RMSF outcomes in endemic regions.