The Seroprevalence and Risk Factors for Spotted Fever Group and Typhus Group Rickettsia Along the Texas–Mexico Border

Rickettsial pathogens are an endemic and emergent source of disease in Texas, with a historically high rate of transmission along the United States-Mexico border. To better understand the prevalence and risk factors for spotted fever group Rickettsia (SFGR) and typhus group Rickettsia (TGR) along the Texas-Mexico border, we conducted a seroprevalence study of adults residing in Starr County, Texas (N = 616). Plasma samples were screened for IgG reactivity to SFGR and TGR using commercially available ELISA. ELISA-positive samples were confirmed using a dual spot IgG indirect immunofluorescent assay. Seropositivity was defined as having a ≥1:128 titer. Analysis was conducted to assess risk factors associated with seropositivity. A higher seroprevalence of TGR (10.9%) was identified compared with SFGR (4.6%) and Rickettsia unspecified (2.0%). These findings add to the growing body of evidence suggesting that both SFGR and TGR are endemic along the Texas-Mexico border.