Seroepidemiological study of Rickettsia felis, Rickettsia typhi, and Rickettsia conorii infection among the population of southern Spain

Rickettsia typhi and Rickettsia conorii, the etiologic agents of, respectively, murine typhus and Mediterranean spotted fever, are recognized as frequent causes of fever of intermediate duration in southern Spain; in addition, in recent years Rickettsia felis has been detected in potential vectors in this area. Nevertheless, limited data exist regarding the actual prevalence of past infection due to these three pathogens. In the present study, the prevalence of past infection due to R. felis, R. typhi, and R. conorii was determined in a representative population of southern Spain during 2002. In addition, the possible risk factors associated with exposure to these pathogens were investigated. An epidemiological survey was completed by all subjects included in the study. Serum samples were tested by indirect immunofluorescence assay. The prevalence of past infection due to R. felis, R. typhi, and R. conorii among the 504 total subjects was 6.5, 3.8 and 8.7%, respectively. In multivariate analysis, infection due to R. felis was independently associated with a high-risk occupation (one that required working outdoors in nature, close contact with domestic animals, or potential contact with rodents) (OR=5.8; 95%CI 2.1-15.6), while infection due to R. typhi was associated with older age (factor of 1.04 [95%CI 1.008-1.068]) and frequent insect bites (OR=10.3; 95%CI 2.3-45.5). Two factors were associated with infection due to R. conorii: a high-risk occupation (OR=9.3; 95%CI 3.7-23.2), and participation in outdoor activities (OR=7.2; 95%CI 1.4-38.5). The results confirm the widespread prevalence of past infection due to R. felis, R. typhi, and R. conorii in the population of southern Spain.