Typhus, Endemic Flea-BorneRickettsia typhiScrub TyphusTyphus, Epidemic Louse-BorneOrientia tsutsugamushiSiphonapteraRickettsia InfectionsLaosRickettsiaBoutonneuse FeverRickettsia conoriiEctoparasitic InfestationsRickettsia prowazekiiDoxycyclineOpossumsAntibodies, BacterialRickettsia felisTunisiaTexasFeverFluorescent Antibody Technique, IndirectSeroepidemiologic StudiesImmunoglobulin MCitiesTrombiculidaeImmunoglobulin GPhthirapteraPolymerase Chain ReactionEnzyme-Linked Immunosorbent AssayLeukemia Virus, MurineDNA, Bacterial