MURINE TYPHUS - UPDATED ROLES OF MULTIPLE URBAN COMPONENTS AND A 2ND TYPHUSLIKE RICKETTSIA

Studies using serologic and polymerase chain reaction-(PCR) facilitate d analysis of field samples from southern Texas indicate the presence of Rickettsia typhi and ELB agent infected cat fleas, Ctenocephalides felis (Bouche), and the first observation of ELB infected vertebrates (opossums). The ELB agent is a recently described typhus-like ricketts ia that is not distinguished from R. typhi or R. prowazekii by current ly available serologic reagents. Restriction digests of PCR products f rom 399 fleas revealed an ELB agent infection rate of 3.8% and a R. ty phi infection rate of 0.8%. Three of nine tested opossums (Didelphis v irginiana) were shown to harbor ELB agent infections. No R. typhi infe cted rats, Rattus norvegicus, or rat-fleas, Xenopsylla cheopis Rothsch ild, were detected among surveyed samples. The persistence of this mur ine typhus disease focus appears to be better accounted for by the pre sence of infected cat fleas, opossums, and other non-rat hosts found i n close association with human populations. Involvement of the ELB age nt in the biology of murine typhus is suggested by its prevalence amon g suspected vectors and reservoir hosts.