Two Pathogens and One Disease: Detection and Identification of Flea-Borne Rickettsiae in Areas Endemic for Murine Typhus in California

Abstract

Results of an environmental assessment conducted in a newly emergent focus of murine typhus in southern California are described. Opossums, Didelphis virginiana Kerr, infested with cat fleas, Ctenocephalides felis Buché, in the suburban area were abundant. Animal and flea specimens were tested for the DNA of two flea-borne rickettsiae, Rickettsia typhi and Rickettsia felis. R. felis was commonly detected in fleas collected throughout this area while R. typhi was found at a much lower prevalence in the vicinity of just 7 of 14 case-patient homes identified. DNA of R. felis, but not R. typhi, was detected in renal, hepatic, and pulmonary tissues of opossums. In contrast, there were no hematologic polymerase chain reaction findings of R. felis or R. typhi in opossums, rats, and cats within the endemic area studied. Our data suggest a significant probability of human exposure to R. felis in the area studied; however, disease caused by this agent is not recognized by the medical community and may be misdiagnosed as murine typhus using nondiscriminatory serologic methods.

Detection of Rickettsia in Rhipicephalus sanguineus Ticks and Ctenocephalides felis Fleas from Southeastern Tunisia by Reverse Line Blot Assay

“…R. felis has been associated with fleas worldwide, in Algeria and Morocco (37), Italy (38), and the United States (39). However, in this investigation, the prevalence of R. felis (1%) is lower than that reported in Morocco (20% in C. felis fleas removed from sheep, cats, and dogs [37]) and in Italy (11.9% in dog and cat fleas [38]).…”

Opossums and Cat Fleas: New Insights in the Ecology of Murine Typhus in Galveston, Texas

“…24,27 In our study, two-thirds of opossums were seropositive for anti-R. typhi antibodies at a conservative cutoff titer (1:128).…”

“…10,25 In southern California, an MIR of 1.7% for R. typhi has been found in pools of fleas collected from Orange County and Los Angeles County opossums. 27 In contrast, fleas collected from opossums in San Bernardino County, an area with fewer reported human cases than Orange and Los Angeles counties, showed no evidence of infection with R. typhi.…”

An Investigation ofBartonellaspp.,Rickettsia typhi, and Seoul Hantavirus in Rats (Rattusspp.) from an Inner-City Neighborhood of Vancouver, Canada: Is Pathogen Presence a Reflection of Global and Local Rat Population Structure?

“…Although these pathogens have been identified in number of different geographic locations (Arikawa et al 1994, Gundi et al 2004, Easterbrook et al 2007a, Heyman et al 2009, Hsieh et al 2010, Psaroulaki et al 2010, Abramowicz et al 2011, studies that specifically seek to quantify their prevalence in urban rat populations have occasionally found one or more of them to be absent (Yanagihara 1990, Ellis et al 1999, Cueto et al 2008, Inoue et al 2008, Jiang et al 2008, Eremeeva et al 2012. In many cases, it is unclear if the pathogen is truly absent, or if absence is a result of undersampling (Yanagihara.…”

“…In many cases, it is unclear if the pathogen is truly absent, or if absence is a result of undersampling (Yanagihara. 1990, Ellis et al 1999, Inoue et al 2008, Jiang et al 2008, Eremeeva et al 2012) and/or variability in disease detection methods (Klein et al 2002, Jiang et al 2008. When this uncertainty is coupled with the relative paucity of research on urban rats, the true distribution of rat-associated zoonoses becomes unclear.…”