Opossums and Cat Fleas: New Insights in the Ecology of Murine Typhus in Galveston, Texas.
Murine typhus is an acute undifferentiated febrile illness caused by Rickettsia typhi The classic reservoir (Rattus spp.) and flea vector (Xenopsylla cheopis) were once culprits of murine typhus in the United States. Vector and rodent control efforts have drastically decreased the prevalence of disease, except in a few endemic foci where opossums and cat fleas play a role in transmission. Since 2012, there has been a reemergence of murine typhus in Galveston, TX. We hypothesize that opossums and cat fleas are involved in the transmission of R. typhi in Galveston. To explore this, we sought to find the seroprevalence of typhus group antibodies from opossums. We also sought to find the prevalence of R. typhi in fleas parasitizing these animals. We collected blood from 12 opossums and found that eight (66.7%) had the presence of anti-R. typhi antibodies. All opossums were infested with fleas; a total of 250 Ctenocephalides felis fleas were collected from these animals. Seven opossums (53.8%) were infested with fleas that had molecular evidence of R. typhi infection, while six (46.2%) were infested with fleas that contained Candidatus Rickettsia senegalensis, an organism closely related to R. felis The minimum flea infection rate for R. typhi was 7.0%. The minimum infection rate for Candidatus R. senegalensis was 6.1%. Our study demonstrates that fleas infected with R. typhi parasitize opossums in Galveston. It is therefore likely that opossums and their fleas play a role in the city's recent reemergence of murine typhus.
Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas. lsblanto@utmb.edu.
Lucas S
LS
Blanton
School of Medicine, University of Texas Medical Branch, Galveston, Texas.
Boluwatife M
BM
Idowu
School of Medicine, University of Texas Medical Branch, Galveston, Texas.
Tyler N
TN
Tatsch
Galveston Police Department Animal Services Unit, Galveston, Texas.
Joshua M
JM
Henderson
Department of Pathology, University of Texas Medical Branch, Galveston, Texas.
Donald H
DH
Bouyer
Department of Pathology, University of Texas Medical Branch, Galveston, Texas.
David H
DH
Walker
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001179:Arthropod Vectors / Q000382:microbiology*; D002415:Cats; D048293:Didelphis / Q000382:microbiology / Q000469:parasitology*; D005260:Female; D058267:Flea Infestations / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology; D006801:Humans; D008297:Male; D012286:Rickettsia typhi / Q000302:isolation & purification* / Q000502:physiology; D013781:Texas / Q000453:epidemiology; D014437:Typhus, Endemic Flea-Borne / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D058260:Xenopsylla / Q000382:microbiology*
D000907:Antibodies, Bacterial