Flea Presence and Abundance Are not Predictors of Bartonella tribocorum Carriage in Norway Rats (Rattus norvegicus) from an Underserved Neighborhood of Vancouver, Canada.

Urban Norway rats (Rattus norvegicus) carry pathogenic Bartonella spp. that are transmitted among rats and from rats to people through arthropod vectors, particularly fleas. There is marked temporospatial variation in Bartonella spp. carriage among Norway rats in Vancouver, Canada, and we investigated whether this variation is associated with flea presence or abundance. Bartonella triborocum was isolated from 96/370 (35%) rats and 211 (57%) rats had fleas with an average of one flea per rat. All fleas were identified as Nosopsyllus fasciatus. There was no significant relationship between B. tribocorum carriage and flea presence or abundance, suggesting that, in contrast to other rat-associated zoonoses transmitted by fleas (e.g., Yersinia pestis) flea indices may not be informative for understanding the ecology of Bartonella spp. in rats, particularly for N. fasciatus.