Bartonella spp. in Rats and Zoonoses, Los Angeles, California, USA

Vijay A.K.B. Gundi, Sarah A. Billeter, Michael P. Rood, and Michael Y. Kosoy

Author affiliations: Centers for Disease Control and Prevention, Fort Collins, Colorado, USA (V.A.K.B. Gundi, S.A. Billeter, M.Y. Kosoy); Los Angeles County Department of Public Health, Baldwin Park, California, USA (M.P. Rood)

Abstract

Bartonella spp. were detected in rats (Rattus norvegicus) trapped in downtown Los Angeles, California, USA. Of 200 rats tested, putative human pathogens, B. rochalimae and B. tribocorum were found in 37 (18.5%) and 115 (57.5%) rats, respectively. These bacteria among rodents in a densely populated urban area are a public health concern.

Bartonella spp. are vector-borne bacteria associated with an increasing array of emerging zoonotic infections in humans and animals (1). Some Bartonella spp. are widely distributed among small mammals in the United States and potentially cause human health concerns because these bacteria may be associated with human diseases (2). However, limited surveys have been conducted to identify infectious agents involved in zoonotic infections in rodents within urban areas of the United States (3). Norway rats (Rattus norvegicus) have been shown to harbor several Bartonella species, including B. tribocorum, B. elizabethae, B. rattimassiliensis, B. phoceensis, B. queenslandensis, and a strain closely related to B. rochalimae (3–6), of which B. elizabethae, B. rochalimae, and B. tribocorum were implicated in human diseases (7–11).
Our study had 3 purposes. The first purpose was to investigate prevalence of Bartonella spp. infections in rodent populations in downtown Los Angeles, California, USA. The second purpose was to evaluate genetic diversity of Bartonella spp. in blood of urban rats by analyzing variations of the citrate synthase (gltA) gene. The third purpose was to compare rates of detection of Bartonella spp. infections in rats between culture and molecular assays.