Bartonella vinsonii subsp. arupensis in Humans, Thailand

Ying Bai

, Michael Y. Kosoy, Maureen H. Diaz, Jonas Winchell, Henry Baggett, Susan A. Maloney, Sumalee Boonmar, Saithip Bhengsri, Pongpun Sawatwong, and Leonard F. Peruski

Author affiliations: Centers for Disease Control and Prevention, Fort Collins, Colorado, USA (Y. Bai, M.Y. Kosoy); Centers for Disease Control and Prevention, Atlanta, Georgia, USA (M.H. Diaz, J. Winchell); Centers for Disease Control and Prevention, Nonthaburi, Thailand (H. Baggett, S.A. Maloney, S. Boonmar, S. Bhengsri, P. Sawatwong, L.F. Peruski)

Abstract

We identified Bartonella vinsonii subsp. arupensis in pre-enriched blood of 4 patients from Thailand. Nucleotide sequences for transfer-messenger RNA gene, citrate synthase gene, and the 16S–23S rRNA internal transcribed spacer were identical or closely related to those for the strain that has been considered pathogenic since initially isolated from a human in Wyoming, USA.

More than 30 species of bartonellae that are highly prevalent in a wide variety of vertebrates have been described. Bartonella bacilliformis, B. henselae, and B. quintana are well-known human pathogens, and several other Bartonella species, including B. elizabethae, B. tamiae, B. vinsonii subsp. arupensis, have been associated with various clinical manifestations in humans (1–3). A link between some of these pathogenic strains and their animal hosts has been documented; for example, B. elizabethae is linked with Rattus rats. However, the reservoir host is unknown for other species, such as B. tamiae, which was isolated in patients from Thailand (2).

B. vinsonii subsp. arupensis was first isolated from a bacteremic cattle rancher in Wyoming, USA, in 1999 (3). Later studies showed that strains identical to B. vinsonii subsp. arupensis were highly prevalent among deer mice (Peromyscus maniculatus), a strictly North American rodent species frequently found across a wide geographic area, including Wyoming. Similar strains of B. vinsonii subsp. arupensis have not been found in other animals in North America, suggesting that deer mice are natural hosts of this bacterium (4).
However, the proposed link between infected mice and B. vinsonii subsp. arupensis infection in humans was challenged when this bacterium was reported in an endocarditis patient in France (5) and 2 febrile patients in Russia (6). The link was further disputed after identification of B. vinsonii subsp. arupensis infection in 2 humans in Thailand (7) and the subsequent inability to identify this strain or related species among the local rodent population, despite intensive investigation in different parts of Thailand (8). B. vinsonii subsp. arupensis was also identified in stray dogs in Thailand (9). In addition, B. vinsonii subsp. arupensis–specific antibodies were reported in febrile patients from Nepal (10). Together, these reports suggest that the spectrum of animal hosts carrying B. vinsonii subsp. arupensis may be underestimated. We report the identification of B. vinsonii subsp. arupensis in 4 more patients in Thailand.