Short Report: Molecular Detection and Identification of Bartonella Species in Rat Fleas from Northeastern Thailand

The presence of Bartonella species in Xenopsylla cheopis fleas collected from Rattus spp. (R. exulans, R. norvegicus, and R. rattus) in Khon Kaen Province, Thailand was investigated. One hundred ninety-three fleas obtained from 62 rats, were screened by polymerase chain reaction using primers specific for the 16S-23S intergenic spacer region, and the presence of Bartonella DNA was confirmed by using the citrate synthase gene. Bartonella DNA was detected in 59.1% (114 of 193) of fleas examined. Sequencing demonstrated the presence of Bartonella spp. similar to B. elizabethae, B. rattimassiliensis, B. rochalimae, and B. tribocorum in the samples tested with a cutoff for sequence similarity ³ 96% and 4 clustered together with the closest match with B. grahamii (95.5% identity). If X. cheopis proves to be a competent vector of these species, our results suggest that humans and animals residing in this area may be at risk for infection by several zoonotic Bartonella species. Bartonella species are small, pleomorphic, gram-negative bacteria that infect a variety of mammalian hosts, including cats, dogs, rodents, ruminants, and humans. Clinical symptoms associated with Bartonella range from mild, influenza-like symptoms to more severe manifestations such as endocarditis, myocarditis, uveitis, bacillary angiomatosis, and peliosis hepatis. 1 Approximately half of the 20 Bartonella species or subspecies identified to date are known or suspected human pathogens, 2 and most are believed to be transmitted by arthro- pod vectors (fleas, lice, sandflies, and ticks). 3 Xenopsylla cheopis, the Oriental rat flea, is a suspected vec- tor of several Bartonella species (B. tribocorum, B. elizabethae, B. queenslandensis, B. rochalimae, and novel Bartonella geno- types), and Bartonella DNA has been detected in these fleas from various locations worldwide. 3-8 Although generally found on rodents, X. cheopis have been found to parasitize humans and are known vectors of the zoonotic agents Yersinia pestis (plague) and Rickettsia typhi (murine typhus). 9 Numerous surveys have been performed to identify the pres- ence of Bartonella species affecting humans and domestic and peri-domestic animals in Thailand. 10-17 Bartonella henselae, (the agent of cat scratch disease), 14 B. tamiae, 10 B. elizabethae, B. rattimassiliensis ,a ndB. tribocorum have been isolated from febrile patients, 15 B. henselae and B. clarridgeiae have been reported in cats, 11 and B. clarridgeiae, B. vinsonii subsp. arupensis, B. elizabethae, B. grahamii, B. quintana, B. taylorii, and novel Bartonella genotypes have been found in dogs. 11,16 In rodent species, B. grahamii, B. elizabethae, Candidatus Bartonella thailandensis, B. coopersplainensis, B. phoceensis, B. rattimassiliensis, B. tribocorum, and novel Bartonella geno- types have been detected by culture and polymerase chain reaction (PCR) analysis. 12,13,17 However, little information has been obtained to identify potential arthropod vectors of Bartonella species in Thailand. Bartonella henselae, B. clarridgeiae and B. koehlerae were detected in Ctenocephalides felis fleas removed from cats 18-20 and B. henselae was identified in two C. canis 19 also collected from cats. Furthermore, a