Bartonella spp. in Bats, Guatemala

To better understand the role of bats as reservoirs of Bartonella spp., we estimated Bartonella spp. prevalence and genetic diversity in bats in Guatemala during 2009. We found prevalence of 33% and identified 21 genetic variants of 13 phylogroups. Vampire bat–associated Bartonella spp. may cause undiagnosed illnesses in humans.

M ultiple studies have indicated that bats might serve as natural reservoirs to a variety of pathogens, including rabies virus and related lyssaviruses, Nipah and Hendra viruses, Marburg virus, and others (1,2). Bats' high mobility, broad distribution, social behavior (communal roosting, fi ssion-fusion social structure), and longevity make them ideal reservoir hosts and sources of infection for various etiologic agents. In addition to viruses, bacteria and ectoparasites have been detected in bats (3)(4)(5) and can potentially cause human infection (6).
Bartonella spp. have been found in rodents, insectivores, carnivores, ungulates, and many other mammals. Naturally infected hematophagous arthropods, such as fl eas, fl ies, lice, mites, and ticks are frequently implicated in transmitting Bartonella spp. (3)(4)(5)7). Detection of Bartonella DNA in the saliva of dogs suggests the possibility that Bartonella spp. can be transmitted through biting (8). Increasing numbers of Bartonella spp. have been identifi ed as human pathogens (9,10). However, a mammalian reservoir has not been determined for some newly identifi ed species, such as B. tamiae (9). Extensive surveillance for Bartonella spp. among diverse groups of animals, including bats, has become crucial.
To our knowledge, Bartonella spp. in bats have been studied only in the United Kingdom and Kenya (11,12). To better understand the role of bats as reservoir hosts of Bartonella spp. and their potential risk for infecting humans and animals, we looked for Bartonella spp. in bats in Guatemala, estimated prevalence, and evaluated the genetic diversity of the circulating Bartonella strains.
Of the 13 phylogroups, phylogroups I, IV, and VII were identifi ed in isolates obtained from different bat species ( Table 2), suggesting that bats of different species may share the same Bartonella strain; whereas 4 species of bats-C. perspicillata, D. rotundus, P. discolor, and P. davyi-were infected with 2-4 Bartonella strains ( Table  2). P. davyi from 2 bats belonged to phylogroups II or VIII.

Conclusions
The Further characterization is necessary to verify whether the Bartonella strains representing a variety of distinct phylogroups represent novel Bartonella species. Unlike the discovery in bats in Kenya (12), host specifi city of Bartonella spp. was not found in bats in Guatemala. Such lack of specifi city may be partly associated with the arthropod vectors that parasitize bats, although we were unable to attempt isolation of agents from the bat ectoparasites. Future studies of bat ectoparasites would enable testing of hypotheses about whether any arthropods may be vectors in the Bartonella spp. transmission cycle and whether ectoparasite specifi city contributes to the lack of host specifi city observed in this study.
The tendency of some bat species to share roosts, reach large population densities, and roost crowded together creates the potential for dynamic intraspecies and interspecies transmission of infections (14). In accordance with this hypothesis, our fi nding that co-infection with multiple Bartonella strains in a single bat species, and even in an individual bat, indicate that active interspecies transmission of Bartonella spp. likely occurs among bats in Guatemala. The specifi city of ectoparasite arthropod vectors among the bat fauna remains unclear and may contribute to interspecies transmission of Bartonella spp. among bats.
The long life spans of bats (average 10-20 years) may have made them major reservoirs that contribute to the maintenance and transmission of Bartonella spp. to other animals and humans. The bite of the common vampire bat has been long recognized to transmit rabies virus to humans throughout Latin America (2). These bats typically feed on the blood of mammals, including domestic animals and humans (15). Predation of vampire bats on humans is a major problem in Latin America (2). If Bartonella spp. can be transmitted to humans through the bite of bats, the need for further studies with vampire bats is imperative. Bartonella spp.-specifi c DNA has been detected in ectoparasites collected from bats (3)(4)(5). Presumably, if Bartonella spp. are transmitted through a bat ectoparasite vector, some, if not all, bat-associated Bartonella spp. could be transmitted to humans because bats are frequent hosts to a wide variety of ectoparasites, including bat fl ies, fl eas, soft ticks, and mites. However, transmission potential might vary with the degree of synanthropic roosting or foraging behavior within the bat community.
Because an increasing number of Bartonella spp. are being associated with human illness, the need to identify the animal reservoirs of these novel Bartonella spp. and to understand their disease ecology is also increasing. Our study of Bartonella spp. in bats has enlarged our scope of this zoonotic potential as we search for the reservoirs that harbor novel and known Bartonella spp.
Dr Bai is an associate service fellow in the Bartonella Laboratory, Bacterial Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention. Her research genotypes based on partial sequences of the citrate synthase gene detected in bats from Guatemala, Kenya, United Kingdom, and some reference Bartonella spp. The phylogenetic tree was constructed by the neighbor-joining method, and bootstrap values were calculated with 1,000 replicates. A total of 21 Bartonella genotypes, forming 13 Bartonella phylogroups, were identifi ed in the bats from Guatemala. Each genotype is indicated by its GenBank accession number in boldface; the phylogroups are marked by Roman numerals I-XIII.