Bats are increasingly recognized as hosts of important viral and bacterial infections, however few experimental studies have monitored long-term infection dynamics in bat populations. This is especially true for vector-borne bacteria, where there can be significant challenges in maintaining both host and vector populations in controlled settings. In order to understand the importance of vector populations in the long-term maintenance of infection prevalence and bacterial diversity, we advocate for the use of semi-natural, long-term experiments capable of detecting changes in infection dynamics linked to the force of infection by vectors. Using blood samples taken from a captive colony of ~100 fruit bats (Eidolon helvum) in Accra, Ghana from July 2009 - March 2012, we monitored the dynamics of Bartonella spp. infection in the population using molecular techniques. Over this period, the population of the suspected bat fly vector population (Cyclopodia greefi) declined, but was then supplemented with additional flies from wild E. helvum in January 2012. We hypothesized that prevalence and species diversity of Bartonella infections in the colony will vary with changes in the bat fly population.
Results/Conclusions
Data indicate that Bartonella prevalence and diversity peaked in January 2010 with 75% of bats infected and 8 Bartonella species present, then began to decline until July 2011 with only 14% of bats infected and 4 Bartonella species present. After the reintroduction of flies in January 2012, prevalence increased to 43% in March 2012 with 6 species present. Changes in relative Bartonella species abundances showed that the species lost over time were uncommon in bats, but some of these uncommon species were more abundant after the reintroduction of flies. This indicates that C. greefi bat flies are likely vectors of Bartonella in E. helvum and play an important role in the maintenance of bacterial diversity in bats. Ongoing occupancy modeling work will explore the influence of within-host processes (including bacterial interactions and host resistance to infection) and alternative transmission routes on the long-term infection dynamics in individual bats.