Meeting Abstract
Ross River virus (RRV) is the most common mosquito-borne pathogen in Australia. Decades of seroprevalence and experimental infection studies have identified macropods (kangaroos and wallabies) as the major reservoir hosts. However, transmission ecology varies with reservoir and vector abundance across the country and recently, infections in urban areas have prompted the question of what animals are acting as reservoirs in cities and regions where macropods are scarce. In South Australia (SA), human infection rates for RRV vary greatly by region as do vector and reservoir abundance. We hypothesized that mosquito abundance and feeding patterns will vary in different regions of SA and may help explain divergent human case rates. To test our hypothesis, we extracted and amplified bloodmeals from mosquitoes trapped in four main ecoregions of SA and matched DNA sequences using a BLAST search in NCBI. The results are surprising: from 206 extracted, amplified and identified bloodmeals, none were acquired from macropods. Possums (marsupials) comprised a larger proportion of meals from urban regions and may be acting as reservoir hosts in cities. Domestic livestock animals (cows and sheep) made up the vast majority of bloodmeals from a rural region with the highest human infection rate. Livestock are generally not considered to be important reservoir hosts for RRV but here we discuss their potential role in transmission ecology. In the context of these findings, we reassess the long-standing idea that macropods are the main reservoir host for RRV and instead we propose that diverse transmission ecologies occur, depending on vector and reservoir availability.
