Regional Comparison of Mosquito Bloodmeals in South Australia: Implications for Ross River Virus Ecology

Abstract

Ross River virus (RRV) is responsible for the most notifications of human arboviral infection in Australia. Seroprevalence and experimental infection studies have implicated macropods (e.g., kangaroos) as the major reservoir hosts. However, transmission ecology varies spatially, and infections in urban areas have prompted the question of what animals serve as reservoirs in 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 would vary among ecoregions of SA and could help explain divergent human case rates. To test our hypothesis, we amplified and sequenced a 457 base pair region of the cytochrome B segment of mitochondrial DNA from blood fed mosquitoes collected in three main ecoregions of SA and identified sequences using a BLAST search in NCBI. Domestic livestock made up the vast majority of bloodmeals from the region with the highest human infection rate. Livestock are generally not considered to be important reservoir hosts for RRV, but our results suggest they may have a role in transmission ecology in some places. Surprisingly, none of the 199 bloodmeal samples were identified as macropod in origin. In the context of these findings, we consider the possible RRV vectors and reservoir hosts in these regions and propose that diverse spatial and temporal transmission ecologies occur in SA, depending on vector and reservoir availability.

Improving public health intervention for mosquito-borne disease: the value of geovisualization using source of infection and LandScan data

“…The scale at which RRV risk operates in SA is unknown but different RRV ecologies exist across the state [28] and vector and virus prevalence appears to vary at the scale of kilometres [34]. The scale at which RRV risk operates in SA is unknown but different RRV ecologies exist across the state [28] and vector and virus prevalence appears to vary at the scale of kilometres [34].…”

Ross River virus in Australian blood donors: possible implications for blood transfusion safety

“…When symptoms do occur, they are usually mild; however, they can include a nonfatal arthritogenic condition known as RRV disease. 14 RRV is believed to have a sylvatic transmission cycle in Australia, with marsupials as the main reservoir hosts, [15][16][17][18] although non-marsupials potentially can act as reservoirs. 10,19 Humans become infected when bitten by infected female mosquitoes, including Aedes (Ae.)…”

Interpreting mosquito feeding patterns in Australia through an ecological lens; an analysis of blood meal studies.

“…For this analysis, the blood meal origin data compiled from the literature were aggregated such that each vertebrate species was grouped into the broader taxonomic groups of Humans, Carnivores (cats, dogs and foxes), Aves (all birds), Diprodontia (all possum and kangaroo species), Artiodactyla (cows, sheep, pigs and goats) and Perisodactyl (horses). Flying fox [21], rodent [22, 23] and rabbit [22, 24] species were excluded from this analysis, as the sample size of blood meals from these species was too small (either one or two studies, with these species comprising less than 9% of blood meal origins within each). To be included in the analysis, mosquito species needed to meet all minimum data criteria of i) their blood meal origins being reported more than twice in the literature, and ii) having an arbitrary minimum of 35 blood meals identified.…”