Our team at EEID 2015 conference!

Members of our team recently attended the Ecology & Evolution of Infectious Diseases (EEID) 13th Annual Conference held May 26-29, 2015 at the Classic Center in Athens, Georgia, USA.

Congratulations to all for an excellent job well done!

Mr. Nicholas Clark was selected for an oral presentation:

Biogeographical variation in blood parasite coinfections in congeneric island birds: a mosaic of parasite-mediated selection?

Nicholas J Clark, Sonya M Clegg

The interplay between host population structure and pathogen burden is an important driver of host-pathogen coevolution. However, this relationship can be complicated by the often-high incidence of pathogen coinfections. We investigated associations between host biogeography and pathogen burden for a multiple parasite system in a south Pacific archipelago. We determined prevalence, diversity and patterns of coinfection for three vector-borne avian blood parasites [avian malaria (Plasmodium, Haemoproteus) and microfilaria spp.] infecting Zosterops spp. in New Caledonia. We relate infection results to host leucocyte profiles and gene flow patterns to examine the potential for distinct host populations to encounter variable selection pressures. Prevalence varied significantly across islands and was positively correlated with both parasite diversity and the occurrence of coinfections. Concentrations of heterophils were significantly elevated in birds with microfilaria/malaria coinfections, indicating a physiological cost of infection. Patterns of gene flow for two widespread hosts revealed low connectivity across islands, suggesting that host populations encountering different parasite communities are also genetically distinct. Our results reveal a biogeographical mosaic of host-parasite interactions that could influence evolutionary processes for New Caledonian Zosterops species.

Mr. John Giles was selected to present a poster:

Population dynamics of Australian fruit bats

John R. Giles (gilesjohnr@gmail.com), Peggy Eby, Alison J Peel, Raina K Plowright, Hamish McCallum

Hendra virus (HeV) has recently emerged as a public health concern in Australia. HeV circulates in the large frugivorous and nectarivorous bats of the genus Pteropus. Infection can spillover into horses, in which virus amplifies before infecting humans. Anthropogenic influence and landscape change have been implicated in the emergence of HeV, as well as analogous bat-borne diseases, such as Ebola and Nipah virus. Understanding the mechanisms driving host – pathogen population dynamics within the context of landscape change is therefore important. We present spatiotemporal models of both food resource distribution and foraging behavior of fruit bats, enabling a landscape scale functional model of bat population dynamics. We employ novel algorithms to analyze patterns in counts at bat roosts , and use models of social foraging behavior that characterize spatiotemporal flux of bat populations. Initial results indicate that bat aggregations are correlated with remotely sensed measures of eucalypt phenology, and the fission-fusion structure of bat populations is driven by hyper-variable patterns of flowering and nectar production across the landscape. Prediction of the mechanistic interaction between food resource variability and bat population distribution facilitates parameterization of models of viral transmission. More broadly, it allows construction of scenarios demonstrating how landscape change influences bat population dynamics, driving spillover of bat-borne pathogens.

Dr. Jaewoon Jeong was selected to present a poster:

Modelling transmission dynamics of a novel Alphacoronavirus in an Australian population

Jaewoon Jeong 1 (j.jeong@griffith.edu.au), Craig S. Smith 2, 3, Alison J. Peel 1, Hamish McCallum 1

1 Griffith Wildlife Disease Ecology Group, Environmental Futures Research Institute, School of Environment, Griffith University, Nathan, Queensland, Australia

2 School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia

3 Queensland Centre for Emerging Infectious Diseases, Biosecurity Queensland, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia

The emergence of severe acute respiratory syndrome (SARS) in 2002 to 2003 in southern China and of Middle East respiratory syndrome (MERS) in Saudi Arabia in 2012 have underscored the potential of coronaviruses to become significant zoonoses. Bats have been identified as the natural reservoir hosts for these and other emerging infectious diseases. However, following the infection status and survival of individual bats is difficult for many coronaviruses. Here, we report analysis of the transmission dynamics of a novel Alphacoronavirus in an Australian population of larged-footed myotis (Myotis macropus), a system which was tractable for a mark recapture study. Previous analysis suggested that this coronavirus was maintained in the population by persistently infected bats. We performed additional analysis using ‘MARK’ and ‘OpenBUGS’ to estimate demographic and transmission parameters, and subsequently used these to build a compartmental model. We found no evidence that sex and age affect the survival, recapture and transition rates. Infection decreased survival slightly, but increased the recapture rate. This study identifies the potential effects of persistent infections in coronavirus transmission dynamics, and adds weight to the suggestion that these mechanisms may be an important in maintaining coronaviruses in bat populations. By extension, this may be applicable to the ecology of other bat RNA viruses.

Professor Hamish McCallum was selected to present a poster:

Trophic cascades as a result of Tasmanian Devil facial tumor disease

Hamish McCallum (h.mccallum@griffith.edu.au), Tracey Hollings, Menna Jones, Nick Mooney

Infectious diseases of wildlife can have consequences beyond their hosts. Tasmanian devil facial tumour disease (DFTD) is a lethal infectious cancer that continues to spread across Tasmania, causing population declines of up to 95%. The Tasmanian devil is the apex mammalian predator in Tasmania and these declines may cause trophic cascades. Four species of mammal, extinct on the Australian mainland, persist in Tasmania. The most likely cause of their extinction on the mainland is predation by feral cats and introduced European red foxes. Cats are widespread in Tasmania and foxes were illegally introduced about a decade ago, although they remain at very low numbers. Devil decline may allow these smaller introduced predators and devil prey species to increase, with major impacts on the Tasmanian ecosystem. We present several independent lines of evidence suggesting that this may already be occurring.