Members of our team recently attended (and presented at) the Wildlife Disease Association's 2015 International Conference.
Photos, poster abstracts and links to full posters from our team can be found below:
Paramyxoviruses in Australian flying-foxes: each to their own?
Alison J Peel 1, Olivier Restif 2, Vicky Boyd 3, Lauren Goldspink 4, Gary Crameri 3, Daniel Edson 4, Hamish McCallum 5, Craig S Smith 4
1. Environmental Futures Research Institute, Griffith University, Nathan, Queensland, Australia
2. Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
3. CSIRO Australian Animal Health Laboratory (AAHL), Geelong, Victoria, Australia
4. Biosecurity Queensland, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia
5. Environmental Futures Research Institute, Griffith University, Nathan, QLD, Australia
Bats are reservoir hosts for many emerging zoonotic pathogens. In Australia, the most widely studied is the paramyxovirus Hendra virus (HeV), yet a diverse community of viruses has been detected in Australian flying-foxes (Smith et al. 2011, Vidgen et al. 2015). Although HeV or anti-HeV virus antibodies have been detected in all four flying-fox species, recent studies investigating aspects of the host-pathogen relationship suggests that the closely related black and spectacled flying-foxes (Pteropus alecto and P. conspicillatus) may be the primary reservoir host (Smith et al. 2014, Goldspink et al. 2015). Natural host-virus systems are complex and there is increasing awareness of the importance of understanding ‘host communities’ (a single virus may have multiple reservoir hosts, each with heterogeneous contributions to pathogen dynamics, persistence and spillover) and ‘viral communities’ (known zoonotic viruses are often detected alongside a wide diversity of viruses in their natural hosts, with unknown pathogenic potential) (Vasco et al. 2007; Viana et al. 2014). The species-specificity of HeV is only just beginning to be elucidated; for other Australian bat paramyxoviruses, it is unknown. A novel high-throughput multiplex PCR (Boyd et al., unpublished) was utilised to simultaneously detect up to nine known bat paramyxoviruses in individual urine samples from three of the four Australian flying-fox species collected in a related study (Edson et al. in prep). Results support the existence of specific host-viral relationships, along with synchronous shedding pulses of multiple viruses. We interpret these results in the context of a novel reservoir framework, reconsidering HeV as part of a multi-hostmulti-virus community. HeV in Australian flying-foxes, and its spillover to horses and humans, is the best understood emerging bat pathogen spillover system, and by examining it in this broader context, this study will provide significant insight into both HeV dynamics and bat virus spillover in general.
Enemy release and novel weapons: the role of avian malaria parasites in the spread of the invasive common myna (Acridotheres tristis) in Australia
Nicholas J Clark 1, Sonya M Clegg 2
1. Environmental Futures Research Institute, Griffith University, Brisbane, QLD, Australia
2. Edward Grey Institute, Oxford University, Oxford, UK
Invasive species can have competitive advantages in non-native ranges through decreased pathogen pressure or through the spread of invasive pathogens that spillover to native species. The common myna (Acridotheres tristis), one of the world's most invasive species, carries a high prevalence of avian malaria (Plasmodium and Haemoproteus spp.) in its native range and is a fierce competitor in its introduced Australian range. We tested whether this competitive advantage stems from pathogen release by comparing malaria prevalence between introduced and native mynas and relating these to prevalence in native Australian birds. We also used a global database of malaria DNA sequences to identify potentially invasive malaria lineages carried by introduced mynas. Malaria prevalence did not differ between introduced and native mynas. However, compared to native birds, Plasmodium prevalence was significantly higher in introduced mynas while Haemoproteus prevalence was significantly lower. Nine Plasmodium lineages were shared between Australia and the myna's native range, and eight of these occurred in both introduced and native mynas. Importantly, four of these shared lineages were also found infecting Australian native birds despite strong phylogeographic evidence for their origination in the myna's native range. We propose that mynas experience a competitive advantage by avoiding Haemoproteus infections in Australia and by harbouring introduced Plasmodium lineages that occasionally spillover to native birds.
Epidemiological and evolutionary implications of seasonal birth pulses in wild mammals
Olivier Restif 1, Alison J Peel, Juliet R C Pulliam, Angela D Lewis, Raina K Plowright, Thomas J O'Shea, David T S Hayman, James L N Wood, Colleen T Webb
1. University of Cambridge, Cambridge, CAMBRIDGESHIRE, United Kingdom
Seasonal birth pulses are frequently observed in wildlife and are expected to affect the dynamics of infectious diseases within populations. We recently showed that the range of birth pulse shapes observed across mammalian species could have a strong impact on the persistence of diseases, as measured by the critical community size1. Here I present the predictions from our model and investigate the potential consequences of seasonal birth pulses for the evolution of virulence in pathogens. I then discuss the implications for the evolution of life history traits in host species.
1. Peel, A., J. Pulliam, A. Luis, R. Plowright, T. O'Shea, D. Hayman, J. Wood, C. Webb and O. Restif (2014). "The effect of seasonal birth pulses on pathogen persistence in wild mammal populations." Proceedings of the Royal Society B: Biological Sciences 281(1786): 20132962.