Predicting climate change impacts on human-infectious parasitic disease in marsupials and the public health implications.
In Australia, it is predicted that climate change will extend the seasonal window for parasite transmission and lead to amplification of parasite populations, disease outbreaks in host populations and spread of disease into naïve populations. Climate change in Australia will also result in heavier and less frequent rainfall leading to greater extremes of wetness and dryness resulting in more variable numbers of parasites and greater nutritional stress on native marsupials with consequent reduced resistance to parasites of all types.
Climate changes will also benefit insects that transmit these parasites. For example, insect vectors such as ticks, mosquitoes and flies will be able to complete more generations/year and tropical insect vectors and the parasites they carry will expand their ranges southwards. There is also a risk that the impact of climate change will increase the likelihood of exotic parasitic diseases entering Australia.
While there has been extensive research into microparasites in marsupials, only limited studies have been conducted on protozoan parasites. The construction of predictive computer models for the effect of climate change on zoonotic parasitic disease in marsupial hosts requires baseline data on protozoans that is currently lacking.
Two honours projects are available as part of this study:
1. Prevalence and genetic characterization of Cryptosporidium and Giardia in marsupials
Cryptosporidium and Giardia are enteric parasites that infect a wide range of hosts and are transmitted by the faecal-oral route and by contamination of water supplies. Their environmental stages (oo/cysts) can be shed in very large numbers, are extremely hardy and easily spread by water. Symptoms vary from mild to severe diarrhoea and even death (Fayer et al. 2004). There is no effective therapy for
Cryptosporidium infection (Carey et al. 2004) and both parasites are considered potential bioterrorist agents in the US (http://www.niaid.nih.gov/biodefense/bandc_priority.htm). Little is known about the occurrence and impact of Cryptosporidium and Giardia in native marsupials; however a recent study revealed the prevalence of Cryptosporidium in 3,557 fecal samples from wild eastern grey kangaroos in
NSW was between 0.32% to 28.5% over a 2-year period. A study of Giardia in Tasmanian native marsupials over a 3-yr period revealed a prevalence of 21% in the 295 animals tested. Research in WA suggests that the prevalence of infection with Giardia in a range of marsupials was 12.4%. Both host adapted and zoonotic species of Cryptosporidium and Giardia have been detected in marsupials, highlighting the potential public health risk via transmission to humans.
The objective of this study is to screen marsupial fecal samples using molecular tools from areas of high and low human interaction in order to determine (a) the prevalence of Cryptosporidium/Giardia in marsupials by PCR and (b) to determine whether human-infectious genotypes of
Cryptosporidium/Giardia are found in marsupials using PCR and sequencing techniques. This study will therefore provide important information on not only the biology of Cryptosporidium/Giardia infecting marsupials as well as the transmission dynamics of Giardia and will also identify if there are any public health implications.

2. Prevalence and genetic characterization of blood-parasites in marsupials
Theileria, Babesia and Trypanosoma are haemoprotozoa (blood parasites) transmitted by insect vectors.
There has been no systematic study of native Australian haemoprotozoa and little is known of their epidemiology and impact.
The objective of this study is to screen marsupial blood samples using molecular tools from areas of high and low human interaction in order to determine (a) the prevalence of haemoprotozoa in marsupials by
PCR and (b) to determine whether human-infectious species of haemoprotozoa are found in marsupials using PCR and sequencing techniques. This study will therefore provide important information on not only the biology of haemoprotozoa infecting marsupials as well as the transmission dynamics of haemoprotozoa and will also identify if there are any public health implications.
Data generated from both these studies will be used to conduct climate change modelling to predict the future impacts of climate change on the emergence of zoonotic disease caused by protozoan parasites on their marsupial hosts.
For more information on the above projects contact:
A/Prof. Una Ryan
Room 3.45
Tel: 9360 2482
Email: Una.Ryan@murdoch.edu
.
Biological characterisation of a new species of Cryptosporidium in pigs
Ever want to be involved in the naming of a new species? A new species of Cryptosporidium has recently been detected in pigs, which is genetically very distinct. In order for this species to be formally described in the literature, more information on its biological characteristics is required. This project aims to characterize both the biological characteristics of this species and to further characterize its molecular characteristics. It is anticipated that the results of this project will contribute greatly to our understanding of cryptosporidiosis in pigs and will also result of the formal naming of this species in the scientific literature .
For more information on the above projects contact:
A/Prof. Una Ryan
Room 3.45
Tel: 9360 2482
Email: Una.Ryan@murdoch.edu