Miramar, New Zealand
Miramar, New Zealand

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Muellner P.,Epi interactive | Muellner P.,Massey University | Zadoks R.N.,Moredun Research Institute | Zadoks R.N.,University of Edinburgh | And 6 more authors.
Spatial and Spatio-temporal Epidemiology | Year: 2011

At the interface of molecular biology and epidemiology, the emerging discipline of molecular epidemiology offers unique opportunities to advance the study of diseases through the investigation of infectious agents at the molecular level. Molecular tools can increase our understanding of the factors that shape the spatial and temporal distribution of pathogens and disease. Both spatial and molecular aspects have always been important to the field of infectious disease epidemiology, but recently news tools have been developed which increase our ability to consider both elements within a common framework. This enables the epidemiologist to make inferences about disease patterns in space and time. This paper introduces some basic concepts of molecular epidemiology in a veterinary context and illustrates the application of molecular tools at a range of spatio-temporal scales. Case studies - a multi-state outbreak of Serratia mastitis, a national control program for campylobacteriosis, and evolution of foot-and-mouth-disease viruses - are used to demonstrate the importance of considering molecular aspects in modern epidemiological studies. The discipline of molecular epidemiology is in its infancy and our contribution aims to promote awareness, understanding and uptake of molecular epidemiology in veterinary science. © 2011 Elsevier Ltd.


Cowled B.D.,University of Sydney | Ward M.P.,University of Sydney | Laffan S.W.,University of New South Wales | Galea F.,Australian Department of Primary Industries and Fisheries | And 8 more authors.
PLoS ONE | Year: 2012

Infectious wildlife diseases have enormous global impacts, leading to human pandemics, global biodiversity declines and socio-economic hardship. Understanding how infection persists and is transmitted in wildlife is critical for managing diseases, but our understanding is limited. Our study aim was to better understand how infectious disease persists in wildlife populations by integrating genetics, ecology and epidemiology approaches. Specifically, we aimed to determine whether environmental or host factors were stronger drivers of Salmonella persistence or transmission within a remote and isolated wild pig (Sus scrofa) population. We determined the Salmonella infection status of wild pigs. Salmonella isolates were genotyped and a range of data was collected on putative risk factors for Salmonella transmission. We a priori identified several plausible biological hypotheses for Salmonella prevalence (cross sectional study design) versus transmission (molecular case series study design) and fit the data to these models. There were 543 wild pig Salmonella observations, sampled at 93 unique locations. Salmonella prevalence was 41% (95% confidence interval [CI]: 37-45%). The median Salmonella DICE coefficient (or Salmonella genetic similarity) was 52% (interquartile range [IQR]: 42-62%). Using the traditional cross sectional prevalence study design, the only supported model was based on the hypothesis that abundance of available ecological resources determines Salmonella prevalence in wild pigs. In the molecular study design, spatial proximity and herd membership as well as some individual risk factors (sex, condition score and relative density) determined transmission between pigs. Traditional cross sectional surveys and molecular epidemiological approaches are complementary and together can enhance understanding of disease ecology: abundance of ecological resources critical for wildlife influences Salmonella prevalence, whereas Salmonella transmission is driven by local spatial, social, density and individual factors, rather than resources. This enhanced understanding has implications for the control of diseases in wildlife populations. Attempts to manage wildlife disease using simplistic density approaches do not acknowledge the complexity of disease ecology. © 2012 Cowled et al.


PubMed | Royal Veterinary College, University of Veterinary and Animal Sciences, University of Montréal and Epi interactive
Type: Journal Article | Journal: Zoonoses and public health | Year: 2016

Advances in the availability and affordability of molecular and genomic data are transforming human health care. Surveillance aimed at supporting and improving food safety and animal health is likely to undergo a similar transformation. We propose a definition of molecular surveillance in this context and argue that molecular data are an adjunct to rather than a substitute for sound epidemiological study and surveillance design. Specific considerations with regard to sample collection are raised, as is the importance of the relation between the molecular clock speed of genetic markers and the spatiotemporal scale of the surveillance activity, which can be control- or strategy-focused. Development of standards for study design and assessment of molecular surveillance system attributes is needed, together with development of an interdisciplinary skills base covering both molecular and epidemiological principles.


PubMed | University of Minnesota and Epi interactive
Type: Journal Article | Journal: PloS one | Year: 2016

Salmonellosis remains one of the leading causes of foodborne disease worldwide despite preventive efforts at various stages of the food production chain. The emergence of multi-drug resistant (MDR) non-typhoidal Salmonella enterica represents an additional challenge for public health authorities. Food animals are considered a major reservoir and potential source of foodborne salmonellosis; thus, monitoring of Salmonella strains in livestock may help to detect emergence of new serotypes/MDR phenotypes and to gain a better understanding of Salmonella epidemiology. For this reason, we analyzed trends over a nine-year period in serotypes, and antimicrobial resistance, of Salmonella isolates recovered at the Minnesota Veterinary Diagnostic Laboratory (MVDL) from swine (n = 2,537) and cattle (n = 1,028) samples. Prevalence of predominant serotypes changed over time; in swine, S. Typhimurium and S. Derby decreased and S. Agona and S. 4,5,12:i:- increased throughout the study period. In cattle, S. Dublin, S. Montevideo and S. Cerro increased and S. Muenster became less frequent. Median minimum inhibitory concentration (MIC) values and proportion of antibiotic resistant isolates were higher for those recovered from swine compared with cattle, and were particularly high for certain antibiotic-serotype combinations. The proportion of resistant swine isolates was also higher than observed in the NARMS data, probably due to the different cohort of animals represented in each dataset. Results provide insight into the dynamics of antimicrobial resistant Salmonella in livestock in Minnesota, and can help to monitor emerging trends in antimicrobial resistance.


Muellner P.,Epi interactive | Stark K.D.C.,Royal Veterinary College | Stark K.D.C.,SAFOSO AG | Dufour S.,University of Montréal | Zadoks R.N.,University of Glasgow
Zoonoses and Public Health | Year: 2016

Advances in the availability and affordability of molecular and genomic data are transforming human health care. Surveillance aimed at supporting and improving food safety and animal health is likely to undergo a similar transformation. We propose a definition of ‘molecular surveillance’ in this context and argue that molecular data are an adjunct to rather than a substitute for sound epidemiological study and surveillance design. Specific considerations with regard to sample collection are raised, as is the importance of the relation between the molecular clock speed of genetic markers and the spatiotemporal scale of the surveillance activity, which can be control- or strategy-focused. Development of standards for study design and assessment of molecular surveillance system attributes is needed, together with development of an interdisciplinary skills base covering both molecular and epidemiological principles. © 2015 Blackwell Verlag GmbH


Mcfadden A.M.J.,Ministry for Primary Industries | Muellner P.,Epi interactive | Baljinnyam Z.,Swiss Agency for Development and Cooperation | Vink D.,Ministry for Primary Industries | Wilson N.,University of Otago
Zoonoses and Public Health | Year: 2016

Many developing countries face significant health burdens associated with a high incidence of endemic zoonoses and difficulties in integrated control measures for both the human and animal populations. The objective of this study was to develop and apply a multicriteria ranking model for zoonoses in Mongolia, a country highly affected by zoonotic disease, to inform optimal resource allocation at the national level. Diseases were evaluated based on their impact on human health, livestock sector health and the wider society through affects on the economic value of livestock, as well as the feasibility of control in both the human and livestock population. Data on disease in Mongolia were collected from various government departments including the Mongolian State Central Laboratory, the Mongolian Department of Veterinary and Animal Breeding, the Mongolian Ministry of Health, Mongolian National Center for Communicable Diseases, the National Center for Zoonotic Disease and expert opinion from a workshop with a number of Mongolian Government officials and researchers. A combined score for both impact of the disease and feasibility of its control was calculated. Five zoonotic diseases were determined to be of high priority from this assessment (i.e. ovine brucellosis, echinococcosis (hydatids), rabies, anthrax and bovine brucellosis). The results supported some of the findings for high-priority diseases (namely brucellosis, rabies and anthrax) from a previous priority setting exercise carried out in Mongolia in 2011, but also identified and ranked additional animal diseases of public health importance. While the process of model development was largely Mongolian specific, the experience of developing and parameterizing this multicriteria ranking model could be replicated by other countries where zoonoses have substantive impacts on both animal and human health. © 2016 Blackwell Verlag GmbH.


PubMed | University of Otago, Swiss Agency for Development and Cooperation, Ministry for Primary Industries and Epi interactive
Type: Journal Article | Journal: Zoonoses and public health | Year: 2016

Many developing countries face significant health burdens associated with a high incidence of endemic zoonoses and difficulties in integrated control measures for both the human and animal populations. The objective of this study was to develop and apply a multicriteria ranking model for zoonoses in Mongolia, a country highly affected by zoonotic disease, to inform optimal resource allocation at the national level. Diseases were evaluated based on their impact on human health, livestock sector health and the wider society through affects on the economic value of livestock, as well as the feasibility of control in both the human and livestock population. Data on disease in Mongolia were collected from various government departments including the Mongolian State Central Laboratory, the Mongolian Department of Veterinary and Animal Breeding, the Mongolian Ministry of Health, Mongolian National Center for Communicable Diseases, the National Center for Zoonotic Disease and expert opinion from a workshop with a number of Mongolian Government officials and researchers. A combined score for both impact of the disease and feasibility of its control was calculated. Five zoonotic diseases were determined to be of high priority from this assessment (i.e. ovine brucellosis, echinococcosis (hydatids), rabies, anthrax and bovine brucellosis). The results supported some of the findings for high-priority diseases (namely brucellosis, rabies and anthrax) from a previous priority setting exercise carried out in Mongolia in 2011, but also identified and ranked additional animal diseases of public health importance. While the process of model development was largely Mongolian specific, the experience of developing and parameterizing this multicriteria ranking model could be replicated by other countries where zoonoses have substantive impacts on both animal and human health.


Muellner P.,Epi interactive | Muellner P.,Massey University | Pleydell E.,Massey University | Pirie R.,Institute of Environmental Science and Research | And 4 more authors.
Eurosurveillance | Year: 2013

Molecular-based surveillance of campylobacteriosis in New Zealand contributed to the implementation of interventions that led to a 50% reduction in notified and hospitalised cases of the country's most important zoonosis. From a pre-intervention high of 384 per 100,000 population in 2006, incidence dropped by 50% in 2008; a reduction that has been sustained since. This article illustrates many aspects of the successful use of molecular-based surveillance, including the distinction between control-focused and strategyfocused surveillance and advances in source attribution. We discuss how microbial genetic data can enhance the understanding of epidemiological explanatory and response variables and thereby enrich the epidemiological analysis. Sequence data can be fitted to evolutionary and epidemiological models to gain new insights into pathogen evolution, the nature of associations between strains of pathogens and host species, and aspects of between-host transmission. With the advent of newer sequencing technologies and the availability of rapid, high-coverage genome sequence data, such techniques may be extended and refined within the emerging discipline of genomic epidemiology. The aim of this article is to summarise the experience gained in New Zealand with molecular- based surveillance of campylobacteriosis and to discuss how this experience could be used to further advance the use of molecular tools in surveillance.


Wilhelm B.,University of Guelph | Muellner P.,Epi interactive | Pearl D.L.,University of Guelph | Rajic A.,University of Guelph | And 2 more authors.
Preventive Veterinary Medicine | Year: 2015

Our study objective was to describe the Canadian Hepatitis E virus (HEV) sequences currently cataloged in GenBank from three populations: commercially raised pigs, retail pork, and locally acquired Hepatitis E cases, and to interpret the molecular evidence they provide. We searched the GenBank for any/all Canadian HEV sequences from these populations, and identified highly similar matches using the Basic Local Alignment Search Tool (BLAST) algorithm, studying sequences of the partial ORF2 gene. We validated the findings made using Multiple Sequence Comparison by Log-Expectation (MUSCLE) and Clustal 2 programs for multiple sequence alignments, as inputs to estimate dendrograms using both neighbour-joining and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) methods. The GenBank search yielded 47 sequences collected from pigs: 32 sequences from two to four month old commercial pigs in Québec, one from three to four month old pigs at a research station in Ontario, one from two month old pigs in a commercial Saskatchewan herd, and 13 collected from finisher pigs in a national survey. Additionally, 14 sequences were collected from a national survey of Canadian retail pork livers, and seven sequences from two Canadian pediatric patients with locally acquired Hepatitis E, both from the province of Québec. All sequences belonged to genotype 3. Eight of the 14 sequences from retail pork livers had human-derived sequences in their top ten BLAST matches; six did not. Those eight sequences having close human BLAST matches clustered within a dendrogram, as did those with no close human BLAST matches. Human sequences with close matches to the eight retail sequences included both of the Québec Hepatitis E cases, as well as sequences from Japanese Hepatitis E cases, and Japanese blood donors. Seven of the eight HEV sequences from retail liver with close human BLAST matches originated in Québec. Kulldorff's spatial scan statistic showed a significant (. P<. 0.05) spatial cluster of these sequences, but not of the overall dataset of 12 HEV sequences collected from Québec retail livers. All seven retail liver sequences with close human matches were processed in-store. We conclude that some Canadian sequences of HEV collected from pigs/pork are more closely related to human sequences than others, and hypothesize that detection of some HEV sequences recovered from Canadian retail pork livers may be associated with exposure to human shedding. More research needs to be conducted at the processing level to help understand the molecular epidemiology of HEV in Canadian retail pork. © 2014.


PubMed | Epi interactive
Type: Journal Article | Journal: Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin | Year: 2013

Molecular-based surveillance of campylobacteriosis in New Zealand contributed to the implementation of interventions that led to a 50% reduction in notified and hospitalised cases of the countrys most important zoonosis. From a pre-intervention high of 384 per 100,000 population in 2006, incidence dropped by 50% in 2008; a reduction that has been sustained since. This article illustrates many aspects of the successful use of molecular-based surveillance, including the distinction between control-focused and strategy-focused surveillance and advances in source attribution. We discuss how microbial genetic data can enhance the understanding of epidemiological explanatory and response variables and thereby enrich the epidemiological analysis. Sequence data can be fitted to evolutionary and epidemiological models to gain new insights into pathogen evolution, the nature of associations between strains of pathogens and host species, and aspects of between-host transmission. With the advent of newer sequencing technologies and the availability of rapid, high-coverage genome sequence data, such techniques may be extended and refined within the emerging discipline of genomic epidemiology. The aim of this article is to summarise the experience gained in New Zealand with molecular-based surveillance of campylobacteriosis and to discuss how this experience could be used to further advance the use of molecular tools in surveillance.

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