Epidemiological models are often constructed from statistical methods (stochastic) and/or differential calculus (deterministic). With the power of modern computational methods, it is possible to construct and model complex problems. One area in veterinaryepidemiology where computer science is especially relevant is in the use of Geographic Information Systems (GIS) to allowing analytic approaches to spatial information.
Rabies remains a disease of significant public health concern. In the Americas, bats are an important source of rabies for pets, livestock, and humans. For effective rabies control and prevention, identifying potential areas for disease occurrence is critical to guide future research, inform public health policies, and design interventions. To anticipate zoonotic infectious diseases distribution at coarse scale, veterinaryepidemiology needs to advance via exploring current geographic ecology tools and data using a biological approach. We analyzed bat-borne rabies reports in Chile from 2002 to 2012 to establish associations between rabies occurrence and environmental factors to generate an ecological niche model (ENM). The main rabies reservoir in Chile is the bat species Tadarida brasiliensis ; we mapped 726 occurrences of rabies virus variant AgV4 in this bat species and integrated them with contemporary Normalized Difference Vegetation Index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The correct prediction of areas with rabies in bats and the reliable anticipation of human rabies in our study illustrate the usefulness of ENM for mapping rabies and other zoonotic pathogens. Additionally, we highlight critical issues with selection of environmental variables, methods for model validation, and consideration of sampling bias. Indeed, models with weak or incorrect validation approaches should be interpreted with caution. In conclusion, ecological niche modeling applications for mapping disease risk at coarse geographic scales have a promising future, especially with refinement and enrichment of models with additional information, such as night-time light data, which increased substantially the model ’ s ability to anticipate human rabies.
Information collected during the course of the longitudinal study was contributed by trainers and not by veterinarians. While this practice ensured that information was collected from the persons responsible for managing training activity and making decisions regarding training or spelling of horses, it also increased the potential for misclassification bias particularly regarding events that resulted in the end of a training preparation. This is discussed in more detail in the companion paper. A number of steps were implemented in an attempt to ensure that data collected had good internal validity. The questionnaire was designed with standardised definitions and predominantly closed questions, and contained summary information about the horse from previous visits. The design of the questionnaire remained the same and every visit was conducted in the same way throughout the study. An explanatory guide to the study was discussed in person with every trainer at the beginning of the study and periodic reports were provided to trainers through the study period. The definitions for training activity score were developed in consultation with trainers by adapting definitions of training speed that were in common use by trainers in New Zealand. All veterinary practices that provided veterinary services to the trainers participating in the study were also visited to discuss the study and copies of all reports were sent to veterinarians. Telephone calls and additional visits were made on occasion to trainers and to veterinarians to discuss aspects of the study and collect additional information.
A convenience sample of 206 dairy herds out of 276 serviced by one veterinary business (Eltham District Veterinary Services) in the Taranaki region (approximately -39.36 to -39.48 latitude, and 174.08 to 174.40 longitude) of New Zealand were recruited. Bulk tank milk samples were tested for virus by PCR and antibody by ELISA in September and October (Spring in New Zealand) in the 2007-2008 production season. The majority of these herds (194, 94%) were tested again 12 months later. The study herds had a relatively low prevalence of infection (13/206 herds were PCR positive in the 2007-2008 season). To increase the precision of prevalence and incidence estimates further herds were enrolled and sampled in the 2009-2010 and 2010-2011 seasons around Eltham, Morrinsville, Hamilton, Ashburton, and Oamaru. These herds (n=133) were enrolled in the National herd fertility study (Brownlie et al. 2011) along with a further 63 herds from a Waikato vet practice (AnexaFVC). The 2007 and 2009 data were classified as season 1, and the 2008 and 2010 data were classified as season 2 for analysis. The number of enrolled herds by season and district is summarised in Table 1. None of the herds had conducted BVD testing before enrolment and results from the first season were not reported to vets or herd managers until after the testing was completed in the second season. Hence, initial results could not have affected farm management practices or disease control decisions associated with BVD. Herds were not prevented from controlling BVD and the herds already doing some form of BVD control continued after enrolment. Of those herd seasons with information available, 72% tested bulls for BVD virus, 16% vaccinated bulls with a BVD killed vaccine, 8% vaccinated cows, and 15% of the 44% that bought cows tested at least some of them.
I would like to thank the farmers involved for their time, completing and returning questionnaires, giving permission to test their bulk milk, the use of their facilities and animals, and for following instructions and recording activities and events; New Zealand dairy farmers for funding the study through DairyNZ; The McKenzie legacy trust for additional funding contributions; Eltham District Veterinary Services for financial support, in-kind contributions (particularly Joan Hughes), and the patience and encouragement from other staff members; Livestock Improvement Corporation for in- kind contributions toward the testing costs, particularly Hinrich Voges who provided valuable feedback and advice about diagnostic testing; my supervisors Cord Heuer, Scott McDougall, and Mark Stevenson for their guidance, advice, and feedback. I would also like to acknowledge my family: my wife Kath and my children Sarah, Esther, and Daniel who sacrificed much for this PhD, and my parents Alistair and Heather Weir for their on-going support.
Funding was required to cover the costs of the consensus meet- ing (e.g, travel, accommodations, and meeting rooms). The deci- sion was made by the steering committee not to seek funding from pharmaceutical or biologic companies commonly associated with veterinary research. Eﬀorts to obtain funding were limited to not- for-proﬁt non-government organizations, academic institutions, and a publishing company. Funding was received from the Cana- dian Association for VeterinaryEpidemiology and Preventive Medicine (CAVEPM), the Centre for VeterinaryEpidemiology (CVER) at the University of Prince Edward Island, the Centre for Public Health and Zoonoses (CPHAZ) at the University of Guelph, Iowa State University, Cornell University, and the pub- lishing company VER Inc, Prince Edward Island, Canada. Suﬃ- cient funds were obtained to pay for all local expenses for the participants at the consensus meeting. Funds to cover travel costs for participants were not obtained; therefore, in general, partici- pants fully funded their own travel and the sources of these funds were not identiﬁed.
Sampling of veterinary personnel and their pets (dogs and/or cats) was undertaken over a two-week period in February 2017 (Hospital A) and April 2017 (Hospital B). Veterinary personnel included veterinarians and support staff (veterinary nurses, kennel hands and administrative staff). Personnel were invited to participate whether or not they had pets at home. Personnel were given written and verbal instructions on how to take samples, then took samples from themselves and their pets, undertaking sampling in their own home. For veterinary personnel, a single sterile swab was used to sample one nostril. For pet dogs and cats, personnel took three separate swabs: one each from the anterior nares (large dogs) or nasal planum (small dogs and cats), oral cavity and perineum. For multipet households, sampling was limited to three dogs and/or three cats. Personnel wore gloves during the procedure and refrigerated samples immediately after sampling. All swabs were collected using Amies TM Agar Gel swabs (Copan Diagnostics, USA).
A web-based survey was conducted by the Federation of Veterinarians of Europe with the support of the European Medicines Agency to gain a better insight into the adverse event reporting habits of veterinary practitioners and the level of information on reported adverse events that flows back to them. It was completed by 3545 veterinarians. The findings indicate marked under-reporting and that the system is poorly equipped to deal with lack of expected efficacy, with few cases reported and most found to be inconclusive. It was also found that feedback systems are greatly lacking. In order to increase spontaneous reporting, there is a need to make reporting easier (eg, by developing mobile apps, to incorporate the reporting into the practice management system software) and to make veterinarians better aware of the importance of reporting and the added value it may bring. Feedback systems should be improved. The best way to motivate reporters is to demonstrate that the reports they submit are indeed useful and contribute to the improved use of veterinary medicinal products. The major role veterinarians can play in improving animal health, welfare and public health by reporting adverse events needs to be further promoted.
Earlier, a question regarding the length of time that someone remains in the profession was posed when considering the difference in the number of females and males entering. The same is certainly worth looking at in relation to the levels of debt. The veterinary profession has certainly changed over recent years, and salaried work for the rapidly increasing number of corporate employers may not be seen as the long-term attractive career option that the profession once was. This may also be true when thinking about entry to vet school too. There are undoubtedly many more attractive ways for high achieving students to ‘get rich’ than entering the veterinary profession and an understanding of the likely debt upon graduation is likely to deter some potential applicants.
This thesis would not have been prepared without the help of molecular epidemiology laboratory (mEpiLab) staffs: Dr. Anne Midwinter, Dr. V.S.R Dukkipati, Lynn Rogers, Sarah Moore, Anthony Pita, Niluka Velathanthri, Angy Reynolds, Errol Kwan, Tessy George, Rukhshana Akhtar, and Neville Haack; and Massey genome services staffs Trish McLenachan and Richard Fong. Thank you all for your technical assistance and laboratory expertise.
these specialist centres and will not include those cases treated conservatively in the primary-care setting. Some studies have attempted to report on risk factors for patel- lar luxation but many have lacked a control population and thus are difficult to interpret [2, 7, 10, 17, 21, 25, 26]. Historically, patellar luxation has been most associated with smaller-size dogs, with smaller breeds reported to have up to 12 times the risk compared with larger breeds [4, 21, 27, 28]. The Orthopaedic Foundation for Animals (OFA) surveys orthopaedic disease in animals voluntarily submitted for evaluation in the US . It ranked the Pomeranian and Yorkshire Terrier as the two most commonly affected breeds with 37.2 % and 24.1 % of submissions affected respectively and has reported small breed dogs in general as having the highest preva- lence of patellar luxation . A study based on Veter- inary Medical Database (VMDB) clinical data from US veterinary teaching hospitals identified the Pomeranian, Silky Terrier and Miniature Pinscher as breeds at sub- stantially increased risk . Recently, however, some stud- ies have suggested that larger breeds, and in particular the Labrador Retriever, may now increasingly be affected [7, 17, 26]. Many of these studies, however, were based on relatively small cohorts (often 150 or fewer dogs), volun- tary submissions or referral caseloads and, consequently, these study populations may be less representative of the true overall demographic than caseloads seen by primary- care practices. The former studies may reflect biased in- clusion of certain subsets of patellar luxation caseloads such as larger body-size, insured, purebred or more se- verely affected dogs . Furthermore, the literature is heavily biased towards reporting case series of patellar lux- ation cases that are mainly managed using surgical tech- niques [7, 9–20] where the absence of an explicit comparison group of unaffected animals prevents distinc- tion between whether commonly affected breeds are truly at increased risk or are just more common in the dog population or more commonly referred . Systematic collection and interrogation of a large merged database of primary-care clinical data would counter many of these limitations by enabling evaluation of patellar luxation within a large group of both affected and non-affected pri- mary care dogs and would therefore be more representa- tive of the general population of dogs .
It seems just like yesterday when I first arrived at the EpiCentre wondering what I was getting myself into. Sitting in front of a computer manipulating numbers all day was not my idea of a veterinarian’s career. After six months of statistical concepts, journal club, study group and everything else that went along with them, I realized I was in the cohort. Surely, this was not part of the original script. Days of my undergraduate training when we used to anxiously wait for the epidemiology session to end and rush for surgery seemed ancient. It was time to make the best out of the situation; I was now one of them anyway.