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Secondly, a non-linear Bayesian model coupled to a microbiology technique for analysing proportional resistance was developed to enable the statistical modelling of environmental AMR load for the first time. This model was compared against existing methods and was shown to better incorporate uncertainty and reduce the biasing of risk factor estimates produced by the varying bacterial abundance in the samples. Using data from a previous study into antimicrobial resistance

Ticks and lice are ectoparasites of veterinary importance to UK livestock. Infestation of livestock can result in economic losses for farmers, caused by reduced animal health and productivity, either by direct feeding effects or through the spread of vector-borne pathogens. A detailed understanding of the prevalence, distribution and associated risk factors for infestation and subsequent vector-borne disease is important to allow effective and targeted control measures to be designed and implemented. Despite this, there is limited national data about tick or louse infestation on livestock farms. The aims of this thesis were to assess the prevalence, distribution, and risk of infestation of ticks and lice and associated vector-borne disease on sheep and cattle farms across Great Britain. A retrospective questionnaire survey was sent to a nationally representitative demographic of sheep and cattle farms to collect data on the presence/absence of livestock infestation (Chapter 2). Tick infestation risk is shown to be spatially aggregated, with areas of significantly elevated risk in north Wales, northwest England and western Scotland (Chapter 3). Overall, the prevalence of farms reporting ticks was 13% for sheep farms and 6% for cattle farms, but in ‘hotspot’ clusters prevalence ranged between 48-100%. The prevalence of farms reporting lice was 16% for sheep farms and cattle farms (Chapter 6). ‘Hotspot’ clusters of farms with louse infestation were only identified for sheep farms, in Wales, northwest England and southwest Scotland, with prevalence in these areas ranging from 31-40%. In the future, it is expected that tick and tick-borne disease risk will change, as tick distribution is strongly influenced by climate. However, Europe-wide models lack sensitivity when predicting future tick distributions. A spatial model was built to predict the future risk of ticks on livestock farms under a range of climate-change scenarios (Chapter 4). Both tick hazard and liv

African swine fever (ASF) is one of the most critical diseases in the pig industry. In Asia, 15 countries have already reported an outbreak as of November 22, 2021. In 2021, China reported the genotype II lower virulent ASF virus (ASFV) and the emergence of genotype I ASFV. ASF is generally known as a contagious and lethal disease, but if chronic infection spreads, then disease control would be more difficult. In the current study, we highlighted the possibility of lower virulent virus distribution throughout China and the subsequent general risk of the virus being released from the country. The kernel density estimation showed that the two highest kernel density areas of ASF notification were located in Northeast and Midwest China. Four of the five provinces where lower virulent ASFV was isolated overlapped with areas of relatively high ASF notification density. In terms of the risk of ASFV spreading from China, eight of the 10 largest airports and three of the 10 largest seaports are located in areas of relatively high ASF notification density. There were flight flow from China to 67 countries and ship flow to 81 countries. Asia had the highest flight flow, followed by Europe, North America, Africa, and Oceania. The highest number of ship flows was also concentrated in Asia, but about 10% of ships head to Africa and South America. Chinese overseas residents were distributed in each continent in proportion to these results. Here, we highlight the potential risk of ASFV spread from China to the world.

Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis, a chronic disease of sheep and goats, characterized by the formation of suppurative abscesses in superficial and visceral lymph nodes and internal organs of small ruminants. Little is known about the male goat`s reproductive pathophysiology inoculated with Corynebacterium pseudotuberculois and its immunogen mycolic acid extract. Hence, this study was designed to determine the concentration of testosterone hormone and proinflammatory cytokines of the experimental animals and to determine the histopathological effectof male reproductive organs and the associated lymph nodes. A total of 12 bucks, divided into 3 treatment groups of equal numbers (4 goats per group) were selected in this study. Group 1 (Negative control group)was inoculated intradermally with 2ml of sterile phosphate buffered saline (PBS) pH7. Group 2 (Positive control group)was inoculated intradermally with 2ml of 1×10⁹ colony forming unit (cfu) of C. pseudotuberculosis. Group 3 (Mycolic acid group) was inoculated intradermally with 2ml of mycolic acid extract. During the post inoculation period of 60 days, the goats were observed for clinical signs. Body temperature was taken daily. Heart rate, respiratory rate and body score were measured on weekly basis. Lymph nodes were checked daily and findings were recorded. All experimental animals in Group 1 survived throughout the course of study period with no evidence of clinical manifestation. There was an increment in body temperature observed from week 0 to week 3 for group 2 (PC) compared to group 1 (NC). In Group 3 (MA), there was an increased in body temperature observed during week 0- 3 but not as severe as group 2. However, the heart rate and respiratory rate of both groups 2 and 3 were normal. The concentration of testosterone hormone in group 2 increased significantly (p < 0.05) in week 4, 5 and 8 but decreased in weeks 1 and 6 post inoculation. In group 3, the mean

Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis, a chronic disease of sheep and goats, characterized by the formation of suppurative abscesses in superficial and visceral lymph nodes and internal organs of small ruminants. Little is known about the male goat`s reproductive pathophysiology inoculated with Corynebacterium pseudotuberculois and its immunogen mycolic acid extract. Hence, this study was designed to determine the concentration of testosterone hormone and proinflammatory cytokines of the experimental animals and to determine the histopathological effectof male reproductive organs and the associated lymph nodes. A total of 12 bucks, divided into 3 treatment groups of equal numbers (4 goats per group) were selected in this study. Group 1 (Negative control group)was inoculated intradermally with 2ml of sterile phosphate buffered saline (PBS) pH7. Group 2 (Positive control group)was inoculated intradermally with 2ml of 1×10⁹ colony forming unit (cfu) of C. pseudotuberculosis. Group 3 (Mycolic acid group) was inoculated intradermally with 2ml of mycolic acid extract. During the post inoculation period of 60 days, the goats were observed for clinical signs. Body temperature was taken daily. Heart rate, respiratory rate and body score were measured on weekly basis. Lymph nodes were checked daily and findings were recorded. All experimental animals in Group 1 survived throughout the course of study period with no evidence of clinical manifestation. There was an increment in body temperature observed from week 0 to week 3 for group 2 (PC) compared to group 1 (NC). In Group 3 (MA), there was an increased in body temperature observed during week 0- 3 but not as severe as group 2. However, the heart rate and respiratory rate of both groups 2 and 3 were normal. The concentration of testosterone hormone in group 2 increased significantly (p < 0.05) in week 4, 5 and 8 but decreased in weeks 1 and 6 post inoculation. In group 3, the mean

Many ‘big data’ streams have recently become available in animal health disciplines. While these data may be able to provide valuable epidemiological information, researchers are at risk of making erroneous inferences if limitations in these data are overlooked. This thesis focused on understanding the better use of two data streams—livestock movement records and genetic sequence data. The first study analysed national dairy cattle movement data in New Zealand to explore whether regionalisation of the country based on bovine tuberculosis risk influenced trade decisions. The results suggested that the observed livestock movement patterns could be explained by the majority of, but not all, farmers avoiding purchasing cattle from high disease risk areas. The second study took an alternative approach—qualitative interviews—to understanding farmers’ livestock purchasing practices. This study suggested that farmers are not necessarily concerned with disease status of source farms and that it may be the reliance on stock agents to facilitate trade that creates the observed livestock movement patterns in New Zealand. The findings from this study also implied that various demographic and production characteristics of animals may influence farmers’ livestock selling practices, which were quantitatively verified in the third study analysing livestock movement data and animal production data. These studies not only showed that analyses based solely on ‘big data’ can be misleading but also provided useful information necessary to predict future livestock movement patterns. The final study evaluated the performance of various genetic sequence sampling strategies in making phylodynamic inferences. We showed that using all available genetic samples can be not only computationally expensive, but also may lead to erroneous inferences. The results also suggested that strategies for sampling genetic sequences for phylodynamic analyses may need to be tailored based on epidemiological ch

‘Go Slow’ myopathy (GSM) is an idiopathic myopathy in dogs in New Zealand, characterised by an acute onset of trembling, weakness and collapse, followed by a prolonged period of exercise intolerance. In the first part of this thesis, the epidemiology of the disease was investigated using a telephone survey to obtain information regarding the diet, exercise, and health of affected dogs. Eighty-six confirmed cases were included in this study, and ingestion of wild pig in the week prior to the onset of clinical signs was a consistent finding (76/86 dogs; 88%; 95% confidence interval = 82 – 95%). Cases occurred most commonly in the upper North Island, particularly in Northland. The aim of the second part of this thesis was to characterise the pathology of GSM in the same 86 dogs included in the epidemiological study, using serum biochemistry (78 dogs), histology (20 dogs), and electron microscopy (4 dogs). Acutely, affected dogs had increased serum creatine kinase and aspartate aminotransferase activities, corresponding with the histological finding of skeletal muscle degeneration in the absence of inflammation. Ultrastructural changes in skeletal muscle included mitochondrial hypertrophy, intramitochondrial inclusions and increased sarcoplasmic glycogen. Similar lesions were observed in the skeletal muscle of wild pigs from areas where GSM occurred in dogs. Affected dogs also had increased serum alanine aminotransferase activities due to accumulation of lipid and glycogen in hepatocytes. Overall, the microscopic findings were consistent with a toxic myopathy. To further investigate the pathogenesis of the disease, liver samples were collected from 15 affected dogs and 24 clinically normal dogs for untargeted metabolic profiling using liquid chromatography-mass spectrometry. Comparison of spectra between affected and normal dogs revealed a widespread decrease in phospholipids, and increases in selected dicarboxylic acids and N-acetylated branch chain amino acids in affe

Факултет ветеринарске медицине представља један од факултета који пружају практична знања и вештине, а планови и програми појединих предмета дају солидну основу да по дипломирању лекар ветеринарске медицине зна да постави сумњу на неку заразну и паразитску болест, обави хируршку операцију, анализира резултате дијагностичких испитивања телесних флуида, уведе животињу у анестезију, обави телење, анализира резултате испитивања квалитета сточарских производа, апликује терапију у зависности од дијагнозе и потреба животиња, саветује сточара у вези технологије узгоја и биосиурносних мера итд. Кроз сваки од наведених (и ненаведених) послова, провлачи се један заједнички именитељ. Наиме, појединачни случајеви тј. пацијенти и најчешће позитиван исход третмана, не би значили пуно ако се не би анализовали са становишта правилности и учесталости појављивања болести и успеха спроведених мера. Као лекари ветеринарске медицине, често у помоћ позивамо статистичаре који нам са мање или више успеха, користећи статистичке методе, објасне како се појединачни случајеви болести уклапају у целу слику односа епизоотиолошких детерминанти: узрока (микроорганизма), пријемчиве врсте животиња (макроорганизма) и спољашњег фактора. Међутим, биолошки закони који представљају основу ветеринарске медицине често или нису до краја познати или по природи ствари нису елементи које статистичари уче. Отуда је од великог значаја да сваки лекар ветеринарске медицине буде и епизоотиолог и да на основу својих искустава (рада), покуша да пронађе закономерности поремећаја здравља, производних карактеристика и добробити у популацијама животињских врста као и да установи који су то фактори који утичу на појаву ових поремећаја, а са циљем изналажења мера за њихово уклањање и/или смањењe штета. Имајући у виду професионални профил епизоотиолога, може да се каже да епизоотиолошка служба обједињује податке о поремећајима здравља, производних карактеристика и добробити животиња и има задатак да анализује добијене информ, The Faculty of Veterinary Medicine is one of the „hands on“ faculties whose curriculum offers a sound base for a graduate to diagnose an infective or parasitic disease, perform a surgical intervention, analyze results of body fluids tests, assist delivery, assess the quality of livestock products, apply treatment according to the diagnosis and need of the animal, offer council to the farmers, etc. In all the listed (and not listed) duties there is a common denominator, as individual cases would not be of relevance if not observed within the framework of disease regularity and incidence, as well as success of the performed measures. Doctors of veterinary medicine very often appeal to the help of statisticians which to a higher or lesser extent, with the aid of statistical methods, explain how individual cases fit within the whole picture of epizootiological factors: cause (microorganisms), susceptible animal (macro organism), and environmental factors. However, biological rules which represent the core of veterinary medicine very often are not elucidated, or are not taken into account by the statisticians. Thus, the importance for every veterinarian to find the epizootiologist within, and according to his/her knowledge and experience try to define the rules according to which a disease develops or production and welfare are affected. At the same time the veterinarian should be able to define which factors affect the presence of these disorders, all with the aim of prevention and/or damage mitigation. Bearing in mind the professional profile of an epizootiologist, it can be said that the epizootiological service encompasses data on health disorders, productive characteristics and animal welfare and within the Ministry of Agriculture has a role to analyze the obtained data, suggest and carry out control measures, combat and eradicate above all infectious diseases. Also, the Directorate for Veterinary Affairs forwards data to the International Office thus collaborating

In this study we combined an inventory of the major applications, geographic regions and diseases covered by participatory epidemiology (PE) activities in the field of animal health since 1980, together with an email discussion forum with PE practitioners from different regions of the world. The inventory included the search of peer-reviewed papers, master and technical reports, conference proceedings, manuals, training materials and projects. The search resulted in a low number of PE activity results until the year 2000, followed by a considerable increase (especially from 2012). Most of the identified activities were implemented in Africa and Asia, and focused on surveillance, disease survey and prioritization, and disease control. Seventy-nine PE practitioners working predominantly in Africa, Asia and Europe (29, 22 and 18 respectively) contributed to the email discussion forum. They proposed various modifications to the existing PE definition and discussed different issues related to the applicatoin of PE, its institutionalization for use in policy development, as well as the priorities for future development. The need to increase the number of PE trained people together with some methodological developments and the application of this methodology in developed countries, were some of the points highlighted during the forum. These factors stress the importance of further developing PE as a useful approach for engaging communities in addressing animal and related public health risks.

The reconversion of illicit crops implies using alternative production systems. The Integrated Sustainable Agriculture and Livestock Nuclei (NISA) project supported these processes. A NISA nucleus consists of 20 to 28 producers who share knowledge of livestock innovation. A previous exercise in participatory epidemiology allowed to identify the most sensitive problems, including parasitic diseases. A transversal epidemiological study was performed in young bovines of different ages to establish parasitic infection dynamics in NISA nuclei in the municipalities of Puerto Rico and La Macarena, as a basis for prevention and control interventions. Ten young cattle and some adult animals were sampled in each farm for hematological and coprological analysis; the weight and condition of each animal were recorded. Weight gain in calves fluctuated between 450 and 500 g/d. Internal parasites were found on all farms, but they were different in importance; Strongyloides papillosus and Toxocara vitulorum presented high counts in cattle from 2 to 5 months of age. Trichostrongylids reached peak of excretion at six months of age. Moderate concentrations of parasites induce immunity; thus, anthelmintic treatment is recommended only at this age. The existence of endemic stability for hemoparasites was suggested. Professional counseling should be directed to ensuring that producers understand these stability processes without abusing drugs, while attending to the components of animal handling and welfare. Rural extension requires accompaniment by public policies and attention to socioeconomic aspects in order to contribute to rural development, which help to the reduction of inequalities in the Colombian countryside., A reconversão de cultivos ilícitos implica respaldar-se em sistemas de produção alternativos. O projeto Núcleos Integrais Sustentáveis Agropecuários (NISA) apoiou estes processos. Um núcleo NISA o conformam entre 20 e 28 produtores que compartilham conhecimentos de inovação pecuária. Um exercício prévio de epidemiologia participativa permitiu conhecer os problemas mais sentidos, entre estes as afecções parasitárias. Realizou-se um estudo epidemiológico transversal em bovinos jovens de diversas idades para estabelecer as dinâmicas de infecção parasitária em núcleos NISA nos municípios de Puerto Rico e La Macarena, como fundamento para intervenções de prevenção e controle. Em cada fazenda foram tomadas amostras de 10 bovinos jovens e alguns animais adultos para análise hematológico e coprológico; se determinou peso e condição de cada animal. O aumento de peso em bezerros flutuou entre 450 e 500 g/d. Foram encontrados parasitas internos em todas as fazendas, mas diferiram em importância; Strongyloides papillosus e Toxocara vitulorum apresentaram altas contagens em bovinos de 2 a 5 meses de idade. Os trichostrongylidos atingiram seu pico de excreção aos seis meses de idade. As concentrações moderadas de parasitas são indutoras de imunidade; portanto, se recomenda tratamento anti-helmíntico somente a esta idade. Sugeriu-se a existência de estabilidade endêmica para hemoparasitas. A assessoria profissional deve estar focada em assegurar que o produtor compreenda estes processos de estabilidade sem abusar dos fármacos, atendendo componentes de manejo e bem-estar animal. A extensão rural requer ser acompanhada de políticas públicas e considerar aspectos socioeconômicos para contribuir para o desenvolvimento rural, o que permite a redução das desigualdades no campo colombiano., La reconversión de cultivos ilícitos implica soportar sistemas de producción alternativos. El proyecto Núcleos Integrales Sostenibles Agropecuarios (NISA) apoyó estos procesos. Un núcleo NISA lo conforman entre 20 y 28 productores que comparten conocimientos de innovación ganadera. Un ejercicio previo de epidemiología participativa permitió conocer los problemas más sentidos, entre ellos las afecciones parasitarias. Se realizó un estudio epidemiológico transversal en bovinos jóvenes de diversas edades para establecer las dinámicas de infección parasitaria en núcleos NISA en los municipios de Puerto Rico y La Macarena, como fundamento para intervenciones de prevención y control. En cada finca se muestrearon diez bovinos jóvenes y algunos animales adultos para análisis hematológico y coprológico; se determinó peso y condición de cada animal. Las ganancias de peso en terneros fluctuaron entre 450 y 500 g/d. Se encontraron parásitos internos en todas las fincas, pero difirieron en importancia; Strongyloides papillosus y Toxocara vitulorum presentaron altos recuentos en bovinos de 2 a 5 meses de edad. Los trichostrongylidos alcanzaron pico de excreción a los seis meses de edad. Las concentraciones moderadas de parásitos son inductoras de inmunidad; por tanto, se recomienda tratamiento antihelmíntico solo a esta edad. Se sugirió la existencia de estabilidad endémica para hemoparásitos. La asesoría profesional debe dirigirse a asegurar que el productor comprenda estos procesos de estabilidad sin abusar de los fármacos, atendiendo componentes de manejo y bienestar animal. La extensión rural requiere ser acompañada de políticas públicas y considerar aspectos socioeconómicos para contribuir al desarrollo rural, lo que reducirá las desigualdades en el campo colombiano.

The reconversion of illicit crops implies using alternative production systems. The Integrated Sustainable Agriculture and Livestock Nuclei (NISA) project supported these processes. A NISA nucleus consists of 20 to 28 producers who share knowledge of livestock innovation. A previous exercise in participatory epidemiology allowed to identify the most sensitive problems, including parasitic diseases. A transversal epidemiological study was performed in young bovines of different ages to establish parasitic infection dynamics in NISA nuclei in the municipalities of Puerto Rico and La Macarena, as a basis for prevention and control interventions. Ten young cattle and some adult animals were sampled in each farm for hematological and coprological analysis; the weight and condition of each animal were recorded. Weight gain in calves fluctuated between 450 and 500 g/d. Internal parasites were found on all farms, but they were different in importance; Strongyloides papillosus and Toxocara vitulorum presented high counts in cattle from 2 to 5 months of age. Trichostrongylids reached peak of excretion at six months of age. Moderate concentrations of parasites induce immunity; thus, anthelmintic treatment is recommended only at this age. The existence of endemic stability for hemoparasites was suggested. Professional counseling should be directed to ensuring that producers understand these stability processes without abusing drugs, while attending to the components of animal handling and welfare. Rural extension requires accompaniment by public policies and attention to socioeconomic aspects in order to contribute to rural development, which help to the reduction of inequalities in the Colombian countryside., A reconversão de cultivos ilícitos implica respaldar-se em sistemas de produção alternativos. O projeto Núcleos Integrais Sustentáveis Agropecuários (NISA) apoiou estes processos. Um núcleo NISA o conformam entre 20 e 28 produtores que compartilham conhecimentos de inovação pecuária. Um exercício prévio de epidemiologia participativa permitiu conhecer os problemas mais sentidos, entre estes as afecções parasitárias. Realizou-se um estudo epidemiológico transversal em bovinos jovens de diversas idades para estabelecer as dinâmicas de infecção parasitária em núcleos NISA nos municípios de Puerto Rico e La Macarena, como fundamento para intervenções de prevenção e controle. Em cada fazenda foram tomadas amostras de 10 bovinos jovens e alguns animais adultos para análise hematológico e coprológico; se determinou peso e condição de cada animal. O aumento de peso em bezerros flutuou entre 450 e 500 g/d. Foram encontrados parasitas internos em todas as fazendas, mas diferiram em importância; Strongyloides papillosus e Toxocara vitulorum apresentaram altas contagens em bovinos de 2 a 5 meses de idade. Os trichostrongylidos atingiram seu pico de excreção aos seis meses de idade. As concentrações moderadas de parasitas são indutoras de imunidade; portanto, se recomenda tratamento anti-helmíntico somente a esta idade. Sugeriu-se a existência de estabilidade endêmica para hemoparasitas. A assessoria profissional deve estar focada em assegurar que o produtor compreenda estes processos de estabilidade sem abusar dos fármacos, atendendo componentes de manejo e bem-estar animal. A extensão rural requer ser acompanhada de políticas públicas e considerar aspectos socioeconômicos para contribuir para o desenvolvimento rural, o que permite a redução das desigualdades no campo colombiano., La reconversión de cultivos ilícitos implica soportar sistemas de producción alternativos. El proyecto Núcleos Integrales Sostenibles Agropecuarios (NISA) apoyó estos procesos. Un núcleo NISA lo conforman entre 20 y 28 productores que comparten conocimientos de innovación ganadera. Un ejercicio previo de epidemiología participativa permitió conocer los problemas más sentidos, entre ellos las afecciones parasitarias. Se realizó un estudio epidemiológico transversal en bovinos jóvenes de diversas edades para establecer las dinámicas de infección parasitaria en núcleos NISA en los municipios de Puerto Rico y La Macarena, como fundamento para intervenciones de prevención y control. En cada finca se muestrearon diez bovinos jóvenes y algunos animales adultos para análisis hematológico y coprológico; se determinó peso y condición de cada animal. Las ganancias de peso en terneros fluctuaron entre 450 y 500 g/d. Se encontraron parásitos internos en todas las fincas, pero difirieron en importancia; Strongyloides papillosus y Toxocara vitulorum presentaron altos recuentos en bovinos de 2 a 5 meses de edad. Los trichostrongylidos alcanzaron pico de excreción a los seis meses de edad. Las concentraciones moderadas de parásitos son inductoras de inmunidad; por tanto, se recomienda tratamiento antihelmíntico solo a esta edad. Se sugirió la existencia de estabilidad endémica para hemoparásitos. La asesoría profesional debe dirigirse a asegurar que el productor comprenda estos procesos de estabilidad sin abusar de los fármacos, atendiendo componentes de manejo y bienestar animal. La extensión rural requiere ser acompañada de políticas públicas y considerar aspectos socioeconómicos para contribuir al desarrollo rural, lo que reducirá las desigualdades en el campo colombiano.

Reproductive performance in rising two-year-old (R2) and mixed-aged (MA) adult hinds is suboptimal in farmed red deer in New Zealand due to failure to conceive, fetal loss, and perinatal and postnatal mortality. Reproductive efficiency (calves weaned/hinds mated) in the last decade has averaged 75% (Statistics New Zealand 2016). Previous studies have identified risk factors for conception/pregnancy. However, while abortions are considered rare, they have been reported at low levels in a few earlier studies, but more recently a clinical investigation reported up to 10% mid-term abortion in four herds. Hence, abortion may be going unobserved on deer farms. This epidemiological study was designed to investigate fetal wastage in farmed deer in New Zealand. The work presented in this thesis includes estimation of incidence and prevalence along with putative investigation into infectious causes based on blood, uteri and aborted fetal tissue, and analysis of farm and management risk factors based on data collected by questionnaire. It also includes the validation of an ELISA for Toxoplasma gondii which, based on recent clinical observations, was considered a likely contributor to abortion. Gold standard and Bayesian methodology showed this test to be 78.9% and 98.8% sensitive and 97.5% and 92.8% specific, respectively. Eighty-five deer farms were recruited over two-years, comprising 87 R2 and 71 MA herds and 22,130 R2 and 36,223MA hinds. The mean pregnancy rate at usual scan (Scan-1) was 82.0% (range: 7.0 - 100%) in R2 hinds and 92.6% (range: 39.8 - 100%) in MA hinds. Observations of aborting fetuses at scanning, along with a pilot study of early abortion confirms that sub-optimum pregnancy scan results are not attributable to sub-optimum conception rate alone as conventionally believed. A second pregnancy scan (Scan-2) was performed after a mean interval of 90 and 87 days from Scan-1 in a subsample of 11,005 R2 and 7,374 MA hinds, respectively, to determine fetal wastage

Facial eczema is a hepatogenous photosensitisation of ruminants caused by sporidesmin produced by the saprophytic fungus Pithomyces chartarum. It is of large concern to the dairy industry, both with its effects on production and the significant animal welfare implications of affected stock. In 2011 DairyNZ and Sustainable Farming Fund invested in research initially aimed at trying to get a better understanding behind the natural spore count variability in paddocks, between paddocks and between farms and to try and find alternative ways of managing facial eczema without zinc. After this research was completed in 2013 it was deemed necessary to try and understand to what extent management of facial eczema was breaking down and possible reasons for these breakdowns. The overall aim of this research was to try and help farmers improve their management of this disease and reduce incidence of facial eczema. A study comparing the spore counts from paddocks containing varying quantities of herbs, clovers and tall fescue showed that the addition of chicory, plantain, lucerne and white clover into a ryegrass pasture did not provide any reduction in spore counts. Tall fescue paddocks showed lower spore counts over time than pure swards of ryegrass. A study comparing the application of lime and nitrogen in comparison to control paddocks showed that application of lime before the risk period for facial eczema (in November), application of lime after a spore count rise, (in March) or urea application (in December) did not affect the number of spores produced by Pithomyces chartarum. A study investigating the variability of spore counts within farm, paddock, grass sample and water aliquot showed that if spore counts are to be used for monitoring purposes to identify when to start and finish facial eczema(FE) prevention programmes, at least three aliquots per wash water should be selected. Finally, a study looking at the different types of management of FE used and their effectiven

Silva S.R., Lourenço E.C., Tassinari W.S. & Famadas K.M. [Descriptive study of the historical series of tick occurrence in dogs assisted in two animal health units in the western zone of the city of Rio de Janeiro.] Estudo descritivo da série histórica de ocorrência de carrapatos em cães assistidos em duas unidades privadas de saúde animal na zona oeste da cidade do Rio de Janeiro. Revista Brasileira de Medicina Veterinária, 38(supl. 3):249-259, 2016. Programa de Pós-Graduação em Ciências Veterinárias, Universidade Federal Rural do Rio de Janeiro, BR465, Km 7, Seropédica, RJ 23890-000, Brasil. E-mail: silvioveteri@yahoo.com.br. Despite ticks relevance for public health, few studies have been carried out aiming at the epidemiology of these parasites in urban environment. There is no study of time series data for tick occurrence, which would be very useful for animal health professionals regarding the prophylaxis and control of these parasites. The aim of this work was to describe the historical series of tick occurrence in dogs assisted in two private animal health units in urban environment, from January 2000 to December 2014. The Noch test was used to verify differences in prevalence between the years, and the chi-square test, to evaluate the prevalence of tick occurrence between the months and between the years. The correlation between prevalence of tick occurrence and temperature was also performed. One thousand and five hundred veterinary medical records were systematically selected. The records of parasitism between the years were not uniform. In 2003, 2004 and 2009 were observed the highest prevalence, 43.00%, 31.00% and 31.00%, respectively in relation to the other years. In February (26,00%) and September (11,80%) were observed the highest and lowest values, respectively, with no differences. No seasonal patterns or temporal trend of the prevalence of tick occurrence in dogs were observed in the study area. There is no evidence that temperature, Apesar da relevância que carrapatos em ambientes possuem para a saúde pública poucos são os estudos direcionados para a epidemiologia desses parasitos em ambiente urbano. Não havendo análises de dados de série temporal, o que seria muito útil para os profissionais da saúde animal com relação à profilaxia e controle desses parasitos. O objetivo deste trabalho foi realizar um estudo descritivo da série histórica de ocorrência de carrapatos em cães assistidos em duas unidades privadas de saúde animal em ambiente urbano no período de janeiro de 2000 a dezembro de 2014. Para tal utilizamos o teste gráfico de Noch para verificar diferenças nas prevalências entre os anos, assim como o teste do qui-quadradro para avaliar a prevalência entre os meses e entre os anos. Foi realizada também a correlação entre prevalência e temperatura. Foram selecionados de forma sistemática 1500 prontuários médicos veterinários. Foi verificado a não uniformidade de registro de parasitismo entre os anos. As maiores prevalências foram nos anos de 2003, 2004 e 2009 com 43,00%, 31,00% e 31,00%. O mês com maior prevalência de parasitismo foi fevereiro (26,00%) e o com menor foi setembro (11,80%), não havendo diferenças significativas. Não foram observados padrões sazonais nem de tendência temporal da prevalência de ocorrência de carrapatos em cães nesta região. Não há evidências de que a temperatura influência no aumento da prevalência da ocorrência de carrapatos em cães no ambiente urbano. A inclusão do diagnóstico específico e estágio do carrapato, bem como o número de carrapatos observados no exame do animal nos prontuários de atendimento foi considerado muito importante para que estudos epidemiológicos mais detalhados envolvendo carrapato/cão possam ser realizados.

Silva S.R., Lourenço E.C., Tassinari W.S. & Famadas K.M. [Descriptive study of the historical series of tick occurrence in dogs assisted in two animal health units in the western zone of the city of Rio de Janeiro.] Estudo descritivo da série histórica de ocorrência de carrapatos em cães assistidos em duas unidades privadas de saúde animal na zona oeste da cidade do Rio de Janeiro. Revista Brasileira de Medicina Veterinária, 38(supl. 3):249-259, 2016. Programa de Pós-Graduação em Ciências Veterinárias, Universidade Federal Rural do Rio de Janeiro, BR465, Km 7, Seropédica, RJ 23890-000, Brasil. E-mail: silvioveteri@yahoo.com.br. Despite ticks relevance for public health, few studies have been carried out aiming at the epidemiology of these parasites in urban environment. There is no study of time series data for tick occurrence, which would be very useful for animal health professionals regarding the prophylaxis and control of these parasites. The aim of this work was to describe the historical series of tick occurrence in dogs assisted in two private animal health units in urban environment, from January 2000 to December 2014. The Noch test was used to verify differences in prevalence between the years, and the chi-square test, to evaluate the prevalence of tick occurrence between the months and between the years. The correlation between prevalence of tick occurrence and temperature was also performed. One thousand and five hundred veterinary medical records were systematically selected. The records of parasitism between the years were not uniform. In 2003, 2004 and 2009 were observed the highest prevalence, 43.00%, 31.00% and 31.00%, respectively in relation to the other years. In February (26,00%) and September (11,80%) were observed the highest and lowest values, respectively, with no differences. No seasonal patterns or temporal trend of the prevalence of tick occurrence in dogs were observed in the study area. There is no evidence that temperature, Apesar da relevância que carrapatos em ambientes possuem para a saúde pública poucos são os estudos direcionados para a epidemiologia desses parasitos em ambiente urbano. Não havendo análises de dados de série temporal, o que seria muito útil para os profissionais da saúde animal com relação à profilaxia e controle desses parasitos. O objetivo deste trabalho foi realizar um estudo descritivo da série histórica de ocorrência de carrapatos em cães assistidos em duas unidades privadas de saúde animal em ambiente urbano no período de janeiro de 2000 a dezembro de 2014. Para tal utilizamos o teste gráfico de Noch para verificar diferenças nas prevalências entre os anos, assim como o teste do qui-quadradro para avaliar a prevalência entre os meses e entre os anos. Foi realizada também a correlação entre prevalência e temperatura. Foram selecionados de forma sistemática 1500 prontuários médicos veterinários. Foi verificado a não uniformidade de registro de parasitismo entre os anos. As maiores prevalências foram nos anos de 2003, 2004 e 2009 com 43,00%, 31,00% e 31,00%. O mês com maior prevalência de parasitismo foi fevereiro (26,00%) e o com menor foi setembro (11,80%), não havendo diferenças significativas. Não foram observados padrões sazonais nem de tendência temporal da prevalência de ocorrência de carrapatos em cães nesta região. Não há evidências de que a temperatura influência no aumento da prevalência da ocorrência de carrapatos em cães no ambiente urbano. A inclusão do diagnóstico específico e estágio do carrapato, bem como o número de carrapatos observados no exame do animal nos prontuários de atendimento foi considerado muito importante para que estudos epidemiológicos mais detalhados envolvendo carrapato/cão possam ser realizados.

An epidemiological study of African swine fever (ASF) was conducted between March 2006 and September 2007 in a rural area adjacent to the Gorongosa National park (GNP) located in the Central Mozambique. Domestic pigs and warthogs were sampled to determine the prevalence of antibodies against ASF virus and the salivary antigens of Ornithodoros spp. ticks, while ticks collected from pig pens were tested for the presence of ASFV. In addition, 310 framers were interviewed to gain a better understanding of the pig value chain and potential practices that could impact on the spread of the virus. The sero-prevalence to ASFV was 12.6% on farms and 9.1% in pigs, while it reached 75% in warthogs. Approximately 33% of pigs and 78% of warthogs showed antibodies against salivary antigens of ticks. The differences in sero-prevalence between farms close to the GNP, where there is greater chance for the sylvatic cycle to cause outbreaks, and farms located in the rest of the district, where pig to pig transmission is more likely to occur, were marginally significant. Ornithodoros spp. ticks were found in only 2 of 20 pig pens outside the GNP, and both pens had ticks testing positive for ASFV DNA. Interviews carried out among farmers indicated that biosecurity measures were mostly absent. Herd sizes were small with pigs kept in a free-ranging husbandry system (65%). Only 1.6% of farmers slaughtered on their premises, but 51% acknowledged allowing visitors into their farms to purchase pigs. ASF outbreaks seemed to have a severe economic impact with nearly 36% of farmers ceasing pig farming for at least 1 year after a suspected ASF outbreak. This study provides the first evidence of the existence of a sylvatic cycle in Mozambique and confirms the presence of a permanent source of virus for the domestic pig value chain.

Decisions regarding transboundary livestock disease control strategies differ from personal decisions, such as buying groceries, in important ways: the stakes are high and the outcome of a decision will affect people in different fields. Decision making for transboundary livestock disease control strategies requires consideration of a number of factors including the epidemiology of the disease, economic cost of control, and environmental and social impact. For example, when applying pre-emptive slaughtering as a control measure for FMD, decision makers need to consider the epidemiologic effectiveness of the control measure, financial loss to farmers, the operational cost of slaughtering, negative impacts on the environment due to burning or burial of culled animals, and the public’s concerns for the welfare of slaughtered animals. Therefore, it can be challenging for decision makers to choose the best control strategy among alternative strategies. The study presented in the thesis describes the application of multi-criteria decision analysis (MCDA) process as a decision support tool for decision making about transboundary livestock disease control strategies using an example of a simulated FMD outbreak. The first research chapter (Chapter 3) investigates the preferences of chief veterinary officers (CVOs) for the criteria of FMD-control strategies in the Asia-Oceania region, which comprises countries free from or having experienced FMD. Criteria were grouped into epidemiologic, economic, and social-environmental. The CVOs in the Asia-Oceania region considered the epidemiologic criterion more important than the economic or the social-environmental criterion. The importance of the economic criterion differed with FMD status of a country: specifically, those countries considered free of FMD ranked the economic criterion as more important than those without. Among the criteria comprising the epidemiologic criterion, the most important was the size of the FMD-infected ar

In epidemiology we are concerned with disease occurrence and its associated explanatory factors. Through analysis of the patterns in disease spread, in space and/or time, we are able to obtain information about possible risk factors and transmission mechanisms. The main focus in spatial epidemiology has been human health. However, economic costs and the concern about zoonoses has fuelled a growing field of veterinary epidemiology. Veterinary epidemiology has the added complication of the `human effect'. For a disease to be recorded we require humans to detect and report the disease, and once reported human intervention is generally applied. This can lead to the true level of disease being under-represented with the loss of information impeding modelling and model predictions. The reliability of statistical analyses depends on the quality of the underlying data. Anomalies could introduce significant bias and lead to inappropriate decision making. Residual analysis is often used to detect anomalous data, but with hierarchical models (common within epidemiology) the highly exible representation of variation can mask outliers. We propose the use of exceedance probabilities as a tool for identifying and assessing anomalous data in spatio-temporal models for routinely collected areal disease count data. We illustrate this methodology through a case study on outbreaks of foot-and-mouth disease (FMD) in Viet Nam for the time period 2006 to 2008. The exceedance probabilities identify several provinces where the number of infected communes was unexpectedly low. These findings are particularly interesting as these provinces are located along major cattle movement pathways within Viet Nam. With epidemic data, the primary interest is the understanding of the transmission of the disease and the effectiveness of intervention strategies. While epidemic curves provide an excellent representation of the temporal patterns, we propose the additional use of a new graphical tool, the `cl

de Almeida C.T., Lorenzon M.C.A. & Tassinari W. de S. [Identification of factors associated with diseases of Africanized honeybees (Apis mellifera L.) on apiaries in the State of Rio de Janeiro]. Identificação de fatores associados à ocorrência de doenças de abelhas africanizadas (Apis mellifera L.) em apiários do estado do Rio de Janeiro. Revista Brasileira de Medicina Veterinária, 35(1):33-40, 2013. Departamento de Matemática, Instituto de Ciências Exatas, Universidade Federal Rural do Rio de Janeiro, BR 465, Km 7, Seropédica, RJ 23890-000, Brasil. E-mail: tassinari@ufrrj.br Africanized bees (Apis mellifera L.) are considered resistant to diseases and pests, however, data from Census 2006 Bee Fluminense warned about the high incidence of diseases, which are the main cause for the loss of hives in the state of Rio de Janeiro. These losses result in major damage to beekeeping class by reducing the productivity of the apiaries. To assist in loss control, this study aims to investigate the cities of Rio de Janeiro with a high prevalence of bee diseases and verify the potential environmental and management factors associated with the occurrence of these diseases. Data from this study are from the survey hives occurred in Rio de Janeiro between 2009 and 2010, through the use of questionnaires in apiaries. We used logistic regression models to measure the association between potential factors and bee diseases. It was found that the cities with the highest prevalence of diseases were: Sapucaia, Mendes, Paracambi, Silva Jardim, Rio Bonito and São José do Vale do Rio Preto. The factors that are related to the occurrence of diseases in apiaries were: beekeeping materials purchased out of state (OR 2.91, 95% CI: 1.26 - 6.70), absence of neighboring beekeepers in a radius of 5 km ( OR 2.59, 95% CI: 1.30 - 5.14), presence of agriculture at 5 km of the apiary (OR 2.50, 95% CI: 1.18 - 5.28), the production division artificial hives (OR 2.57, 95% CI: 1.22 to 5.41), p, As abelhas africanizadas (Apis mellifera L.) são consideradas resistentes às doenças e pragas, no entanto, dados do Censo Apícola Fluminense de 2006 alertaram sobre a alta ocorrência de doenças, que constituem a principal causa para as perdas de colmeias no estado do Rio de Janeiro. Estas perdas resultam em grandes prejuízos para a classe apícola, por diminuir a produtividade dos apiários. Para auxiliar no controle das perdas, este trabalho tem por objetivos investigar os municípios do estado do Rio de Janeiro com alta prevalência de doenças apícolas e verificar os potenciais fatores ambientais e de manejo associados a ocorrência destas doenças. Os dados deste estudo foram provenientes do levantamento apícola ocorrido no estado do Rio de Janeiro entre os anos de 2009 e 2010, por meio da aplicação de questionários nos apiários. Utilizaram-se modelos de regressão logística para mensurar a associação entre possíveis fatores e as doenças apícolas. Verificou-se que os municípios de maior prevalência de doenças foram: Sapucaia, Mendes, Paracambi, Silva Jardim, Rio Bonito e São José do Vale do Rio Preto. Os fatores que estão relacionados com a ocorrência de doenças nos apiários foram: materiais apícolas adquiridos fora do estado (OR 2,91; IC 95%: 1,26 - 6,70), ausência de vizinhos apicultores em um raio de 5 km (OR 2,59; IC 95%: 1,30 - 5,14), presença de cultivo agrícola a 5 km do apiário (OR 2,50; IC 95%: 1,18 - 5,28), realização de divisão artificial de colmeias (OR 2,57; IC 95%: 1,22 - 5,41), higiene insatisfatória dos apicultores (OR 3,72; IC 95%: 1,47 - 9,38), a não ocorrência de florada de alecrim na época de colheita de mel (OR 1,94; IC 95%: 1,02 - 3,69) e a inexistência de assistência técnica aos apicultores (OR 3,18; IC 95%: 1,20 - 8,45). Medidas para aplicação das boas práticas de produção são urgentes, especialmente, nos municípios com maior prevalência de doenças apícolas.

de Almeida C.T., Lorenzon M.C.A. & Tassinari W. de S. [Identification of factors associated with diseases of Africanized honeybees (Apis mellifera L.) on apiaries in the State of Rio de Janeiro]. Identificação de fatores associados à ocorrência de doenças de abelhas africanizadas (Apis mellifera L.) em apiários do estado do Rio de Janeiro. Revista Brasileira de Medicina Veterinária, 35(1):33-40, 2013. Departamento de Matemática, Instituto de Ciências Exatas, Universidade Federal Rural do Rio de Janeiro, BR 465, Km 7, Seropédica, RJ 23890-000, Brasil. E-mail: tassinari@ufrrj.br Africanized bees (Apis mellifera L.) are considered resistant to diseases and pests, however, data from Census 2006 Bee Fluminense warned about the high incidence of diseases, which are the main cause for the loss of hives in the state of Rio de Janeiro. These losses result in major damage to beekeeping class by reducing the productivity of the apiaries. To assist in loss control, this study aims to investigate the cities of Rio de Janeiro with a high prevalence of bee diseases and verify the potential environmental and management factors associated with the occurrence of these diseases. Data from this study are from the survey hives occurred in Rio de Janeiro between 2009 and 2010, through the use of questionnaires in apiaries. We used logistic regression models to measure the association between potential factors and bee diseases. It was found that the cities with the highest prevalence of diseases were: Sapucaia, Mendes, Paracambi, Silva Jardim, Rio Bonito and São José do Vale do Rio Preto. The factors that are related to the occurrence of diseases in apiaries were: beekeeping materials purchased out of state (OR 2.91, 95% CI: 1.26 - 6.70), absence of neighboring beekeepers in a radius of 5 km ( OR 2.59, 95% CI: 1.30 - 5.14), presence of agriculture at 5 km of the apiary (OR 2.50, 95% CI: 1.18 - 5.28), the production division artificial hives (OR 2.57, 95% CI: 1.22 to 5.41), p, As abelhas africanizadas (Apis mellifera L.) são consideradas resistentes às doenças e pragas, no entanto, dados do Censo Apícola Fluminense de 2006 alertaram sobre a alta ocorrência de doenças, que constituem a principal causa para as perdas de colmeias no estado do Rio de Janeiro. Estas perdas resultam em grandes prejuízos para a classe apícola, por diminuir a produtividade dos apiários. Para auxiliar no controle das perdas, este trabalho tem por objetivos investigar os municípios do estado do Rio de Janeiro com alta prevalência de doenças apícolas e verificar os potenciais fatores ambientais e de manejo associados a ocorrência destas doenças. Os dados deste estudo foram provenientes do levantamento apícola ocorrido no estado do Rio de Janeiro entre os anos de 2009 e 2010, por meio da aplicação de questionários nos apiários. Utilizaram-se modelos de regressão logística para mensurar a associação entre possíveis fatores e as doenças apícolas. Verificou-se que os municípios de maior prevalência de doenças foram: Sapucaia, Mendes, Paracambi, Silva Jardim, Rio Bonito e São José do Vale do Rio Preto. Os fatores que estão relacionados com a ocorrência de doenças nos apiários foram: materiais apícolas adquiridos fora do estado (OR 2,91; IC 95%: 1,26 - 6,70), ausência de vizinhos apicultores em um raio de 5 km (OR 2,59; IC 95%: 1,30 - 5,14), presença de cultivo agrícola a 5 km do apiário (OR 2,50; IC 95%: 1,18 - 5,28), realização de divisão artificial de colmeias (OR 2,57; IC 95%: 1,22 - 5,41), higiene insatisfatória dos apicultores (OR 3,72; IC 95%: 1,47 - 9,38), a não ocorrência de florada de alecrim na época de colheita de mel (OR 1,94; IC 95%: 1,02 - 3,69) e a inexistência de assistência técnica aos apicultores (OR 3,18; IC 95%: 1,20 - 8,45). Medidas para aplicação das boas práticas de produção são urgentes, especialmente, nos municípios com maior prevalência de doenças apícolas.

The aim of this thesis was to develop a disease model to evaluate the effectiveness of movement restriction and vaccination for the control of equine influenza in the New Zealand horse population. In order to achieve this aim, a series of epidemiological investigations into the characteristics, movement behaviour and biosecurity practices of the New Zealand horse population were conducted. The New Zealand equine population has never experienced an outbreak of the highly infectious, respiratory virus, equine influenza (EI). As such, New Zealand horses are naїve to the virus and completely susceptible to infection. Disease models are one tool that can be used to examine the effectiveness of control strategies and can be used to initiate informed discussion regarding potential control options. In order to develop an EI InterSpread plus model, data were required regarding the New Zealand equine population. Data were collected via cross-sectional survey regarding the non-commercial horse population, through face-to-face interviews with stud managers and through the analysis of data regarding race meetings. Properties keeping horses for competition, recreation or racing were more likely to report a movement event than properties that did not. Movement events and the frequency of movement increased with increasing numbers of mares and stallions on a stud farm and with the presence of a shuttle stallion. There were significant differences between Standardbreds and Thoroughbreds travelling to race meetings and horses travelled further to attend premier race meetings. The level of biosecurity practiced was low and unlikely to be effective at preventing EI transmission during an outbreak. The disease model investigated three vaccination strategies in conjunction with movement restriction, compared to movement restriction alone. Additionally, the timeliness of vaccination strategies and enhanced surveillance were investigated. The results of the InterSpread plus model showed th

Early detection of highly pathogenic avian influenza (HPAI) in its natural reservoirs is a prerequisite for preventing disease spread to humans. The risk of introduction of H5N1 HPAI was assessed in order to design a risk-based surveillance system in Spain. Areas at highest risk for H5N1 HPAI followed a northeast-southwest direction, with two significant clusters located in the north and the southwest of the country. Most (83%) of the veterinary units (VUs) obtained fewer samples than would have been expected if samples had been collected using a risk-based design. In October 2009, a HPAI outbreak was reported for the first time in a Spanish layer farm located in a VU at high risk for HPAI, but no samples were collected. This risk-based surveillance approach will increase the cost-effectiveness of HPAI surveillance in Spain and can be easily extended to and adopted by other countries and regions throughout the world. © 2010 Cambridge University Press.

Overuse of antimicrobials in food-animal production is thought to be a major risk factor for the development of resistant bacterial populations. Data on non-human antimicrobial usage is essential for planning of intervention strategies to lower resistance levels at the country, region or herd levels. In this study we evaluated Danish national antimicrobial usage data for five antimicrobial classes used in slaughter pigs in different herd sizes and data on the number of slaughter pigs produced per herd, between 2002 and 2008, in Denmark. The objective was to ascertain if there is an association between herd size and amount of antimicrobials consumed. During this period, the overall number of herds with slaughter pigs decreased by 43%, with larger herds becoming more prevalent. The tetracycline treatment incidence (TI) rate increased from 0·28 to 0·70 animal-defined daily dose (ADD)/100 slaughter pig-days at risk while macrolide TI presented a more moderate increase, from 0·40 to 0·44 ADD/100 slaughter pig-days at risk during the study period. Linear regression analyses revealed a significant association between herd size and TI rates for tetracyclines, macrolides, sulfonamides/trimethoprim and cephalosporins, with small herds presenting significantly higher TI than moderate, large and the largest herds. This study highlights the importance of establishing an antimicrobial consumption monitoring programme, integrated with comprehensive food-animal production surveillance. Further research should be performed to address the potential causes of the detected associations between herd sizes and antimicrobial consumption in pigs.

Johne's disease (JD), caused by Mycobacterium avium subspecies paratuberculosis (MAP) is a chronic, debilitating enteritis of cattle, other domestic livestock and some wildlife species. JD was first identified in the late 1800s and today it is a worldwide problem in dairy cattle. Heavily infected cows have reduced milk production, a higher risk of removal from the herd and low slaughter value. Several countries have implemented national level control strategies. In New Zealand, JD was first reported in 1912 and today the prevalence of infected dairy herds is thought to be high. To improve our understanding of the epidemiology of JD and to evaluate the feasibility of a national control strategy, four studies were conducted. The first study was a questionnaire based case-control study to identify associations between management practices and the occurrence of clinical JD on farms from four regions of New Zealand. The second study was on the effect of sub-clinical JD on milk production and the risk of removal from the herd in four dairy herds over four milking seasons. The effect of misclassification of disease status on productivity estimates was also studied. In the third study diagnostic test result data from the productivity study was combined with a novel Bayesian regression model to estimate performance of the ELISA and faecal culture tests as a function of covariates and utilising repeated tests on individual cows. Finally, results from these three studies were used to adapt an existing JD simulation model, 'JohneSSim', to represent the epidemiological behaviour of JD in New Zealand dairy herds. Control strategies for the disease were simulated and evaluated based on their cost effectiveness. Of the 427 farmers responding to the questionnaire, 47% had suspected clinical cases of JD in their herd in the preceding 5 years. Only 13% of suspected infected herds had an average incidence of greater than 0.5 cases per 100 cow years at risk. The disease was not consider

Brucella ovis was first identified in the New Zealand farmed deer population in 1996 but little was known about the disease in deer. These experiments were undertaken to investigate the epidemiology, pathophysiology and diagnosis of B. ovis infection in deer. In addition, B. ovis isolates from commercial rams and stags were strain typed by pulsed-field gel electrophoresis. Transmission of infection was demonstrated from infected rams to stags grazing in the same paddock, suggesting that the initial source of infection for deer in New Zealand was likely to have been from rams. Transmission between stags did not occur after shifting non-infected stags into paddocks immediately vacated by infected stags, or after grazing non-infected stags in a paddock adjacent to infected stags over a five and a half month period. This suggests that the risk of transmission of B. ovis by the environment or indirect deer to deer contact is low. Stags became infected with B. ovis after experimental inoculation of the conjunctival, nasal and rectal mucous membranes. Behavioural observations identified that stags in all-male groups interact by mounting, sniffing the prepuce and perineum and spraying fluid from an extruded penis, which are considered high risk for the transmission of B. ovis. It was established that while stags are initially as susceptible to B. ovis infection as rams the majority of stags stop shedding B. ovis in semen within 11 months of infection, suggesting resolution of infection. In contrast, all rams remained infected with B. ovis and shed the organism in semen for at least 21 months. During the B. ovis shedding phase of infection, the majority of stags produced semen that had poor sperm motility and morphology and contained large numbers of leukocytes and cellular debris. However, following cessation of shedding stags produced semen that had good sperm motility and morphology, although leukocytes were still present. The sensitivity of the commercially available ser

A comprehensive geographical study and reporting system is presented. Animal disease data from both Thailand and New Zealand were explored and analysed using spatial analysis methods. The particular technique useddepended on the form of the data, aim of the investigation and the epidemiology of the diseaseof interest. Results and methods from some of these analyses were then included in the development of a simple geographical disease reporting and analysis system for Thailand. A number of methods were used to investigate the presence of temporal clustering, spatial clustering and spatio-temporal clustering of foot and mouth disease (FMD) reporting data in Thailand during January 1995 to May 1997. Temporal clustering in the time series of individual districts and individual provinces was found in many districts and provinces. Some of these provinces also showed the evidence of unimodal patterns. Spatial clustering was detected both at the district and province level. Space-time clustering was found at the district level. An exploratory analytical approach was used to investigate spatial clustering of bovine leukaemia virus (BLV) infection in New Zealand dairy herds. Two spatial clusters of BLV positive herds were detected in the Bay of Plenty area (p =0.001) and in the northern part of the South Island (p =0.082). We recommend that further investigations be conducted to define possible reasons for the presence of these observed clusters. The geographical patterns of FMD were described and risk maps of FMD outbreak occurrence in Thailand were developed using logistic regression and classification tree models (CART). The potential impact of spatial autocorrelation on the logistic regression models was assessed. CART models incorporating cost-sensitivity were constructed to develop sets of decision rules for the likelihood of FMD outbreak occurrence. Receiver-operating characteristic (ROC) curves were used to quantify and compare the value of the different models for p

Neospora has become a commonly recognized infectious cause of abortion in dairy cattle. The organism is associated with mid to late term abortion outbreaks with rates exceeding 30% in some herds. Cows infected with this organism exhibit no other clinical signs. While this disease has been reported in other parts of the country, no assessment of Neospora seroprevalence has been undertaken in the Southeast. This study sampled commercial dairy herds to assess Neospora seroprevalence in dairy cows and investigate its significance as an abortifacient agent in Virginia. Twenty four herds participated in the study. Twelve herds had DHIA reported annual abortion rates of 6% or greater (high abortion rate herds) and twelve herds had abortion rates of 2% or less (low abortion rate herds). High abortion rate herds were each paired to a low abortion rate herd (control) herd within the same county. A single blood sample was collected from all cows confirmed to be 90 to 240 days pregnant, with a maximum of thirty samples per herd. A random sample of cows was selected in herds with more than 30 pregnant cows between 90 and 240 days gestation. Neospora antibody titers were determined using a serum ELISA test at the California Veterinary Diagnostic Laboratory. Both mean and median seroprevalence of high and low abortion rate herds were compared using the Mann-Whitney Rank Sum test and the Median test, respectively. No significant difference was found in either case (p=0.56, p=0.41). These findings suggest that Neospora does not contribute significantly to the average abortion rate in Virginia's dairy cattle.

The science of geology has given rise to techniques for managing and analysiing spatial data. The techniques often deal with samples that represent a continuum, such as mineral samples taken from various locations. Some animal health data is similar in nature to geo-statistical data, such as climate data or soil samples from various points on a farm. Animal health data is commonly discrete rather than continuous in space. Farms are represented as point or area features and attributes of the farm are attached to the features. Spatial analysistechniques were reviewed and comment made about their usefulness and validity in disease management. The spatial data available in New Zealand for managing diseases was examined. Spatial data at a farm level is available in the national database management system Agribase, which records details of rural enterprises. The level of data completeness in Agribase was determined. The number of farms without spatial references varied from 10 to 18 percent, depending on the method used to update Agribase. Spatial data is available for cattle and deer herds in the National Livestock Database (NLDB). The number of herds without spatial data varied from 8 to 15 percent. Changes in the management of land information in New Zealand are resulting in an improvement in the quality and completeness of spatial data. In summary for the management of endemic and exotic diseases, farms should be represented as area features. Point coverage's can be generated from these area features and used in some applications, such as simulation models, and for labelling purposes. To function acceptable the applications tested required that 85% of farms or herds were represented spatially.

Neospora has become a commonly recognized infectious cause of abortion in dairy cattle. The organism is associated with mid to late term abortion outbreaks with rates exceeding 30% in some herds. Cows infected with this organism exhibit no other clinical signs. While this disease has been reported in other parts of the country, no assessment of Neospora seroprevalence has been undertaken in the Southeast. This study sampled commercial dairy herds to assess Neospora seroprevalence in dairy cows and investigate its significance as an abortifacient agent in Virginia. Twenty four herds participated in the study. Twelve herds had DHIA reported annual abortion rates of 6% or greater (high abortion rate herds) and twelve herds had abortion rates of 2% or less (low abortion rate herds). High abortion rate herds were each paired to a low abortion rate herd (control) herd within the same county. A single blood sample was collected from all cows confirmed to be 90 to 240 days pregnant, with a maximum of thirty samples per herd. A random sample of cows was selected in herds with more than 30 pregnant cows between 90 and 240 days gestation. Neospora antibody titers were determined using a serum ELISA test at the California Veterinary Diagnostic Laboratory. Both mean and median seroprevalence of high and low abortion rate herds were compared using the Mann-Whitney Rank Sum test and the Median test, respectively. No significant difference was found in either case (p=0.56, p=0.41). These findings suggest that Neospora does not contribute significantly to the average abortion rate in Virginia's dairy cattle.

Studies were made of the occurrence and distribution of bovine tuberculosis in the Taumarunui and Masterton veterinary districts, within which endemic wildlife tuberculosis is widespread. These districts were compared with the movement control herds of the surveillance areas of New Zealand, which are free of wildlife tuberculosis. The study covers the period from 1985-1990. The frequencies of tuberculosis infection for different categories of herds and different veterinary districts were examined and comparisons made of rates and risk of disease between the herd categories and districts under consideration. A comparison of incidence measures showed a strong positive correlation between cumulative, corrected and true incidence values. Cumulative and corrected cumulative incidence values calculated for calendar, financial and test years were compared. Some disparity was found between annual cumulative incidences and annual corrected cumulative incidences calculated on the basis of calendar and test years, with measures calculated on the basis of test year having the highest values. Regional comparisons showed that movement control herds in surveillance areas had higher incidences of tuberculosis than did herds in the Taumarunui and Masterton veterinary districts. Beef dry stock herds had higher incidences of tuberculosis than did dairy or beef breeding enterprises. Endemic areas had the highest incidence of all tuberculosis area classes. Simple regression analyses indicated that the risk of tuberculosis for any animal in a herd was more closely related to the level of infection in adult cows than any other age or sex group. Cumulative incidence in yearlings was a poor predictor of risk for individual animals in a herd but there was a stronger relationship for the level of infection in 2 year-old animals. Stepwise logistic regression was used to explore and quantify associations between cumulative incidence and putative risk factors. The odds of cattle testing positive

Current systems to ensure safety of meat are to a large degree based on a "procedural" approach which specifies what inspection actions will be taken to protect human health. Both knowledge and disease priorities have changed substantially over recent decades, and moreover the scale of the problems created by any breakdowns in protection has escalated greatly, as food trading and consumption patterns have changed. It is now recognized that meat hygiene needs to focus primarily on ways by which the risk that product will represent a hazard to human health can be effectively reduced, rather than merely ensuring compliance with a defined set of procedures. In addition to human food safety, meat inspection has the potential to contribute information to improve animal health on a national and a local scale. This thesis examines example issues in order to identify possible approaches to the development of decision support systems which assist in protecting meat consumers and improving the health of livestock on farms. The main areas which were explored for this purpose were respiratory disease in lambs and chemical residues in slaughter animals. A literature review of pneumonia and pleurisy in lambs showed that numerous factors have been proposed as predisposing causes for these diseases, but there was surprisingly little valid experimental or observational research evidence to support such statements. A hazard analysis was performed for the micro-organisms which have been isolated from pneumonic lungs. The major commonly detected organisms did not appear to cause a risk to healthy people. However there were a number of micro-organisms which are isolated on occasion from pneumonic and sometimes from healthy sheep lungs that might cause human disease. A case-control study was carried out as an exploratory means to identify risk factors and to generate hypotheses about causal processes. A number of risk factors were initially identified at univariate level. At the second st

A series of epidemiological studies was carried out to identify methods of improving productivity of New Zealand and Thai pig herds. Disease surveillance at slaughter of 2,807 finisher pigs from 3 piggeries in the North Island of New Zealand was conducted over a 13 month period. This was used to establish and apply procedures suited to New Zealand conditions, for monitoring the subclinical status of 8 production-limiting diseases and 1 zoonotic disease. Enzootic pneumonia, sarcoptic mange and oesophagogastric ulcer were the most commonly observed lesions. Seasonal patterns were found for enzootic pneumonia, pleurisy and ascariasis lesions. Seasonal effects were found to be associated in part with temperature variation. The effectiveness of simultaneous administration of commercial Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae vaccines was assessed in 380 pigs from an indoor commercial piggery. These vaccines produced significant improvement of growth rate during the high risk period for clinical pneumonia, and increased slaughter weight. Enzootic pneumonia lesions were significantly reduced by more than 50%, but pleurisy and pleuropneumonia lesions were not significantly reduced. No evidence of synergy between the vaccines in influencing lesion severity for pleuropneumonia was detected. A longitudinal study of thirty cohort pigs was conducted within the vaccination trial, to describe the epidemiological pattern of subclinical A. pleuropneumoniae infection of healthy pigs. A. pleuropneumoniae was first isolated at 4 weeks of age from one vaccinated pig. The incidence of A. pleuropneumoniae infection reached a maximum of 54% and 40% at 11 weeks of age in vaccinated and control pigs. No evidence was found to support the hypothesis that infection with M. hyopneumoniae increases susceptibility to A. pleuropneumoniae infection. Pig production data from 16 Thai and 18 New Zealand pig herds for 1991, and from 14 Thai and 16 New Zealand herds for 1992 were ana

A serological survey of pig sera from six regional areas throughout New Zealand indicated that 60% had titres to Leptospira interrogans serovar pomona and 13% to serovar tarassovi. Pig sera from the North Island districts had higher titres to pomona than those from the South Island districts, however the converse was true for titres to tarassovi. A serological survey of bacon weight pigs at slaughter revealed that 60% had titres to pomona, 53% to bratislava, while titres to tarassovi were undetectable. There was no significant linear association between the magnitude of corresponding pomona and bratislava titres. Pomona was isolated from 53% of pigs kidneys, however attempts to isolate bratislava were unsuccessful. The median prevalence of infection in bacon pigs from farms with endemic pomona infection, at the time of slaughter was 80%. A retrospective study of farming practices revealed that vaccination of breeding pigs had no effect on the infection status of their grower pigs at slaughter. It was also found that farms which reared their grower pigs to pork weight for slaughter were free of leptospiral infection, as were farms with less than fifty breeding sows. Cross sectional serological and cultural prevalence studies of grower pigs on farms with endemic pomona infection revealed that pigs less than ten weeks of age were not leptospiruric and had low or undetectable titres to pomona. Pigs between ten and twenty weeks of age showed an increasing prevalence of both leptospiruria and pomona titres. Further prospective studies indicated that piglets acquire passive immunity from their dams, which has a half life of around sixteen days. The majority of pigs less than fourteen weeks of age appear to be resistant to infection, thereafter the level of their passive immunity wanes and they become infected and leptospiruric. The weekly incidence of leptospiruria for pigs in an infected grower house was usually between 10% and 20%. Following infection, the intensity of l

Veterinary Epidemiology: Principles and Methods was published in 1987 by Iowa State University Press, Ames IA. Rights for this work have been reverted to the authors by the original publisher. The authors have chosen to license this work with a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license. (See: https://creativecommons.org/licenses/by-nc-nd/4.0) For any reuse or distribution, you must make clear to others the license terms of this work. Any of these conditions can be waived if you get permission from the copyright holder. Nothing in this license impairs or restricts the author's moral rights. IN ADDITION: the authors allow non-commercial distribution of translated and reformatted versions with attribution and without additional permission. Table of contents I: Basic principles 1. Epidemiologic concepts 2. Sampling methods 3. Measurement of disease frequency and production II: Studying disease in animal populations 4. Descriptive epidemiology 5. Disease causation 6. Surveys and analytic observational studies 7. Design of field trials 8. Theoretical epidemiology: systems analysis and modeling. III: Animal health economics 9. Animal health economics IV: Applied epidemiology 10. Rationale, strategies, and concepts of animal disease control 11. Monitoring disease and production 12. Field investigations About the book The purpose of this textbook is to provide an introductory, yet comprehensive, source of information on epidemiology for veterinary students, researchers, and practitioners. There has not been a textbook that presents analytic epidemiology as a science, basic to veterinary medicine's efforts in health management (herd health) as well as in clinical medicine.