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Title: Investigation and control of animal diseases and infections, including zoonoses
Author: Pritchard, Geoff C.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2012
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This thesis brings together my published work in the field of investigation and control of animal diseases and infections, including zoonoses. It was undertaken between 1980 and 2011 whilst employed by the former Veterinary Investigation Service and Veterinary Laboratories Agency (VLA), firstly based in Norwich, Norfolk and subsequently in Bury St Edmunds, Suffolk. Part 1 covers a broad spectrum of predominantly novel and emerging conditions, or unusual manifestations of known diseases, and is subdivided into separate sections for pigs, sheep, cattle, goats and birds. These investigations used clinical field work, diagnostic necropsies and currently available or newly introduced laboratory tests, and relied heavily on initial referrals from local veterinary practitioners and extensive subsequent cooperation from farm managers or owners. Part 2 covers zoonotic diseases and infections, including separate sections on Escherichia coli (mainly verocytotoxigenic serogroup 0157), cryptosporidiosis and Q fever. Most of the work on zoonoses was undertaken during the period from 2004 onwards when I was VLA project leader for non-statutory zoonoses and it includes investigations into human outbreaks of zoonotic disease initiated at the request of public health professionals. In both parts of the thesis the publications have been grouped within their respective sections to demonstrate progression of ideas and activities, including relevant test development. In the early 1980s, pig producers in East Anglia and elsewhere experienced devastating piglet losses from transmissible gastroenteritis (TGE). The subsequent history of TGE in Britain until its eventual demise by the end of the 20th century is charted in the pig disease section. Other pig topics include swine influenza, a previously undescribed zinc induced copper deficiency anaemia in swill fed pigs and farm biosecurity Although sheep are a minor species in East Anglia, a number of new and emerging conditions were recognised, often before being seen in other regions. The foremost is maedi-visna which was first identified in indigenous sheep in Norfolk in 1983 and soon became strongly associated with the area. Other conditions recorded include a high morbidity ovine vulvitis outbreak and the Dandy-Walker syndrome. Despite a relatively small cattle industry, the region has exhibited many unusual bovine diseases including probably the most severe outbreak of acute bovine virus diarrhoea (BVD) ever recorded in Britain. The emergence of fascioliasis in East Anglia is also detailed. Close involvement with the former MAFF Cattle Health Scheme in the late 1980s led to an interest in herd biosecurity, abortion and the development of milk antibody tests for Leptospira Hardjo, and BVD and IBR virus infections. These tests were subsequently introduced within the VLA and used for assessing and monitoring herd disease status. Regular bulk milk antibody screening of a high health status dairy herd led to the detection of novel high morbidity non-pathogenic IBR virus infection. Publications on several new or emerging diseases of goats and birds are also included in Part 1. Cattle are the principal reservoir of VTEC 0157 and the primary source of most human infection. A number of outbreak investigations, particularly on farms open to the public, revealed the extent of infection in a diverse range of other animal species including sheep, pigs, horses, goats and camelids. An outbreak amongst visitors to a wildlife gardens in Norfolk was linked to contact with wild rabbits co-grazing with infected cattle. Cryptosporidium parvum infection is prevalent in young ruminants and has led to zoonotic outbreaks amongst visitors to farms. A series of investigations used a newly adopted sensitive fluorescent antibody test to define the extent of sub-clinical infection in pigs, calves and lambs, including orphan lambs being bottle-fed by visitors to an open farm. 0 fever emerged as a zoonosis of increased importance following human outbreaks in Britain and a massive outbreak in the Netherlands. My participation in a multi-disciplinary outbreak control team for a Q fever outbreak in Cheltenham in 2007 led to the development of improved diagnostic tests (PCR and ELISA) which were subsequently used for farm outbreak investigations and surveys in Britain. Other zoonoses featured include Leptospira Icterohaemorrhagicae infection acquired from pet rats and zoonotically acquired Corynebacterium ulcerans diphtheria.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (D.Sc.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available