Avian intestinal spirochaetosis (AIS) is a relatively recently recognized disease of commercial layer and meat breeder chickens resulting from colonization of the gastrointestinal tract by anaerobic spirochaetal bacteria of the genus Brachyspira. AIS is characterised by delayed and/or reduced egg production and chronic diarrhoea. This thesis describes an investigation into the prevalence, pathogenicity and control of species of avian intestinal spirochaete in Australia. Faeces samples from chickens in 22 flocks of laying hens, 19 broiler flocks and 28 breeder flocks in Queensland, New South Wales, Victoria, Tasmania and South Australia were subjected to selective anaerobic culture for Brachyspira species. Spirochaete isolates then were speciated using phenotypic characteristics and specific polymerase chain reaction amplifications. A highly significant association was found between colonisation with Brachyspira species and the occurrence of wet litter and/or reduced production in both broiler breeder and layer flocks in eastern Australia. Multilocus enzyme electrophoresis (MLEE) then was used to help confirm the identity of the spirochaetes, and to examine their genetic relationships and disease associations. MLEE divided the isolates into five known Brachyspira species groups: Brachyspira murdochii, B. intermedia, B. pilosicoli, B. innocens, and “B. pulli”. Three new MLEE groups each containing single isolates were also identified. All farms with production problems or wet litter were colonised with the pathogenic species, B. intermedia and/or B. pilosicoli. The pathogenic potential of single isolates of B. pilosicoli and B. innocens then were experimentally evaluated in adult broiler breeders, confirming that infection with B. pilosicoli can result in serious egg production losses, whilst B. innocens is non-pathogenic. Antimicrobial susceptibility testing showed that the pathogenic spirochaetes B. pilosicoli and B. intermedia were both susceptible to tiamulin, lincomycin, metronidazole and tetracycline, while a lack of susceptibility to tylosin was found in some isolates of B. intermedia and B. pilosicoli. Some isolates of B. pilosicoli were not susceptible to ampicillin. Additional studies showed that zinc bacitracin, a common feed additive, can increase susceptibility to colonisation with B. pilosicoli. Both tiamulin and lincomycin were shown to be effective in treating infection with B. pilosicoli in adult birds.

Thesis (Ph.D.)--Murdoch University, 2003. / Thesis submitted to the Division of Veterinary and Biomedical Sciences. Bibliography: leaves 171-191.

Thesis (Ph.D.)--Murdoch University, 2006. / Thesis submitted to the Division of Health Sciences. Bibliography: leaves 242-283.

Thesis (Ph.D.)--Murdoch University, 2008. / Thesis submitted to the Faculty of Health Sciences. Includes bibliographical references.

Thesis (Ph.D.)--Murdoch University, 2009. / Thesis submitted to the Faculty of Creative Technologies and Media. Includes bibliographical references (leaves 196-222)

Made available in DSpace on 2016-04-28T20:15:36Z (GMT). No. of bitstreams: 1 2006-Raquel Silva Lisboa.pdf: 3491225 bytes, checksum: e18ca335db22717674936719fe4abae7 (MD5) Previous issue date: 2006-02-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Avian spirochetosis is an acute septicemic disease, cosmopolite, of a variety of avian species caused by Borrelia anserina (Sakharoff, 1891). This spirochete is usually present in the blood of infected birds during the early stages of the disease. The present study assesses the experimental transmission of B. anserina by infected ticks Argas miniatus, observing the pre-patent and patent period, and comparing the clinical and hematological alterations. Twenty-seven fowls of the species Gallus gallus were randomly allocated into three groups composed by nine animals each. One group was exposed to B. anserina infected ticks (group 1), other one to ticks free of this agent (group 2), besides one group not exposed to ticks (group 3). Blood smears of the fowls were taken, daily, since the first day the fowls were exposed to the ticks, up to the 25? day after exposure (DAE). Blood samples were collected three days before exposure, three DAE, eight DAE, and for the last time in eighteen DAE for hematologic tests. The examination of group three s smears revealed a great number of spirochetes. The biological parameters of the pre-patent and patent period for this group were, 6 ? 0,83 and 5 ? 1,96 days, respectively. Group 2 and group 3 blood smears were negatives during the whole period under exam. About the clinical signs observed, since the sixth and seventh DAE, the fowls of group 1 presented: nibs bristle, pale crist, somnolence, inappetence, loss of weight and green diarrhoea wich were continuing until the 12? DAE coinciding with the end of the spirochetemia, after this, occured clinical evolution which self-cure. In agreement with the hematological evaluation results, the fowls exposed to infected ticks showed a normocytic normochromic anemia in eight DAE, leucocytosis with initial heterophilia and monocytosis in concomitance with the spirochetemia. After the patent period, eighteen DAE, a linphocytosis was detected. The present study confirmed the viability of the experimental transmission of B. anserina by infected ticks A. miniatus. Infected G. gallus with avian spirochetosis showed clinical alterations wich cursed in concomitance to the spirochetemia period, evoluting to selfcure, moreover hematological alterations compatible with the bacterial infection. / A Borreliose avi?ria ? uma doen?a septic?mica aguda, cosmopolita, que acomete diferentes esp?cies avi?rias, sendo causada por Borrelia anserina (Sakharoff, 1891). Esta espiroqueta pode ser encontrada no plasma sang??neo das aves infectadas durante os est?gios iniciais da doen?a. Os objetivos do presente trabalho foram estudar a transmiss?o experimental de B. anserina por carrapatos Argas miniatus infectados, observando o per?odo pr?-patente e per?odo de pat?ncia, e estudo comparativo das altera??es cl?nicas e hematol?gicas. Um total de 27 aves da esp?cie Gallus gallus foram divididas em tr?s grupos inteiramente casualizados contendo nove animais cada. Um grupo foi exposto a carrapatos infectados por B. anserina (grupo 1); outro a carrapatos livres deste agente (grupo 2); al?m de um grupo n?o exposto aos carrapatos (grupo 3). Realizaram-se esfrega?os sang??neos das aves, diariamente, a partir do primeiro dia em que as aves foram expostas aos carrapatos, at? o 25? dia ap?s a exposi??o (DPE). Amostras de sangue foram coletadas tr?s dias antes da exposi??o aos carrapatos, tr?s DPE, oito DPE e uma ?ltima 18 DPE para a realiza??o dos hemogramas. O exame dos esfrega?os das aves do grupo 1 revelou grande n?mero de espiroquetas. Os par?metros biol?gicos de per?odo pr?-patente e de per?odo de pat?ncia para este grupo foram, em dias, 6 ? 0,83 e 5 ? 1,96, respectivamente. Os esfrega?os sang??neos do grupo 2 e do grupo 3 mantiveram-se negativos durante todo o per?odo experimental. Em rela??o ?s manifesta??es cl?nicas observadas, a partir do sexto e s?timo DPE, as aves do grupo 1 apresentaram os seguintes sinais cl?nicos: penas arrepiadas, crista p?lida, sonol?ncia, perda do apetite, perda de peso e diarr?ia esverdeada. Estes sinais continuaram at? o 12? DPE, coincidindo com o t?rmino da espiroquetemia, em seguida houve evolu??o do quadro cl?nico para a cura das aves. De acordo com os resultados das avalia??es hematol?gicas, as aves expostas aos carrapatos infectados por B. anserina (grupo 1 apresentaram um quadro de anemia normoc?tica normocr?mica em oito DPE, leucocitose com heterofilia e monocitose iniciais que cursaram paralelamente com a espiroquetemia. Ap?s o per?odo de pat?ncia da infec??o, dezoito DPE, detectou-se uma linfocitose. O presente trabalho confirmou a viabilidade da transmiss?o de B. anserina em G. gallus experimentalmente infestados por A. miniatus. G. gallus infectados apresentaram altera??es cl?nicas que cursaram paralelamente ao per?odo de espiroquetemia, evoluindo para auto-cura, al?m de altera??es hematol?gicas compat?veis com infec??o bacteriana.