Teat disorders predispose ewes to mastitis after challenge with Mannheimia haemolytica

Faculty of Veterinary Science, University of Thessaly, PO Box 199, 43100 Karditsa, Greece.
Veterinary Research (Impact Factor: 2.82). 01/2006; 37(1):89-105. DOI: 10.1051/vetres:2005042
Source: PubMed


In order to study the effects of sheep teat disorders on the protection of the mammary gland, we used a Mannheimia haemolytica isolate, which did not cause clinical mastitis when deposited into intact teats. In the first experiment, this was deposited into the duct of teats with orf (Group A, n=5) or papilloma (Group B, n=3). In the second, teats were chapped and then, the organism was deposited into the duct (Group C, n=7) or on the skin (Group D, n=4). Ewes with healthy teats were controls (Group E, deposition into duct, n=5; Group F, deposition on skin, n=2). The ewes in Groups A, B or C developed clinical mastitis 5 h later, whilst the ewes in Group D developed it 2 d later; no control ewe developed clinical mastitis. In ewes with teat lesions, the organism was isolated from secretion samples and the California Mastitis Test became positive 5 h after challenge; neutrophils and lymphocytes were seen in Giemsa-stained secretion films from Group A or B ewes, whilst macrophages, neutrophils and lymphocytes in films from Group C or D ewes; neutrophils were predominating in films from Group E or F ewes. Inside the teats of Group A, B, C or D ewes, folds, hyperaemia and mucosal thickness were seen; histologically, subepithelial leucocytic infiltration was seen. In Group A or B ewes, no evidence of lymphoid tissue at the teat duct-cistern border was found. In Group C or D ewes, intense erosion and ulceration of the teat skin and conspicuous lymphoid tissue at the teat duct-cistern border, were evident; lesions characteristic of haemorrhagic mastitis were in the mammary parenchyma. In control ewes, subepithelial leucocytic infiltration in the teat duct and lymphoid tissue as above, were evident. We postulate that teat lesions can be predisposing factor to mastitis, by adversely affecting defences and speeding the process of infection and making it more severe.

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Available from: Ioannis Taitzoglou, Feb 21, 2014
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    • "These focal lymphoid accumulations were later characterised and found to contain CD79 + , CD3 + , γδ T cells, CD68 + and MHC-II + cells (Mavrogianni et al., 2007; Fragkou et al., 2010). However, in cases of Orf Virus infection in the teats, these structures could not be observed (Mavrogianni et al. 2006a), as was also the case in chapped teats (Fragkou et al., 2007a). In these cases, bacterial deposition even at the tip of the teat resulted in clinical mastitis, confirming the protective role of these structures. "
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    ABSTRACT: Bacterial mastitis is a significant welfare and financial problem in sheep flocks. This paper reviews the recently published literature, including publications that highlight the significance and virulence factors of the causal agents, especially Staphylococcus aureus and Mannheimia haemolytica, the primary causes of the disease. Research has also contributed to the understanding of risk factors, including genetic susceptibility of animals to infections, supporting future strategies for sustainable disease control. Pathogenetic mechanisms, including the role of the local defenses in the teat, have also been described and can assist formulation of strategies that induce local immune responses in the teat of ewes. Further to well-established diagnostic techniques, i.e., bacteriological tests and somatic cell counting, advanced methodologies, e.g., proteomics technologies, will likely contribute to more rapid and accurate diagnostics, in turn enhancing mastitis control efforts. Copyright © 2015 Elsevier B.V. All rights reserved.
    Veterinary Microbiology 07/2015; DOI:10.1016/j.vetmic.2015.07.009 · 2.51 Impact Factor
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    • "Mortality associated with CE is low, but unless proper care is given to infected animals, mortality can increase, as complications such as fly infestation of affected tissues and secondary infections can be quite common [4]. Depending upon the location of the lesions, infected animals may be unwilling to nurse, eat, or walk [5], and in lactating ewes, udder lesions may also cause mastitis [6]. Infected lambs or kids may need to be hand-fed, as they can transmit the disease by suckling other females. "
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    ABSTRACT: Orf virus is a parapoxvirus that causes recurring contagious ecthyma or orf disease in goat, sheep and other wild and domestic ruminants. Infected animals show signs of pustular lesions on the mouth and muzzle and develop scabs over the lesions. Although the infection is usually cleared within 1-2 months, delayed growth and associated secondary infections could still impact the herds. Orf virus can also infect humans, causing lesions similar to the animals in pathological histology. Prior infection of orf virus apparently offers little protective immunity against future infections. Several gene products of orf virus have been identified as responsible for immunomodulatory functions. In our recent study of orf virus isolates from an area along the Minjiang River in northern Fujian Province, we found a high heterogeneity among isolates from 10 farms within a 120-kilometer distance. Only two isolates from locations within 1 km to each other had same viral genes. There is no correlation between the geographical distance between the corresponding collection sites and the phylogenetic distance in ORFV011 or ORV059 genes for any two isolates. This finding suggests that there are diverse populations of orf virus present in the environment. This may in part contribute to the phenomenon of recurring outbreaks and heighten the need for better surveillance.
    PLoS ONE 10/2013; 8(10):e66958. DOI:10.1371/journal.pone.0066958 · 3.23 Impact Factor
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    • "However, in all cases, pregnancy was carried to term in all affected animals. In the second outbreak, animals from the flock infected with the 'GRE-2 teat 2004' strain were subsequently used in an experimental study, where it was shown that Orf virus infection in teats of ewes leads to depletion of local mammary defences and predisposes animals to mastitis [24]. Those experimental findings were allied to the clinical evidence recorded in the same farm, where higher frequency of mastitis was recorded among the Orf virus-infected animals [25]. "
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    ABSTRACT: Although orf is endemic around the world, there are few descriptions of Orf virus strains and comparisons of these strains. We report the sequence and phylogenetic analysis of the partial B2L gene of Orf virus from two outbreaks of the disease in Greece. The first was an outbreak of genital form of the disease in a flock imported from France, whilst the second was an outbreak of the disease in the udder skin of ewes and around the mouth of lambs in an indigenous flock. Phylogenetic analysis was performed on a part (498 bp) of the B2L gene of 35 Parapoxvirus isolates, including the two Orf virus isolates recovered from each of the two outbreaks in the present study. This analysis revealed that the maximum nucleotide and amino-acid variation amongst Orf virus strains worldwide (n = 33) was 8.1% and 9.6%, respectively. The homology of the nucleotide and amino-acid sequences between the two Greek isolates was 99.0% and 98.8%, respectively. The two Greek isolates clustered only with Orf virus strains. We suggest that there can be differences between strains based on their geographical origin. However, differences in the origin of strains or in the clinical presentation of the disease may not be associated with their pathogenicity. More work is required to determine if differing clinical presentations are linked to viral strain differences or if other factors, e.g., flock immunity, method of exposure or genetic susceptibility, are more important to determine the clinical presentation of the infection.
    Virology Journal 01/2012; 9(1):24. DOI:10.1186/1743-422X-9-24 · 2.18 Impact Factor
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