an epidemiological study of listeriosis in dairy cattle

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showing signs of disease. Although the analysis of data collected in this study is not conclusive some farming practices were associated with the excretion of the organism. A significant number of isolates of L. monocytogenes were obtained from animals and the environment over a 10 month period. A complete analysis of these isolates with the use of newer molecular typing methods (e.g. RAPD) could have provided information on temporal distribution of the strains of L. monocytogenes and its relation with the infection in animals but this was not possible because of the time and financial constraints. However the limited number of isolates examined provided some information about the distribution of strains obtained from the faeces and the environment. The use of animal waste on agricultural land is known to help maintain the existence of the organism in the farm environment. The importance of dung management was demonstrated in both the cross-sectional and the longitudinal study. In this part of the study there were two distinct patterns of excretion on the farms. The first pattern fitted well with the seasonal occurrence of clinical Listeriosis in the northern hemisphere but the second pattern was distinct (Chapter 6). As explained earlier it was difficult to establish why this difference occurred. The main factor associated with this difference was the feeding of maize silage but it is possible that this was a confounder. It may have been that different “strains” of L. monocytogenes were involved in infection on these farms. This could only be explained if all the isolates made during the study were analysed. Control of clinical listeriosis is complex due to scarcity of representative field data and a lack of understanding of its epidemiology. This study indicates that a large proportion of cattle may excrete the organism without showing overt nervous signs or silage eye. It is possible that there were more subtle clinical signs and the 217
chance finding of L. monocytogenes in the only 1 of the abortion samples examined supports this. L. monocytogenes is also known to be associated with mastitis and the observation that “strains” of L. monocytogenes which were found in faecal samples were also found in the bulk tank merits further investigation of udder infection and the presence of L. monocytogenes in milk. The isolates collected in this study have partially been identified. Further analysis of these strains will allow a more detailed analysis of the strain specific patterns of infection in these herds. The data obtained during the longitudinal study will also provide empirical data which will be of value in developing theoretical models of the disease process. In conclusion, this study has identified farm level risk factors which may be utilised to try and reduce the incidence of clinical disease. It has provided information of the longitudinal pattern of infection in dairy herds and has raised a number of questions about the inter-relationship between strains and between infection and disease. 218
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AN EPIDEMIOLOGICAL STUDY OF LISTERI
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In the second part of the study a l
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I would like to thank to Metin Oztu
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DECLARATION I declare that apart fr
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2. 2. Materials and Methods 47 2. 2
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4. 4. Discussion 125 CHAPTER 5 A pi
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CHAPTER 1 LIST OF TABLES AND FIGURE
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Table 3. 11. The relationship betwe
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CHAPTER 5 Table 5. 1. Date of visit
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Figure 6. 4. The monthly faecal exc
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Listeralla hepatolytica. In the sam
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Listeriolysin O (Fernandaz-Garayzab
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L. monocytogenes was the only recog
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Table 1. 2. Serovar distribution of
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Serotyping is based on the identifi
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electrophoresis. Different strains
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and others (1995) came to the concl
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animals suggests that L. monocytoge
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Immunity reducing Septicaemia facto
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monocytogenes and a prerequisite to
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a variable number of cases of encep
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The relationship between age and Li
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a reservoir from which it spreads t
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1. 8. Clinical signs and pathology
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is seldom clinical illness in the d
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Bacterial culture is widely used fo
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Differential diagnosis: Listerial m
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Since elimination of L. monocytogen
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first description, it was only 1980
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and meat products have resulted in
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infectious dose for the infection i
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a longitudinal study involving five
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in Britain. In this part of the stu
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groups were excluded from analysis.
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The proportions of farms with cases
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Table 2. 3. The proportion of anima
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percentage 50 45 40 35 30 25 20 15
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Milking cows (%) Rep. heifers (%) D
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Abortion 274 (57.8%) 28 (21.9%) Ner
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with others (Kanuk and Berenson 197
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occurred in replacement heifers and
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CHAPTER 3 The relationship between
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(ii) Cases in milking cows: Farms r
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To assess the relationship between
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) Duration of housing: If animals w
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d) Presence of moles: Farmers were
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listeriosis. Maize silage feeding a
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found between the duration of feedi
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a) Type of housing : Housing animal
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Herd sizes n Y N OR P value x Y N O
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of disease. Similarly storing feed
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a) Type of forages: Feeding maize s
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) Use of bedding: Using straw beddi
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) Source of forages: Home made gras
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1.29-18.22) whereas straw bedding i
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100 2 34 2.33 0.01 X 2 22 3.35 0.01
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a) Dung disposal: Storage of manure
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vaccination against Leptospirosis +
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suppression of the growth of Lister
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1989, Sargison 1993). It is also po
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L. monocytogenes has been isolated
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association (Kirkwood 1988, Thrusfi
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The predictor variables that met ou
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Forage feeding Maize silage Hay Str
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indoor feeding fed ad libitum on th
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cases of Listeriosis in sheep 2.9 1
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and controlling moles in fields wer
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Cases of Listeriosis in beef cattle
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This model was similar to the Model
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Table 4. 9. The multivariate relati
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5) Nervous signs: Cases of Listerio
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feeders, maize silage feeding in ri
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A contradictory finding was made ab
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selective enrichment broth, at refr
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growth of some strains of Listeria
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5. 2. 2. Bacteriology : a) Culture
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culturing negative LSEB (1/10w/v) s
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6) Sugar tests: Listeria are capabl
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uffered saline (PBS), pH 7.2, centr
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Investigation of non-specific bindi
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and 0.94 for L. monocytogenes (17/1
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Detection limit of the method: A si
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Relationship between housing, silag
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5 13 3 3 1 3 1 1 1 6 14 1 4 5 3 1 0
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Table 5. 11. The relationship betwe
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frequency of isolation of L. monocy
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CHAPTER 6 A study of the dynamic of
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There were no sample size calculati
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4 of the farms had their silage ana
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a) Faecal samples: Faecal samples w
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• • • 1 5 9 6. 2. 5. Sample p
Page 183 and 184: A total of 944 isolates of L. monoc
Page 185 and 186: UK), 0.5μM DNA primer, 1 unit Supe
Page 187 and 188: entered and left the herd over the
Page 189 and 190: Table 6. 7. Monthly frequency of ex
Page 191 and 192: Table 6. 8. The relationship betwee
Page 193 and 194: (MA) mean age, (n) number, (R) rang
Page 195 and 196: frequency of excretion (P
Page 197 and 198: There was no evidence from this far
Page 199 and 200: ) Environmental samples: Both L. in
Page 201 and 202: monocytogenes. By April the proport
Page 203 and 204: A total of 211 milking cows were ex
Page 205 and 206: 100 % 90 80 70 60 50 40 30 20 10 0
Page 207 and 208: The number of new cases each month
Page 209 and 210: monocytogenes was also isolated fro
Page 211 and 212: Table 6. 18 The isolates, their ori
Page 213 and 214: Table 6. 19. The distribution of th
Page 215 and 216: On farm C pattern 1 was detected in
Page 217 and 218: Figure 6. 8. The repeatability of R
Page 219 and 220: Figure 6. 10. The distribution of s
Page 221 and 222: Figure 6. 12a. The RAPD pattern obt
Page 223 and 224: 1988, Husu 1990) and from zero to a
Page 225 and 226: experimentally been shown that ther
Page 227 and 228: periods. However, on farms B and E
Page 229 and 230: A large number of L. monocytogenes
Page 231 and 232: Figure 6. 13. Animal-environment cy
Page 233: Some important farming practices we
Page 237 and 238: Asahi, O., Hosoda, T. and Akuyama,
Page 239 and 240: Bourry, A. and Poutrel, B. (1996) B
Page 241 and 242: Chakraborty, T., Ebel, F., Wehland,
Page 243 and 244: delGarso, L. and Wallop, W. (1975)
Page 245 and 246: Eveland, W.C. (1963) Demonstration
Page 247 and 248: Fraser, J.A. and Sperber, W.H. (198
Page 249 and 250: Golden, D.A, Beuchat, L.R. and Brac
Page 251 and 252: humans. In Miller, A.J.,. Smith, J.
Page 253 and 254: Jones, F.S. and Little, R.B. (1934)
Page 255 and 256: Listeria innocua by oral inoculatio
Page 257 and 258: Low, J.C. and Donachie, W.A. (1997)
Page 259 and 260: McBride, M.E. and Girard, K.F. (196
Page 261 and 262: Nieman, R.E. and Lorber, B. (1980)
Page 263 and 264: Peters, M., Pohlenz, J., Jaton, K.,
Page 265 and 266: Bakteriologie, Mikrobiologie und Hy
Page 267 and 268: Seeliger, H.P.R. (1981) Apathogenic
Page 269 and 270: Tilney, L.G. and Portnoy, D.A. (198
Page 271 and 272: Walker, J.K., Morgan, J.H., McLauch
Page 273 and 274: APPENDIX 3 PREPARATION OF BACTERIOL
Page 275 and 276: Cool to 50 0 C Mix Solution A with
Page 277 and 278: Phosphate buffered saline (PBS; 10x
Page 279 and 280: APPENDIX 2 THE OVERALL RESULTS OF U
Page 281 and 282: Grass silage Y N OR (95% CL) p Valu
Page 283 and 284: storage Y N OR (95% CL) p Value cla
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source home made 38 182 0.6 (0.1-16
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source home made 34 345 0.8 (0.3-2.
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source barley 27 251 0.93(0.6-1.6)
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source potatoes 2 11 1.4 (0.-7.7) 0
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in a covered barn 73 595 0.8 (0.4-1
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sawdust 0 16 0.0 (0.0-2.73) 0.3 str
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APPENDIX 5 THE QUESTIONNAIRE AND TH
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Abbreviations: 1 first blood sampli
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B 113 1 114 1 115 1 116 1 117 1 118
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B 104 1 104 2 104 3 105 1 105 2 105
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B 20 1 20 2 20 3 21 1 21 2 21 3 19
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0.169 1.157 1.134 1.467 1.356 0.145
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Plate 4 Layout and ODs B 73 1 73 2
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UNIVERSITY OF BRISTOL LISTERIOSIS I
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PART C : HERD SIZE :--BETWEEN JULY
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(please circle one for each) 3. Wha
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etween which months were your milki
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not stored beneath the slats compos
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STUDY OF LISTERIOSIS IN DAIRY CATTL
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STUDY OF LISTERIOSIS IN DAIRY CATTL
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Now I would like to get some detail
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Root crops : ______________________
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In this section I will be asking qu
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33. Which days of the week bulk tan
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-what was used to treat? -what was
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an epidemiological study of listeriosis in dairy cattle

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