an epidemiological study of listeriosis in dairy cattle

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practices during the indoor and outdoor periods. Housing may have also played an important role in the higher excretion rates. In this study it was impossible to differentiate the effect of these two practices. Both changed at the same time. No apparent association between age and monthly excretion rate was observed. However there was a statistically significant association between age and frequency of detection of the organism. Younger animals shed the organism more frequently than older animals. This concurs with experimental findings in which it has been shown that younger animals excrete L. monocytogenes in their faeces for longer period than older animals (Miettinen and Husu 1991). In this study the ELISA assay was optimised by carrying out coating with different concentrations of antigen and at different temperatures and inserting an extra step to avoid non-specific binding. The specificity of the ELISA assay using different antigens demonstrated that LLO and antibody binding was specific; antibody activity was absorbed using LLO, culture supernatant and heat killed organisms. The absorption of antibody activity using heat killed organisms was surprising because LLO is not considered to be a cell associated antigen. This result probably reflects the fact that the heat killed bacteria was prepared from unwashed organisms which contained LLO. In this study serum samples were collected once and that was at the end of the silage feeding and housing period. The results indicate that all animals tested seemed to have antibodies to L. monocytogenes and this supports the results of our bacteriological investigations. However, it was not possible to determine whether there were animals exposed to L. monocytogenes before silage feeding or winter housing commenced. In the following chapter the optimised and standardised culture and ELISA techniques were used to identify animals infected with L. monocytogenes in a longitudinal survey. 155
CHAPTER 6 A study of the dynamic of infection with Listeria 6. 1. Introduction: monocytogenes, in herds of milking cows L. monocytogenes is ubiquitous in the environment and it is frequently isolated from healthy or diseased individuals (Gray and Killinger 1966, Farber and Paterkins 1991). One of the routes of transmission of L. monocytogenes infections in people is the ingestion of contaminated food. Many outbreaks and sporadic cases of Listeriosis follow the consumption of contaminated foodstuffs (Blenden and others 1987, Ralovich 1987, Lund 1990, Broome and others 1990, Farber and Paterkins1991, McLauchlin 1996). Contamination can occur at the primary production stage (at farm level), at the processing stage (factories, slaughterhouses, etc.) or alternatively after the processing stage (at home, retailers etc.). Many studies have been carried out to determine the degree of contamination with L. monocytogenes and its isolation pattern at all of these stages (Fenlon and Wilson 1989, Carosella 1990, Husu and others 1990b, Greenwood and others 1991, Jacquet and others 1993, Fenlon and others 1995a, Fenlon and others 1996). Studies have also revealed that different strains of L. monocytogenes may be better adapted to different stages of production and processing (Greenwood and others 157
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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
Page 121 and 122: L. monocytogenes has been isolated
Page 123 and 124: association (Kirkwood 1988, Thrusfi
Page 125 and 126: The predictor variables that met ou
Page 127 and 128: Forage feeding Maize silage Hay Str
Page 129 and 130: indoor feeding fed ad libitum on th
Page 131 and 132: cases of Listeriosis in sheep 2.9 1
Page 133 and 134: and controlling moles in fields wer
Page 135 and 136: Cases of Listeriosis in beef cattle
Page 137 and 138: This model was similar to the Model
Page 139 and 140: Table 4. 9. The multivariate relati
Page 141 and 142: 5) Nervous signs: Cases of Listerio
Page 143 and 144: feeders, maize silage feeding in ri
Page 145 and 146: A contradictory finding was made ab
Page 147 and 148: selective enrichment broth, at refr
Page 149 and 150: growth of some strains of Listeria
Page 151 and 152: 5. 2. 2. Bacteriology : a) Culture
Page 153 and 154: culturing negative LSEB (1/10w/v) s
Page 155 and 156: 6) Sugar tests: Listeria are capabl
Page 157 and 158: uffered saline (PBS), pH 7.2, centr
Page 159 and 160: Investigation of non-specific bindi
Page 161 and 162: and 0.94 for L. monocytogenes (17/1
Page 163 and 164: Detection limit of the method: A si
Page 165 and 166: Relationship between housing, silag
Page 167 and 168: 5 13 3 3 1 3 1 1 1 6 14 1 4 5 3 1 0
Page 169 and 170: Table 5. 11. The relationship betwe
Page 171: frequency of isolation of L. monocy
Page 175 and 176: There were no sample size calculati
Page 177 and 178: 4 of the farms had their silage ana
Page 179 and 180: a) Faecal samples: Faecal samples w
Page 181 and 182: • • • 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
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1988, Husu 1990) and from zero to a
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experimentally been shown that ther
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periods. However, on farms B and E
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A large number of L. monocytogenes
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Figure 6. 13. Animal-environment cy
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Some important farming practices we
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chance finding of L. monocytogenes
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Asahi, O., Hosoda, T. and Akuyama,
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Bourry, A. and Poutrel, B. (1996) B
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Chakraborty, T., Ebel, F., Wehland,
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delGarso, L. and Wallop, W. (1975)
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Eveland, W.C. (1963) Demonstration
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Fraser, J.A. and Sperber, W.H. (198
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Golden, D.A, Beuchat, L.R. and Brac
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humans. In Miller, A.J.,. Smith, J.
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Jones, F.S. and Little, R.B. (1934)
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Listeria innocua by oral inoculatio
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Low, J.C. and Donachie, W.A. (1997)
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McBride, M.E. and Girard, K.F. (196
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Nieman, R.E. and Lorber, B. (1980)
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Peters, M., Pohlenz, J., Jaton, K.,
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Bakteriologie, Mikrobiologie und Hy
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Seeliger, H.P.R. (1981) Apathogenic
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Tilney, L.G. and Portnoy, D.A. (198
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Walker, J.K., Morgan, J.H., McLauch
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APPENDIX 3 PREPARATION OF BACTERIOL
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Cool to 50 0 C Mix Solution A with
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Phosphate buffered saline (PBS; 10x
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APPENDIX 2 THE OVERALL RESULTS OF U
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Grass silage Y N OR (95% CL) p Valu
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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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