PhD thesis - University of Hertfordshire Research Archive

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proffer a description of their ethnic origin. Future studies should take such potential shortfalls into consideration. 7.6 Patient exposure history in relation to the weekly periodicity of Campylobacter jejuni infection. The seasonality of Campylobacter infection in the UK is well described and is noted for the annual sharp increase in incidence which occurs consistently in late spring/early summer. The pattern of infection over shorter time periods had not been investigated previously. Accordingly, the day of onset for 5606 UK-acquired cases of C. jejuni infection reported in the first two years of the study was calculated and examined (paper 6 (Gillespie et al., 2005)). Disease incidence was greatest on the days during or immediately following the weekend and cases who were ill at this time (N=3438) were more likely to have consumed Halal meats, offal, restaurant food or water from a private supply than cases whose illness onset occurred later in the week (N=2168). Furthermore, compared with those who had not eaten in restaurants, cases with a „weekend illness‟ were more likely to have consumed foods from takeaway kebab shops and Indian restaurants. It is tempting to conclude that, given the usual incubation period for Campylobacter infection, cases with illness onset at the weekend or soon after would have been exposed towards the end of the previous week. However, the incubation period for Campylobacter infection is thought to be inversely proportional to dose, and therefore the consumption of potentially heavily contaminated (e.g. offal or Halal meats) foods or untreated or poorly treated water might precipitate illness soon after. To our knowledge this is the first time that the weekly periodicity of an infection has been studied. The findings suggest that individuals undertake activities at the weekends which affect their risk of Campylobacter infection. Such potential daily differences in exposure should be considered when designing case-control studies of Campylobacter infection, as interviewing cases and controls on different days will increase the likelihood of differential recall bias. This method could also 51
provide useful insights into the epidemiology of other infections, and not just those causing gastrointestinal illness. 7.7 Host susceptibility and exposure history in relation to clinical presentation for indigenously-acquired Campylobacter jejuni infection. Human infection with campylobacter presents usually as an acute enteritis. Diarrhoea, malaise, fever and abdominal pain are the most commonly reported symptoms. However, whilst nausea is common with Campylobacter infection, vomiting is less so. A case-case comparison was undertaken to examine host, microbiological and environmental factors which might give rise to this particular clinical manifestation in UK-acquired cases of C. jejuni infection (paper 7 (Gillespie et al., 2006)). Bloody diarrhoea was studied in the same way as it was reported at a similar frequency as vomiting. Initially, UK-acquired cases from the entire study who reported vomiting (N=3346; 35.8%) and bloody diarrhoea (N=2661; 28.5%) were compared separately with cases who reported neither symptom (N=3335). However, it became apparent that these two manifestations were linked, since cases who reported one were more likely to experience the other. Separate analyses revealed similar levels of morbidity (length of illness and hospital admission) and a similar risk exposure profile, hence cases who reported either symptom (N=4043) were compared with those who reported neither. Cases who did not respond to one or both of these symptom questions (N=1972) were excluded from the analysis. Cases who reported vomiting and/or bloody diarrhoea were more likely to experience a longer illness and to be admitted to hospital than cases who reported neither. Self-reported vomiting and/or bloody diarrhoea was more common amongst females but decreased with age. It was more commonly reported by cases who reported the consumption of poultry other than chicken, pre-packed sandwiches or sausages, or amongst cases who reported engineering work on, or supply problems with, their water supply. 52
Page 1 and 2: Population-Based Sentinel Surveilla
Page 3 and 4: The research carried out by the can
Page 5 and 6: Dedication. This thesis is dedicate
Page 7 and 8: 7. Results (the published work). ..
Page 9 and 10: Statement identifying the degree fo
Page 11 and 12: Paper Reference Page 6 Gillespie IA
Page 13 and 14: Statement of the candidate’s cont
Page 15 and 16: Declaration form. I, Iain Andrew Gi
Page 17 and 18: 2. History. In contrast to other co
Page 19 and 20: The application of veterinary techn
Page 21 and 22: The incidence of laboratory-confirm
Page 23 and 24: were elderly or had a pre-existing
Page 25 and 26: they would for other bacterial gast
Page 27 and 28: papers (Pearson et al., 1977; Bruce
Page 29 and 30: Studies were most frequently conduc
Page 31 and 32: The content of peer-reviewed public
Page 33 and 34: infection. An approximation of the
Page 35 and 36: hypotheses a „blank canvas‟ app
Page 37 and 38: 6. Materials and methods. Regional
Page 39 and 40: presentation and severity, foreign
Page 41 and 42: together, etc). The results of the
Page 43 and 44: and improve response during the stu
Page 45 and 46: The published work. 7.1 Epidemiolog
Page 47 and 48: community illness was more common a
Page 49 and 50: north west England and in Yorkshire
Page 51: community was no different from oth
Page 55 and 56: Cases in case-control studies of la
Page 57 and 58: 8. Discussion. The research carried
Page 59 and 60: The sentinel health authorities wer
Page 61 and 62: fundamentally flawed. Since the app
Page 63 and 64: control studies. The potential role
Page 65 and 66: Campylobacter spp. from cattle farm
Page 67 and 68: Cameron, S., Ried, K., Worsley, A.,
Page 69 and 70: Doyle, L. P. 1948, "The etiology of
Page 71 and 72: other industrialised countries," in
Page 73 and 74: Hanel, C. M. & Atanassova, V. 2007,
Page 75 and 76: Hudson, S. J., Lightfoot, N. F., Co
Page 77 and 78: Kessel, A. S., Gillespie, I., O'Bri
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Page 81 and 82: Department of Health and Human Serv
Page 83 and 84: Potter, R. C., Kaneene, J. B., & Ha
Page 85 and 86: Siemer, B. L., Harrington, C. S., N
Page 87 and 88: Sopwith, W., Birtles, A., Matthews,
Page 89 and 90: Campylobacter infection: a general
Page 91: The published work 90
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Table A1.1: Notable events in the h
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Year Human medicine Veterinary medi
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Levy, A. J. 1928, "A gastro-enterit
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Appendix 2. An assessment of the ro
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compare the period after 2000 with
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condition was significantly associa
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Deaths/100,000 cases 600 500 400 30
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Table A2.1: Factors affecting the u
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Appendix 3. An analytical review of
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to indigenously acquired infection
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susceptibility to Campylobacter inf
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year demonstrated that only the num
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Table A3.1 Reported epidemiological
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Table A3.3 Selected reported risk f
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Table A3.5. The effect of various r
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Deming, M. S., Tauxe, R. V., Blake,
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Harris, N. V., Weiss, N. S., & Nola
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Kist, M. & Rossner, R. 1985a, in Ca
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Oosterom, J., den Uyl, C. H., Banff
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Severin, W. P. J. 1982, "Epidemiolo
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Appendix 4. The Campylobacter Senti
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