Epidemiology of Q fever among dairy cattle and dairy farmers, Chiang Mai, Thailand 2015 Public Deposited

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  • March 20, 2019
Creator
  • Doung-ngern, Pawinee
    • Affiliation: Gillings School of Global Public Health, Department of Epidemiology
Abstract
  • Q fever is a zoonosis, caused by the gram negative bacteria Coxiella burnetii. Knowledge of the epidemiology of Q fever in Thailand is limited. This study was conducted to determine the burden and the risk factors of C.burnetii infection in dairy cattle farms and farmers in Chiang Mai, Thailand. A prospective cohort study was conducted in five dairy cooperatives where evidence of C.burnetii was reported. The project included three components 1) a cohort study among farmers, 2) bulk tank milk (BTM) screening, and 3) farm investigation and specimen collection from cows and their environments in milk positive farms. Samples and data collection were obtained at baseline, 6, and 12 month intervals. Human sera were tested using Indirect Immunofluorescense Assay; cow sera and BTM were tested using Enzyme Linked Immunosorbent Assay; and vaginal swab and environmental samples were tested using Polymerase Chain Reaction. Baseline data were analyzed using logistic regression and Generalized Estimating Equation models to estimate the odds ratio (OR) and 95% confidence interval (CI). Among 306 randomly selected farms, 282 farms (92.2%) and 532 from 637 randomly selected farmers (83.5%) participated. The prevalence of C.burnetii antibodies in BTM was 40.8% (115/282) and the C.burnetii seroprevalence among farmers was 16.9% (90/532). Investigation in BTM positive farms showed C.burnetii seroprevalence was 28.4% (224/790) at the individual cow level and 91.9% (91/99) at the farm level. Multivariate analysis showed that having more than 80% of cows ≥ 2 years of age (OR 2.34, 95%CI 1.09 - 5.06) and having an infected farms within 1 km (OR 2.88, 95%CI 1.17 – 7.06) were positively associated with the odds of C.burnetii antibodies in BTM. Cleaning the birthing area (OR 0.27, 95%CI 0.08 - 0.86) and quarantining newly purchased animals (OR 0.54, 95%CI 0.30 - 0.97) provided protection. Working in a milk positive farm and exposure to birth products during calving were associated with seropositivity among farmers. This study provides useful information for Q fever prevention and control. Health education regarding Q fever prevention should be provided to farmers and public health and animal health officers in high risk areas in Thailand.
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  • In Copyright
Advisor
  • Koch, Gary
  • Emch, Michael
  • Meshnick, Steven R.
  • Weber, David
  • Kersh, Gilbert
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2016
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