Dynamics and risk of transmission of bovine tuberculosis in the emerging dairy regions of Ethiopia

G. A. Mekonnen, A. J.K. Conlan, S. Berg, B. T. Ayele, A. Mihret, A. Olani, H. Asgedom, J. L.N. Wood, G. Ameni, Abraham Aseffa, Bamlak Tessema, Bizuneh Belachew, Eshcolewyene Fekadu, Fantanesh Melese, Gizachew Gemechu, Hawult Taye, Rea Tschopp, Shewit Haile, Sosina Ayalew, Tsegaye HailuAdam Bekele, Chilot Yirga, Mulualem Ambaw, Tadele Mamo, Tesfaye Solomon, Solomon Gebre, Getachew Gari, Mesfin Sahle, Abde Aliy, Asegedech Sirak, Gizat Almaw, Mekdes Tamiru, Sintayehu Guta, Alan Clarke, Henrietta L. Moore, Catherine Hodge, R. Glyn Hewinson, Martin Vordermeier, Javier Nunez-Garcia, Berecha Bayissa, Aboma Zewude, Adane Worku, Lemma Terfassa, Mahlet Chanyalew, Temesgen Mohammed, Yemisrach Zeleke

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The Ethiopian government has several initiatives to expand and intensify the dairy industry; however, the risk of bovine tuberculosis (bTB) spread is a challenge. To assess the rate of expansion and risk factors for transmission of bTB within-herds, we carried out a repeated cross-sectional survey at two time points, 2016/17 and 2018, in three regional cities, namely, Gondar, Hawassa and Mekelle, representing the emerging dairy belts of Ethiopia. The total number of herds involved was 128, comprising an average of 2303 cattle in each round. The Single Intradermal Comparative Cervical Tuberculin (SICCT) test was used to identify reactor status and data on herd-level risk factors were collected using a structured questionnaire. In the first survey, the apparent prevalence of bTB, as measured by the SICCT test, was 4.5% (95% CI 3.7–5.4%) at the individual animal-level and 24% (95% CI 17.5–32%) at the herd-level. There was no statistically significant change in the overall apparent prevalence or regional distribution at the second survey, consistent with the infection being endemic. The incidence rate was estimated at 3.6 (95% CI 2.8–4.5) and 6.6 (95% CI 3.0–12.6) cases/ 100 cattle (or herd)-years at the animal- and herd-levels, respectively. Risk factors significantly associated with the within-herd transmission of bTB were age group and within-herd apparent prevalence at the start of the observation period. We noted that farmers voluntarily took steps to remove reactor cattle from their herds as a consequence of the information shared after the first survey. Removal of reactors between surveys was associated with a reduced risk of transmission within these herds. However, with no regulatory barriers to the sale of reactor animals, such actions could potentially lead to further spread between herds. We therefore advocate the importance of setting up regulations and then establishing a systematic bTB surveillance programme to monitor the impact prior to implementing any control measures in Ethiopia.

Original languageEnglish
Article numbere69
JournalEpidemiology and Infection
Volume149
DOIs
Publication statusPublished - 2021

Keywords

  • Apparent prevalence
  • Ethiopia
  • bovine tuberculosis
  • emerging dairy belts
  • incidence rate
  • positive reactors removal
  • risk factors

ASJC Scopus subject areas

  • Infectious Diseases
  • Epidemiology

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