TY - JOUR
T1 - Dynamics and risk of transmission of bovine tuberculosis in the emerging dairy regions of Ethiopia
AU - Mekonnen, G. A.
AU - Conlan, A. J.K.
AU - Berg, S.
AU - Ayele, B. T.
AU - Mihret, A.
AU - Olani, A.
AU - Asgedom, H.
AU - Wood, J. L.N.
AU - Ameni, G.
N1 - Publisher Copyright:
© 2021 Cambridge University Press. All rights reserved.
PY - 2021
Y1 - 2021
N2 - 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 2,303 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 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 of regulations and then establishing a systematic bTB surveillance programme to monitor the impact prior to implementing any control measures in Ethiopia.
AB - 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 2,303 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 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 of regulations and then establishing a systematic bTB surveillance programme to monitor the impact prior to implementing any control measures in Ethiopia.
KW - Bovine tuberculosis
KW - Ethiopia.
KW - apparent prevalence
KW - emerging dairy belts
KW - incidence rate
KW - positive reactors removal
KW - risk factors
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U2 - 10.1017/S0950268821000480
DO - 10.1017/S0950268821000480
M3 - Article
C2 - 33622436
AN - SCOPUS:85101585626
SN - 0950-2688
JO - Epidemiology and Infection
JF - Epidemiology and Infection
ER -