Investigation of an outbreak of brucellosis in a mixed dairy farm and evaluation of a test and slaughter strategy to release the herd out of the quarantine

Authors: Mohamed El-Diasty, Khaled Salah, Fatma I. El-Hofy, Ashraf A. Abd El Tawab and Enas A. Soliman

Ger. J. Vet. Res 2022. vol. 2, Iss. 1 pp:1-9
Doi: https://doi.org/10.51585/gjvr.2022.1.0028

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Abstract:

An outbreak of brucellosis in a mixed dairy farm with 508 animals (370 cows, 120 sheep, and 18 camels) at Fayoum governorate, North Upper Egypt, was investigated. A storm of abortion and several cases of retained placenta were reported among cows and ewes in April 2020. Serodiagnosis of brucellosis was done using Rose Bengal Test (RBT) and Buffered Acidified Plate Antigen Test (BAPAT). The Milk Ring Test (MRT) was applied to the milk of seropositive animals. A total of 89 samples were used for isolation of Brucella and isolates were confirmed using Abortus, Melitensis, Ovis, Suis-PCR (AMOS-PCR). Test and slaughter strategy was applied to eradicate brucellosis from the farm based on RBT every month until three successive negative tests were obtained. Results showed that the seroprevalences of brucellosis based on RBT and BAPAT were 9.5%, 35%, and 50% in cattle, sheep, and camels, respectively. Despite 50% of male camels being seropositive, no clinical signs have been reported. The MRT identified fewer positive cases than BAPAT and RBT, thus, it cannot be used alone to eliminate the infection from the farm. A total of 31 Brucella isolates were recovered from cows and sheep on the farm. All isolates were confirmed as Brucella melitensis bv3 based on bacteriological examination and Brucella AMOS-PCR confirmed all isolates as Brucella melitensis.  No positive reactors at the 6th, 7th, 8th, 9th, and 10th examinations were reported after the implementation of the test and slaughter strategy. In conclusion, extensive animal farming and mixed breeding are potential risk factors for interspecies transmission of brucellosis. Additionally, the test and slaughter strategy could be helpful to release the herd out of quarantine, however, application of biosecurity practices and fair compensation policy for owners should be implemented.

Keywords:

Bovine, sheep, abortion, brucellosis, B. melitensis.

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