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چکیده
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Background and purpose: Vaccination is one of the basic ways to control brucellosis in animals. All animal brucella vaccines are live and zoonotic and can infect humans. Milk is the most important source of vaccine strain excretion in vaccinated animals. The purpose of this research is to investigate the possibility of the secretion of Brucella abortus RB51 vaccine strain from the milk and blood of vaccinated animals. Materials and methods: two groups of 23 adult and lactating Holstein cows, group 1; Full dose of IRIBA (10-34×109 CFU) and group 2; reduced IRIBA (1-3.4×109 CFU) were vaccinated. PCR of milk and whole blood samples performed on days 3, 10, 17, 24, 31 and 38 was to detect the genome of Brucella abortus bacteria. Findings: The first presence of bacterial genome in milk was observed 10 days after vaccination [group 1 (8.7%) and group 2 (4.35%)]. The highest excretion of bacteria was related to 24 days after vaccination [group 1 (43.48%), group 2 (26.09%), (p-value<0.05)]. The udder excretion of bacteria in group 1 (13.04%) was compared to group 2 (8.7%), (p-value>0.05). The presence of bacterial genome in the blood of group 1 (1.45%) and group 2 was 0.72% (p-value>0.05). Conclusion: Bacterial genomes are present in milk and blood of both group post vaccination, therefore consumption of milk and non-pasteurized dairy products of vaccinated animals, especially around the 24th day after vaccination can be one of the potential zoonotic sources for humans. It is necessary to train at risk persons such as milkers and wear glasses and gloves.
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