Direct detection of brucella species in blood clots from live- stock in Northern Tanzania

Abstract

Brucellosis is an endemic zoonotic disease of public health priority in many sub-Saharan countries, where robust tools for detection of Brucella in animal populations are needed for sur- veillance. Blood collected from 501 animals at a ranch suspecting brucellosis was tested for Brucella infection using molecular and serological techniques. Information on animal species, sex and abortion history were recorded. Blood clot DNA extracts were tested using two Brucella spp. genus specific targets, IS711 and bcsp31. Samples positive for both targets were subjected to a multiplex species-specific assay targeting alkB for B. abortus and BMEI1162 for B. melitensis. All sera were tested using the Rose Bengal test. Brucella spp. DNA was detected by qPCR in a total of 58 (11.6%) of 501 blood samples. B. abortus was identified in 18 and B. melitensis in 22 of the 58 samples posi- tive for Brucella spp. A total of 73 (14.6%) of 501 sera tested positive by RBT with poor agreement (kappa = 0.102) between the RBT and Brucella spp. qPCR assay results. Brucella abortus was found in cattle and goats, while B. melitensis was detected in cattle, sheep and goats. These findings sup- port the use of molecular assays alongside serology in brucellosis surveillance programs.

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Keywords

Brucellosis, Livestock, Blood clots, qPCR assays, Tanzania

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