Occurrence of brucellosis in pigs kept in confinement and free ranging systems in the Democratic Republic of the Congo

Abstract

Swine brucellosis is a zoonosis disease affecting pigs widely. It is caused by Brucella suis whose distribution is not well documented in various areas including the Democratic Republic of the Congo (DRC). This study was initiated to determine the extent of swine brucellosis in pigs kept in confinement or in divagation in peri-urban and rural areas of Kinshasa and Kongo Central provinces of the DRC. A total of 814 samples were collected in both provinces. ELISA and Rose Bengal Test (RBT) were performed to screen all the collected samples. A prevalence of 4.42% and 3.19% of cumulative IgG seroprevalence of B. suis was obtained in both provinces sampled using ELISA and RBT, respectively. At the province level, no difference was obtained in the seroprevalence obtained in Kinshasa and Kongo Central when ELISA (3.53% and 5.38%, RR: 0.6570 p=0.20; χ2 =1.23) or RBT (2.59% and 3.85%, p=0.41; χ2 =0.66) were used, respectively. Similarly, the seroprevalence obtained in animals aged between 7-12 months and those aged more than 12 months did not show any significant difference using ELISA (3.53% and 5.54%, p=0.166; χ2 =1.9167) or RBT (3.09% and 3.32%, p=0.85; χ2 =0, 04), respectively. When animals reared in confinement or divagation systems were compared, no differences were also obtained using ELISA (6.76% versus 3.62%, p=0.058; χ2 =3.5980) or RBT (3.86% and 2.97%, p=0.525; χ2 =0.4038), respectively. However higher seroprevalence was recorded in males compared to females using ELISA (8.06% versus 3.15%, p=0.0028; χ2 =8.90) or RBT (5.68% versus 2.32%, p=0.017; χ2 =5.7256), respectively. Similarly, when animals were compared based on their breeds, higher seroprevalences were recorded in indigenous pig breed compared to improved breed ones using ELISA (15.18% and 2.7%, p=0.001; χ2 =32.65) or RBT (9.82% and 2.1%, p=0.001; χ2 =16, 04), respectively. As far as it can be ascertained, this study reports the first investigation of swine brucellosis infecting indigenous and improved pig breeds in Kinshasa and Kongo Central provinces in the DRC. The presence of brucellosis antibodies in animals in these provinces highlights a high public health concern for this major zoonotic disease not well documented in health care structures in RDC.