A retrospective study (2007–2015) on brucellosis seropositivity in livestock in South Africa

Abstract

In South Africa, brucellosis testing and record‐keeping are done by several laboratories, thus it is difficult to access any organized data to assess the status of the disease. This study evaluated the seropositivity for brucellosis using Rose Bengal test and complement fixation test in suspect cattle, sheep, goats and pigs sera submitted to Bacterial Serology Laboratory, Agricultural Research Council‐Onderstepoort Veterinary Research (ARC‐OVR) from nine provinces in the country during the period 2007–2015. This retrospective data analysis was conducted to estimate the occurrence of brucellosis in the country from the submitted samples, identify variables that affected seropositivity for brucellosis, investigate existing gaps in data recording and make recommendations on important variables to facilitate better data capture and inferences on brucellosis. Nine years of data were collated and analysed to detect association (seropositivity over time regarding animal species and location). Of the 764,276 animals tested, the distribution of samples was 90.50% (691,539/764,276), 5.19% (39,672/764,276), 3.92% (29,967/764,276) and 0.41% (3,098/764,276) for cattle, sheep, goats and pigs, respectively. The seropositivity for brucellosis by animal species was 6.31% (43,666/691,539, 95% CI: 6.26–6.37), 2.09% (828/39,672, 95% CI: 1.95–2.23), 0.63% (189/29,967, 95% CI: 0.55–0.73) and 0.13% (4/3,098, 95% CI: 0.05–0.33) in cattle, sheep, goats and pigs respectively. The data available did not capture information on the age, sex, breed and other host risk factors that would have been related to seropositivity for brucellosis. The data provide an understanding of the disease occurrence and confirm that brucellosis is enzootic in South Africa. Improved and standardized data collection can be used to pro‐actively drive, monitor, change or formulate policies to mitigate the challenges brought about by brucellosis in the livestock sector in South Africa.

Characterisation of Brucella species and biovars in South Africa between 2008 and 2018 using laboratory diagnostic data

“…The high detection frequency for B. abortus reported in this study coincide with findings reported by Kolo et al. (2020) which found cattle seropositive samples were the highest during the same period (2010–2014) as our study. The differentiation of B. abortus into biovars showed the isolation of B. abortus biovar‐1 and B. abortus biovar‐2 in cattle, antelope and unspecified wildlife in RSA.…”

“…The detection frequency for B. abortus was high from 2010 to 2012 and low between 2017 and 2018; however, the reason for this variation could be due to the severe drought with the country experienced in 2015-2018 period as it may have affected livestock(AgriSA, 2019;Klipple & Costello, 1960). The high detection frequency for B. abortus reported in this study coincide with findings reported byKolo et al (2020) which found cattle seropositive samples were the highest during the same period (2010-2014) as our study. The differentiation of B. abortus into biovars showed the isolation of B. abortus biovar-1 and B. abortus biovar-2 in cattle, antelope and unspecified wildlife in RSA.…”

“…A total of 963 Brucella strains were isolated between 2008 and 2018 at the Brucella reference laboratory (ARC‐OVR). The reason for a low number of Brucella strains isolated and reported in this study compared to 44,687 seropositive animals tested between 2007 and 2015 in RSA (Kolo et al., 2020) could be that bacteriological diagnosis using biotyping is less sensitive, expensive, time‐consuming and involves hazardous culture hence is only recommended as a confirmatory test (Poester et al, 2010). It is also subjective meaning that requires expertise and it is likely prone to inconsistency between laboratories (DAFF, 2017; Lucero et al., 2005; Whatmore et al., 2014).…”

“…It also provides useful information on the changing patterns of animal brucellosis, which is important in determining the animal species and geographical areas that are prone to contamination by Brucella species and biovars (Sayan & Gürbilek, 2014). In addition, a retrospective seroprevalence study conducted previously (Kolo et al, 2020) showed overall seropositivity of 5.85% (44,687/764,276) for brucellosis in cattle, sheep, pigs and goats, with individual animal species seropositivity at 6.31%, 2.09%, 0.63% and 0.13%, respectively, from 2007 to 2015. The above-mentioned study also showed that the provincial seropositivity distribution among tested animals varies widely with a range of 1.84%-17.65%.…”

“…The above‐mentioned study also showed that the provincial seropositivity distribution among tested animals varies widely with a range of 1.84%–17.65%. Although the study (Kolo et al., 2020) only accounts for samples tested at ARC‐OVR laboratory, it is important as the results of study indicate the likelihood of infections within the country.…”