Evaluation and application of a milk antibody ELISA for assessing the prevalence and incidence of bovine tuberculosis in dairy herds in Hubei Province, China

Abstract

Bovine tuberculosis (bTB) is a chronic zoonotic disease that is endemic in China. Current in-vitro tests for bTB are mainly based on blood assays. Collection of samples results in some stress to the sampled cattle and associated economic losses for the herd owner. This study was designed to investigate the relationship between milk and serum antibody tests for bTB in dairy cows using 85 cows with milk and corresponding blood samples. Totally 4,395 milk samples were used to assesse the apparent (test) prevalence and incidence of bTB using the milk antibody ELISA. The association between levels of bTB milk antibody and milk quality was also evaluated. Milk and serum antibody tests showed a good correlation with a 87.5% (95% CI: 61.7%, 98.4) positive agreement and 98.7% (95% CI: 95.4, 99.8) negative agreement. The animal level lactoprevalence ranged from 0.3% (95% CI: 0, 1.2) to 33.3% (95% CI: 26.6, 40.6) in different farms and the incidence rate ranged from 0 head/cow-month (95% CI: 0, 0.02) to 0.04 head/cow-month (95% CI: 0.02, 0.07). Twenty percent of sampled farms met the criteria for bTB control in China. The prevalence on large-scale farms was lower (p < 0.001) than on small farms. The bTB milk antibody levels had a negative correlation with milk yield and a positive correlation with somatic cell count (SCC), milk protein percentage (MPP) and percentage of total solids (TS). According to this research, milk ELISA could be used as a supplement of blood samples to assist in the surveillance for bTB and for alerting control and eradication of bTB.

Individual- and Herd-Level Milk ELISA Test Status and Incidence for Paratuberculosis in Hubei Province, China

“…It incorporates non-invasive methodologies that impose minimal stress on animals, thus providing a more ethical alternative. Milk antibody tests are widely used in the detection of many diseases, such as bovine tuberculosis [23], Q fever [30], Mycoplasmopsis bovis [31], and the bovine gammaherpesvirus 4 [32]. These findings coalesce to underscore the utility of a milk-based ELISA as a productive and viable alternative to serum-based assays for detecting MAP and bTB in dairy cattle.…”

“…A critical distinction to be considered is that the procurement of blood samples necessitates the employment of invasive methodologies, including venipuncture. Such procedures have been documented to elicit stress responses and inflict discomfort on the animals [23]. Conversely, the acquisition of milk samples is an integral and customary practice in dairy farming.…”

“…All data and information concerning the milk yield and quality, including the percentages of fat, protein, lactose, total solids, and urea nitrogen in the milk and the somatic cell counts (SCCs, ×1000 cell/mL), were provided by DHI by using the CombiFoss FT + milk composition and somatic cell analyzer, as previously described [23]. The complete information on both the milk quality and the milk antibody tests were available for 1596 and 1256 individual animals from 12 and 13 cow farms in January and April 2018, respectively.…”

“…Quantitative research reported that milk samples could replace serum samples in identifying infected herds by an antibody ELISA [21,22]. Milk-based ELISA testing has various benefits, including ease of use, a reduced impact on animal welfare, and accessibility due to frequent milk collection [23], and it ensures the animals' safety and minimizes occupational hazards for farm workers. It was reported that, globally, 1-3% of milk tested positive in cows either clinically or subclinically infected with MAP [2].…”