Assessment of fluorescence polarization assay: a candid diagnostic tool inBrucella abortusstrain 19 vaccinated areas

Turning chaotic sample group clusterization into organized ones by feature selection: Application on photodiagnosis of Brucella abortus serological test

Bovine brucellosis diagnosis is a major problem to be solved; the disease has a tremendous economic impact with significant losses in meat and dairy products, besides the fact that it can be transmitted to humans. The sanitary measures instituted in Brazil are based on disease control through diagnosis, animal sacrifice, and vaccination. Although the currently available diagnostic tests show suitable quality parameters, they are time-consuming, and the incidence of false-positive and/or false-negative results is still observed, hindering effective disease control. The development of a low-cost, fast, and accurate brucellosis diagnosis test remains a need for proper sanitary measures at a large-scale analysis. In this context, spectroscopy techniques associated with machine learning tools have shown great potential for use in diagnostic tests. In this study, bovine blood serum was investigated by UV-vis spectroscopy and machine learning algorithms to build a prediction model for Brucella abortus diagnosis. Here we first pre-treated the UV raw data by using Standard Normal Deviate method to remove baseline deviation, then apply principal component analysis - a clustering method - to observe the group formation tendency; the first results showed no clustering tendency with a messy sample score distribution, then we properly select the main principal components to improve clusterization. Finally, by using machine learning algorithms (SVM and KNN), the predicting models achieved a 92.5% overall accuracy. The present methodology provides a test result in an average time of 5 min, while the standard diagnosis, with the screening and confirmatory tests, can take up to 48 h. The present result demonstrates the method's viability for diagnosing bovine brucellosis, which can significantly contribute to disease control programs in Brazil and other countries.

Prioritizing smallholder animal health needs in East Africa, West Africa, and South Asia using three approaches: Literature review, expert workshops, and practitioner surveys

Managing the health needs of livestock contributes to reducing poverty and improving the livelihoods of smallholder and pastoralist livestock keepers globally. Animal health practitioners, producers, policymakers, and researchers all must prioritize how to mobilize limited resources. This study employed three approaches to prioritize animal health needs in East and West Africa and South Asia to identify diseases and syndromes that impact livestock keepers. The approaches were a) systematic literature review, b) a series of expert workshops, and c) a practitioner survey of veterinarians and para-veterinary professionals. The top constraints that emerged from all three approaches include endo/ ectoparasites, foot and mouth disease, brucellosis, peste des petits ruminants, Newcastle disease, and avian influenza. Expert workshops additionally identified contagious caprine pleuropneumonia, contagious bovine pleuropneumonia, mastitis, and reproductive disorders as constraints not emphasized in the literature review. Practitioner survey results additionally identified nutrition as a constraint for smallholder dairy and pastoralist small ruminant production. Experts attending the workshops agreed most constraints can be managed using existing veterinary technologies and best husbandry practices, which supports a shift away from focusing on individual diseases and new technologies towards addressing systemic challenges that limit access to veterinary services and inputs. Few research studies focused on incidence/ prevalence of disease and impact, suggesting better incorporation of socio-economic impact measures in future research would better represent the interests of livestock keepers.

The seroprevalence of brucellosis and molecular characterization of Brucella species circulating in the beef cattle herds in Albania

Background

Brucellosis is a ubiquitous zoonotic disease globally. It is endemic among bovines, sheep, and goats in Albania. The national control and eradication programs for brucellosis has been applied on sheep and goat farms as well as large dairy cattle farms, i.e., those with more than ten milking cows. The current study aims at estimating the herd and average individual animal prevalence of brucellosis in the national beef cattle herds, the missing information that was essential to propose the most appropriate control measures for this sub-population. Rose Bengal Test (RBT), Fluorescence Polarization Assay (FPA), and Enzyme-Linked Immunosorbent Assay (ELISA) were used as serological tests and classical bacteriology for isolation. Results were also used to investigate the difference in sensitivity between the assays used.

Methodology

In total, 655 animals from 38 beef cattle herds from six southern districts of Albania were sampled. Sera were tested using RBT, FPA, and ELISA. Fifteen positive cows and a bull from eight high-prevalence positive herds were slaughtered, and particular tissue samples were collected for bacteriology.

Results

The overall herd seroprevalence in the tested beef cattle population was 55%, while the overall average within-herd prevalence (including only positive herds) was 38.3%, 42.7%, and 45.6% determined by the RBT, ELISA, and FPA, respectively. FPA was used for the first time in the diagnosis of bovine brucellosis in Albania, and its sensitivity was higher than RBT and ELISA. Three B. abortus strains were identified, two from the supra-mammary lymph node of two cows and one from the epididymis of a seropositive bull.

Conclusion

Brucellosis was highly prevalent in beef cattle in the southern part of Albania, and B. abortus was isolated from this subpopulation. To the best of our knowledge, this is the first statistically based survey of bovine brucellosis in beef herds in Albania. Using the FPA in parallel with other serological tests improved overall diagnostic sensitivity. Test and slaughter policy is not a rational approach for the control of brucellosis in beef cattle in Albania, and vaccination is only applicable, including strict control of the movement of animals.

Comparative evaluation of fluorescence polarization assay and competitive ELISA for the diagnosis of bovine brucellosis vis-a-vis sero-monitoring

Brucellosis is an important zoonosis that constitutes a serious public health hazard which is caused by a bacterium belonging to the genus Brucella. In the present study, two highly specific serological tests for brucellosis diagnosis, fluorescence polarization assay (FPA) and competitive ELISA (cELISA) were standardized in the laboratory, evaluated and compared with rose bengal plate test (RBPT), indirect ELISA (iELISA) and commercial cELISA kit. For test evaluation, 1386 serum samples [apparently healthy animals (n = 260), samples from Brucella infected farms (n = 701) and B. abortus S19 vaccinated animals (n = 425)] were analyzed to assess suitable diagnostic test in B. abortus S19 post vaccinated bovine population. In apparently healthy brucellosis free farms, RBPT, iELISA, in-house FPA and cELISA were found to be highly specific than commercial cELISA. Commercial cELISA kit was comparatively more sensitive than other serological tests in samples collected from infected farms. The FPA showed sensitivity nearly equal to RBPT and in-house cELISA showed greater sensitivity than RBPT in infected farms. In animals with persistent vaccinal antibodies, only in-house FPA and cELISA recorded higher specificity of 87.64 and 90.27%, respectively. The other tests, RBPT and iELISA displayed similar reactivity with vaccine antibodies to that of infection antibodies whereas commercial cELISA kit showed an intermediate specificity of 47.69%. With these findings, RBPT, iELISA and cELISA are suggested for screening infected herds, and in-house developed FPA and cELISA tests with a proven specificity can be used for confirmatory diagnosis of brucellosis in B. abortus S19 post vaccinated animal populations.