Accuracy of Two Point-of-Care Tests for Rapid Diagnosis of Bovine Tuberculosis at Animal Level using Non-Invasive Specimens

Abstract

Bovine tuberculosis (BTB) testing in cattle requires a significant investment of time, equipment, and labor. Novel, rapid, cheaper and accurate methods are needed. The Alere Determine TB lipoarabinomannan antigen (LAM-test) is a World Health Organization-endorsed point-of-care urine test designed to detect active TB disease in humans. The Lionex Animal TB Rapid Test (Lionex-test) is a novel animal specific TB diagnostic blood test. An animal level analysis was performed using urine (n = 141) and milk (n = 63) samples from depopulated BTB-suspected cattle to test the accuracy of the LAM-test when compared to results of positive TB detection by any routine BTB tests (BOVIGAM, necropsy, histology, culture, PCR) that are regularly performed by the United States Department of Agriculture (USDA). The agreement between the urine LAM-test and USDA standard tests were poor at varying testing time points. The same milk samples did not elicit statistically significant agreement with the Lionex-test, although positive trends were present. Hence, we cannot recommend the LAM-test as a valid BTB diagnostic test in cattle using either urine or milk. The Lionex-test's production of positive trends using milk samples suggests larger sample sizes may validate the Lionex-test in accurately diagnosing BTB in cattle using milk samples, potentially providing a quick and reliable field test for BTB.Bovine tuberculosis (BTB) is a zoonotic disease caused by the bacterium Mycobacterium bovis 1,2 . The Cooperative State-Federal TB Eradication Program, including the United States Department of Agriculture (USDA), state animal health agencies, and US livestock producers, have nearly eliminated M. bovis infection from cattle in the US 3,4 . Although inspectors test more than one million animals a year for BTB and have taken steps to eradicate this disease, M. bovis is still present 5 . Globally, M. bovis is typically spread from cattle to cattle but in the US, wildlife (e.g. white tail deer, elk, bison, badgers, etc.) more frequently infect cattle, particularly in Michigan, which is the focus of this study 5,6 . Thus, domestic cattle and wildlife pose a potential threat to human health 5,6 . Indeed, BTB is typically transmitted from cattle to humans primarily through consumption of unpasteurized dairy products or occasionally contaminated meats 2,7,8 . Current diagnostic testing and eradication protocols along with pasteurization have caused the prevalence of BTB to drop significantly in the US as well as in other developed countries 9,10 .In 2016, the World Health Organization (WHO) estimated 147,000 cases of zoonotic TB with 12,500 deaths 11 . Globally, however, the median proportion of M. bovis cases of the total TB cases reported in humans ranges from 15.4 to 26.1% in African countries like Ethiopia, Nigeria, and Tanzania 1 .Diagnosis of BTB is difficult since animals with disease often do not show signs until the infection has reached an advanced stage 8,9 . In some countries, delay in BTB diagnosis may increase transmission rates from an...

Evaluation of Three Commercial Interferon-γ Assays in a Bovine Tuberculosis Free Population

“…Although such programs were able to significantly reduce the prevalence of the disease and some industrialized countries are considered to have official bTB-free status, specific geographical areas are still faced with this burden. Despite remarkable public and private efforts, the causes of this failure are multiple, including the varying clinical signs, intrinsic features of these bacteria such as the broad host spectrum and environmental resilience, the transmission modalities, and the absence of accurate antemortem diagnostic test applicable in the field (3)(4)(5).…”

Cell-Mediated Immunological Biomarkers and Their Diagnostic Application in Livestock and Wildlife Infected With Mycobacterium bovis

“…A significant challenge in the development of CMI biomarkers for M. bovis in wildlife is the difficulty in obtaining sufficient reference samples to investigate and validate diagnostic assays. The lack of validated ante mortem tests makes diagnostic tests even more challenging to perform under field conditions, particularly in endemic settings (19,56). Furthermore, the procurement of gold standard reference cohorts remains a trade-off between obtaining reliable samples and the loss of valuable animals, particularly for negative cohorts, that are required to obtain data from post mortem examination and mycobacterial culture (43).…”

“…A suitable diagnostic biomarker or multiple marker biosignature, for infection or disease, is a host-(or pathogen-) specific molecule/protein that is associated with the underlying pathological process (28,55). Identification of biomarker-based assays that can enable more accessible, affordable, and efficient diagnosis has been a high priority for TB and bTB diagnostic research in recent years (28,56). Considering the World Health Organization's target product profiles, that define the performance and operational characteristics of suitable tests, it is expected that non-DNA markers are more likely to meet practical and cost targets (28,57).…”

“…To date, the only method of determining an animal's true infection status is comprehensive post mortem examination and a battery of mycobacteriological, immunological, histopathologic, and molecular tests (19). Accurate ante mortem, in-field reference tests for infection and/or active bTB disease are lacking (56). Current understanding of the pathogenesis of M. bovis infection is also confounded by the multitude of susceptible animal hosts and the complexity of the host-pathogen interactions (36,51).…”

Etiological factors in triggering non-specific allergic reactions to tuberculin in cattle

“…Diagnosis of tuberculosis remains an urgent task for veterinary medicine worldwide (Ramos et al, 2015;Averill et al, 2020). The issues of paraallergic and pseudoallergic reactions to tuberculin remain not fully clarified in animals from tuberculosis-free farms in Ukraine.…”