Bayesian Estimation of Diagnostic Accuracy of Three Diagnostic Tests for Bovine Tuberculosis in Egyptian Dairy Cattle Using Latent Class Models.

Ibrahim Elsohaby,Jawher I Alahadeb,Attia A Elgedawy,Yasser S Mahmmod,Eman Mahrous,Mohamed M El-Diasty,Fatma I El Hofy,Marshal M Mweu,Heba A Ahmed

doi:10.3390/vetsci8110246

Abstract

The aim of the present study was to calculate the sensitivity (Se) and specificity (Sp) of the single cervical tuberculin test (SCT), rapid lateral flow test (RLFT), and real-time polymerase chain reaction (RT-PCR) for the diagnosis of Mycobacterium bovis (M. bovis) infection in Egyptian dairy cattle herds within a Bayesian framework. The true M. bovis infection within-herd prevalence was assessed as a secondary objective. Data on the test results of SCT, RLFT, and RT-PCR for the detection of M. bovis were available from 245 cows in eleven herds in six major governorates in Egypt. A Bayesian latent class model was built for the estimation of the characteristics of the three tests. Our findings showed that Se of SCT (0.93 (95% Posterior credible interval (PCI): 0.89–0.93)) was higher than that of RT-PCR (0.83 (95% PCI: 0.28–0.93)) but was similar to the Se of RLFT (0.93 (95% PCI: 0.31–0.99)). On the contrary, SCT showed the lowest Sp estimate (0.60 (95% PCI: 0.59–0.65)), whereas Sp estimates of RT-PCR (0.99 (95% PCI: 0.95–1.00)) and RLFT (0.99 (95% PCI: 0.95–1.00)) were comparable. The true prevalence of M. bovis ranged between 0.07 and 0.71. In conclusion, overall, RT-PCR and RLFT registered superior performance to SCT, making them good candidates for routine use in the Egyptian bovine tuberculosis control program.

Highlights

Bovine tuberculosis is an important zoonotic disease transmitted either directly via contact with infected animals or indirectly via the ingestion of contaminated raw or undercooked milk, milk products, meat, and meat products [1]
Bovine tuberculosis is a tuberculosis infection in cattle for which the primary causative agent is Mycobacterium bovis (M. bovis), which is a member of the Mycobacterium tuberculosis complex (MTC) [2]
The single cervical tuberculin test (SCT), rapid lateral flow test (RLFT), and real-time polymerase chain reaction (RT-PCR) results were available for the 245 cows involved in the study

Summary

Introduction

Bovine tuberculosis (bTB) is an important zoonotic disease transmitted either directly via contact with infected animals or indirectly via the ingestion of contaminated raw or undercooked milk, milk products, meat, and meat products [1]. Economic losses due to bTB in terms of the impact on productivity are notoriously difficult to assess. Some studies have reported significant economic losses due to a reduction in milk production, weight, infertility, and meat condemnation as well as losses from mortality [3]. There are several methods for the diagnosis of bTB. These include direct techniques (detecting M. bovis), such as culture and PCR, or indirect methods that measure delayed hypersensitivity reactions, e.g., the skin test or the gamma interferon test [4]. Indirect methods may encompass an antibody response assessment through the application of serological tests such as ELISA and lateral flow immunoassays [5]. Studies suggest that a combination of antigens may increase the test sensitivity (Se) without compromising its specificity (Sp) [7]

Objectives

Methods

Conclusion