Diagnostic detection methods for Mycobacterium avium subsp. paratuberculosis in white-tailed deer

Area of Science:

• Veterinary Microbiology
• Wildlife Disease Diagnostics
• Bovine Tuberculosis Research

Background:

• Mycobacterium avium subsp. paratuberculosis (Map) causes Johne's disease, a significant concern in farmed animals.
• Asymptomatic carriers pose a challenge for disease control in wildlife populations like white-tailed deer (WTD).
• Accurate diagnostic methods are crucial for managing Map in WTD to prevent transmission.

Purpose of the Study:

• To evaluate and compare the diagnostic performance of various testing methods for Map infection in asymptomatic WTD.
• To identify the most suitable and effective diagnostic approach for Map detection in this species.
• To assess the utility of serological, microscopic, DNA-based, and culture-based tests.

Main Methods:

• Comparison of agar gel immunodiffusion (AGID), enzyme-linked immunosorbent assay (ELISA), Ziehl-Neelsen staining, bacterial culture, and polymerase chain reaction (PCR) assays.
• Inclusion of culture slant (CS)-PCR on feces and tissues, and direct PCR on uncultured tissues.
• Classification of deer as infected based on positive culture or PCR, and suspect based on serological results without confirmatory evidence.

Main Results:

• Culture of tissues identified 62.5% of deer as infected.
• CS-PCR on feces detected Map in 80% of deer, while CS-PCR on tissues detected it in 81.3%.
• Direct PCR on tissues identified 31.3% of deer, and ELISA identified 13.3% as suspect; AGID was negative for all.

Conclusions:

• Culture slant PCR (CS-PCR) demonstrated superior performance for detecting Map in both antemortem fecal and postmortem tissue samples from WTD.
• CS-PCR is recommended for enhancing Map detection in white-tailed deer across all infection stages.
• The study highlights the limitations of traditional methods and the effectiveness of molecular diagnostics for Map surveillance in wildlife.