Molecular epidemiology and pathological burden of Mycobacterium avium subsp. paratuberculosis in staple livestock from Pakistan: implications for zoonotic surveillance and livestock productivity

Abstract

ABSTRACT Paratuberculosis (Johne’s disease), caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic granulomatous enteritis affecting domestic and wild ruminants worldwide, with significant economic losses. Its potential zoonotic implications in humans have increased concern globally. Despite its global importance, limited data exist on MAP prevalence in Pakistan’s Khyber Pakhtunkhwa province. A cross-sectional study was conducted in Peshawar district, Pakistan, using a multimodal diagnostic approach. Serum (n = 350), fecal (n = 350), and tissue samples (intestine and mesenteric lymph nodes; n = 400) were collected from cattle and buffaloes. Samples were analyzed using indirect enzyme-linked immunosorbent assay, Ziehl-Neelsen staining, histopathology, and PCR targeting IS900, IS1311, and Mycobacterium bovis-specific genes. Seroprevalence of MAP was 9% (17/175) in cattle and 4% (7/175) in buffaloes (P = 0.03). Acid-fast bacilli were detected in 22% (39/175) of cattle and 10% (19/175) of buffalo fecal samples. Gross pathological lesions, including thickness/corrugation in the intestine and hemorrhages/edematous swelling in the mesenteric lymph node, were found at higher frequencies in cattle compared to buffaloes. PCR confirmed MAP in 5% of cattle and 3% of buffalo tissue samples, while one cattle sample harbored M. bovis. Emaciated animals exhibited significantly higher lesion severity (P < 0.001). This study confirms endemic MAP infection in staple livestock of the study area, with higher susceptibility in cattle. This study underscores the importance of molecular diagnostics in surveillance and the critical role of abattoirs in monitoring disease prevalence. The presence of MAP and co-detection of M. bovis highlight the need for integrated control strategies under a One Health framework to investigate and mitigate potential zoonotic risks and production losses in resource-limited dairy systems. IMPORTANCE This study provides the first comprehensive molecular epidemiological data on Mycobacterium avium subsp. paratuberculosis (MAP) in cattle and buffaloes from Khyber Pakhtunkhwa, Pakistan. Using a multimodal approach (serology, histopathology, and PCR), it reveals significant infection rates, with cattle being more susceptible than buffaloes. The work is critically significant as it confirms the endemic presence of MAP in a key dairy region and highlights a concurrent infection with Mycobacterium bovis, underscoring a compounded potential zoonotic risk. These findings emphasize the urgent need for integrated One Health strategies to mitigate transmission through improved surveillance, milk pasteurization, and control programs in resource-limited settings. This study provides the first comprehensive molecular epidemiological data on Mycobacterium avium subsp. paratuberculosis (MAP) in cattle and buffaloes from Khyber Pakhtunkhwa, Pakistan. Using a multimodal approach (serology, histopathology, and PCR), it reveals significant infection rates, with cattle being more susceptible than buffaloes. The work is critically significant as it confirms the endemic presence of MAP in a key dairy region and highlights a concurrent infection with Mycobacterium bovis, underscoring a compounded potential zoonotic risk. These findings emphasize the urgent need for integrated One Health strategies to mitigate transmission through improved surveillance, milk pasteurization, and control programs in resource-limited settings.