An Exploratory One Health Investigation of Mycobacterium tuberculosis Complex at the Camel-Human Interface in Abu...

This exploratory cross-sectional One Health study characterized LIODetect TB-ST antibody reactivity in dromedary camels and abattoir workers in Abu Dhabi Emirate and investigated tuberculosis-compatible lesions in slaughtered camels. Sera from 356 camels sampled from farms and livestock holdings (izbas), 393 camels presented for slaughter at Al Bawadi Abattoir, and 86 abattoir workers were screened with LIODetect TB-ST. All 25 LIODetect-reactive slaughtered camels underwent detailed postmortem examination; nonreactive slaughtered camels were not examined postmortem. Lesions identified in two reactive camels were evaluated by histopathology, Ziehl-Neelsen staining, and IS6110 polymerase chain reaction (PCR). LIODetect reactivity was detected in 33/356 field camels (9.3%, 95% CI: 6.5%-12.8%), 25/393 slaughtered camels (6.4%, 95% CI: 4.2%-9.2%), and 3/86 workers (3.5%, 95% CI: 0.7%-9.9%). No recorded characteristic was associated with reactivity among field camels. Among slaughtered camels, age group and body condition showed exploratory statistical associations with reactivity, but category-specific estimates were imprecise. Two of the 25 reactive slaughtered camels (8.0%) had granulomatous lymphadenitis with acid-fast bacilli, and lesion tissue from both animals contained IS6110-detectable Mycobacterium tuberculosis complex (MTBC) DNA. LIODetect TB-ST has not been validated for prevalence estimation in dromedaries; therefore, these proportions describe assay reactivity rather than true infection prevalence. Because postmortem examination was restricted to reactive animals, the 2/25 finding cannot estimate lesion prevalence, false-negative frequency, or positive predictive value. The three reactive workers represent an occupational-health surveillance signal, not evidence of active tuberculosis or camel-to-human transmission. Systematic meat inspection, validated camel diagnostics, culture and species-level molecular characterization, traceable animal movements, and linked veterinary and occupational-health surveillance are needed.