Preliminary investigation on the seroprevalence and co-exposure of Brucella spp. and Mycobacterium avium subsp. paratuberculosis in dromedary camels from the Eastern Province of Saudi Arabia

Brucellosis and paratuberculosis are zoonotic pathogens that affect animal and human health worldwide. Although both diseases are endemic in Saudi Arabia, little is known about their concurrent and potential epidemiological or immunological interactions in dromedary camels. This study investigated the serological evidence and associated risk factors of single and mixed infections with Brucella spp. and Mycobacterium avium subspecies paratuberculosis (MAP) in camels from the Eastern Province of Saudi Arabia. A total of 320 serum samples were collected from 253 female and 67 male camels and screened for Brucella antibodies using the Rose Bengal Test and competitive ELISA, and for MAP antibodies using indirect ELISA. The overall seroprevalence of brucellosis and paratuberculosis was 12.5% and 15.3%, respectively, with 2.2% of camels showing serological evidence of co-infection. Brucellosis was most prevalent in Hamra camels (15.4%), while Sawahli camels had the highest MAP seropositivity (20.0%). Although female (11.5%) camels showed numerically higher brucellosis seroprevalence than males (6.0%), this difference was not statistically significant. On the other hand, mixed infection was significantly more frequent in males (6.0%) than females (1.2%) ( p = 0.04). Older camels (≥ 6 years) were at higher risk of brucellosis seropositivity (12.4%) than younger animals (< 6 years, 5.8%) ( p = 0.03). Pregnant females had a significant ( p = 0.02) increase in MAP prevalence (22.2%) compared to non-pregnant females (10.6%). These findings highlight a notable overlap in the serological profiles of Brucella and MAP infections, suggesting shared risk factors or possible immune cross-modulation in camels. The coexistence of anti- Brucella antibodies in approximately 15% of MAP-seropositive camels underscores the need to reconsider diagnostic and control strategies under a One Health framework. Understanding such interactions could improve surveillance programs and inform targeted interventions for the camel industry in Saudi Arabia and other endemic regions.