Associations between management factors and seroprevalence of Mycobacterium avium subsp. paratuberculosis in dromedary camels
Introduction
Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne’s disease, a chronic granulomatous inflammation of the intestine that primarily affects wild and domestic ruminants including camels [1], [2], [3] and could be linked to human Crohn’s disease [4]. MAP is a Gram-positive, fastidious, acid-fast, and slow-growing bacillus that requires mycobactin for in vitro cultivation in the laboratory [5], [6]. Two main types of MAP affect different animal species, cattle (C) and sheep (S) types [7]. The genetic typing of MAP isolates from camels indicated an association with sheep type [8], [9].
Infected animals have chronic diarrhea, severe loss of body weight, emaciation and a decline in milk and wool production [10], [11] and have the ability to shed MAP in feces and milk for up to two years before the onset of clinical signs [12]. Susceptible animals get infected via the fecal-oral route from contaminated pasture, feed stuffs, soil, water or during suckling [13]. Diagnosis of MAP is difficult due to the latency and slow progression of MAP infection [14]. However, serological tests such as ELISA are only useful in detecting animals with mounted antibody response and cannot confirm whether an animal is currently infected [15].
In Saudi Arabia, camels constitute an important part of the livestock, and their breeding and rearing are considered a national socio-cultural heritage. The camel population is estimated to be more than 830,000 heads [16], accounting for more than half of the total livestock. Camels are used for many purposes including milk, meat, and fur production. Furthermore, camel shows and racing have gained popularity in recent years.
Currently, some studies on MAP infection in ruminants have been conducted worldwide [17], [18]. MAP infection has been reported in camels in Saudi Arabia [3], [19], [20], [21], UAE [22], Oman [23], Iran [24], Egypt [25], Tunisia [26], North American llamas and alpacas [27], South American alpacas [28] and Australian alpacas [29]. Although evidence from clinical cases, post-mortem abattoir examinations and veterinarian observations indicate that paratuberculosis is becoming a growing health problem in many camel herds, no studies have been conducted to estimate the prevalence of paratuberculosis in camel herds. Thus, the current study was performed to determine the herd- and camel-level seroprevalence, as well as the management factors associated with MAP seroprevalence in dromedary camels in the Eastern Province, Saudi Arabia.
Section snippets
Study area and sample size
Eastern Province is located on the eastern side of Saudi Arabia and shares the borders with five countries, including Oman, United Arab Emirates, Qatar, Kuwait and Iraq. The study covered the northern part of the Eastern Province including, Hafar Al Batin, Qaryat Al Olaya and Khafji. Camel populations have grown by 5.2% per year since 1961, making up more than 50% of Saudi Arabia's total livestock [30]. Camel production is critical to the livestock economy of the kingdom.
A cross-sectional study
Study population
In total, 391 camels from 67 herds in the Eastern Province, Saudi Arabia, were tested for antibodies against MAP (Table 1). Herd size ranged from 10 to 300 camels with a median of 50. Herd size was categorized into three groups: small (<36 camels; 33%), medium (36 – 75 camels; 43%) and large (>75 camels; 24%) herds. Herd data revealed that 92.5% of the herds were compromised of camels only, and 7.5% of the herds were managed with other animals. Camels in 86.6% of the herds had access to
Discussion
This is the first study in Saudi Arabia to investigate MAP seroprevalence and associated management factors at herd- and camel-level. Thus, the results are not comparable to the previous Saudi Arabian studies, where the MAP seroprevalence was only calculated at the camel/individual-level [9], [36]. In the present study, the herd-level seroprevalence of MAP was 40.3%, which is higher than the 9.2% reported among camel herds in Oman [23]. Furthermore, the MAP camel-level seroprevalence (16.1%)
Conclusion
The present study revealed that MAP is highly prevalent in dromedary camels in Eastern Province, Saudi Arabia. Furthermore, this research identified herd-level factors associated with seroprevalence of MAP. The identified factors indicated the need for improving biosecurity measures, particularly those related to calving and the introduction of new animals into the herd. These measures would not only be beneficial for MAP control and prevention, but they would also improve the general health of
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
The authors would like to thank the camel herders for accepting to participate in this study. The authors also thank all the technicians who helped with the data collection.
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