Prevalence and molecular investigation of caseous lymphadenitis among the slaughtered sheep at Duhok Abattoirs; experimental infection with Corynebacterium pseudotuberculosis in rabbits

Abstract

Caseous lymphadenitis is a chronic infection caused by Corynebacterium pseudotuberculosis that affects the lymphatic system, resulting in abscesses in the lymph nodes and internal organs. This study was conducted to determine the prevalence rate of caseous lymphadenitis among slaughtered sheep in Duhok abattoirs, Duhok, Iraq and to investigate to what extend rabbits can develop caseous lymphadenitis just like that in sheep. A total of 1052 carcasses of sheep were randomly selected (939 males and 113 females) and carefully inspected for detection any suspected caseous lymph adenitis. The isolated Corynebacterium pseudotuberculosis from lymph nodes of sheep carcasses were identified by PCR before used in in vivo infection in rabbits. Data revealed that the prevalence rate of caseous lymphadenitis was at 1.9% among the slaughtered sheep and the prevalence rates were higher in females and older ages than that of males and younger ages, respectively. Experimentally infected rabbits developed various clinical signs were ranging from in inappetence to sudden death, mainly during first week of infection. Histopathologically, the infected rabbits developed caseous lymphadenitis and pyogranuloma after a time point of 10 days post-infection. Liver, spleen and lymph nodes of infected rabbits showed caseonecrotic foci with multiple micro-granulomas with presence of thick pyogenic membrane infiltrated with leukocytic cells; these findings are strictly resemblance to that reported in sheep. The obtained preliminary data of using rabbits as an animal model is promising which will enhance a better understanding the pathogenesis of caseous lymphadenitis in animals.

First study on molecular epidemiology of caseous lymphadenitis in slaughtered sheep and goats in Duhok Province, Iraq

“…The data found that the rates of CLA in sheep and goats were 0.94% and 1.93%, respectively. These findings are in line with prevalence rates that were reported in slaughtered goats (1.1%) at the local slaughterhouses in Elazig Province, in the east of Turkey ( Çetinkaya et al , 2002 ) and 2.4% in clinically examined goats in Rajasthan, India ( Kumar et al , 2012 ) and in line with the prevalence rate (1.93%) in sheep slaughtered in Sumel district of Duhok Province, Iraq ( Issa et al , 2021 ). Whereas, higher rates of CLA in sheep (26.3%) and goats (45.5%) were reported by Algammal (2016) in Menoufia Governorate, Egypt, and Rizk et al (2019) who reported the prevalence rate of the disease (13%) in sheep and goat in Beni-Suef Governorate in Egypt.…”

“…However, differences in the prevalence of disease between study locations were found in terms of gender. The higher rates in females are probably due to the fact that females of sheep and goats in the study area were usually kept for s longer period than males for breeding purposes which exposes females to predisposing factors like pregnancy, shearing, and interaction with sick animals, as previously reported by Yitagesu et al (2020) and supported by Issa et al (2021) . Whereas, our data found that the prevalence rate in sheep in Sumel was significantly higher ( p < 0.01) in rams than ewes which is probably due to the intensive husbandry where rams physically interact more than ewes during the mating season, the risk of pressing on and rupturing abscesses increases.…”

“…PCR was used to confirm the identity of the isolated C. pseudotuberculosis . According to Issa et al (2021) , DNA was extracted using the thermal lysis technique. Briefly, isolates were plated out onto 5% sheep blood agar and incubated at 37°C for 48 hours using −20°C glycerol stocks.…”

“…CLA in small ruminants is diagnosed using a variety of techniques and methods, including clinical signs and characteristics of the lesions, isolation, and identification of the causative agent from pus discharge ( Nassar et al , 2016 ), serological methods ( Yitagesu et al , 2020 ), and PCR ( Issa et al , 2021 ; Terab et al , 2021 ) which is the most reliable, accurate, and rapid method, and it shows high resolution and repeatability in the genetic discrimination of bacterial strains ( Taha, 2022 ). Accordingly, this study aimed to estimate the prevalence rate of CLA among slaughtered sheep and goats and to determine the role of different associated risk factors such as the animals’ species, age, and sex, as well as the geographical distribution of the disease in different locations in Duhok Province, Iraq.…”

Detection and Molecular Characterization of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Carriage Isolates from Healthy Domestic Animal in Duhok Province

“…Suspected colonies of S. aureus by traditional methods were further confirmed by the detection of the S. aureus-specific thermostable nuclease gene (nuc) by using PCR [14]. DNA was extracted according to the literature [15,16]. Briefly, a few bacterial colonies were resuspended in 500 μl of deionized doubled distilled water and mixed very well using vortex.…”