Isolation and molecular confirmation of Brucella suis biovar 2 from slaughtered pigs: an unanticipated biovar from domestic pigs in Egypt

Abstract

Background Brucella suis is a zoonotic pathogen with a serious impact on public health and the pig industry worldwide. Information regarding B. suis in pigs in Egypt is scarce. This study aimed to investigate the prevalence of B. suis in slaughtered domestic pigs at El-Basatin abattoir in Cairo, Egypt. A total of 1,116 domestic pigs slaughtered in 2020 were sampled for Brucella isolation and identification. Identified Brucella isolates were molecularly confirmed at species, and biovar levels using Bruce ladder PCR and Suis ladder multiplex PCR. Additionally, high-risk practices of 16 abattoir workers (4 veterinarians, 10 butchering and evisceration workers, and 2 scalding workers) were investigated using a pre-piloted structured questionnaire. Results Brucella isolates were recovered from 1.3% of examined pigs (n = 14) at consistently low rates (1.1—2.9%) across the year of sampling from February to December 2020. All isolates were confirmed as B. suis biovar (bv) 2. Remarkably, 92.9% (13/14) of isolates showed atypical ability to produce H2S and hence were considered as B. suis bv2 atypical phenotype. The prevalence was higher in males (1.8%) than in females (0.9). However, this difference was not significant (Odds ratio = 1.9; CI 95% 0.7 – 5.7; P = 0.2). No detectable pathological lesions were associated with B. suis bv2 infection in examined pigs. All strains were isolated from cervical lymph nodes, highlighting a potential oral transmission. High-risk practices were recorded among swine abattoir workers in this study: 75% do not wear gloves or disinfect their knives daily, and 18.8% were willing to work with open wound injuries. Conclusions To the best of our knowledge, this is the first isolation of B. suis bv2 in Egypt. Detection of H2S producing B. suis bv2 atypical phenotype is alarming as it may result in misinterpretation of these isolates as highly human pathogenic B. suis bv1 in Egypt and possibly elsewhere. Further epidemiological tracing studies are crucial for the detection of the origin of this biovar. Including pigs in the national surveillance program of brucellosis, and an education program for swine abattoir workers about occupational risk of B. suis is a need in Egypt.

Spatio-Temporal Distribution of Brucellosis in European Terrestrial and Marine Wildlife Species and Its Regional Implications

“…B. suis bv 2 may be transmitted to domesticated animals. It has been isolated from domestic pigs in Egypt [ 96 ], but it is rarely described as a cause of human brucellosis among hunters [ 97 ]. Nevertheless, the presence of B. suis bv 2 in wild boars and hares is a potential source of spillover and spill-back infection in wildlife and domestic livestock.…”

Is Hepatitis E Virus a Neglected or Emerging Pathogen in Egypt?

“…The previous finding was reported almost 15 years ago and, since this time, no further studies were performed to confirm the association between pigs and HEV infection in Egypt. However, the number of pig abattoirs has been increasing in recent years in Egypt and recent studies have reported that pigs could be a source of infections for Trichinella spiralis and Brucella suis in humans [99,100].…”

Brucellosis Seroprevalence, REP-PCR-Based Genotyping, and Virulence-Associated Genes Distribution Among Brucella melitensis Strains Isolated from Ruminants in Kafr Elsheikh Governorate of Egypt

“…The respiratory tract, gastrointestinal tract, conjunctiva, broken skin, and any mucous membrane that comes into contact with contaminated fluids or tissues are further entry routes for Brucella. In Egypt, B. melitensis is the most prevalent Brucella species in ruminants [3] followed by B. abortus and less frequently by B. suis biovar 1 and 2 [4,5]. Recently, B. canis DNA was detected in the blood of stray and owned dogs in Egypt [6].…”