One Health approach for Brucella canis: Serological and molecular detection in animal-hoarding individuals and their dogs

Animal hoarding disorder (AHD) is classified as a psychiatric obsessive-compulsive condition characterized by animal accumulation and often accompanied by unsanitary conditions and animal cruelty. Although AHD may increase pathogen transmission and spread, particularly for zoonotic diseases, human and dog exposure in such cases has yet to be fully established. Accordingly, this study aimed to assess Brucella canis in 19 individuals with AHD (11 households) and their 264 dogs (21 households) in Curitiba, the eighth largest city in Brazil, with approximately 1.8 million habitants. Anti-B. canis antibodies were detected by the 2-mercaptoethanol microplate agglutination test (2ME-MAT) and by a commercial lateral flow immunoassay (LFIA), while molecular detection of previously positive seropositive samples was performed by conventional PCR. Although all the human samples were 2ME-MAT negative, 12/264 (4.5%, 95% Confidence Interval: 2.0-7.0%) dog samples were 2ME-MAT and LFIA positive, with 2ME-MAT titers ranging from 20 to 640. At least one dog in 4/21 (19.0%, 95% CI: 2.0-46.0%) households was seropositive. Despite the absence of seropositivity in individuals with AHD and the comparatively low seroprevalence in dogs, B. canis circulation and outbreaks should be considered in such human populations due to the high burden and recurrent character of B. canis exposure in high-density dog populations and the constant introduction of susceptible animals.

Seroprevalence of Human Brucellosis among Syrian Refugees in Jordan, 2022

Introduction

Brucellosis is prevalent in Mediterranean countries. The aim of this study was to determine the seroprevalence of brucellosis and associated factors among Syrian refugees in Jordan.

Methods

A cross-sectional study was conducted among adult Syrian refugees who attended the Public Health Lab (PHL) in Al Mafraq governorate, during the period of May-June 2022 to obtain a health certificate, which is legally required to receive governmental authorization for employment in Jordan. Blood samples were obtained from participants and a serum specimen was tested for the presence of IgG antibodies against Brucella using enzyme-linked immunosorbent assay (ELISA) IgG kits (Vircell Microbiologists, Granada, Spain).

Results

A total of 1562 Syrian refugees were enrolled in the study. Their ages ranged between 18 and 74 years, with a median age of 30 years at presentation. The majority were males (75.9%, n = 1186) and 24.1% (n = 376) were females. The Brucella ELISA IgG results were positive for 149 persons, with an overall seroprevalence rate of 9.5% (95% confidence interval: 8.0%-11.0%). Having animal-related occupations, residing outside refugee camps, consuming unpasteurized milk, handling animals or their tissues, and slaughtering animals within 6 months of study inclusion were significantly higher among the seropositive group. In the multivariate analysis, IgG-positive persons were 13 times more likely to report being diagnosed with brucellosis (OR = 13.1, 95% CI: 6.1-28.3; p ≤ 0.001). In addition, they were more likely to reside in the city of Al Mafraq, as opposed to a refugee camp (OR = 1.9, 95% CI: 1.1-3.2; p = 0.025) and to have handled animals within 6 months of study inclusion (OR = 3.1, 95% CI: 1.1-8.9; p = 0.035).

Conclusions

In conclusion, one-tenth of adult Syrian refugees were tested positive for Brucella ELISA IgG. Being diagnosed with brucellosis, residing in the city of Al Mafraq, as opposed to a refugee camp, and handling animals within 6 months of study inclusion were significantly associated with being positive for Brucella ELISA IgG. This study illustrates the need for improved brucellosis control measures via comprehensive vaccination of animals and enhanced laboratory detection and surveillance capacities, in addition to emphasizing the need for increased awareness sessions among Syrian refugees on the safe use and preparation of dairy products and safety practices of handling animals and their tissues.

The emergence of Brucella canis as a public health threat in Europe: what we know and what we need to learn

The zoonotic bacteria, Brucella canis, is becoming the leading cause of canine brucellosis in Europe. In dogs, it causes reproductive problems as well as non-specific lameness or discospondilitis. In humans, B. canis can be origin of chronic debilitating conditions characteristic to its genus such as undulant fever, splenomegaly, and lymphadenopathy. Although B. canis shows some pathogenic characteristics similar to B. abortus and B. melitensis, it lacks surface O-polysaccharide, like nonzoonotic B. ovis. This review shows that host-B. canis interactions are still poorly understood, with many knowledge and capability gaps, causing relatively poor sensitivity and specificity of existing diagnostic tools. Currently, there is no vaccine for this rough Brucella species. Besides, antimicrobial therapy does not guarantee bacterial elimination, and infection relapses are frequently reported, increasing the risks of antibiotic resistance development. B. canis has been detected in dogs in almost all European countries which increased human exposure, but currently there is no systematic surveillance. Moreover, B. canis caused brucellosis is not included in Animal Health Law, and therefore there is no legal framework to tackle this emerging infectious disease. To map out the diagnostic strategies, identify risks for human infections and propose management scheme for infected pet and kennel dogs, we present current understanding of canine B. canis caused brucellosis, outline major knowledge gaps and propose future steps. To address and highlight challenges veterinary and public health services encounter in Europe, we developed two B. canis infection scenarios: of a single household pet and of a kennel dog in larger group.

Update on Brucella canis: Understanding the Past and Preparing for the Future

The genus Brucella is known by veterinarians as a primary cause of reproductive diseases. It is widely known to cause financial devastation in livestock species, and is lesser known as a problem for dog breeders and fanciers with similar reproductive diseases seen in dogs. Now there are concerns about the dispersal of Brucella canis into countries that have enjoyed a fairly low incidence, through the importation of dogs from endemic countries. B canis, much like Brucella abortus, suis or mellitensis, is zoonotic and handling or working with infected dogs can lead to human disease. Only within the last few decades has the risk of brucellosis in dogs, and the people who own and work with them, been more fully acknowledged. This review will focus on new information that has been obtained since our last B canis article in 2018. Readers are encouraged to look to that article for information not presented within this update. Current B canis epidemiology along with a complete review of diagnostic testing options will be covered. Regulations for the international movement of dogs will be discussed in addition to concerns for increased zoonosis potential. Future goals would include better management of this disease including proposed screening of all imported dogs. Canine brucellosis prevention, owner and shelter/rescue education along with proposed therapies for the future will also be explored.

Canine Brucellosis: An Update

Canine brucellosis is an infectious and zoonotic disease caused by Brucella canis, which has been reported worldwide, and is a major public health concern due to close contact between dogs and humans. In dogs, canine brucellosis manifests with abortion outbreaks, reproductive failure, enlargement of lymph nodes, and occasionally affects the osteoarticular system, although the occurrence of asymptomatic infections in dogs are not uncommon. In humans, the disease is associated with a febrile syndrome, commonly with non-specific symptoms including splenomegaly, fatigue, and weakness. Infection of dogs occurs mostly by the oronasal route when in contact with contaminated tissues such as aborted fetuses, semen, urine, and vaginal secretions. In humans, contact with contaminated fluids from infected dogs is an important source of infection, and it is an occupational risk for veterinarians, breeders, laboratory workers, among other professionals who deal with infected animals or biological samples. The diagnosis in dogs is largely based on serologic methods. However, serologic diagnosis of canine brucellosis remains very challenging due to the low accuracy of available tests. Molecular diagnostic methods have been increasingly used in the past few years. Treatment of infected dogs is associated with a high frequency of relapse, and should be employed only in selected cases. Currently there are no commercially available vaccines for prevention of canine brucellosis. Therefore, development of novel and improved diagnostic methods as well as the development of efficacious and safe vaccination protocols are needed for an effective control of canine brucellosis and its associated zoonotic risk.

Comparison of three methods for recovery of Brucella canis DNA from canine blood samples

Brucella canis, a gram-negative, facultative intracellular and zoonotic bacterium causes canine brucellosis. Direct methods are the most appropriate for the detection of canine brucellosis and bacterial isolation from blood samples has been employed as gold-standard method. However, due to the delay in obtaining results and the biological risk of the bacterial culturing, the polymerase chain reaction (PCR) has been successfully used as an alternative method for the diagnosis of the infection. Sample preparation is a key step for successful PCR and protocols that provide high DNA yield and purity are recommended to ensure high diagnostic sensitivity. The objective of this study was to evaluate the performance of PCR for the diagnosis of B. canis infection in 36 dogs by testing DNA of whole blood obtained through different extraction and purification protocols. Methods 1 and 2 were based on a commercial kit, using protocols recommended for DNA purification of whole blood and tissue samples, respectively. Method 3 was an in-house method based on enzymatic lysis and purification using organic solvents. The results of the PCR on samples obtained through three different DNA extraction protocols were compared to the blood culture. Of the 36 dogs, 13 (36.1%) were positive by blood culturing, while nine (25.0%), 14 (38.8%), and 15 (41.6%) were positive by PCR after DNA extraction using methods 1, 2 and 3, respectively. PCR performed on DNA purified by Method 2 was as efficient as blood culturing and PCR performed on DNA purified with in-house method, but had the advantage of being less laborious and, therefore, a suitable alternative for the direct B. canis detection in dogs.

Immunochemical characterization of antigens of Brucella canis and their use in seroprevalence study of canine brucellosis

OBJECTIVE

To explore immunochemical characterization of antigens of Brucella canis (B. canis), and the use in seroprevalence study of canine brucellosis.

METHODS

External hot phosphate buffer saline extract (HPBSE) and internal sonicated (SA) antigens were prepared from B. canis strain MEX 51 and immunochemically characterized. These antigens were used to test 527 serum samples of dogs by 2-mercaptoethanol-tube agglutination test (2 ME-TAT), agar gel immunodiffusion test (AGID), dot-ELISA and indirect enzyme-linked immunosorbent assay (I-ELISA) to assess the seroprevalence of canine brucellosis.

RESULTS

The protein content of HPBSE and SA antigens was 0.387 mg/mL and 0.195 mg/mL, respectively, whereas carbohydrate content was 0.174 mg/mL and 0.150 mg/mL, respectively. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (12.5%) of HPBSE and SA, revealed 6 and 8 visible peptide bands ranging from 18-80 kDa and 12-45 kDa, respectively. Western blot analysis showed immunodominant bands of MW 12, 28, 39 and 45 kDa for HPBSE and 20-24 kDa for SA. The AGID revealed HPBSE as more specific antigen than SA but both I-ELISA and dot-ELISA indicated SA antigen to be more specific and reliable than HPBSE. The seroprevalence of canine brucellosis was 2.27% by 2ME-TAT, 1.5% by AGID, 3.03% by dot-ELISA and 16.12% by I-ELISA.

CONCLUSIONS

On the basis of the results of present study, we concluded that HPBSE is suitable antigen for AGID, which is more specific; whereas SA antigen is suitable for I-ELISA, which is highly sensitive. Therefore, initial screening of serum samples should be carried out by I-ELISA followed by confirmation with AGID.

Expression of the capsid protein of Chikungunya virus in a baculovirus for serodiagnosis of Chikungunya disease

Chikungunya virus (CHIKV) causes endemic or epidemic outbreaks of CHIK fever, which typically manifests as a febrile illness. To develop a CHIKV-specific diagnostic test, CHIKV capsid protein was expressed using a baculovirus expression system. The seroreactvity of the recombinant CHIKV capsid protein was evaluated by ELISA and immuochromatographic assay (ICA), using 40 anti-CHIKV-positive and 20 anti-CHIKV-negative sera, an additional 20 normal sera samples from healthy Koreans, and 20 anti-Dengue virus sera samples. The sensitivity of the recombinant CHIKV capsid protein was 85% and 87.5% as measured by ELISA and ICA, respectively. The specificity of the recombinant CHIKV capsid protein was 100% both by ELISA and by ICA. No cross-reactivity of the capsid protein was seen with anti-Dengue virus sera samples. There was a significant correlation between the ELISA- and ICA-measured seroreactivities of the recombinant CHIKV capsid protein for anti-CHIKV IgM-positive sera samples. These results suggest that the recombinant CHIKV capsid protein could be used in a diagnostic test for identifying CHIKV disease.