Human Brucella Research Articles

Etiological characteristics of Brucella melitensis in Henan Province, 2013-2022

Objective: To analyze the genus, drug resistance/virulence and phylogenetic characteristics of Brucella strains isolated from brucellosis surveillance sentinels in Henan Province from 2013 to 2022, and provide baseline data for the surveillance, early warning and outbreak tracing of brucellosis. Methods: Blood samples were collected from patients with Brucella infection for strain isolation, culture and species identification, drug susceptibility test, whole genome sequencing, splicing and assembly, functional/virulence/resistance gene prediction analysis and phylogenetic tree drawing based on single nucleotide polymorphism (SNP). Results: In 36 brucellosis patients, the majority were men (86.11%, 31/36), young adults aged 18-50 (88.89%, 32/36) and farmers/herdsmen (72.22%, 26/36). A total of 36 strains of Brucella melitensis were isolated, and average 1 305 functional proteins of 21 categories were predicted by strain genome; all the strains carried four main virulence factors (pmm, VirB group, BtpA/BtpB, BvrS/BvrR). The drug sensitivity rate was 100.00% to six types of antibiotics including levofloxacin, rifampicin, doxycycline, streptomycin, tetracycline and gentamicin, they showed different resistances to three antibiotics including compound trimethoprim-sulfamethoxazole, ciprofloxacin and ampicillin. The strains carried four types of resistance genes and two clusters of resistance genes, with four combinations of genotypes, the resistance mechanisms included antibiotic degradation/modification enzymes, resistant nodular cell differentiation (RND) efflux pumps, 16S/23S ribosomal rRNA binding site mutations, etc. The number of SNP differed in the genomes of 36 Brucella melitensis strains ranged from 0 to 454 and phylogenetic tree was divided into three major branches, with relative branch distances between 0.000 0 and 0.498 6 for each strain. Conclusions: Human Brucella melitensis strains isolated from surveillance sentinels in Henan from 2013 to 2022 carried multiple virulence and antibiotic resistance genes and had different drug resistance phenotypes. Single nucleotide polymorphism analysis and phylogenetic tree analysis showed significant differences in phylogenetic relationships among different strains.

Brucella canis and Chlamydia spp.: insights into canine infections, diagnostics, and potential tick-borne transmission

Brucella and Chlamydia spp. are zoonotic pathogens with significant implications for both human and animal health. Brucella species, which is responsible for brucellosis, manifest in a range of clinical symptoms and present substantial zoonotic risks. Though less commonly reported, canine infections with Brucella raise concerns about the potential for transmission to humans and highlight the need for continued vigilance in veterinary settings. Chlamydia spp. is notable for its ability to cause diverse diseases in animals, from mild infections to severe systemic illnesses. In dogs, Chlamydia infections can lead to symptoms such as conjunctivitis, respiratory disorders, and reproductive issues, including infertility and abortion. The zoonotic potential of Chlamydia, particularly Chlamydia felis, emphasises the need for thorough monitoring and control measures in both domestic animals and humans. Ticks play a significant role in the transmission of these pathogens. Research has identified Chlamydia spp. in ticks; however, the exact epidemiological implications remain unclear. Similarly, Brucella has been detected in ticks, but conclusive evidence of tick-borne transmission to humans or between animals is still lacking. Improved diagnostic tools and control strategies are essential for managing the risks associated with Brucella and Chlamydia infections in both animals and humans, with a particular focus on the role of ticks as potential vectors.

Protein disulfide isomerase A4 binds to Brucella BtpB and mediates intracellular NAD+/NADH metabolism in RAW264.7 cells

The Toll/interleukin-1 receptor (TIR) signaling domain is distributed widely in mammalian Toll-like receptors and adaptors, plant nucleotide-binding leucine-rich repeat receptors, and specific bacterial virulence proteins. Proteins that possess TIR domain exhibit NADase activity which is distinct from the canonical signaling function of these domains. However, the effects of bacterial TIR domain proteins on host metabolic switches and the underlying mechanism of NADase activity in these proteins remain unclear. Here, we utilized Brucella TIR domain-containing type IV secretion system effector protein, BtpB, to explore the mechanism of NADase activity in host cells. We showed that using ectopic expression BtpB not only generates depletion of NAD+ but also loss of NADH and ATP in RAW264.7 macrophage cells. Moreover, immunoprecipitation-mass spectrometry, co-immunoprecipitation, and confocal microscope assays revealed that BtpB interacted with host protein disulfide isomerase A4 (PDIA4). The Brucella mutant strain deleted the gene for BtpB, significantly decreased PDIA4 expression. Furthermore, our data revealed that PDIA4 played an important role in regulating intracellular NAD+/NADH levels in macrophages, and PDIA4 overexpression restored the decline of intracellular NAD+ and NADH levels induced by Brucella BtpB. The results provide new insights into the metabolic regulatory activity of TIR domain proteins in the critical human and animal pathogen Brucella.

Design a novel of Brucellosis preventive vaccine based on IgV_CTLA-4 and multiple epitopes via immunoinformatics approach

Brucellosis is a zoonotic disease caused by Brucella, which is difficult to eliminate by conventional drugs. Therefore, a novel multi-epitope vaccine (MEV) was designed to prevent human Brucella infection. Based on the method of “reverse vaccinology”, cytotoxic T lymphocyte epitopes (CTLEs), helper T lymphocyte epitopes (HTLEs), linear B-cell epitopes (LBEs) and conformational B-cell epitopes (CBEs) of four Brucella proteins (VirB9, VirB10, Omp 19 and Omp 25) were obtained. In order to keep the correct protein folding, the multiple epitopes was constructed by connecting epitopes through linkers. In view of the significant connection between human leukocyte antigen CTLA-4 and B7 molecules found on antigen presenting cells (APCs), a new vaccine (V_C4MEV) for preventing brucellosis was created by combining CTLA-4 immunoglobulin variable region (IgV_CTLA-4) with MEV protein. Immunoinformatics analysis showed that V_C4MEV has a good secondary and tertiary structure. Additionally, molecular docking and molecular dynamics simulation (MD) revealed a robust binding affinity between IgV_ CTLA-4 and the B7 molecule. Notably, the vaccine V_C4MEV was demonstrated favorable immunogenicity and antigenicity in both in vitro and in vivo experiments. V_C4MEV had the potential to activate defensive cells and immune responses, offering a hopeful approach for developing vaccines against Brucella in the upcoming years.

Low Seroprevalence Of Brucella Spp. Among Remote Colombian Communities From The Sierra Nevada De Santa Marta

Brucella species cause a high burden of disease globally, infecting both humans and animals; however, One Health has been under-appreciated in Colombia. This study aimed to determine the seroprevalence of Brucella spp. in two remote indigenous communities from the Sierra Nevada de Santa Marta, Colombia. These communities live in close contact with their livestock, indicating a potential susceptibility to zoonotic pathogens. The livestock routinely kept by these communities include cattle, small ruminants and pigs, the known hosts of human pathogenic Brucella spp.. A low level of exposure to Brucella spp. was documented, with only one positive participant among 539 participants (0.2%; 95% CI 0.0 – 1.0). Nevertheless, due to the high risk that zoonoses pose, we recommend discussions with the community for the potential establishment of One Health surveillance studies for the early detection and prevention of future zoonotic disease threats.

Bm Delta-pgm, a vaccine for the control of Brucella melitensis with cross-species protective properties.

Brucellosis remains one of the most worldwide distributed zoonosis inflicting serious economical and human health problems in many areas of the world. The disease is caused by different species of the genus Brucella that have different tropisms towards different mammals being the most relevant for human health Brucella abortus, Brucella melitensis and Brucella suis that infect cows, goats/sheep, and swine respectively. For B. melitensis, considered the species with more zoonotic potential and highly aggressive for animals, only one vaccine is available to date in the market: Rev 1. This attenuated strain has the disadvantage that is has a very high residual virulence for animals and humans and, for this reason, it is applied by ocular instillation which is technically challenging in many productive settings. For this reason, the search for new vaccines for caprine and ovine brucellosis is an active topic of research. We describe here the construction of a novel highly attenuated vaccine strain (Bm Delta-pgm) that confers excellent levels of protection against B. melitensis in the mouse model of infection. This strain is a clean deletion of the phosphoglucomutase (pgm) gene that codes for a protein that catalyzes the conversion of glucose-6-P to glucose-1-P, which is used as a precursor for the biosynthesis of many polysaccharides, including the O-antigen of the lipopolysaccharide and cyclic beta glucans. Our results indicate that vaccination with Bm Delta-pgm induces a robust memory cellular immune response but no antibody production against the O-antigen. Cross protection experiments show that this new vaccine protects against B. abortus and B. suis raising the possibility that Bm Delta-pgm could be used as a universal vaccine for the most important Brucella species.

Molecular characterization and antimicrobial susceptibility of human Brucella in Northeast China.

Northeast China has always been an area with severe brucellosis prevalence. This study will identify Brucella in Northeast China and test its resistance to antibiotics, in order to clarify its resistance mechanism. Brucella is a widespread and highly pathogenic bacteria that poses serious threats to public health and animal husbandry. In this study, 61 Brucella isolates were identified by abortus-melitensis-ovis-suis polymerase chain reaction (AMOS-PCR) for biotypes and epidemic potential was clarified by multi-locus sequence analysis. Whole-genome sequencing (WGS) was performed and the antibiotic susceptibility of the Brucella strains against 13 antibiotics was detected with the use of E-test strips. The results showed that all of the isolates were Brucella melitensis ST8, group CC4 with little genetic variation and obvious geographical characteristics. All 61 Brucella isolates were sensitive to doxycycline, tetracycline, minocycline, levofloxacin, ciprofloxacin, gentamicin, and streptomycin, while 24.6%, 86.9%, 65.6%, 27.9%, 3.3%, and 1.6% were resistant to rifampin, azithromycin, cefepime, cefoperazone/sulbactam, cefotaxime, and meperidine/sulfamethoxazole, respectively. This is the first report of cephalosporin-resistant B. melitensis in China. The WGS results indicated that about 60% of the antibiotic resistance genes were associated with efflux pumps (mainly the resistance nodulation division family). Brucellosis is usually treated with antibiotics for several months, which can easily lead to the emergence of antibiotic resistance. To ensure the effectiveness and safety of antibiotics for treatment of brucellosis, continuous surveillance of antibiotic susceptibility is especially important.

Unusual Abscess Caused by Brucella Melitensis

Brucellosis is a zoonotic infectious disease which any organ can be involved. Soft tissue lesions are rare manifestations of brucellosis. Brucella breast abscess in animal is not uncommon; involvement of the breast in human brucella is extremely rare. Breast abscess involvement was reported to 0.7% of the patient with brucellosis. We report the microbiological findings of breast abscess due to brucella. A 38-year-old woman living in the rural area of Kerman, Iran, presented with an abscess in the right breast. The sampling of the abscess aspiration and preparation of smears showed inflammatory fluid. Culture and PCR performed from the sample identified the presence of Brucella melitensis. The lesion had diminished in size after 8 weeks of treatment with combined doxycycline and rifampin. The possibility of breast abscess being caused by Brucella should be considered in countries, especially in endemic regions. Besides, isolated Brucella spp from microbiological cultures is important for a definitive diagnosis.

Multiple Locus Variable-Number Tandem Repeat Analysis Genotyping of Human Brucella melitensis Isolates from West of Iran

Background & Objective: Brucellosis is an endemic disease with a high prevalence in Iran whose highest frequency is in the western region of the country. Genetic diversity investigation is an important method to determine the epidemiological relationship of Brucella isolates in different geographical areas. Therefore, the present study aimed to investigate the genetic diversity of human Brucella melitensis (B. melitensis) strains using the Multiple Locus Variable-Number Tandem Repeat Analysis (MLVA) Typing method in the west of the country.
 Materials & Methods: In this study, 20 strains of isolated B. melitensis were collected from the human serum samples of suspected Brucellosis in the west of the country and were analyzed by MLVA-16 method.
 Results: The results showed that 3 genotype numbers 42, 43 and 47 were identified using MLVA-8 method and using MLVA-11 method genotypes 125, 138 and 111 were recognized. Also, 16 different genotypes were detected from the analysis of the isolates by MLVA-16 method which shows a high degree of polymorphism among the isolates due to the high genetic diversity of the isolates in Panel 2B loci.
 Conclusion: The results showed the high genetic diversity of B. melitensis isolates in the west of the country and their genetic relationship with the known strains in the neighboring countries of the Eastern Mediterranean area, as well as the importance of the MLVA method in identifying the source of infection.

Antimicrobial resistance profiles of human Brucella melitensis isolates in three different microdilution broths: the first multicentre study in Bosnia and Herzegovina

Brucellosis is a ubiquitous emergent bacterial zoonotic disease causing significant human morbidity in Bosnia and Herzegovina. So far, a high rate of resistant Brucella has been found worldwide. This study prospectively analysed the rates of resistance among human Brucella melitensis strains isolated in Bosnia and Herzegovina. This study included 108 B. melitensis isolates from 209 patients diagnosed at five medical centres in Bosnia and Herzegovina. The resistance profiles of the B. melitensis isolates for the 13 most commonly used antimicrobials were studied in standard Brucella broth (BB) and cation-adjusted Mueller-Hinton broth (CAMHB) supplemented with 4% lysed horse blood or 5% defibrinated sheep blood. Of the 209 patients, B. melitensis blood cultures were positive for 111 (53.1%). Among the 108 isolates investigated, 91 (84.3%) were resistant to trimethoprim-sulfamethoxazole on BB, but not on either CAMHB. Nearly all isolates (>90%) were resistant to azithromycin on BB and both CAMHBs. We observed a high rate of B. melitensis resistance to azithromycin. The high rate of resistance to trimethoprim-sulfamethoxazole that we observed was related to BB, so an alternative broth should be used, such as the enriched CAMHBs in this study, for evaluating resistance to trimethoprim-sulfamethoxazole. Whole-genome sequencing studies are needed to understand the development of antimicrobial resistance in B. melitensis strains isolated from humans.

Brucellosis in Herat Province, Afghanistan: Epidemiological Status and Risk Factors

Background: Human brucellosis, also known as Malta fever, is an acute systemic zoonotic disease in several parts of the world. The most pathogenic Brucella specie is Brucella melitensis that occurs in the human population of all age groups and of both sexes. Objectives: The present study aimed to investigate human Brucella infection in Afghanistan. Methods: The participants in this cross-sectional study were 44 patients diagnosed with Brucella infection during eight months and confirmed using Wright test by physicians of Iran Clinic Hospital. For data analysis, a statistical model was used through SPSS. Results: The most affected patients were female housewives (40.9%) and students (18.18%). The most frequent clinical manifestations were recurrent attacks of fever (95.34%), weight loss (81.39%), loss of appetite (79.06%), musculoskeletal pain (69.76%), boredom (67.44%), and lethargy (60.46%). A total of 41 (93.18%) patients mentioned the consumption of unpasteurized milk as the source of infection. Conclusions: The study results revealed that the main route of Brucella transmission in Afghanistan is the consumption of contaminated dairy products. The highest prevalence of brucellosis was observed among the young and middle-aged populations and housewives.

Determination of investigation of the link between human and animal Brucella isolates in Iran using multiple-locus variable number tandem repeat method comprising 16 loci (MLVA-16)

BackgroundEpidemiological studies are important tools to assess the diversity of Brucella isolates and to estimate their epidemiological relationship among isolates from different geographical origins. In this study the MLVA16 (multiple-locus variable number tandem repeat analysis based on 16 loci) was employed to investigate the diversity of Brucella spp. Isolated from humans and animals for epidemiological purposes and to determine the most common Brucella genotypes in Iran. MethodsWe designed a molecular-based study to evaluate the potential reservoirs of human brucellosis. After isolation and identification of 54 Brucella spp human and animal specimens from three regions of Iran, bacterial genomic DNA was extracted MLVA with three panel was used for the genotyping of isolates. The size of PCR products were analyzed and converted to repeat unit numbers using a published allele numbering system and data set was imported into Bionumerics. ResultsThree isolates (5.55%) were identified as Brucella abortus and 51 (94.44%) as Brucella melitensis. Two isolates of Brucella abortus were from humans and one from an animal. Thirty-four Brucella melitensis isolates were from humans and 17 from animals. Using MLVA16-genotyping, 54 isolates with genetic similarity coefficient of 80% were divided into 46 genotypes and 22 genotypes were represented by a single isolate, while 4, 2, 1 and 2 genotypes were represented by 2, 3, 4 and 7 isolates, respectively. The most prevalent genotype was represented by 14 isolates. There were two other frequent genotypes each represented by seven isolates, among which only one was restricted to a geographic region. Discriminatory power for each locus was determined in this study and panel 2B shows the high discretionary power [Bruce04 (0.837), Bruce30 (0.806), Bruce 09 (0.787), Bruce 07 (0.772), Bruce16 (0.766)]. ConclusionMLVA16 analysis of 54 Brucella isolates showed high level polymorphism in their genotypes. Only two genotypes, each observed in seven isolates, were related to one another and only one of these genotypes were found in to two separate regions.

Molecular Detection of Brucella melitensis Associated Reproductive Failure in Native Sheep Flock: Potential Public Health Pathogen from Tropical Region of Tamil Nadu

Brucellosis remains a global burden since the last century. In India, both animal and human brucella infections drastically increase every year. Outbreaks of 40 ewe’s abortion were investigated in native sheep’s from the tropical region of Tamil Nadu. Aborted maternal and fetal tissues were initially subjected to Stamps Modified Ziehl Neelsen (S-ZN) staining method. The DNA was extracted and screened for Brucella genome by Brucella cell surface salt extractable proteins (bcsp31) gene based PCR assay. Further, PCR positive samples were subjected for AMOS PCR for B. abortus, B. ovis, B. melitensis and B. suis identification and differentiation. S-ZN staining of aborted tissues revealed pink, coccobacilli organisms giving presumptive identification of Brucella sp. Molecular detection of brucellosis by bcsp31 gene based PCR in placental tissues and fetal abomasal contents of both the animals yielded a specific amplicon of 223 bp confirming it as Brucella genus infection. Molecular detection and differentiation by AMOS PCR revealed a specific amplicon of 731 bp indicating the involvement of B. meletensis infection in the native free-ranging sheep flock. It is a potent public health pathogen, highly essential to be monitored for the strategic control of brucellosis.

Human brucellosis outbreaks in Klang district, Malaysia

Background: Human brucellosis is a rare zoonotic disease in Malaysia. Case description: We report two outbreaks of eight human brucella cases which occurred from October 2018 till February 2019 in the Klang district. A total of five confirmed and three probable brucella cases were reported. Of this, four patients had brucellosis after consuming unpasteurized goat's milk from a single goats farm while the other four are farm workers from a cattle farm. Among eight cases, two were children aged 6 and 10 years old. All eight cases presented with fatigue, anorexia and prolonged fever. Four of them presented with headache, myalgia and weight loss while three had arthralgia and one experienced night sweats. Mean duration from onset of symptoms to diagnosis was 45 days, longest duration being 87 days. Six of them developed transaminitis and four of them had haematological abnormalities. Two of those with hematological abnormalities had pancytopenia. Two had hepatomegaly and two had splenomegaly. Two patients were treated as neurobrucellosis as they presented with severe headache and hyperreflexia respectively. One had positive Brucella PCR from his cerebrospinal fluid analysis. Five patients were confirmed brucellosis by PCR detection from blood culture. Three probable Brucella cases were diagnosed based on clinical presentation, positive Brucella IgG titre and an epidemiological link. All the patients required an average of 14 days of hospitalizations and received at least 6 weeks of combination antibiotic. All eight recovered without long term sequalae. Discussion: From these two outbreaks, we find that all patients had prolonged fever and non-specific symptoms with routine laboratory investigations being inconclusive. In both outbreaks, a positive epidemiological link to consuming unpasteurized goat milk and handling of cattle was the important clue to diagnosis. In addition, timely recognition of neurobrucellosis is crucial as the choices and duration of antibiotic might differ from our usual regime. Conclusion: In conclusion, assessment of exposure risk to brucella is prudent while taking history for all patients presenting with fever of unknown origin as it will lead to early diagnosis, early treatment and minimised risk of laboratory staff exposure.

MALDI-TOF MS and genomic analysis can make the difference in the clarification of canine brucellosis outbreaks

Brucellosis is one of the most common bacterial zoonoses worldwide affecting not only livestock and wildlife but also pets. Canine brucellosis is characterized by reproductive failure in dogs. Human Brucella canis infections are rarely reported but probably underestimated due to insufficient diagnostic surveillance. To improve diagnostics, we investigated dogs in a breeding kennel that showed clinical manifestations of brucellosis and revealed positive blood cultures. As an alternative to the time-consuming and hazardous classical identification procedures, a newly developed species-specific intact-cell matrix-assisted laser desorption/ionization–time of flight mass spectrometry analysis was applied, which allowed for rapid identification of B. canis and differentiation from closely related B. suis biovar 1. High-throughput sequencing and comparative genomics using single nucleotide polymorphism analysis clustered our isolates together with canine and human strains from various Central and South American countries in a distinct sub-lineage. Hence, molecular epidemiology clearly defined the outbreak cluster and demonstrated the endemic situation in South America. Our study illustrates that MALDI-TOF MS analysis using a validated in-house reference database facilitates rapid B. canis identification at species level. Additional whole genome sequencing provides more detailed outbreak information and leads to a deeper understanding of the epidemiology of canine brucellosis.

A Proof of Principle for the Detection of Viable Brucella spp. in Raw Milk by qPCR Targeting Bacteriophages.

Brucellosis is still a global health issue, and surveillance and control of this zoonotic disease in livestock remains a challenge. Human outbreaks are mainly linked to the consumption of unpasteurized dairy products. The detection of human pathogenic Brucella species in food of animal origin is time-consuming and laborious. Bacteriophages are broadly applied to the typing of Brucella isolates from pure culture. Since phages intracellularly replicate to very high numbers, they can also be used as specific indicator organisms of their host bacteria. We developed a novel real-time PCR (qPCR) assay targeting the highly conserved helicase sequence harbored in all currently known Brucella-specific lytic phages. Quality and performance tests determined a limit of detection of <1 genomic copy/µL. In raw milk artificially contaminated with Brucella microti, Izv phages were reliably detected after 39 h of incubation, indicating the presence of viable bacteria. The qPCR assay showed high stability in the milk matrix and significantly shortened the time to diagnosis when compared to traditional culture-based techniques. Hence, our molecular assay is a reliable and sensitive method to analyze phage titers, may help to reduce the hands-on time needed for the screening of potentially contaminated food, and reveals infection risks without bacterial isolation.

Diagnosis of human and canine Brucella canis infection: development and evaluation of indirect enzyme-linked immunosorbent assays using recombinant Brucella proteins

Brucella canis, a Gram-negative coccobacilli belonging to the genus Brucellae, is a pathogenic bacterium that can produce infections in dogs and humans. Multiple studies have been carried out to develop diagnostic techniques to detect all zoonotic Brucellae. Diagnosis of Brucella canis infection is challenging due to the lack of highly specific and sensitive diagnostic assays. This work was divided in two phases: in the first one, were identified antigenic proteins in B. canis that could potentially be used for serological diagnosis of brucellosis. Human sera positive for canine brucellosis infection was used to recognize immunoreactive proteins that were then identified by performing 2D-GEL and immunoblot assays. These spots were analyzed using MALDI TOF MS and predicted proteins were identified. Of the 35 protein spots analyzed, 14 proteins were identified and subsequently characterized using bioinformatics, two of this were selected for the next phase. In the second phase, we developed and validated an indirect enzyme-linked immunosorbent assays using those recombinant proteins: inosine 5′ phosphate dehydrogenase, pyruvate dehydrogenase E1 subunit beta (PdhB) and elongation factor Tu (Tuf). These genes were PCR-amplified from genomic DNA of B. canis strain Oliveri, cloned, and expressed in Escherichia coli. Recombinant proteins were purified by metal affinity chromatography, and used as antigens in indirect ELISA. Serum samples from healthy and B. canis-infected humans and dogs were used to evaluate the performance of indirect ELISAs. Our results suggest that PdhB and Tuf proteins could be used as antigens for serologic detection of B. canis infection in humans, but not in dogs. The use of recombinant antigens in iELISA assays to detect B. canis-specific antibodies in human serum could be a valuable tool to improve diagnosis of human brucellosis caused by B. canis.

Comparison of knowledge, attitude, and practices of animal and human brucellosis between nomadic pastoralists and non-pastoralists in Kenya

BackgroundThe seroprevalence of brucellosis among nomadic pastoralists and their livestock in arid lands is reported to be over10-fold higher than non-pastoralists farmers and their livestock in Kenya. Here, we compared the seroprevalence of nomadic pastoralists and mixed farming with their knowledge of the disease and high-risk practices associated with brucellosis infection.MethodsAcross-sectional study was conducted in two counties - Kiambu County where farmers primarily practice smallholder livestock production and crop farming, and Marsabit County where farmers practice nomadic pastoral livestock production. Stratified random sampling was applied, in which sublocations were initially selected based on predominant livestock production system, before selecting households using randomly generated geographical coordinates. In each household, up to three persons aged 5 years and above were randomly selected, consented, and tested for Brucella spp IgG antibodies. A structured questionnaire was administered to the household head and selected individuals on disease knowledge and risky practices among the pastoralists and mixed farmers compared. Multivariable mixed effects logistic regression model was used to assess independent practices associated with human Brucella spp. IgG seropositivity.ResultsWhile the majority (74%) of pastoralist households had little to no formal education when compared to mixed (8%), over 70% of all households (pastoralists and mixed farmers) had heard of brucellosis and mentioned its clinical presentation in humans. However, fewer than 30% of all participants (pastoralists and mixed farmers) knew how brucellosis is transmitted between animals and humans or how its transmission can be prevented. Despite their comparable knowledge, significantly more seropositive pastoralists compared to mixed farmers engaged in risky practices including consuming unboiled milk (79.5% vs 1.7%, p < 0.001) and raw blood (28.3% vs 0.4%, p < 0.001), assisting in animal birth (43.0% vs 9.3%, p < 0.001), and handling raw hides (30.6% vs 5.5%, p < 0.001).,ConclusionNomadic pastoralists are more likely to engage in risky practices that promote Brucella Infection, probably because of their occupation and culture, despite having significant knowledge of the disease.

The prevalence and risk factors for human Brucella species infection in a cross-sectional survey of a rural population in Punjab, India

Brucellosis is an important neglected zoonosis. Effective cattle vaccines are available but are infrequently used in India, where rural households commonly own one or two cattle as sources of protein and income. We assessed the prevalence of infection and risk factors in humans. We conducted a cross-sectional sero-survey in randomly selected individuals in 60 villages in Punjab. Infection prevalence was assessed by positive Rose Bengal testing or immunoglobulin G enzyme-linked immunosorbent assay. Risk factors were adjusted for potential confounding using multivariable analyses. Of the 1927 subjects who were approached, 93% agreed to participate. Age-standardised prevalence for Brucella infection was 2.24% (95% confidence interval [CI] 1.61 to 3.11). More than 60% of households kept cattle and 10% assisted with calving or abortions. Nearly all individuals consumed boiled cow/buffalo milk from their own or neighbours' cattle and 3.3% consumed goat's milk. There was a 2.18 times increased odds (95% CI 0.96 to 4.95) of infection with calving/abortions and a 4.26 times increased odds (95% CI 1.33 to 13.6) with goat's milk but not bovine milk consumption. An association with calving/abortions and goat's milk consumption was seen. Brucella vaccination of household livestock would reduce the risk to humans in such settings. Additional measures include biosecurity training around calving/abortions, education to boil all milk and for healthcare workers to test for brucellosis.

Human NK cell receptor KIR2DS4 detects a conserved bacterial epitope presented by HLA-C.

Natural killer (NK) cells have an important role in immune defense against viruses and cancer. Activation of human NK cell cytotoxicity toward infected or tumor cells is regulated by killer cell immunoglobulin-like receptors (KIRs) that bind to human leukocyte antigen class I (HLA-I). Combinations of KIR with HLA-I are genetically associated with susceptibility to disease. KIR2DS4, an activating member of the KIR family with poorly defined ligands, is a receptor of unknown function. Here, we show that KIR2DS4 has a strong preference for rare peptides carrying a Trp at position 8 (p8) of 9-mer peptides bound to HLA-C*05:01. The complex of a peptide bound to HLA-C*05:01 with a Trp at p8 was sufficient for activation of primary KIR2DS4+ NK cells, independent of activation by other receptors and of prior NK cell licensing. HLA-C*05:01+ cells that expressed the peptide epitope triggered KIR2DS4+ NK cell degranulation. We show an inverse correlation of the worldwide allele frequency of functional KIR2DS4 with that of HLA-C*05:01, indicative of functional interaction and balancing selection. We found a highly conserved peptide sequence motif for HLA-C*05:01-restricted activation of human KIR2DS4+ NK cells in bacterial recombinase A (RecA). KIR2DS4+ NK cells were stimulated by RecA epitopes from multiple human pathogens, including Helicobacter, Chlamydia, Brucella, and Campylobacter. We predict that over 1,000 bacterial species could activate NK cells through KIR2DS4, and propose that human NK cells also contribute to immune defense against bacteria through recognition of a conserved RecA epitope presented by HLA-C*05:01.