MLVA-16 Genotyping of Brucella abortus and Brucella melitensis Isolates from Different Animal Species in Egypt: Geographical Relatedness and the Mediterranean Lineage

Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022

Brucella melitensis is a zoonotic pathogen that poses a worldwide public health challenge. In recent years, whole-genome sequencing has become a widely accepted molecular typing method for the genomic epidemiology of brucellosis. This study reports the genomic characteristics of 24 B. melitensis strains isolated from human infections in southern Tunisia over 35 years (1988-2022). We utilized WGS to analyze the clonal relationships of these strains, their relatedness to international sequences, their antimicrobial resistance determinants, and their virulence factors. Our findings revealed a high genetic stability over three decades. All isolates were identified as B. melitensis biovar 3 and were assigned to the same sequence type, ST11, using the MLST-9 scheme. Using the MLST-21, Tunisian sequences shared 20 out of 21 alleles and were assigned to 2 closely related STs (ST89 and ST114). Phylogenetic analysis indicated that all Tunisian sequences were grouped into a single subcluster within lineage I, the West Mediterranean clade, and were highly related to other strains from the Maghreb region (Morocco and Algeria). Antimicrobial resistance analysis revealed no classical resistance determinants. However, mprF, bepCDEFG genes, and missense mutations in rpoB, gyrA, gyrB, and parC genes were identified. Virulence analysis identified 67 genes, predominantly involved in lipopolysaccharide biosynthesis and the type IV secretion system. To our knowledge, this study represents the first genomic investigation of B. melitensis strains circulating in Tunisia. Our findings underscore the importance of genomic surveillance in understanding the epidemiology and evolution of brucellosis in North Africa.

Molecular and serological investigation of Brucella species in kennel and farm dogs in Iran

INTRODUCTION

Brucellosis is still a significant emerging threat to public health, as it can infect humans, wild, domestic animals, and livestock. Hence, the current study aims to determine the frequency of canine brucellosis (CB), its relationship with clinical findings and reproductive disorders in kennel and farm dogs, and its importance on public health.

MATERIALS AND METHODS

From January 2022 to December 2023, a total of 150 blood samples were taken from 100 adult dogs in breeding kennels and 50 shepherd dogs in breeding farms in Kerman, Iran. Rose Bengal test (RBT) and Wright tests were used for the primary screening of Brucella abortus (B. abortus) and Brucella melitensis (B. melitensis) species, and conventional IS711-based PCR and real-time polymerase chain reaction (RT-PCR) were performed to determine the Brucella genus and species in all samples.

FINDINGS

In kennel dogs, 34 % (34/100) had a history of breeding disorders, and 30 % (30/100) were RBT-positive. Moreover, B. canis and B. abortus species were detected in kennel dogs. Among farm dogs, 16 % (8/50) had a history of breeding disorders, and 28 % (14/50) were RBT positive. Additionally, B. canis, B. abortus, and B. melitensis species were detected in farm dogs. Feeding with unpasteurized milk was significantly related to a positive RBT in kennel dogs (p = 0.009), and there was a significant correlation between breeding disorders and seropositivity in kennel (p = 0.045) and farm dogs (p = 0.03).

CONCLUSION

The current study represents a significant advancement in understanding CB in Iran by the first molecular detection of B. canis, revealing B. melitensis and B. abortus as important pathogens in kennel and farm dogs and highlighting the public health significance of disease in Iran.

Animal Brucellosis in Egypt: Review on Evolution, Epidemiological Situation, Prevalent Brucella Strains, Genetic Diversity, and Assessment of Implemented National Control Measures

Brucellosis is a neglected zoonotic disease that has a significant economic and public health impact, especially in endemic countries. This review delves deeply into brucellosis's current epidemiological situation and potential sources of livestock infection in Egypt during the last two decades. MLVA-16 and Whole Genome Sequencing based on core-genome SNP analyses confirm the presence of different B. abortus and B. melitensis outbreak strains, both older widely disseminated Brucella strains and newly introduced ones. Despite implementing the test-and-slaughter control strategy over forty years, the disease is still endemic, and different Brucella species circulate among several animal species. The raising of mixed animal species in the same households or farms, exposure to aborted animals, and lack of public awareness about brucellosis transmission are among the main risk factors for increasing livestock brucellosis prevalence in Egypt. Young animals' voluntary vaccination, lack of a nationwide animal identification system, and uncontrolled animal movement stand beyond the ineffectively applied control strategy and may be subdued by applying mass vaccination to decrease disease prevalence dramatically and target imported camels, domestic pigs, and dogs (housed and stray) in the national control surveillance. Increasing awareness through educational campaigns is compulsory to reduce brucellosis transmission risk to livestock/humans.

In silico MLVA Analysis of Brucella melitensis from Human and Livestock in Iran

Brucellosis, a zoonotic disease caused by Brucella spp. globally, is of great significance not only to livestock but also to public health. The most significant of the twelve species is Brucella melitensis. This article is devoted to the endemic region of Iran and aims to uncover the molecular epidemiology of B. melitensis. Biotyping, AMOS-PCR, Bruce-ladder PCR, and the in silico method of MLVA were employed to test 40 B. melitensis isolates from humans, cows, sheep, goats, camels, and horses which are found in thirteen Iranian provinces throughout the years 2015 to 2022. The data from the MLVA-8 analysis showed that there were seven genotypes that could be identified, and the most commonly identified genotype was genotype 63. The data from the MLVA-10 analysis showed that there were seven genotypes, with genotype 213 being the most prevalent in Iran. The data from the MLVA-11 analysis showed that there were eight genotypes, with genotype 111 being the most prevalent in Iran. The MLVA and SNP analysis results showed that the bacteria were grouped into two main groups, known as the Eastern Mediterranean and American groups. Moreover, the outcomes from these analyses have added considerably to our understanding of the genetic/historical relationships among the isolates. Our study indicates a high prevalence of B. melitensis biovar 1 in Iran, accounting for 82.5% of the isolates. The study provides insight into such matters as the complex epidemiology of B. melitensis in Iran, suggesting different ways of transmission and sources of infection. This research points out the vital significance of the continuation of the surveillance and curation of B. melitensis in the diverse species of animals and humans. The simplicity and efficiency of MLVA-based molecular epidemiology offer information on the geographic distribution and genetic diversity of B. melitensis and, therefore, help in the devising of targeted strategies for the prevention of disease in animals.

Comprehensive epidemiological evaluation of ruminant brucellosis and associated risk factors in some Egyptian Governorates

Background and Aim

Brucellosis contributes to significant economic losses due to abortion, weak newborns, infertility, and up to 20% reductions in milk yield in carrier animals. This study aimed to estimate the prevalence of ruminant brucellosis in six Egyptian governorates. This study aimed to estimate the prevalence of ruminant brucellosis and evaluate the risk factors regarding the epidemiological status, highlighting the importance of early carrier detection for the success of control programs.

Materials and Methods

A total of 3000 ruminants were investigated. Blood and serum samples were collected for routine hemato-biochemical analysis (complete blood picture and metabolic panel). In addition, genotoxicity analysis was performed, whereas tissue samples were collected for histopathological analysis. The buffered acidified plate antigen test (BAPAT), Rose Bengal plate test (RBPT), and complement fixation test (CFT) were used for serological diagnosis of brucellosis. The obtained bacterial colonies were typed using Brucella abortus-, melitensis-, ovis-, and suis-polymerase chain reaction (AMOS-PCR), depending on the variability of the IS711 fragment among Brucella spp. Serum trace elements, oxidative stress, and acute phase proteins were compared according to body condition score (BCS) and clinical condition images within the study population.

Results

Mastitis and abortion were the key recorded symptoms (9.966%, 299/3000 and 6%, 180/3000, respectively); however, symptomless individuals were predominant (82.9%, 2487/3000). Blood lymphocytosis was prominent even in asymptomatic animals. Nutritional and food conversion conditions were defined as low, moderate, or high BCS. Brucella overall seropositivity by BAPAT, RBPT, and CFT was 6.1% (182/3000), 5.6% (168/3000), and 5.1% (154/3000) in ruminant species within the included governorates, respectively. Upon diagnosis, 154 seropositive cases developed 93 bacterial isolates and a 731-bp PCR fragment whose sequences confirmed Brucella melitensis biovar 3. Serum metabolic and biochemical profiles, acute phase proteins, trace elements, and oxidative stress concentrations were indicative of loss of functionality in the liver and kidneys, malnutrition and malabsorption syndrome, and DNA damage, particularly in the low-BCS groups (p < 0.0001). Granulomatous lesions were most prominent in the lymph nodes, spleen, uterus, and udder of the dams, while placental multifocal necrosis with thrombosis was recorded in aborted fetuses. There were 8 types of chromosomal aberrations detected in peripheral white blood cells. The highest frequency was for dicentric aberrations 0.025% (25/1000), whereas the lowest 0.009% (9/1000) was for acentric, ring, fusion, and polyploidy. The difference between species was significant for BCS; 14.2% in low-BCS cattle and camels and 8.4% in high-BCS buffaloes.

Conclusion

B. melitensis biovar 3 is prevalent in Egypt. Mixed-rearing systems are the main risk factors for interspecies transmission among ruminants. The difficulty in accurately diagnosing all infected animals, particularly carriers, is a major limitation of eradication and control programs. Different biomarkers could be indicators and/or sensors for performance and/or infectivity conditions in animal herds; however, they require further optimization. Early detection using molecular technologies, highly descriptive, quantitative, sensitive, and specific methods, as alternatives to serological diagnosis (CFT, BAPAT, and RBT), is urgently needed to enhance the efficiency of brucellosis-specific prophylaxis. Such a comprehensive procedure is the World Organization for Animal Health dependent decision.

Seroprevalence and risk factors of brucellosis in pastoralists and their livestock in Central Equatoria State, South Sudan

BACKGROUND

Brucellosis poses serious public health implications and substantial economic losses in pastoral rural settings in South Sudan. In humans, brucellosis is almost always originating from animals. Current literature provides scant data regarding the seroprevalence of brucellosis in South Sudan. This cross-sectional study investigates the seroprevalence of brucellosis among the pastoral community and livestock and identifies risk factors for the disease from two Counties, Terekeka and Juba in Central Equatoria State (CES), South Sudan.

METHODOLOGY

A total of 986 sera; from humans (n = 143), cattle (n = 478), sheep (n = 86), and goats (n = 279) were randomly collected from 17 cattle camps in CES. Sera for the humans, cattle and goats were screened for Brucella-specific antibodies using Rose Bengal plate test (RBPT) and further confirmed by competitive enzyme-linked immunosorbent assay (c-ELISA) in series due to the cost of testing. All the sera from sheep were tested in parallel using RBPT and c-ELISA as the sheep samples were few and were all tested negative on the RBPT. A camp was considered positive when at least one animal of either species tested positive on the c-ELISA. A structured questionnaire was used to collect information on potential individual and herd level risk factors. Univariate analysis using binary logistic regression with a confidence interval of 95% at a p-value of ≤ 0.05 was used to identify the association between the potential individual risk factors and Brucella seropositivity. The investigated risk factors for livestock included age, sex, species, prior abortion history, retained placenta, parity, and reproductive status. Variables found to have associations in univariate analysis (p = 0.25) with Brucella seropositivity were further included in multivariable logistic regression. The risk factors investigated for humans included, gender, age, educational level, occupation, marital status, drinking of raw milk, aiding female animals during delivery, eating undercooked meat and blowing of air into the cow's uterus through the vagina, a practice in South Sudan.

RESULTS

The study revealed seroprevalence of 21.7%, 11.8%, and 4.8% in cattle, goats, and humans, respectively. Our results indicated that all sheep serum samples were negative on both RBPT and c-ELISA. The seropositive in the 13 camps from Terekeka County was 100.0% (13/13) compared to 50.0% (2/4) seropositive from 4 camps in Juba County. All the variables investigated in the univariate analysis of risk factors in cattle were significantly associated with Brucella seropositivity: sex (OR:4.5, 95% CI: 2.2-8.9, p<0.001), age (OR:6.6, 95% CI: 2.3-19.1, p:<0.001), abortion history (OR:3.1, 95% CI: 1.8-5.2, p:<0.001), retained placenta (OR:2.5, 95% CI: 1.4-4.4, p = 0.001), parity (OR:2.3, 95% CI: 1.1-4.7, p = 0.020), However, in small ruminants, none of the potential risk factors were associated with Brucella seropositivity. In humans, blowing air through a cow's vagina (OR: 1.4, 95%CI: 0.782-2.434, p = 0.035) was the only variable found to be significantly associated with Brucella seropositivity in the univariate analysis. The forceful blowing of air into a cow's vagina to induce milk letdown is a common practice among the pastoral communities in South Sudan. The multivariable logistic regression model identified sex, age, and abortion history as statistically significant factors for Brucella seropositivity in cattle. The odds of seropositivity were nearly threefold (OR: 2.8; 95% CI: 1.3-5.8, p = 0.006) higher in cows compared to bulls (male cattle). Cattle over two years old had higher odds of Brucella seropositivity than young animals (OR: 3.5, 95% CI: 1.2-10.3-, p: 0.025). Cows with a history of abortion had higher odds of Brucella seropositivity (OR: 2.8, 95% CI: 1.6-4.7, p = 0.001).

CONCLUSION

This study reports the occurrence of brucellosis in goats and its absence in sheep in (CES), South Sudan. The present study also shows the occurrence of brucellosis in cattle, goats and people in the pastoral community and recommends for the implementation of the One Health approach and awareness campaigns for effective mitigation of this disease.

Genomic analysis of Brucella isolates from animals and humans, Türkiye, 2010 to 2020

BackgroundBrucellosis is a bacterial zoonosis causing severe illness in humans and animals and leading to economic losses in the livestock production in Türkiye and other endemic countries.AimWe aimed at investigating genomic differences of Brucella isolates from animals and humans in Türkiye.MethodsWe used whole genome sequencing (WGS) to assess the genetic diversity of Brucella isolates from 41 provinces in Türkiye and compared with isolates from other countries. We applied allele-based typing and core genome single nucleotide polymorphism (cgSNP) determination.ResultsOf the 106 Turkish Brucella isolates included, 57 were B. abortus and 49 were B. melitensis. One B. melitensis and two B. abortus isolates were identified as vaccine strains. Most (n = 55) B. abortus isolates clustered in three major branches, with no spatial discernible pattern. Of the B. melitensis isolates, 48 were assigned to the Eastern Mediterranean lineage with no discernible patterns between host species, location and sampling date. The Turkish isolates clustered with isolates from neighbouring countries such as Greece and Syria, but some also with isolates from human patients in European countries, like Germany, Norway and Sweden, suggesting that the source may be travel-related.ConclusionSeveral B. melitensis and B. abortus lineages are circulating in Türkiye. To decrease the prevalence and prevent brucellosis in animals and humans, stricter control measures are needed, particularly in areas where humans and animals have close contact. Furthermore, illegal transportation of animals across borders should be more closely controlled and regulated.

Epidemiological Investigation of Animal Brucellosis in Domestic Ruminants in Greece from 2015 to 2022 and Genetic Characterization of Prevalent Strains

Brucellosis is one of the most important zoonotic diseases in Greece, causing a significant burden on both human and animal vitality as well as economic loss. The present study was conducted from 2015 to 2022 on 711,415 serum samples by determining the seroepidemiology of Brucellosis among livestock in 24 geographical areas in Greece using the Rose Bengal Test (RBT) and the complement fixation test (CFT) and further performing genetic analysis of Brucella spp. by species-specific real-time PCR and MLVA Brucella analysis. A total of 3086 serum samples from goats, sheep, and cattle showed positive results using the RBT and CFT, and only strongly positive samples (n = 800) were preserved in the Βlood Bank of the Veterinary Laboratory of Brucellosis. From these, 212 sera samples were randomly selected for molecular and genetic analysis. The results indicated that the incidence rate of Brucellosis is higher in cattle herds in comparison with other animal species. Overall, 48 samples tested positive by real-time PCR, of which forty-seven of them were B. abortus and one was B. melitensis. Genetic analysis of two B. abortus samples revealed a common pattern, indicating two Bruce04, two Bruce18, four Bruce07, two Bruce09, three Bruce16, and four Bruce30 for both samples, which, interestingly, were not identical with the known genotypes in the public MLVA Brucella database. Our findings substantiate that animal Brucellosis remains a health issue in Greece, with a stable but apparent incidence rate, and further investigation is needed to fully characterize the newly identified Brucella strains in Greece.

Molecular typing methods to characterize Brucella spp. from animals: A review

Brucellosis is an infectious disease of animals that can infect humans. The disease causes significant economic losses and threatens human health. A timely and accurate disease diagnosis plays a vital role in the identification of brucellosis. In addition to traditional diagnostic methods, molecular methods allow diagnosis and typing of the causative agent of brucellosis. This review will discuss various methods, such as Bruce-ladder, Suiladder, high-resolution melt analysis, restriction fragment length polymorphism, multilocus sequence typing, multilocus variable-number tandem repeat analysis, and whole-genome sequencing single-nucleotide polymorphism, for the molecular typing of Brucella and discuss their advantages and disadvantages.

An Evaluation of the Lineage of Brucella Isolates in Turkey by a Whole-Genome Single-Nucleotide Polymorphism Analysis

Brucellosis is a disease caused by the Brucella (B.) species. It is a zoonotic disease that affects farm animals and causes economic losses in many countries worldwide. Brucella has the ability to persist in the environment and infect the host at low doses. Thus, it is more important to trace brucellosis outbreaks, identify their sources of infection, and interrupt their transmission. Some countries already have initial data, but most of these data are based on a Multiple-Locus Variable-Number Tandem-Repeat Analysis (MLVA), which is completely unsuitable for studying the Brucella genome. Since brucellosis is an endemic disease in Turkey, this study aimed to examine the genome of Turkish Brucella isolates collected between 2018 and 2020, except for one isolate, which was from 2012. A total of 28 strains of B. melitensis (n = 15) and B. abortus (n = 13) were analyzed using a core-genome single-nucleotide polymorphism (cgSNP) analysis. A potential connection between the Turkish isolates and entries from Sweden, Israel, Syria, Austria, and India for B. melitensis was detected. For B. abortus, there may be potential associations with entries from China. This explains the tight ties found between Brucella strains from neighboring countries and isolates from Turkey. Therefore, it is recommended that strict measures be taken and the possible effects of uncontrolled animal introduction are emphasized.

Phylogenetic Analysis of Brucella melitensis Strains Isolated from Humans Using 16S rRNA Sequencing and Multiple Locus Variable Number of Tandem Repeats Analysis-16

Background: Brucellosis is the most important public health problem worldwide, and the annual incidence of the disease in humans is 2.1 million. The Brucella genome is highly conserved, with over 90% similarity among species. The aim of this study was to perform species-level identification of Brucella spp. strains isolated from humans diagnosed with brucellosis and to further investigate the phylogenetic relationships using multiple locus variable number of tandem repeats analysis (MLVA)-16 and 16S rRNA sequencing analysis. Materials and Methods: Brucella spp. was isolated from the blood cultures of 54 patients who tested positive for brucellosis through serological examinations. Real-time PCR was used to identify the isolates in species, and the genus level of Brucella was confirmed with 16S rRNA. All isolates were subjected to phylogenetic analysis using variable number of tandem repeat analysis with multiple loci. Results: Subsequent analysis via real-time PCR confirmed these isolates to be of the Brucella melitensis species. The 16S rRNA sequence analysis showed 100% homogeneity among the isolates. MLVA revealed the formation of five different genotypic groups. While two groups were formed based on the 16S rRNA sequence analysis, five groups were formed in the MLVA. Conclusions: The study concluded that 16S rRNA sequence analysis alone did not provide sufficient discrimination for phylogenetic analysis but served as a supportive method for identification. MLVA exhibited higher phylogenetic power. The widespread isolation of B. melitensis from human brucellosis cases highlights the importance of controlling brucellosis in small ruminants to prevent human infections.

Investigation of the Proportion of Brucella abortus and Brucella melitensis in Sheep and Goat Milk

Despite the implementation of brucellosis eradication programs in Iran, this disease is still endemic and highly prevalent among ruminants in this country. The infection of small ruminants with Brucella abortus may play a significant role in the continuation of brucellosis among the herds of ruminants. This study investigated the proportion of B. abortus and Brucella melitensis in 150 samples of sheep and goat's raw milk which were obtained from Lorestan and Hamadan provinces in the western part of Iran using the PCR method. The results revealed that among the Brucella spp. positive samples, 26.5% and 73.4% of the samples were infected with B. abortus and B. melitensis, respectively. The incidence rates of B. abortus among the sheep and goats samples were 6.8% and 12.5%, respectively. There was a significant difference between goats and sheep regarding the proportion of B. abortus. Three samples (2%) (2 goats and one sheep) were simultaneously infected with both B. melitensis and B. abortus. This article renews our knowledge about the causative agent of brucellosis in small ruminants and shows that B. abortus has a relatively high prevalence among those animals in the western regions of Iran, and its role as one of the main factors of abortion among small ruminants should not be ignored. The information provided in the present study is important for the surveillance program, as eradication programs and strategies to prevent the spread of B. abortus among small ruminants that have not been vaccinated against this microorganism may be adapted accordingly.

A review of three decades of use of the cattle brucellosis rough vaccine Brucella abortus RB51: myths and facts

Cattle brucellosis is a severe zoonosis of worldwide distribution caused by Brucella abortus and B. melitensis. In some countries with appropriate infrastructure, animal tagging and movement control, eradication was possible through efficient diagnosis and vaccination with B. abortus S19, usually combined with test-and-slaughter (T/S). Although S19 elicits anti-smooth lipopolysaccharide antibodies that may interfere in the differentiation of infected and vaccinated animals (DIVA), this issue is minimized using appropriate S19 vaccination protocols and irrelevant when high-prevalence makes mass vaccination necessary or when eradication requisites are not met. However, S19 has been broadly replaced by vaccine RB51 (a rifampin-resistant rough mutant) as it is widely accepted that is DIVA, safe and as protective as S19. These RB51 properties are critically reviewed here using the evidence accumulated in the last 35 years. Controlled experiments and field evidence shows that RB51 interferes in immunosorbent assays (iELISA, cELISA and others) and in complement fixation, issues accentuated by revaccinating animals previously immunized with RB51 or S19. Moreover, contacts with virulent brucellae elicit anti-smooth lipopolysaccharide antibodies in RB51 vaccinated animals. Thus, accepting that RB51 is truly DIVA results in extended diagnostic confusions and, when combined with T/S, unnecessary over-culling. Studies supporting the safety of RB51 are flawed and, on the contrary, there is solid evidence that RB51 is excreted in milk and abortifacient in pregnant animals, thus being released in abortions and vaginal fluids. These problems are accentuated by the RB51 virulence in humans, lack diagnostic serological tests detecting these infections and RB51 rifampicin resistance. In controlled experiments, protection by RB51 compares unfavorably with S19 and lasts less than four years with no evidence that RB51-revaccination bolsters immunity, and field studies reporting its usefulness are flawed. There is no evidence that RB51 protects cattle against B. melitensis, infection common when raised together with small ruminants. Finally, data acumulated during cattle brucellosis eradication in Spain shows that S19-T/S is far more efficacious than RB51-T/S, which does not differ from T/S alone. We conclude that the assumption that RB51 is DIVA, safe, and efficaceous results from the uncritical repetition of imperfectly examined evidence, and advise against its use.

Brucellosis and One Health: Inherited and Future Challenges

One Health is the collaborative efforts of multiple disciplines to attain optimal health for people, animals and the environment, a concept that historically owes much to the study of brucellosis, including recent political and ethical considerations. Brucellosis One Health actors include Public Health and Veterinary Services, microbiologists, medical and veterinary practitioners and breeders. Brucellosis awareness, and the correct use of diagnostic, epidemiological and prophylactic tools is essential. In brucellosis, One Health implementation faces inherited and new challenges, some aggravated by global warming and the intensification of breeding to meet growing food demands. In endemic scenarios, disease awareness, stakeholder sensitization/engagement and the need to build breeder trust are unresolved issues, all made difficult by the protean characteristics of this zoonosis. Extended infrastructural weaknesses, often accentuated by geography and climate, are critically important. Capacity-building faces misconceptions derived from an uncritical adoption of control/eradication strategies applied in countries with suitable means, and requires additional reference laboratories in endemic areas. Challenges for One Health implementation include the lack of research in species other than cattle and small ruminants, the need for a safer small ruminant vaccine, the need to fill in the infrastructure gap, the need for realistic capacity-building, the creation of reference laboratories in critical areas, and the stepwise implementation of measures not directly transposed from the so-called developed countries.

Molecular epidemiological characteristics of Brucella in Guizhou Province, China, from 2009 to 2021

Introduction

Brucellosis was made statutorily notifiable in 1955, in China, while in Guizhou Province, the pathogen of human brucellosis was isolated for the first time in 2011. However, currently, the brucellosis epidemic is becoming more and more severe in Guizhou Province. The type distribution and genetic characteristics of Brucella in Guizhou Province, as well as its evolutionary relationship with domestic and foreign strains, are still unclear.

Methods

MLST, MLVA, and rpoB typing techniques were used for the molecular epidemiological study of the 83 Brucella isolates in Guizhou province.

Results

Among the 83 Brucella strains, MLST identified three ST genotypes, of which ST39 is a newly reported type in China. MLVA-16 generated 49 genotypes, and MLVA-11 generated 5 known genotypes and 2 unreported genotypes. Six genotypes were identified by rpoB technology.

Discussion

MLVA has a high resolution, but differences at the Bruce 04 and 16 loci cannot exclude associations between epidemics, and combining MLST and rpoB typing methods for epidemiologic tracing can avoid erroneous judgments. Moreover, through the combined analysis of the three typing techniques, the possible origin of the new Brucella can be reasonably inferred, which is also conducive to promoting the subsequent research of the novel Brucella.

Whole-genome sequencing for genetic diversity analysis of Iranian Brucella spp. isolated from humans and livestock

Brucellosis is one of the most common zoonoses in the Middle East. It is causing economic losses to the livestock industry and has a great public health concern. Little is known about the genetic diversity and distribution of brucellae in Iran. Therefore, forty Brucella spp. strains (B. abortus and B. melitensis) isolated from animals and humans were analyzed by whole genome sequencing (WGS) technology using single nucleotide polymorphism (SNP) analysis and core genome multilocus sequence typing (cgMLST). Brucella isolates were obtained from lymph nodes (cows and camels), milk (cows, camels and sheep), and aborted foetus samples (sheep and goats), as well as cerebrospinal fluid and blood of humans. The isolates were originating from thirteen provinces of Iran and isolated between 2015 and 2020. According to in-silico MLST, ST8 and ST2 were the most frequent sequence types in B. melitensis and B. abortus, respectively. Based on phylogeographic reconstruction using cgSNP analysis, the investigated Iranian B. melitensis strains belonged to the American and Mediterranean lineages of the B. melitensis phylogeny. Furthermore, cgSNP analysis revealed a similarity between Iranian B. abortus isolates and strains from Iraq and Egypt. Therefore, the origin of the Iranian strains can be suggested to be strains from neighboring and Middle East countries. Moreover, cgMLST analysis showed that the Iranian B. melitensis strains were closely relative to strains recovered from sheep and humans in Iraq, Afghanistan, Syria, Turkmenistan, and Pakistan. In the current panel of strains, cgMLST and cgSNP analysis provided an appropriate and accurate tool for effective traceback analyses for Brucella spp. from Iran. The results of cgSNP and cgMLST helped to understand the geographic distribution and interspecies transmission of Iranian strains and highlight the importance of specific brucellosis control measures in Iran with regard to the One-Health approach.

Genotyping of Brucella isolates from animals and humans by Multiple-Locus Variable-number Tandem Repeat Analysis (MLVA)

This study investigates country-wide genotype variations through the genotyping of Brucella strains isolated from domestic ruminants and humans. The Brucella spp. isolated from samples taken from animals and humans were first identified as B. abortus and B. melitensis by real-time PCR, and the MLVA-16 approach was then used for the genotyping of the identified isolates. For the study, 416 Brucella spp. were isolated from aborted fetus samples examined between 2018 and 2021, and 74 Brucella spp. from infected humans. Of the 74 human isolates analyzed, 1.3% were identified as B. abortus and 98.7% (73/74) as B. melitensis. The MLVA-16 typing method revealed 30 clonal groups for B. abortus and 37 clonal groups for B. melitensis from which the dominant genotypes and similarities with human isolates in Türkiye were determined.

Original and introduced lineages co-driving the persistence of Brucella abortus circulating in West Africa

Introduction

Brucellosis, a serious public health issue affecting animals and humans, is neglected in West Africa (WA).

Methods

In the present study, bio-typing, multi-locus sequence typing (MLST), multiple-locus variable-number tandem repeat analysis (MLVA), and whole genome sequencing single-nucleotide polymorphism (WGS-SNP) analysis were used to characterize the Brucella abortus (B. abortus) strains from WA.

Results

All of the 309 strains analyzed in this study were extracted and downloaded from the international MLVA bank and were from 10 hosts (cattle, humans, ovine, buffalo, dromedaries, horse, sheep, zebu, dog, and cat) distributed in 17 countries in WA. Based on the bio-typing, three biovars, dominated by B. abortus bv.3, were observed and reported across seven decades (1958–2019). With MLST, 129 B. abortus strains from the present study were sorted into 14 STs, with ST34 as the predicted founder. These 14 STs clustered into the global MLST data into three clone complexes (C I–C III) with the majority of strains clustering in C I, while C II forms an independent branch, and C III harbors three STs shared by different continents. These data revealed that most cases were caused by strains from native lineages. According to the MLVA-11 comparison, 309 strains were divided into 22 MLVA-11 genotypes, 15 of which were unique to WA and the remaining seven had a global distribution. MLVA-16 analysis showed that there were no epidemiological links among these strains. Based on the MLVA data, B. abortus strains from WA have high genetic diversity, and predominated genotypes were descended from a native lineage. While the MLVA-16 globally highlights that the dominant native and few introduced lineages (from Brazil, the USA, South Korea, Argentina, India, Italy, Portugal, the UK, Costa Rica, and China) co-driving the B. abortus ongoing prevalence in WA. The high-resolution SNP analysis implied the existence of introduced B. abortus lineages, which may be reasonably explained by the movement and trade of dominant hosts (cattle) and/or their products.

Discussion

Our results indicated that B. abortus strains in WA consist of native and introduced strains that necessitate control such as vaccination, testing, slaughtering, and movement control by the relevant country authorities to reduce brucellosis in livestock.

Determination of Virulence-Associated Genes and Antimicrobial Resistance Profiles in Brucella Isolates Recovered from Humans and Animals in Iran Using NGS Technology

Brucellosis is a common zoonotic disease in Iran. Antimicrobial-resistant (AMR) Brucella isolates have been reported from different developing countries, posing an imminent health hazard. The objective of this study was to evaluate AMR and virulence-associated factors in Brucella isolates recovered from humans and animals in different regions of Iran using classical phenotyping and next generation sequencing (NGS) technology. Our findings revealed that B. melitensis is the most common species in bovines, small ruminants and camels. B. abortus was isolated only from one human case. Probable intermediate or resistant phenotype patterns for rifampicin, trimethoprim-sulfamethoxazole, ampicillin-sulbactam and colistin were found. Whole genome sequencing (WGS) identified mprF, bepG, bepF, bepC, bepE, and bepD in all isolates but failed to determine other classical AMR genes. Forty-three genes associated with five virulence factors were identified in the genomes of all Brucella isolates, and no difference in the distribution of virulence-associated genes was found. Of them, 27 genes were associated with lipopolysaccharide (LPS), 12 genes were related to a type IV secretion system (virB1-B12), two were associated with the toll-interleukin-1 receptor (TIR) domain-containing proteins (btpA, btpB), one gene encoded the Rab2 interacting conserved protein A (ricA) and one was associated with the production of cyclic β-1,2 glucans (cgs). This is the first investigation reporting the molecular-based AMR and virulence factors in brucellae isolated from different animal hosts and humans in Iran. Iranian B. abortus and B. melitensis isolates are still in vitro susceptible to the majority of antibiotics used for the treatment of human brucellosis. WGS failed to determine classical AMR genes and no difference was found in the distribution of virulence-associated genes in all isolates. Still, the absence of classical AMR genes in genomes of resistant strains is puzzling, and investigation of phenotypic resistance mechanisms at the proteomic and transcriptomic levels is needed.

Tracking the distribution, genetic diversity and lineage of Brucella melitensis recovered from humans and animals in Egypt based on core-genome SNP analysis and in silico MLVA-16

Brucellosis is one of the most common neglected zoonotic diseases globally, with a public health significance and a high economic loss in the livestock industry caused by the bacteria of the genus Brucella. In this study, 136 Egyptian Brucella melitensis strains isolated from animals and humans between 2001 and 2020 were analysed by examining the whole-core-genome single-nucleotide polymorphism (cgSNP) in comparison to the in silico multilocus variable number of tandem repeat analysis (MLVA-16). Almost all Egyptian isolates were belonging to the West Mediterranean clade, except two isolates from buffalo and camel were belonging to the American and East Mediterranean clades, respectively. A significant correlation between the human case of brucellosis and the possible source of infection from animals was found. It seems that several outbreak strains already existing for many years have been spread over long distances and between many governorates. The cgSNP analysis, in combination with epidemiological metadata, allows a better differentiation than the MLVA-16 genotyping method and, hence, the source definition and tracking of outbreak strains. The MLVA based on the currently used 16 markers is not suitable for this task. Our results revealed 99 different cgSNP genotypes with many different outbreak strains, both older and widely distributed ones and rather newly introduced ones as well. This indicates several different incidents and sources of infections, probably by imported animals from other countries to Egypt. Comparing our panel of isolates to public databases by cgSNP analysis, the results revealed near relatives from Italy. Moreover, near relatives from the United States, France, Austria and India were found by in silico MLVA.

Epidemic characteristics and transmission risk prediction of brucellosis in Xi'an city, Northwest China

Human brucellosis (HB) has re-emerged in China since the mid-1990s, and exhibited an apparent geographic expansion shifted from the traditional livestock regions to the inland areas of China. It is often neglected in non-traditional epidemic areas, posing a serious threat to public health in big cities. We carried out a retrospective epidemiological study in Xi'an, the largest city in northwestern China. It utilizes long-term surveillance data on HB during 2008–2021 and investigation data during 2014–2021. A total of 1989 HB cases were reported in Xi'an, consisting of 505 local cases, i.e., those located in Xi'an and 1,484 non-local cases, i.e., those located in other cities. Significantly epidemiological heterogeneity was observed between them, mainly owing to differences in the gender, occupation, diagnostic delays, and reporting institutions. Serological investigations suggested that 59 people and 1,822 animals (sheep, cattle, and cows) tested positive for brucellosis from 2014 to 2021, with the annual average seroprevalence rates were 1.38 and 1.54%, respectively. The annual animal seroprevalence rate was positively correlated with the annual incidence of non-local HB cases. Multivariate boosted regression tree models revealed that gross domestic product, population density, length of township roads, number of farms, and nighttime lights substantially contributed to the spatial distribution of local HB. Approximately 7.84 million people inhabited the potential infection risk zones in Xi'an. Our study highlights the reemergence of HB in non-epidemic areas and provides a baseline for large and medium-sized cities to identify regions, where prevention and control efforts should be prioritized in the future.

Tracking the Distribution of Brucella abortus in Egypt Based on Core Genome SNP Analysis and In Silico MLVA-16

Brucellosis, caused by the bacteria of the genus Brucella, is one of the most neglected common zoonotic diseases globally with a public health significance and a high economic loss among the livestock industry worldwide. Since little is known about the distribution of B. abortus in Egypt, a total of 46 B. abortus isolates recovered between 2012–2020, plus one animal isolate from 2006, were analyzed by examining the whole core genome single nucleotide polymorphism (cgSNP) in comparison to the in silico multilocus variable number of tandem repeat analysis (MLVA). Both cgSNP analysis and MLVA revealed three clusters and one isolate only was distantly related to the others. One cluster identified a rather widely distributed outbreak strain which is repeatedly occurring for at least 16 years with marginal deviations in cgSNP analysis. The other cluster of isolates represents a rather newly introduced outbreak strain. A separate cluster comprised RB51 vaccine related strains, isolated from aborted material. The comparison with MLVA data sets from public databases reveals one near relative from Argentina to the oldest outbreak strain and a related strain from Spain to a newly introduced outbreak strain in Egypt. The distantly related isolate matches with a strain from Portugal in the MLVA profile. Based on cgSNP analysis the oldest outbreak strain clusters with strains from the UK. Compared to the in silico analysis of MLVA, cgSNP analysis using WGS data provides a much higher resolution of genotypes and, when correlated to the associated epidemiological metadata, cgSNP analysis allows the differentiation of outbreaks by defining different outbreak strains. In this respect, MLVA data are error-prone and can lead to incorrect interpretations of outbreak events.

Seroprevalence trend of human brucellosis and MLVA genotyping characteristics of Brucella melitensis in Shaanxi Province, China, during 2008-2020

In this study, a total of 179,907 blood samples from populations with suspected Brucella spp. infections were collected between 2008 and 2020 and analyzed by the Rose Bengal plate test (RBPT) and serum agglutination test (SAT). Moreover, conventional biotyping, B. abortus-melitensis-ovis-suis polymerase chain reaction (AMOS-PCR), and multiple-locus variable-number tandem repeat analysis (MLVA) was applied to characterize the isolated strains. A total of 8103 (4.50%) samples were positive in RBPT, while 7705 (4.28%, 95% confidence interval (CI) 4.19-4.37) samples were positive in SAT. There was a significant difference in seroprevalence for human brucellosis over time, in different areas and different cities (districts) (χ² = 2 = 32.23, 1984.14, and 3749.51, p < .05). The highest seropositivity (8.22% (4, 965/60393; 95% CI 8.00-8.44) was observed in Yulin City, which borders Inner Mongolia, Ningxia, and Gansu Province, China, regions that have a high incidence of human brucellosis. Moreover, 174 Brucella strains were obtained, including nine with B. melitensis bv. 1, 145 with B. melitensis bv. 3, and 20 with B. melitensis variants. After random selection, 132 B. melitensis were further genotyped using MLVA-16. The 132 strains were sorted into 100 MLVA-16 genotypes (GTs) (GT 1-100), 81 of which were single GTs represented by singular independent strains. The remaining 19 shared GTs involved 51 strains, and each GT included two to seven isolates from the Shaan northern and Guanzhong areas. These data indicated that although sporadic cases were a dominant epidemic characteristic of human brucellosis in this province, more than 38.6% (51/132) outbreaks were also found in the Shaan northern area and Guanzhong areas. The 47 shared MLVA-16 GTs were observed in strains (n = 71) from this study and strains (n = 337) from 19 other provinces of China. These data suggest that strains from the northern provinces are a potential source of human brucellosis cases in Shaanxi Province. It is urgent to strengthen the surveillance and control of the trade and transfer of infected sheep among regions.

Whole-Genome Sequencing for Tracing the Genetic Diversity of Brucella abortus and Brucella melitensis Isolated from Livestock in Egypt

Brucellosis is a highly contagious zoonosis that occurs worldwide. Whole-genome sequencing (WGS) has become a widely accepted molecular typing method for outbreak tracing and genomic epidemiology of brucellosis. Twenty-nine Brucella spp. (eight B. abortus biovar 1 and 21 B. melitensis biovar 3) were isolated from lymph nodes, milk, and fetal abomasal contents of infected cattle, buffaloes, sheep, and goats originating from nine districts in Egypt. The isolates were identified by microbiological methods and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Differentiation and genotyping were confirmed using multiplex PCR. Illumina MiSeq^® was used to sequence the 29 Brucella isolates. Using MLST typing, ST11 and ST1 were identified among B. melitensis and B. abortus, respectively. Brucella abortus and B. melitensis isolates were divided into two main clusters (clusters 1 and 2) containing two and nine distinct genotypes by core-genome SNP analysis, respectively. The genotypes were irregularly distributed over time and space in the study area. Both Egyptian B. abortus and B. melitensis isolates proved to be genomically unique upon comparison with publicly available sequencing from strains of neighboring Mediterranean, African, and Asian countries. The antimicrobial resistance mechanism caused by mutations in rpoB, gyrA, and gyrB genes associated with rifampicin and ciprofloxacin resistance were identified. To the best of our knowledge, this is the first study investigating the epidemiology of Brucella isolates from livestock belonging to different localities in Egypt based on whole genome analysis.

Trans-species transmission of Brucellae among ruminants hampering brucellosis control efforts in Egypt

AIMS

This study aimed to identify the genotypic fingerprinting of Brucella melitensis biovar 3 isolates from ruminants in Kafr El-Sheikh, Egypt, to compare with other peers globally and to highlight the epidemiology and potential causes of brucellosis control failure.

METHODS AND RESULTS

A multilocus variable-number tandem-repeat analysis (MLVA 16) was carried out on 41 B. melitensis bv3 isolates, 31 from the preferential hosts (28 sheep and three goats) and 10 from atypical hosts (nine cattle and one buffalo), identified by bacteriological and molecular techniques. MLVA-16 analysis revealed 19 genotypes with nine as singletons. The most prevalent genotypes were M3_K.E (3,5,3,13,1,1,3,3,7,43,8,7,6,7,5,3), M13_K.E (3,5,3,13,1,1,3,3,7,43,8,5,8,7,7,3) and M5_K.E (3,5,3,13,1,1,3,3,7,43,8,4,8,7,11,3) circulating between different animal species. The B. melitensis isolation from aborted cows in farms that had never reared small ruminants indicates the likelihood of cow to cow B. melitensis transmission. Different genotypes of B. melitensis could be isolated from the same animal. The local geographic distribution of genotypes showed a very close genetic relatedness with genotypes reported outside the study area. Worldwide, our genotypes were mostly related to the Western Mediterranean lineage and less likely to the America's clonal lineage.

CONCLUSION

There is a high genetic similarity of B. melitensis bv3 genotypes among different ruminant species, and the same animal could be infected with different genotypes. There is a high probability of spreading of B. melitensis among atypical hosts in the absence of the original hosts. The genetic relatedness of B. melitensis bv3 genotypes in the study area with other different geographic areas highlighted the national and international ruminants movement role as a potential factor for maintaining B. melitensis infection.

SIGNIFICANCE AND IMPACT OF THE STUDY

Further investigations are required to understand the impact of the presence of more than one genotype of B. melitensis in the same animal on the efficacy of brucellosis control strategies.

Emerging diversity and ongoing expansion of the genus Brucella

Remarkable genetic diversity and breadth of host species has been uncovered in the Brucella genus over the past decade, fundamentally changing our concept of what it means to be a Brucella. From ocean fishes and marine mammals, to pond dwelling amphibians, forest foxes, desert rodents, and cave-dwelling bats, Brucella have revealed a variety of previously unknown niches. Classical microbiological techniques have been able to help us classify many of these new strains but at times have limited our ability to see the true relationships among or within species. The closest relatives of Brucella are soil bacteria and the adaptations of Brucella spp. to live intracellularly suggest that the genus has evolved to live in vertebrate hosts. Several recently discovered species appear to have phenotypes that are intermediate between soil bacteria and core Brucella, suggesting that they may represent ancestral traits that were subsequently lost in the traditional species. Remarkably, the broad relationships among Brucella species using a variety of sequence and fragment-based approaches have been upheld when using comparative genomics with whole genomes. Nonetheless, genomes are required for fine-scale resolution of many of the relationships and for understanding the evolutionary history of the genus. We expect that the coming decades will reveal many more hosts and previously unknown diversity in a wide range of environments.

Investigation of Genetic Relatedness of Brucella Strains in Countries Along the Silk Road

In this study, MLVA (multiple-locus variable-number tandem repeat analysis) genotype data of Brucella strains from 11 countries along the Silk Road were downloaded from the MLVAbank. MLVA data of strains were applied to the constructed Minimum Spanning Tree to explore the species/biovars distribution, geographic origins, and genetic relationships of the strains analyzed. Moreover, whole-genome sequencing–single-nucleotide polymorphism (WGS-SNP) phylogenetic analysis of the genome of Brucella melitensis strains from GenBank was performed to discriminate the relatedness of strains further and investigate the transmission pattern of B. melitensis brucellosis. A total of 1,503 Brucella strains were analyzed in this study: 431 Brucella abortus strains (29.8%), 1,009 B. melitensis strains (65.7%), and 63 Brucella suis strains (4.5%). B. melitensis biovar 3 was the dominant species and was shown to be widespread in all of the examined regions, suggesting that the prevention and surveillance of the B. melitensis population are a main challenge in these countries. A wide host spectrum was observed for this Brucella population; many animal reservoirs are a potential reason for the continuous brucellosis circulation in these countries. Although the B. abortus strains from the examined regions had common geographic origins, only a few shared genotypes were observed in different countries. These data revealed that the majority of B. abortus strains were spreading within the national borders. However, the B. melitensis strains from Italy originated from a Western Mediterranean lineage; strains from the other 10 countries originated from Eastern Mediterranean lineage, and this lineage was shared by strains from three to nine different countries, suggesting that the introduction and reintroduction of the disease in the 10 countries might have occurred in the past. Furthermore, the most shared MLVA-16 genotypes were formed in the B. melitensis strains from China, Kazakhstan, and Turkey, suggesting that the introduction and trade in sheep and goats have occurred frequently in these countries. WGS-SNP analysis showed that the B. melitensis in this study originated from the Malta (Italy) region. According to their territorial affiliation between four clade strains from these countries in genotype B, the absence of a clear differentiation suggests that strains continuously expand and spread in countries along with Silk Road. Active exchange and trade of animals (sheep and goats) among these countries are reasonable explanations. B. suis strains from different nations showed unique geographic origins and epidemiological characteristics. Therefore, there is an urgent need for the control of transfer and trade of infected sheep (goats) in countries along the Silk Road, namely, the strengthening of the entry–exit quarantine of sheep and goats and improvements in the diagnosis of animal brucellosis.