Exploring the Diversity of Field Strains of Brucella abortus Biovar 3 Isolated in West Africa

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.

Brucellosis in Ethiopia: A comprehensive review of literature from the year 2000-2020 and the way forward

Brucellosis is a zoonotic disease of considerable economic and public health significance globally. Despite the limited bacteriological evidence, a large number of serological works revealed that it is prevalent both in livestock and humans in Ethiopia. The current comprehensive review was carried out to provide apparent pooled seroprevalence (APS) estimates at individual animal and herd levels in livestock, and identify factors causing variability between studies conducted over the last two decades, show the spatial distribution, as well as summarizes Brucella species reported from livestock. It also provides APS of brucellosis in humans and evaluates the public health awareness of zoonotic brucellosis. In this review, systematic and synthetic review approaches were followed to summarize the available information. For the systematic review and meta-analysis, articles were selected based on predefined criteria. Data extracted from these articles were analyzed using meta-analytical approaches to provide APS estimates and in-between study variations for humans and all livestock species considered. Sensitivity analyses and bias assessments were conducted using influence plot analysis and, Egger's and Begg's statistics along with funnel plots, respectively. Synthetic review approaches were used to summarize data on isolates and public health awareness. Pooled seroprevalence estimate of brucellosis at national level was 2.6% (95% CI, 2.2-3.0) in cattle, 4% (95% CI, 3.1-5.1) in goats, 3% (95% CI, 2.3-3.9) in sheep and 3% (95% CI, 2.4-3.7) in camels. At a herd level, 16.3% (95% CI, 12.9, 20.5) of cattle, 12.1% (7.1, 19.9) of goat, 13.3% (7.6, 22.1) of sheep and 19.7% (13.8, 27.4) of camel herds in the country had at least one seropositive animal. Cattle in the pastoral/agropastoral production systems had significantly higher (p < 0.05) APS compared to mixed crop-livestock and urban/peri-urban dairy production systems. Pooled seroprevalence of brucellosis in small ruminants (8.3%, 95% CI, 6.3, 10.8) and camels (4.4%, 95% CI, 3.5, 5.6) in Afar were significantly higher (p<0.05) than in other regions. Reports conducted using ELISA and serial Rose Bengal plate test (RBPT)-ELISA had higher (p<0.05) APS estimates than serial RBPT and complement fixation test. Brucella melitensis and B. abortus were reported from goats and cattle, respectively, from three available reports. The APS of brucellosis in humans was 5% (95% CI: 3.3, 7.3). Public awareness of brucellosis was low (18.4%), while, practices that expose humans to Brucella infection were high. Scenario-based control interventions on regions and production systems using one health approach are suggested. This article is protected by copyright. All rights reserved.

Molecular epidemiology of Brucella species in mixed livestock-human ecosystems in Kenya

Brucellosis, caused by several species of the genus Brucella, is a zoonotic disease that affects humans and animal species worldwide. Information on the Brucella species circulating in different hosts in Kenya is largely unknown, thus limiting the adoption of targeted control strategies. This study was conducted in multi-host livestock populations in Kenya to detect the circulating Brucella species and assess evidence of host-pathogen associations. Serum samples were collected from 228 cattle, 162 goats, 158 sheep, 49 camels, and 257 humans from Narok and Marsabit counties in Kenya. Information on age, location and history of abortion or retained placenta were obtained for sampled livestock. Data on age, gender and location of residence were also collected for human participants. All samples were tested using genus level real-time PCR assays with primers specific for IS711 and bcsp31 targets for the detection of Brucella. All genus positive samples (positive for both targets) were further tested with a speciation assay for AlkB and BMEI1162 targets, specific for B. abortus and B. melitensis, respectively. Samples with adequate quantities aggregating to 577 were also tested with the Rose Bengal Test (RBT). A total of 199 (33.3%) livestock and 99 (38.5%) human samples tested positive for genus Brucella. Animal Brucella PCR positive status was positively predicted by RBT positive results (OR = 8.3, 95% CI 4.0-17.1). Humans aged 21-40 years had higher odds (OR = 2.8, 95% CI 1.2-6.6) of being Brucella PCR positive compared to the other age categories. The data on detection of different Brucella species indicates that B. abortus was detected more often in cattle (OR = 2.3, 95% CI 1.1-4.6) and camels (OR = 2.9, 95% CI 1.3-6.3), while B. melitensis was detected more in sheep (OR = 3.6, 95% CI 2.0-6.7) and goats (OR = 1.7, 95% CI 1.0-3.1). Both B. abortus and B. melitensis DNA were detected in humans and in multiple livestock host species, suggesting cross-transmission of these species among the different hosts. The detection of these two zoonotic Brucella species in humans further underpins the importance of One Health prevention strategies that target multiple host species, especially in the multi-host livestock populations.

Brucella melitensis, a latent "travel bacterium," continual spread and expansion from Northern to Southern China and its relationship to worldwide lineages

Brucellosis caused by Brucella melitensis is considered to be one of the most important zoonotic diseases in China. In this study, Conventional bio-typing, MLVA (multiple locus variable-number tandem repeat analysis), and WGS (whole-genome sequencing)-SNP (single nucleotide polymorphism) were used to study the genetic similarity of B. melitensis in northern and southern China and analyze its relationship with worldwide lineages. Currently, the distribution of species/biovars of B. melitensis has obviously changed, and B. melitensis has become the dominant species in southern regions of China. Strains from the southern had a common geographic origin with strains from the northern. Many MLVA-16 events were shared in the genotypes of the southern and northern strains, suggest that genotypic movement occurred from north to south. Based on WGS-SNP analysis, strains from different provinces were closely related and may have descended from one common ancestor, suggests that the southern strains originated from northern China. These data indicate that B. melitensis is a latent “travel bacterium” that spread and expanded from North China to South China. Moreover, B. melitensis strains from China are also genetically related to strains from other Asian regions (Kazakhstan, Russia, Mongolia, and India). The movement of infected sheep and their products requires control.

Complete Genome Sequencing of 10 Brucella abortus Biovar 3 Strains Isolated from Water Buffalo

Brucellosis is a zoonotic disease that affects both humans and animals. Its distribution is global, concentrated in the Mediterranean area, India, Central Asia, and Latin America. Here, we present a complete genome assembly of 10 Brucella abortus strains isolated from water buffaloes farmed in the Campania region of Italy.