Spatiotemporal Analysis of Glanders in Brazil

Cross-border surveillance of sheep and goat rabies in Brazil

Since Brazil has the largest territory in South America and borders 10 other countries, rabies control is strategic to prevent cross-border spread. However, prevention and control of rabies in small ruminants is neglected. The present study evaluated the spatiotemporal distribution and temporal trends of rabies in small ruminants in Brazil between 2005 and 2023. Official data on rabies case notifications and the population density of goats and sheep from the Brazilian states were used. Descriptive epidemiology and temporal analyses of high-risk clusters and trends were conducted. Rabies cases were reported in all states, except for the Federal District, Roraima, Amapá, Amazonas, and Rondônia. In sheep, 174 cases were reported, with an emphasis on Paraná (25.29 %), being highest. There were 64 cases in goats, with a highlight on Bahia (37.50 %) and Maranhão (18.75 %). However, Espírito Santo presented the highest incidence risk (IR) for goats and sheep. The highest peaks in IR occurred in 2005, 2006 and 2013. A temporal trend of decreasing goat cases was observed in northeastern Brazil from 2005 to 2023. In sheep, the Northeast region showed a downward trend in rabies cases. Three high-risk clusters were identified: the primary cluster for goats occurred in 2006, and for sheep, between 2005 and 2013. Rabies in small ruminants occurs across all Brazilian regions, with high-risk areas in the Northeast, Southeast, and South, as well as a risk of cross-border transmission. These findings support animal health authorities in strengthening rabies control for small ruminants and reducing the risk of transboundary spread.

Spread analysis of glanders in the state of Piauí, northeastern Brazil

Brazil is strategic in controlling neglected zoonoses, such as glanders, in its territory. Among the Brazilian states, Piauí is a strategic state for the spread of the disease in the country. The present study aimed to evaluate the spatial and temporal distribution of official cases of glanders in Piauí between 2015 and 2022. The glanders cases were located in the municipalities of the north and central-north mesoregions, mainly in Campo Maior, Teresina and Altos. The highest incidence risk (IR) occurred in of Altos (IR = 257.9), Sussuapara (IR = 158.4), and Teresina (IR = 157.7). A primary cluster was formed with a relative risk of 14.88 between 2019 and 2022, encompassing 34 municipalities in the north and central-north regions. In Piauí, glanders is well localized, with the potential for spread across borders. This is the first study demonstrating the distribution of reported cases of glanders in the state of Piauí.

Glanders Diagnosis in an Asymptomatic Mare from Brazil: Insights from Serology, Microbiological Culture, Mass Spectrometry, and Genome Sequencing

This manuscript elucidates the occurrence of glanders in an asymptomatic mare from Brazil presenting positive Burkholderia mallei antibody titers. The diagnosis was established through a multi-pronged approach encompassing microbiological culture, mass spectrometry, and genome sequencing. The outbreak occurred in 2019 in Tatuí, São Paulo, Brazil, and the infected mare, despite displaying no clinical symptoms, had multiple miliary lesions in the liver, as well as intense catarrhal discharge in the trachea. Samples were collected from various organs and subjected to bacterial isolation, molecular detection, and identification. The strain was identified as B. mallei using PCR and confirmed by MALDI-TOF mass spectrometry. Whole-genome sequencing revealed a genome size of 5.51 Mb with a GC content of 65.8%, 5871 genes (including 4 rRNA and 53 tRNA genes), and 5583 coding DNA sequences (CDSs). Additionally, 227 predicted pseudogenes were detected. In silico analysis of different genomic loci that allow for differentiation with Burkholderia pseudomallei confirmed the identity of the isolate as B. mallei, in addition to the characteristic genome size. The BAC 86/19 strain was identified as lineage 3, sublineage 2, which includes other strains from Brazil, India, and Iran. The genome sequencing of this strain provides valuable information that can be used to better understand the pathogen and its epidemiology, as well as to develop diagnostic tools for glanders.

Serological and Bacteriological Surveillance of Glanders Among Horses in Central Region of Iran

Glanders is the oldest and very contagious disease among horses caused by Burkholderia mallei. The disease occurs as a chronic form in horses. Hence, because of the prolonged shedding, numerous horses can potentially get infected by one horse with glanders. Glanders is endemic in Iran and this causes occasional occurrence in horse population of the country. The aim of this study was to determine the incidence of B.mallei infection in horses in two central provinces of Iran. A total of 517 serum samples were collected from stable horses in Tehran and Alborz provinces. Among the studied horses, seven presented fever, anorexia, dyspnea, subcutaneous abscesses, nasal and cutaneous discharges, emaciation, and lymphadenopathy. Nasal and ocular discharges and subcutaneous abscesses were sampled for bacterial culture and PCR. The sera were examined by means of complement fixation test (CFT) and indirect enzyme-linked immunosorbent assay (iELISA). Seropositive cases were further examined by Mallein test. The results derived from the present study indicated that only 1.35% of the studied horses were positive in CFT, iELISA and Mallein test, of which only in 42.85% B.mallei was successfully cultured on blood agar and glycerinated nutrient media and confirmed by PCR. Periodic serological tests along with quarantine can benefit reduction of the occurrence of the disease in horses in Iran.

Molecular detection of Burkholderia mallei in different geographic regions of Brazil

Glanders is a contagious disease of equids caused by the Gram-negative bacterium Burkholderia mallei. In Brazil, the disease is considered to be reemerging and has been expanding, with records of equids with positive serology in most of the federative units. However, there are few reports describing the genotypic detection of the agent. This study demonstrated the detection of B. mallei by species-specific PCR directly from tissues or from bacterial cultures, followed by amplicon sequencing in equids (equines, mules, and asinines) with positive serology for glanders in all five geographic regions of Brazil. The molecular evidence of B. mallei infection in serologically positive equids in this study expands the possibility of strain isolation and the conduction of epidemiological characterizations based on molecular information. The microbiological detection of B. mallei in cultures from nasal and palate swabs, even in equids without clinical manifestations, raises the possibility of environmental elimination of the agent.

Current status of glanders in Brazil: recent advances and challenges

Glanders is an infectious disease that causes serious damage to the equine production chain in countries where it occurs endemically and poses a risk to public health. This study aimed to conduct an integrative review of the advances in the knowledge of glanders in Brazil over the last three decades since its re-emergence. Documentary research was conducted for the period between the years 2000 and 2022. SCOPUS and PUBMED databases were used to search for scientific articles, dissertations, and thesis, in addition to the Brazilian Digital Library of Thesis and Dissertations (BDTD). A total of 41 documents were retrieved, including 12 dissertations, five theses, and 24 scientific articles. The Federal Rural University of Pernambuco (UFRPE) group provided a noteworthy amount of material on this topic (25 documents, four theses, three dissertations, and 18 scientific articles). During this period, ten dissertations, one thesis, and six scientific articles published by other groups in other states of the Federation were also identified. It was concluded that there was a significant number of scientific publications with relevant data on the clinical, epidemiological, pathological, microbiological, serological, and molecular characteristics of glanders disease in Brazil. Additionally, training of human resources regarding this disease led to an increase in the nucleation of research groups, especially in the northeast region of Brazil. Despite significant advances, new research groups and specific funding are still needed for the development of more accurate diagnostic methods, immunizing production, training of veterinarians to recognize the disease, and more robust programs to control and eradicate the disease in Brazil.

Sequencing-Based Genotyping of Pakistani Burkholderia mallei Strains: A Useful Way for Investigating Glanders Outbreaks

Burkholderia (B.) mallei is a host-adapted equine pathogen that causes glanders, a re-emerging zoonotic disease, which is endemic in Pakistan and other developing countries and seriously impacts the global equine movement. Due to globalization, the geographical restriction of diseases vanishes and the lack of awareness of and experience with eradicated diseases in industrialized countries also promotes the re-introduction of infections in these regions. Owing to the high equine population, the Pakistani province Punjab is a potential hotspot where several glanders outbreaks have been seen over last two decades. For determining the genomic diversity of B. mallei in this and other equine-populated prefectures, the genomes of 19 B. mallei strains isolated between 1999 and 2020 in different locations were sequenced and their genotypes were determined. Particularly, for genetically highly homogenous pathogens like B. mallei genotyping techniques require a high discriminatory power for enabling differentiation on the strain level. Thus, core-genome single nucleotide polymorphism (cgSNP) analysis was applied for distinguishing the highly similar strains. Furthermore, a whole-genome sequence-based core genome multi locus sequence typing (cgMLST) scheme, specific to B. mallei, was developed and additionally applied to the data. It was found that B. mallei genotypes in Pakistan persisted over time and space and genotype clusters preferred connection with a time point rather than the place of isolation, probably due to frequent equine movement, which promotes the spread of glanders. The cgMLST approach proved to work in accord with SNP typing and may help to investigate future glanders outbreaks.

Molecular characterization of Burkholderia mallei strains isolated from horses in Brazil (2014-2017)

Glanders is an infectious zoonosis caused by Burkholderia (B.) mallei that mainly affects equids. The objective of this work was to provide additional knowledge on the diversity of the strains circulating in Brazil. Six Burkholderia mallei isolates obtained during necropsies of glanderous horses between 2014 and 2017 in two different states (Pernambuco and Alagoas) were analyzed by polymerase chain reaction-high-resolution melting (PCR-HRM). While four strains (9902 RSC, BM_campo 1, BM_campo 3 and UFAL2) clustered in the L3B2 branch, which already includes the Brazilian 16-2438_BM#8 strain, two strains (BM_campo 2.1 and BM_campo 2.2) clustered within the L3B3sB3 branch, which mostly includes older isolates, from Europe and the Middle East. Whole genome sequencing of two of these strains (UFAL2 and BM_campo 2.1), belonging to different branches, confirmed the HRM typing results and refined the links between the strains, including the description of the L3B3Sb3Gp1SbGp1 genotype, never reported so far for contemporary strains. These results suggest different glanders introduction events in Brazil, including a potential link with strains of European origin, related to colonization or trade.

Geographical and temporal spread of equine rabies in Brazil

In Brazil, the horse is frequently used in cultural activities, sports, and in rural and urban work, implementing the economy in different social classes. Among the diseases in horses with zoonotic potential, rabies has been neglected in the country, increasing the risk of spreading the disease across borders. The present study evaluated the spatiotemporal distribution and temporal trend of rabies in horses in Brazil between 2010 and 2019. During this period, 1290 cases of rabies were detected in horses in Brazil, mainly in the states of São Paulo (21.7%) and Mato Grosso (13.3%). However, Espírito Santo stood out, with an incidence risk (IR) of 139.7 cases of rabies per 100,000 horses. The years 2013 and 2017 had higher peaks of IR for the disease, and the states that contributed to this increase were Mato Grosso, São Paulo, and Espírito Santo. There was no monthly seasonality of the disease among the states. The temporal trend revealed an increase for the northeastern region (Annual Percentage Change [APC]: 8.9%) and for Alagoas State (APC: 26.6%). In the spatiotemporal analysis, three high-risk clusters were formed: (i) cluster A (Relative Risk [RRs]: 6.21), involving only Minas Gerais, between 2017 and 2019; (ii) cluster B (RRs: 6.18), involving only Mato Grosso, between 2011 and 2013; and (iii) cluster C (RRs:4.71), involving the states of Rio de Janeiro and Espírito Santo, between 2010 and 2014. Only the states of Roraima and Amapá had no cases of equine rabies during the study period. Therefore, rabies in horses occurs in all Brazilian regions, with areas at high risk of infection concentrated in the Southeast. However, attention should be directed to the north-eastern and northern states, where notifications were infrequent, with an unknown risk in relation to the spread of rabies to transboundary regions. This is the first study evaluating the interstate distribution of rabies in equine species in regions of Brazil.

Spatiotemporal distribution and temporal trends of brucellosis and tuberculosis in water buffalo (Bubalus bubalis) in Brazil

The buffalo herds in Brazil have been an alternative for increasing the economy in different biomes. For this reason, knowledge of the spatial distribution of diseases of mandatory notification in buffalo herds, such as brucellosis and tuberculosis, is essential to guarantee the quality of exported animal products, as well as assist in strategies of national control and eradication programs. In the present study, we aimed to evaluate the spatiotemporal distribution and temporal trends of brucellosis and tuberculosis in buffalo in Brazilian states between 2012-2019. During this period, 474 cases of brucellosis and 604 cases of tuberculosis were observed in buffalo in Brazil, with no significant differences between the total number of cases and incidence risk. The spatial distribution for the states was mostly heterogeneous, showing similarities of occurrences for both diseases in the south, north, and the states of Minas Gerais and Pernambuco. In the eight years evaluated, tuberculosis showed cyclical variation every 1-2 years; however, for brucellosis, there was a cyclical trend only between 2012-2015, with a significant decrease until 2018. Among Brazilian states, Pará had greater disease case numbers, with 34 % for brucellosis and 40.6 % for tuberculosis. Temporal trend analysis showed an increase for Pernambuco (annual percentage change [APC]: 21.0 [CI = 20.3; 21.8]), Paraná (APC: 27.1 [CI = 5.6; 53.0]), and Santa Catarina (APC: 10.4 [CI = 0.8; 21.0]) for brucellosis, and for tuberculosis, only for Santa Catarina state (APC: 24.1 [CI = 15.5; 33.3]). Spatiotemporally, there were four high-risk brucellosis clusters with a primary cluster, cluster A (relative risk [RRs] = 53.42, P < 0.001), involving the state of Amazonas between 2014-2015. For tuberculosis, there were three states of high risk, with a primary cluster, cluster E (RRs = 28.18, P < 0.001), involving the states of Pará, Roraima, Amazonas, Rondônia, and Acre in 2014. In conclusion, brucellosis and tuberculosis in buffalo in Brazil are heterogeneously distributed, with well-defined regions of high historical risk of infection. Among these regions, the states of Amazonas, Pará, Amapá, and Minas Gerais stand out due to the higher risk of infection for both brucellosis and tuberculosis, alerting Brazilian authorities to the need for disease control actions.

A glycoengineered antigen exploiting a conserved protein O-glycosylation pathway in the Burkholderia genus for detection of glanders infections

We recently described a protein O-glycosylation pathway conserved in all species of the Burkholderia genus that results in the synthesis and incorporation of a trisaccharide glycan to membrane-exported proteins. Here, we exploited this system to construct and evaluate a diagnostic tool for glanders. Burkholderia mallei, the causative agent of glanders, is a highly infectious and fatal zoonotic pathogen that infects horses, mules, donkeys, and occasionally humans. A highly sensitive and specific diagnostic tool is crucial for the control, elimination, and eradication of B. mallei infections. We constructed plasmids carrying synthetic genes encoding a modified, previously unannotated Burkholderia glycoprotein containing three glycosylation sequons fused to the cholera toxin B-subunit. The resulting proteins were glycosylated in the B. cenocepacia K56-2 parental strain, but not in glycosylation-deficient mutants, as determined by SDS-PAGE and fluorescent lectin blots. One of these glycoproteins was used as an antigen in ELISA and western blots to screen a panel of serum samples collected from glanders-infected and healthy horses, which were previously investigated by complement fixation test and indirect ELISA based on a semi-purified fraction of B. mallei. We show that ELISA and western blot assays based on our glycoprotein antigen provide 100% specificity, with a sensitivity greater than 88%. The glycoprotein antigen was recognized by serum samples collected from patients infected with B. pseudomallei, B. mallei, B. multivorans, and B. cenocepacia. Our results indicate that protein O-glycosylation in Burkholderia can be exploited as a biomarker for diagnosis of Burkholderia-associated infections.

Current Advances in Burkholderia Vaccines Development

The genus Burkholderia includes a wide range of Gram-negative bacterial species some of which are pathogenic to humans and other vertebrates. The most pathogenic species are Burkholderia mallei, Burkholderia pseudomallei, and the members of the Burkholderia cepacia complex (Bcc). B. mallei and B. pseudomallei, the cause of glanders and melioidosis, respectively, are considered potential bioweapons. The Bcc comprises a subset of Burkholderia species associated with respiratory infections in people with chronic granulomatous disease and cystic fibrosis. Antimicrobial treatment of Burkholderia infections is difficult due to the intrinsic multidrug antibiotic resistance of these bacteria; prophylactic vaccines provide an attractive alternative to counteract these infections. Although commercial vaccines against Burkholderia infections are still unavailable, substantial progress has been made over recent years in the development of vaccines against B. pseudomallei and B. mallei. This review critically discusses the current advances in vaccine development against B. mallei, B. pseudomallei, and the Bcc.

A genetic variant of Burkholderia mallei detected in Kuwait: Consequences for the PCR diagnosis of glanders

Glanders is a contagious zoonotic disease caused by Burkholderia mallei. Following the detection of glanders positive horses using the OIE complement fixation test, the tissues of two horses were analysed by PCR. While PCR systems targeting the Burkholderia pseudomallei complex gave positive signals, the species-specific PCR systems targeting B. mallei (fliP-IS407A) and B. pseudomallei (orf11)-the OIE recommended targets-resulted in negative signals. However, the presence of B. mallei in these tissues was confirmed with a recently described B. mallei-specific real-time PCR system and genotyping with MLST- and SNP-based methods, performed on the most positive tissue, identified a genotype closely related to B. mallei strains recently isolated in the Middle East. This study leads to recommendations regarding the use of PCR systems for the molecular diagnosis of glanders, especially in regions where the circulating B. mallei strains have not yet been fully genetically characterized.

Development of a microsphere-based immunoassay for the serological detection of glanders in equids

Burkholderia mallei is the etiologic agent of glanders, an infectious disease of solipeds, with renewed scientific interest due to its increasing incidence in different parts of the world. More rapid, sensitive and specific assays are required by laboratories for confirmatory testing of this disease. A microsphere-based immunoassay consisting of beads coated with B. mallei recombinant proteins (BimA, GroEL, Hcp1, and TssB) has been developed for the serological diagnosis of glanders. The proteins' performance was compared with the OIE reference complement fixation test (CFT) and an indirect enzyme-linked immunosorbent assay (iELISA) on a large panel of sera comprised of uninfected horses (n=198) and clinically confirmed cases of glanders from India and Pakistan (n=99). Using Receiver Operating Characteristics (ROC) analysis and adjusting the cutoff levels, Hcp1 (Se=100%, Sp=99.5%) and GroEL (Se= 97%, Sp=99.5%) antigens exhibited the best specificity and sensitivity. Neither Hcp1 and GroEL proteins, nor iELISA reacted with doubtful and positive CFT samples from glanders free countries which further confirmed the false positive reactions seen in CFT.

Serological surveillance and clinical investigation of glanders among indigenous equines in India from 2015 to 2018

Equine glanders is an infectious and notifiable bacterial disease caused by Burkholderia mallei. The disease has been reported in South American, African and Asian countries including India. Here, we present the outcome of glanders serosurveillance carried out between January 2015 and December 2018 to know the status of equine glanders among different states in India. A total of 102,071 equid sera from 299 districts of twenty-one states and one union territory were tested for glanders. Samples were screened with Hcp1 indirect ELISA followed by confirmatory diagnosis by CFT. During this four-year surveillance, a total of 932 glanders-positive cases were detected from 120 districts of 12 states. The study also revealed increasing trend of glanders from 2016 onwards with maximum occurrence in northern India. Overall seroprevalence ranged between 0.62% (95% CI, 0.52-0.72) and 1.145% (95% CI, 1.03-1.25). Seasonal shifting from winter to summer (March to June) coincided with highest number glanders incidence with corresponding seroprevalences of 1.2% (95% CI, 1.09-1.30). The present surveillance unveils territorial ingression of glanders to six states like Jammu & Kashmir, Gujarat, Rajasthan, Madhya Pradesh, Delhi and Tamil Nadu. In addition, re-emerging cases have been reported in Maharashtra, Haryana and Punjab after a gap of 10 years. Lack of awareness, little veterinary care and unrestricted movement of equids across state borders might have led to the introduction and establishment of the infection to these states. We believe that information from this study will provide a baseline data on glanders for devising surveillance and control strategies in India. Being a zoonotic disease, the persistence of glanders poses a potential threat to occupationally exposed humans especially equine handlers and veterinarians. Therefore, targeted surveillance of human population from each glanders outbreak is also recommended.