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.

Epidemiological changes and molecular characteristics of Brucella strains in Ningxia, China

Objective

Human brucellosis causes serious public health concerns in Ningxia, China.

Methods

This study employed epidemiological, bacteriological, and multiple-locus variable-number tandem repeat analysis (MLVA) methods to conduct an epidemiological investigation, which is necessary for devising tailored control strategies.

Results

Between 1958 and 2022, 29,892 cases were reported, with an average annual number of cases and incidence of 467 and 7.1/100,000, respectively. The epidemic situation gradually worsened, with cases escalating from 26 cases in 2005 to 6,292 in 2022, with the incidence rate rising from 0.441 in 2005 to 86.83 in 2022. Geographically, the disease spread from a single affected county in 2004 to encompass all 22 counties in 2022. Yanchi County had the highest incidence, followed by the Hongsibao and Tongxin counties. These data suggest that Brucella infection has become a rampant regional concern in human brucellosis. Between 1958 and 2019, a total of 230 Brucella strains were identified across four studied hosts. These strains comprised four species with 12 biovars, including B. melitensis bv. 1, bv. 2, bv. 3, B. abortus bv. 1, bv. 3, bv. 4, bv. 5, bv. 6, bv. 7, B. suis bv. 1 and bv. 3, and B. canis. These data highlight the high species/biovars and host diversity of the Brucella population, posing a substantial challenge to brucellosis surveillance. There was an apparent transition from multiple species/biovars historically to the current dominance of a single species, B. melitensis, emphasizing the requirement for strengthening surveillance of B. melitensis. Genotypes 42 and 116, constituting 96.2% of the total number of genotypes, predominated in panel 1 and MLVA-11, indicating that all strains belong to the East Mediterranean lineage. MLVA cluster analysis revealed persistent transmission of dominant circulating genotypes, presenting an epidemic pattern characterized primarily by epidemiologically related cases with a few sporadic cases. Strains in this study exhibited high genetic homogeneity with strains from the Northwest, and those from Kazakhstan and Mongolia.

Conclusion

The epidemic situation of human brucellosis has gradually worsened; the rampant epidemic of the disease has become a regional concern. The present study highlights that implementing the of targeted surveillance and intervention strategies is urge.

Global Estimate of Human Brucellosis Incidence

Brucellosis is a major public health concern worldwide, especially for persons living in resource-limited settings. Historically, an evidence-based estimate of the global annual incidence of human cases has been elusive. We used international public health data to fill this information gap through application of risk metrics to worldwide and regional at-risk populations. We performed estimations using 3 statistical models (weighted average interpolation, bootstrap resampling, and Bayesian inference) and considered missing information. An evidence-based conservative estimate of the annual global incidence is 2.1 million, significantly higher than was previously assumed. Our models indicate Africa and Asia sustain most of the global risk and cases, although areas within the Americas and Europe remain of concern. This study reveals that disease risk and incidence are higher than previously suggested and lie mainly within resource-limited settings. Clarification of both misdiagnosis and underdiagnosis is required because those factors will amplify case estimates.

Exploring risk transfer of human brucellosis in the context of livestock agriculture transition: A case study in Shaanxi, China

With the booming of worldwide agriculture intensification, brucellosis, one of the most neglected zoonotic diseases, has become an increasing challenge for global public health. Although the transmission patterns of human brucellosis (HB) have been studied in many regions, the dynamic transfer processes of risk and its driving factors remain poorly understood, especially in the context of agricultural intensification. This study attempted to explore the risk transfer of HB between the exact epidemic areas and the neighboring or distant low-risk areas to explain the impact of livestock agriculture intensification and foodborne infections on the transmission of HB in Shaanxi Province as a case study. We adopted multiple approaches, including test-based methods, model-based methods, and a geographical detector to detect the spatial-temporal dynamic changes of high-risk epidemic areas of HB at the county scale. We also quantitatively estimated how the related factors drove the risk transfer of the disease. Results confirmed the risk transfer pattern of HB with an expansion from north to south in Shaanxi Province and identified two primary transfer routes. In particular, in the traditional epidemic areas of the Shaanbei plateau, the farm agglomeration effect can significantly increase the risk of HB. Meanwhile, retail outlets for milk and dairy products were partially responsible for the foodborne infections of HB in the emerging epidemic areas of Xi'an. This study not only contributed helpful insights to support HB control and prevention in the rapid transition of livestock agriculture but also provided possible directions for further research on foodborne HB infections in urbanized areas.

Seroepidemiological study of human brucellosis in the Northeast region of Meghalaya, India

Introduction

Brucellosis is a neglected zoonotic disease of major public health concern. In India, the incidence of brucellosis remains vastly underreported due to its non-specific clinical presentation and sub-optimal sensitivity of existing gold standard tests. Studies in Northeast India have shown high incidences of brucellosis in livestock, but the region lacks data on human brucellosis despite its high associated risk. In the present study, we report the seroprevalence of human brucellosis and its associated risk factors in Meghalaya, Northeast India.

Materials and Methods

A prospective observational study was conducted in East Khasi Hills and Ri.Bhoi districts of Meghalaya, from July 2018 to July 2020. A total of 1046 suspected patients with febrile illness along with associated risk factors were recruited through camps and various diagnostic laboratories in the defined region as per the pre.specified inclusion and exclusion criteria. Baseline, demographics, and clinical characteristics were recorded of all the consenting participants. Blood samples were analyzed for brucellosis-specific IgM antibodies through enzyme-linked immunosorbent assay (ELISA).

Results and discussion

The overall seroprevalence of brucellosis was found to be 11.37% in Meghalaya. Among recruited participants, females were found to be more susceptible than males. Risk factors such as consumption of meat were found to be more significantly associated with brucellosis disease in the study region. Among the clinical presentations, pyrexia of unknown origin, myalgia, and chronic fatigue syndrome were found to be significantly associated with brucellosis disease in IgM.positive cases.

Conclusion

Our result suggests further epidemiological investigations for human brucellosis in Northeast India toward improved advocacy for accurate diagnosis, and development of proper response mechanism in areas of high endemicity.

Lateral Flow Immunoassay for Visible Detection of Human Brucellosis Based on Blue Silica Nanoparticles

Brucellosis is a highly contagious zoonosis chronic infectious disease with a strong latent capability to endanger human health and economic development via direct or indirect ways. However, the existing methods for brucellosis diagnosis are time-consuming and expensive as they require a tedious experimental procedure and a sophisticated experimental device and performance. To overcome these defects, it is truly necessary to establish a real-time, on-site, and rapid detection method for human brucellosis. Here, a lateral flow immunoassay (LFIA) with a rapid, sensitive, and alternative diagnostic procedure for human brucellosis with a high degree of accuracy was developed based on blue silica nanoparticles (SiNPs), Staphylococcal protein A (SPA), and surface Lipopolysaccharide of Brucella spp. (LPS), which can be applied for rapid and feasible detection of human brucellosis. To our knowledge, this is the first report that uses blue SiNPs as a signal probe of LFIA for the rapid diagnosis of human brucellosis. The precursor of blue SiNPs@SPA such as colorless SiNPs and blue SiNPs was synthesized at first and then coupled with SPA onto the surface of blue SiNPs by covalent bond to prepare blue SiNPs@SPA as a capture signal to catch the antibody in the brucellosis-positive serum. When SPA was combined with the antibodies in the brucellosis-positive serum, it was captured by LPS on the test line, forming an antigen-antibody sandwich structure, resulting in the T line turning blue. Finally, the results showed that it is acceptable to use blue SiNPs as visible labels of LFIA, and standard brucellosis serum (containing Brucella spp. antibody at 1,000 IU/ml) could be detected at a dilution of 10-5 and the detection limit of this method was 0.01 IU/ml. Moreover, it also demonstrated good specificity and accuracy for the detection of real human serum samples. Above all, the blue SiNPs-based LFIA that we developed provides a rapid, highly accurate, and inexpensive on-site diagnosis of human brucellosis, and shows great promise in clinical diagnostics for other diseases.

Factors Associated With Diagnostic Delays in Human Brucellosis in Tongliao City, Inner Mongolia Autonomous Region, China

The diagnostic delays pose a huge challenge to human brucellosis (HB), which increases the risk of chronicity and complications with a heavy disease burden. This study aimed to quantify and identify the associated factors in the diagnostic delays to its prevention, reduction, and elimination. This study analyzed risk factors associated with the diagnostic delays in a cross-sectional study with data collected from Tongliao City, Inner Mongolia Autonomous Region of China. Diagnostic delays were defined with a cutoff of 30, 60, and 90 days. In different delay groups, risk factors of diagnostic delays were analyzed by univariate analysis and modeled by multivariate logistic regression analysis. A total of 14,506 cases were collected between January 1, 2005, and December 31, 2017, of which the median diagnostic delays was 29 days [interquartile range (IQR): 14–54 days]. Logistic regression analysis indicated that the older age category was associated with longer diagnostic delays across all groups. Longer diagnostic delays increase with age among three delay groups (p for trend <0.001). Occupation as herdsman was associated with shorter diagnostic delays in group 1 with 30 days [adjusted odds ratio (aOR), 0.890 (95% CI 0.804–0.986)]. Diagnostic delays was shorter in patients with brucellosis who were reported in CDC in all delay groups [aOR 0.738 (95% CI 0.690–0.790), 0.539 (95% CI 0.497–0.586), and 0.559 (95% CI 0.504–0.621)]. Pastoral/agricultural area was associated with shorter diagnostic delays in group 1 with 30 days [aOR, 0.889 (95%CI 0.831–0.951)] and group 3 with 90 days [aOR, 0.806 (95%CI 0.727–0.893)]. Stratified analysis showed that the older age category was associated with an increased risk of a long delay in both genders (p < 0.05). The older age group-to-youth group OR increased along with increased delay time (p for trend <0.001). Furthermore, the pastoral/agricultural area was associated with a shorter delay in males (p < 0.05). Delays exist in the diagnosis of HB. We should pay great attention to the risk factors of diagnostic delays, such as older population, non-herdsman, non-pastoral/agricultural area, non-disease prevention, and control agencies. Effective measures should shorten the diagnostic delays, achieve early detection, diagnosis, and treatment, and reduce the risk of HB's chronicity, complications, and economic burden.

The incidence and clinical manifestations of human brucellosis in a referral hospital in Southern Saudi Arabia between 2015 and 2019

We determined the incidence and clinical manifestations of human brucellosis from patients who attended a referral hospital in South of Saudi Arabia. A record-based retrospective study was conducted from January 2015 to December 2019 at King Abdulla Hospital, Bisha, Saudi Arabia. Information on patients' demographic characteristics, detailed records of signs and symptoms, and the laboratory findings were reviewed. Of 6,586 patients included, 15.8% (n = 1,041) were infected with brucellosis. The age of infected individuals ranged from five to 95 years, with an average of 35.1 ± 21.2 years. Most infected patients were male (72.3%). Young adults (26-44 years) were the most common age group with the disease (34.1%). The annual rate of infection significantly decreased (P < 0.0001) from 33.2% in 2015 to 12.5% in 2019. An escalating number of brucellosis cases was seen in the spring and peaked during the summer. Fever (35.3%), joint pain (25.5%), generalized body ache (10.7%), and neurological symptoms (10.0%) were the most frequent clinical manifestation associated with brucellosis. Joint pain was commonly found among children (44.4%). Neurological findings were more frequent among adult patients. The study concluded that brucellosis is endemic in Southern Saudi Arabia and needs local health authority to implement preventive and educational program measures. Infected patients may present with diverse, nonspecific clinical manifestations that require intuition from clinicians to detect the disease.

Different Clinical Manifestations of Human Brucellosis in Pregnant Women: A Systematic Scoping Review of 521 Cases from 10 Countries

Introduction

This systematic scoping review aims to assess the frequency and severity of clinical manifestations of pregnant women with brucellosis.

Methods

Three literature databases, PubMed, Web of Science and China National Knowledge Infrastructure (CNKI), and two search engines (Google and Yahoo) were adopted to identify the relevant articles that published until 31 December 2019. Two investigators independently screened the publications and extracted the data; the case reports and case series which described at least two symptoms or clinical manifestations of pregnant women with brucellosis were included.

Results

A total of 27 articles describing the information of 521 pregnant women with brucellosis were included. Serum agglutination test was the most common laboratory test in the diagnosis of brucellosis. A total of 36 clinical manifestations were extracted from the included articles, and the most common clinical manifestations were fever (400, 76.8%), joint pain/swelling/arthralgia (389, 74.7%), sweats (382, 73.3%), fatigue/asthenia/weakness (262, 50.3%) and back pain (189, 36.3%). Among the 32 included individual cases that with available obstetric outcome information, 10 (31.3%) suffered preterm delivery, 12 (37.5%) had an abortion and 3 (9.8%) had intrauterine fetal death.

Conclusion

Brucellosis is popular and threatening for pregnant women. Regarding the localized body system complications, osteoarticular system was mostly involved, the obstetrics outcomes were severe among pregnant women with brucellosis. The detailed clinical and epidemiological characteristics in this scoping review may add a better and more complete understanding of the disease for both physicians and policy-makers, and provide evidence for timely diagnosis, adequate therapy and better prevention.

Analysis of the Epidemiological, Clinical Characteristics, Treatment and Prognosis of Human Brucellosis During 2014-2018 in Huludao, China

Purpose

To describe the incidence trend, demographic and clinical characteristics, treatment and prognosis, epidemiological history and risk factors of human brucellosis in Huludao, China.

Patients and Methods

A total of 1887 brucellosis patients were reported in Huludao, China from January, 2014 to December, 2018 and the case questionnaires from 1149 patients were collected from Huludao Municipal Center for Disease Control and Prevention. Demographic characteristics of the patients and the information relating to the patients' clinical manifestations, diagnosis, treatment and prognosis were collected and analyzed.

Results

The number of annually reported brucellosis patients has dropped from 711 to 187 during the study period, with the incidence decreased from 27.31/100,000 in 2014 to 7.15/100,000 in 2018. A total of 1149 individual data were collected, with a mean age of 49.59±13.14 years and 75.7% were male. Patients aged more than 60 years were more likely to have arthralgia/myalgia than the other age groups, and patients who had an enlarged spleen in male were more than female (P<0.05). There were more acute brucellosis cases, less sub-acute and chronic brucellosis cases in the ethnic minority (83.6%, 5.5% and 11.0%, respectively) than that in the Han nationality (64.7%, 22.2% and 13.0%, respectively, P<0.05). For antibiotic therapy, "Doxycycline plus rifampicin or streptomycin" was the most commonly used drug combination. Sheep/goat was the main contacted animal and feeding/grazing was the most frequent transmission route; no personal protective measures were the major risk factor.

Conclusion

The incidence of human brucellosis is still high in Huludao, China, and this is mostly associated with contacting with domestic animals and barely taking protective measures. The most common clinical manifestations of brucellosis patients in Huludao were fatigue, hyperhidrosis, fever, and arthralgia/myalgia, the most common route of exposure was feeding and grazing, and the major species of livestock was sheep/goat. The most commonly adopted treatment option was antibiotic therapy, and most patients responded well to treatment. The integrality and accuracy of the notifiable epidemiological case questionnaire needs to be improved in order to provide more factual and objective information for both the physicians and policy-makers.

Epidemiological features of human brucellosis in Tongliao City, Inner Mongolia province, China: a cross-sectional study over an 11-year period (2007-2017)

OBJECTIVES

To describe the epidemiology of human brucellosis in the past decade and provide evidence of disease control in Tongliao city, which is one of the highest-risk areas of human brucellosis in Inner Mongolia province, China.

DESIGN

Cross-sectional study.

PARTICIPANTS

Clinically and bacteriologically confirmed human brucellosis cases.

PRIMARY AND SECONDARY OUTCOME MEASURES

An analysis of the reported cases of human brucellosis during 2007-2017 was carried out to describe the age, sex and occupational distributions of the cases. The time series analysis model and the geographical information system were explored to describe the seasonality and spatiotemporal distribution, respectively, at the county level.

RESULTS

A total of 13 938 cases of human brucellosis was collected in Tongliao from 2007 to 2017; the majority was aged 25 years to 59 years (85.4%) and the male-to-female ratio was 2.64:1; most of them were agriculturalists (81.9%) and pastoralists (12.4%). The incidence rates increased dramatically from 9.22/100 000 in 2007 to 69.16/100 000 in 2011 with an annual increase of 14.99%. They decreased during 2012-2016 (annual decrease of 8.37%) and rose again in 2017 (44.32/100 000). The disease peaked during March-July, with a clear periodicity and trend of monthly anterior displacement since 2012. Jarud Banner, the region located in the north-west of Tongliao, had the highest accumulated incidence rate (130.1/100 000) compared with other counties. The high-risk regions were spread from the north-west to the south and east of Tongliao during the past decade.

CONCLUSIONS

The prevalence of human brucellosis in Tongliao was aggravated during the past decade and peaked during March-July. High-risk areas were mainly concentrated in the counties with extensive prairies and livestock.

Laboratory Diagnosis of Human Brucellosis

The clinical presentation of brucellosis in humans is variable and unspecific, and thus, laboratory corroboration of the diagnosis is essential for the patient's proper treatment. The diagnosis of brucellar infections can be made by culture, serological tests, and nucleic acid amplification assays. Modern automated blood culture systems enable detection of acute cases of brucellosis within the routine 5- to 7-day incubation protocol employed in clinical microbiology laboratories, although a longer incubation and performance of blind subcultures may be needed for protracted cases. Serological tests, though they lack specificity and provide results that may be difficult to interpret in individuals repeatedly exposed to Brucella organisms, nevertheless remain a diagnostic cornerstone in resource-poor countries. Nucleic acid amplification assays combine exquisite sensitivity, specificity, and safety and enable rapid diagnosis of the disease. However, long-term persistence of positive molecular test results in patients that have apparently fully recovered is common and has unclear clinical significance and therapeutic implications. Therefore, as long as there are no sufficiently validated commercial tests or studies that demonstrate an adequate interlaboratory reproducibility of the different homemade PCR assays, cultures and serological methods will remain the primary tools for the diagnosis and posttherapeutic follow-up of human brucellosis.

Acute Febrile Illness Caused by Brucella abortus Infection in Humans in Pakistan

Brucellosis is a zoonosis of great and worldwide public health concern that can cause a severe febrile illness in humans. In Pakistan, brucellosis is a critical problem in both animals and humans. This study aimed to gain insight into its prevalence and to analyze the potential risk factors of patients with acute febrile illness (AFI) of an unknown cause, at the hospitals of Rawalpindi and Islamabad in Pakistan. In total, 446 blood samples were collected from patients and screened for brucellosis using the Rose Bengal Plat Test (RBPT). All the serum samples were investigated for Brucella DNA using specific real-time PCR. Age, sex, occupation, urbanicity, socioeconomic status and history of animal contact were recorded and assessed as potential risk factors. The proportion of acute febrile illness patients for whom brucellosis could be suspected was 10.1% by the RBPT. Brucella DNA was detected in 26 (5.8%) cases and identified as B. abortus. Contact with infected animals, consumption of raw milk and socioeconomic status showed a highly significant (p < 0.05) correlation with seropositivity. Elderly patients (19.7% RBPT and 12.1% PCR) and females (13% RBPT and 9.3% PCR) were of high risk of brucellosis. Patients suffering from brucellosis-related manifestations should be screened for brucellosis, especially those in contact with animals or those consuming their unprocessed products, given the increased risk. The results of this study, which highlight that Brucella abortus as an important cause of acute febrile illnesses in humans, aid the development of effective control strategies for human brucellosis in Pakistan.

A comparison of three data mining time series models in prediction of monthly brucellosis surveillance data

The early and accurately detection of brucellosis incidence change is of great importance for implementing brucellosis prevention strategic health planning. The present study investigated and compared the performance of the three data mining techniques, random forest (RF), support vector machine (SVM) and multivariate adaptive regression splines (MARSs), in time series modelling and predicting of monthly brucellosis data from 2005 (March/April) to 2017 (February/March) extracted from a national public health surveillance system in Hamadan located in west of Iran. The performances were compared based on the root mean square errors, mean absolute errors, determination coefficient (R² ) and intraclass correlation coefficient criteria. Results indicated that the RF model outperformed the SVM and MARS models in modeling used data and it can be utilized successfully utilized to diagnose the behaviour of brucellosis over time. Further research with application of such novel time series models in practice provides the most appropriate method in the control and prevention of future outbreaks for the epidemiologist.

Outbreak of Occupational Brucellosis at a Pharmaceutical Factory in Southeast China

Brucellosis is an occupational disease affecting workers in butcher shops, the milking and dairy product industry, causing more than 500 000 new cases around the world. As a national statutory B infectious disease in China, morbidity of brucellosis is rapidly increasing in recent years. We report an occupational outbreak of brucellosis infection in a pharmaceutical factory. Exposure was a result of manual operation in the process line, close contact with sheep placentas, insufficient disinfection and repeated using of protective suits and infected by aerosol dissemination. Improved preventive methods, appropriate public health measures and spread of health education would be helpful to prevent the occupational outbreak of brucellosis in future.

Human brucellosis mimicking axial spondyloarthritis: a challenge for rheumatologists when applying the 2009 ASAS criteria

Although the development of the 2009 SpA classification criteria by Assessment of SpondyloArthritis international Society (ASAS) represents an important step towards a better definition of the early disease stage particularly in axial spondyloarthritis (axSpA), the specificity of the criteria has been criticized these days. As the commonest zoonotic infection worldwide, human brucellosis can mimic a large number of diseases, including SpA. This study was performed to determine the frequency of rheumatologic manifestations in patients with brucellosis and the chance of misdiagnosing them as having axSpA in central China. The results showed that clinical manifestations of axSpA could be observed in brucellosis. Over half of patients had back pain, and one fifth of the patients with back pain were less than 45 years old at onset and had the symptom for more than 3 months. Two young males were falsely classified as suffering from axSpA according to the ASAS criteria, and one with MRI proved sacroiliitis was once given Etanercept for treatment. Therefore, differential diagnosis including human brucellosis should always be kept in mind when applying the ASAS criteria, even in traditionally non-endemic areas.

Isolation and Identification of Brucella melitensis Biovar 3 from Vaccinated Small Ruminants: A Public Health Threat in Kosovo

In 2011, a human brucellosis case with severe clinical symptoms was reported at the University Clinic for Infectious Diseases in Prishtina, Kosovo. A trace-back investigation was conducted to find the source of human infection. A total of 49 blood samples and 15 corresponding milk samples from sheep and goats raised on the patient's farm were taken for serological and molecular analysis. Serology using RBT and CFT revealed 11 positive animals. Twelve milk samples were PCR positive. A Brucella strain isolated from a goat's milk sample was classified as Brucella melitensis biovar 3, indicating the first ever isolation and report in Kosovo. The use of the Bruce-ladder PCR provided differentiation between the field strain and the vaccine strain. Hence, the accidental transmission of the vaccine strain Rev 1 that was previously used for the vaccination of the farm animals could be excluded. The findings of this study show that brucellosis is still a public health threat in Kosovo despite control measures.

The Prevalence of Brucellosis in Cattle, Goats and Humans in Rural Uganda: A Comparative Study

A cross-sectional study was conducted to determine the presence of brucellosis in cattle, goats and humans in farms from south-western Uganda and identify risk factors associated with brucellosis in these three host groups. Data and serum samples were collected from 768 cattle, 315 goats and 236 humans, with 635 samples of bovine milk, from 70 farms in two different study areas in south-western Uganda. Sera from livestock were tested with the Rose Bengal Plate test, using B. abortus and B. melitensis antigens, and human sera were tested with a commercial IgG/IgM lateral flow assay. Milk samples were tested using the OIE-approved milk ring test. Screening tests for brucellosis were positive in 14% of cattle serum, 29% of bovine milk, 17% of goat serum and 11% of human serum samples. There were significant differences in the test prevalence of brucellosis by study site, with levels higher in the study area near Lake Mburo National Park than in the study area near Queen Elizabeth National Park. Multivariable regression models identified risk factors associated with increasing test positivity at the individual and farm levels for cattle, goats and humans. Positive associations were seen between increasing seropositivity of brucellosis in goats, cattle and humans. Results of multivariable analyses suggest that improvements in farm biosecurity and hygiene may reduce the risk of brucellosis on the farm and suggest a role for ticks in bovine brucellosis. Although cattle are the focus of brucellosis control in Uganda, the significant associations between seropositivity in humans and seropositivity in goats suggest that brucellosis in goats may be an important contributor to the epidemiology of the disease on the farm.

Seroepidemiological survey of human brucellosis in and around Ludhiana, India

Studies have been done on public health significance of brucellosis using serology with little or no emphasis to risk factors. Therefore, this study was designed to investigate seroprevalence of brucellosis and assess epidemiological variables associated with human brucellosis. After obtaining verbal consent, 241 peripheral blood samples were collected from occupationally exposed groups with and without pyrexia of unknown origin. A structured questionnaire was prepared to gather risk factors, such as occupation, age, sex, history of consuming raw milk and other unpasteurised dairy products, direct contact with domestic animals, general knowledge about the route of transmission and awareness level. Purposive sampling was used to select the key informants. All serum samples were first screened by Rose Bengal Plate Test (RBPT) and further analysed by Standard Tube Agglutination Test (STAT). The results revealed that 24.5% were positive by RBPT and diagnosis was established in 26.6% using STAT with a titre range between 80 and 1,280 IU/ml. Among occupational groups, prevalence was 17.8% in veterinarians and pharmacists but was not statistically significant. The most common clinical symptoms at presentation were fever, headache, back pain, arthralgia and myalgia. No female reactor was found and the mean age and standard deviation of seropositive patients was 34.69±10.97 years. Risk factors such as residence in rural area, participation in vaccination of animals and eating during working hours were significantly associated (P<0.05) with brucellosis by univariate and multivariate analysis. In conclusion, to deal with occupation-related disease like brucellosis, awareness on risk factors must be part of extension education campaign. Besides, regular surveillance of the disease needs to be integrated into control and prevention programme at a local and national level.

Polymerase chain reaction (PCR) assay for rapid diagnosis and its role in prevention of human brucellosis in Punjab, India

OBJECTIVES

Brucellosis is the most common zoonotic disease that has been diagnosed mainly by serological tests and blood culture to some extent. This study was designed to establish a PCR technique for rapid diagnosis to be used in surveillance activities.

METHODS

The purpose of this study was firstly explained to the study population and verbal consent was obtained before sample collection. Peripheral blood was collected from 116 occupationally exposed groups with and without pyrexia of unknown origin from various districts of Punjab. Samples were subjected to blood culture, serological tests and DNA extraction was done using conventional laboratory extraction procedure. A primer pair B4/B5 that amplifies a gene encoding a 31 kDa immunogenic outer membrane protein (bcsp31) of Brucella species was used for PCR amplification.

RESULTS

The results showed that 8 (7%) of the cases had positive PCR and the detection threshold of primers used in this study were 715 cfu/ml. PCR results were 51.3% accurate for sensitivity of 12.6% and specificity of 100% using STAT as gold standard.

CONCLUSIONS

Early-case reporting is possible by rapid tests like PCR. Thus, PCR is a promising diagnostic tool for routine investigation and surveillance of brucellosis which is the key element for management of prevention and control programmes. But patient condition before testing, optimal clinical specimen, sample volume used, simple and efficient DNA extraction protocol are the points of concern for PCR to be used as a routine test in clinical laboratory practice.

TNFA promoter polymorphism and susceptibility to brucellosis

The aim of this study was to investigate the possible influence of the tumor necrosis factor alpha (TNFA) gene promoter polymorphisms and HLA class II genes on the susceptibility to or development of human brucellosis. TNFA genotypes (at positions -308 and -238) were determined in 59 patients with brucellosis and 160 healthy controls by polymerase chain reaction-restriction fragment length polymorphism. There were no significant differences between the patients and the controls for the TNFA-238 genotypes. However, when the overall TNFA-308 genotype distribution of the brucella patients was compared with that of the control subjects, a significant skewing was observed (P = 0.02). The TNFA-308.1/2 genotype was present at significantly higher frequency in the total patient as a whole compared with control subjects (30% versus 15%; P = 0.01, odds ratio (OR) 2.49, 95% confidence interval (CI) 1.16-5.33). No statistically significant differences in the distribution of HLA-DRB1 or DQB1 alleles were observed between brucella patients and control subjects. Stratification to correct for interdependence of TNFA-308.2 and HLA-DR3 alleles confirmed that, in spite of their strong linkage disequilibrium, the association of TNFA-308.2 with brucellosis was independent of HLA-DR3.