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

https://www.tandfonline.com/doi/pdf/10.1080/22221751.2020.1788995

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

Hinggan League is located in the Northeast of the Inner Mongolia Autonomous Region, the historically endemic area of animal and human brucellosis In this study, the epidemiological characteristics of human brucellosis were analyzed, and the genotypic profile and antimicrobial susceptibilities of Brucella melitensis strains isolated from humans in Hinggan League were investigated The epidemic characteristics were described using case number, constituent ratio, and rate The 418 human blood samples were collected and tested by bacteriology, and suspect colonies were isolated and identified by conventional biotyping assays, the VITEK 20 microbial identification system, and AMOS (Brucella abortus, B melitensis, B ovis, and B suis)-PCR Subsequently, all strains were genotyped using multiple-locus variable-number tandem repeat analysis (MLVA) assays, and the antimicrobial susceptibility pattern of Brucella strains against the 10 most commonly used antibiotics was determined by microdilution method A total of 22 848 cases of human brucellosis were reported from 2004 to 2019, with an annual average incidence of 872/100 000 The incidence rates in developed areas of animal husbandry (Horqin Youyi Qianqi [1612/100 000] and Horqin Youyi Zhongqi [1121/100 000]) were significantly higher than those in forest areas (Arxan [192/100 000]) (χ2 = 32561, P < 0001) In addition, peak morbidity occurred during May–August, accounting for 726% (16582/22 848) of cases The highest number of cases occurred in the 40+ age group, accounting for 444% (10 137/22484) of cases, and morbidity in males was significantly higher than that in females in all age groups (χ2 = 29997, P < 0001), the most common occupation was farmers A total of 54 B melitensis strains were divided into 37 genotypes (GT1–37) with 80–100% genetic similarity All 25 strains were sensitive to seven tested antibiotics, phenotypic resistance to cotrimoxazole and azithromycin was observed in 5 (20%) and 25 (100%) of the isolates, respectively Human brucellosis exhibited a significant increasing trend and B melitensis is the main pathogen responsible for human brucellosis in this region Improved surveillance of infected animals (sheep) and limiting their transfer and trade are optional strategies for decreasing the incidence of this disease

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Epidemiologically characteristics of human brucellosis and antimicrobial susceptibility pattern of Brucella melitensis in Hinggan League of the Inner Mongolia Autonomous Region, China.

A time-resolved fluorescence lateral flow immunoassay for rapid and quantitative serodiagnosis of Brucella infection in humans.

Background Human brucellosis imposes a heavy burden on the health and economy of endemic regions. Since 2011, China has reported at least 35,000 human brucellosis cases annually, with more than 90% of these cases reported in the northern. Given the alarmingly high incidence and variation in the geographical distribution of human brucellosis cases, there is an urgent need to decipher the causes of such variation in geographical distribution. Method We conducted a retrospective epidemiological study in Shaanxi Province from January 1, 2005 to December 31, 2018 to investigate the association between meteorological factors and transmission of human brucellosis according to differences in geographical distribution and seasonal fluctuation in northwestern China for the first time. Results Human brucellosis cases were mainly distributed in the Shaanbei upland plateau before 2008 and then slowly extended towards the southern region with significant seasonal fluctuation. The results of quasi-Poisson generalized additive mixed model (GAMM) indicated that air temperature, sunshine duration, rainfall, relative humidity, and evaporation with maximum lag time within 7 months played crucial roles in the transmission of human brucellosis with seasonal fluctuation. Compared with the Shaanbei upland plateau, Guanzhong basin had more obvious fluctuations in the occurrence of human brucellosis due to changes in meteorological factors. Additionally, the established GAMM model showed high accuracy in predicting the occurrence of human brucellosis based on the meteorological factors. Conclusion These findings may be used to predict the seasonal fluctuations of human brucellosis and to develop reliable and cost-effective prevention strategies in Shaanxi Province and other areas with similar environmental conditions.

Spatiotemporal expansion of human brucellosis in Shaanxi Province, Northwestern China and model for risk prediction

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.

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

The rate of brucellosis, a zoonotic disease, has rapidly increased in humans brucellosis(HB) in recent years. In 1950–2018, a total of 684,380 HB cases (median 2274/year (interquartile range (IQR) 966–8325)) were reported to the National Infectious Disease Surveillance System in mainland China. The incidence of HB peaked in 2014 (4.32/100,000), and then showed a downward trend; we predict that it will maintain a steady downward trend in 2019–2020. Since 2015, the incidence of HB has shown opposite trends in the north and south of China; rates in the north have fallen and rates in the south have increased. In 2004–2018, the most significant increases in incidence of HB were in Yunnan (IQR 0.002–0.463/100,000), Hubei (IQR 0.000–0.338/100,000), and Guangdong (IQR 0.015–0.350/100,000). The areas where HB occurs have little overlap with areas with high per capita GDP in China. The “high–high” clusters of HB are located in northeastern China (Inner Mongolia, Heilongjiang, Jilin, Liaoning, Ningxia, Shanxi, and Gansu), and the “low–low” clusters of HB are located in southern China (Yunnan, Jiangxi, Shanghai, Guangxi, Guangdong, Zhejiang, Guizhou, and Hunan). In recent years, the incidence of HB in China has been controlled to some extent, but the incidence of HB has increased in southern China, and the disease has spread geographically in China from north to south. Further research is needed to address this change and to continue to explore the relationship between the incidence of HB and relevant factors.

https://www.mdpi.com/1660-4601/17/7/2382/pdf

Epidemiological Characteristics and Spatiotemporal Trend Analysis of Human Brucellosis in China, 1950-2018.

To measure the seroprevalence of high-exposure populations in brucellosis endemic areas and report the outcome and duration of seropositive asymptomatic subjects, we screened 595 family members of shepherds in Jilin Province, China and then followed up 15 seropositive asymptomatic subjects for 18 months. We found that the seropositive rate of 15.5%. Nearly half of seropositive asymptomatic subjects (7/15) developed into brucellosis in the short term; others were still seropositive asymptomatic or had decreased SAT titer in a longer time.

Brucellosis screening and follow-up of seropositive asymptomatic subjects among household members of shepherds in China.

Background Brucellosis is a critical zoonotic disease in the world, it is the non-specific arthralgia that make brucellosis patients easily misdiagnosed as rheumatoid arthritis (RA) in endemic regions. Elevated rheumatoid factor (RF) is an essential indicator of RA, and the RF in brucellosis patients is significantly higher than healthy people. Therefore, this study further explored the distribution of RF and the relevant factors of the RF positivity in brucellosis patients with arthralgia, in order to strengthen the recognition of physicians for brucellosis patients with RF positivity, especially in brucellosis-endemic areas, so as to avoid misdiagnosis and untimely treatment that may lead to malignant outcomes. Methodology and principal findings The medical records of all 572 brucellosis inpatients were collected in the Sixth People's Hospital of Shenyang, China from 2015 to 2016. After excluding 106 patients without arthralgia, 5 patients who unwilling to perform RF testing and 16 patients with diseases that may affect RF, 445 brucellosis inpatients with arthralgia were involved in this retrospective cross-sectional study. 143 (32.1%) patients with RF >10 IU/ml were classified into the RF positive group, with an average level of 16.5[12.2, 34.7] IU/ml, of which 45 (10.1%) patients were high-positive with RF >30 IU/ml. Multivariate logistic regression model was used to further analyze the relevant factors of the RF positivity and found that age, wrist joint pain and elevated C-reactive protein (CRP) were positively associated with RF positivity, with OR of 1.02 (P = 0.024), 8.94 (P = 0.008) and 1.79 (P = 0.019), respectively. Conclusion The prevalence of positive RF in brucellosis patients with arthralgia was critical, nearly one-third of patients had RF positive. Elderly men brucellosis patients with arthralgia, wrist joint pain and elevated CRP were at high risk of positive RF. It is reminded that physicians should focus on differential diagnosis during clinical diagnosis and treatment, especially in brucellosis-endemic regions.

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Prevalence and relevant factors of positive RF in brucellosis patients with arthralgia.

To investigate the risk factors for brucellosis in suspected cases of the disease. A self-designed questionnaire was developed to collect data from 3557 people whose initial visit site was the Songyuan Center for Disease Control and Prevention (CDC) from January 1st, 2009 to December 31st, 2012. After collecting blood samples, a plate agglutination test (PAT) and serum agglutination test (SAT) were used to distinguish the patients with brucellosis from the suspected cases. Sex, occupation (farmers and herdsmen), contact with abortion products, and contact with feces were the main risk factors for brucellosis in the suspected cases (all P < 0.05). No difference existed between the confirmed cases and suspected cases in the demographic characteristics, contact with animals (except swine), contact with substances, or clinical symptoms (except fever). However, the confirmed cases showed significant differences from people without brucellosis in demographic characteristics, contact with animals (except cattle and swine), contact with substances, and clinical symptoms. Suspected cases exhibited significant differences from people without brucellosis in the demographic characteristics (except education), contact with animals (except swine), contact with substances (except dust), and clinical symptoms (except chills and acratia). Brucella was cultured from the blood samples of three of 30 suspected cases with fever. Using AMOS-PCR and agarose electrophoresis, the detailed species of Brucella strain was identified as Brucella melitensis. Abortion products and feces are the main risk factors for brucellosis in suspected cases of the disease. Pyrexia in suspected cases with a history of contact with abortion products or feces should raise suspicion for the disease.

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Jingjing Luo

Papers

Epidemiological Characteristics and Spatiotemporal Trend Analysis of Human Brucellosis in China, 1950-2018.

Brucellosis screening and follow-up of seropositive asymptomatic subjects among household members of shepherds in China.

Prevalence and relevant factors of positive RF in brucellosis patients with arthralgia.

Associated factors in distinguishing patients with brucellosis from suspected cases