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

Abstract

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.

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

“…A similar effect was observed in Shaanxi, where the increased brucellosis incidence was closely related to the development of large-scale small ruminant (goat and sheep) farms in Guanzhong and some southern Shaanxi regions (An et al, 2021). Notably, Yanchi County is located in the easternmost region of Ningxia, adjacent to the Inner Mongolia Autonomous Region, Gansu (Wei et al, 2019), and Shaanxi (An et al, 2022), which are cluster areas of human brucellosis (Yang et al, 2020). Previous studies showed that the highest seropositivity was observed in Yulin City, Shaanxi, which borders regions that have a high incidence of human brucellosis, including Inner Mongolia, Ningxia, and Gansu (An et al, 2022).…”

“…This offers a plausible explanation for why the strains from Yanchi county led to multiple-point outbreaks of human brucellosis. A similar effect was observed in Shaanxi, where the increased brucellosis incidence was closely related to the development of large-scale small ruminant (goat and sheep) farms in Guanzhong and some southern Shaanxi regions (An et al, 2021). Notably, Yanchi County is located in the easternmost region of Ningxia, adjacent to the Inner Mongolia Autonomous Region, Gansu (Wei et al, 2019), and Shaanxi (An et al, 2022), which are cluster areas of human brucellosis (Yang et al, 2020).…”

“…Notably, Yanchi County is located in the easternmost region of Ningxia, adjacent to the Inner Mongolia Autonomous Region, Gansu (Wei et al, 2019), and Shaanxi (An et al, 2022), which are cluster areas of human brucellosis (Yang et al, 2020). Previous studies showed that the highest seropositivity was observed in Yulin City, Shaanxi, which borders regions that have a high incidence of human brucellosis, including Inner Mongolia, Ningxia, and Gansu (An et al, 2022). The high disease burden in this region raises questions about the effectiveness of public health measures.…”

A scoping review on the epidemiology and public significance of Brucella abortus in Chinese dairy cattle and humans

“…Nearly half of the molecular studies (9/21) were conducted in Inner Mongolia, where about half of the Brucella isolates (441/888) were acquired. Notably, one study isolated 174 Brucella strains in Shannxi Province accounting for 19.6% of the total [ 62 ]. B. melitensis represented about three-quarters of the total isolates from both humans and dairy cattle, followed by B. abortus (18.8%).…”

Analysis of the Brucella melitensis epidemic in Xinjiang: Genotyping, polymorphism, antibiotic resistance and tracing

“…This study also downloaded and collected published MLVA typing data from MLVA bank databases (http://mlva.i2bc.paris-saclay.fr/brucella/) and published studies [11][12][13][14][15][16][17][18][19] (Table S2). If multiple data points were available from the same province/site/country, the data for MLVA-16 analysis were chosen in this study.…”