Investigation on natural foci of brucellosis in Qinghai province, 1964−2021

Objective To study the natural foci of brucellosis in Qinghai province and provide basis for prevention and control of brucellosis.

Methods  A total of 108 strains of Brucella were isolated from different areas and hosts in Qinghai province from 1964 to 2021 as the research objects. The biological characteristics of the strains were determined by traditional biological methods and molecular biological methods, and the spatial distribution and change characteristics were analyzed by geographic information system. Multiple locus variable-number tandem repeat analysis（MLVA）-16 genotyping method was used to study the natural pathogenicity of brucellosis in Qinghai Plateau.

Results A total of 108 strains of brucella were collected and distributed in 23 counties and cities, among which the top five counties were Menyuan county, Golmud city, Gonghe county, dulan county and Huangzhong county. There were obvious temporal and spatial differences in the biotypes of brucella in Qinghai province. The biotype of 83 strains of brucella were sheep type 3, accounting for 76.85%. The biotypes were diverse from 1964 to 1988, and only sheep type 3 was isolated from 2013 to 2021, with a single biotype. Sheep type 1 was distributed in dulan county and Gonghe county, sheep type 2 was distributed in Gonghe county, Xinghai county and Tongde county, cattle types 3 and 7 were distributed in Zhiduo county, and pigs types 1 and 2 were distributed in Datong county, zeku county and Tongde county. 108 strains were clustered into 67 MLVA-16 genotypes, 94 strains were 42, 6 strains were 43, 2 strains were 47, 2 strains were 28, 1 strain was 63, 1 strain was 36, 1 strain of brucella was 112 and 1 strain of brucella was 6. There were 20 groups of shared genotypes. The hosts of shared genotype strains No.26, No.27, No.32 and No.64 were human, sheep and yak; the hosts of shared genotype strains No.19 and No.22 were human and rock sheep; the hosts of shared genotype strains No.11 were antelope and rock sheep; the hosts of shared genotype strains No.17 were yak and rock sheep; the hosts of shared genotype strains No.42 were human and Marmota himalayana; and the hosts of shared genotype strains No.38 were 8.

Conclusion The existence of brucellosis in wild animals was a potential hazard to the development of animal husbandry and human life, and the technical system and system of monitoring and early warning of wild animal diseases should be improved.