Epidemiological and etiological characteristics of human brucellosis in Arong banner, Hulunbeier, Inner Mongolia Autonomous Region, 2018–2022

Objective To analyze the epidemiological characteristics of brucellosis in Arong banner of Hulunbeier, Inner Mongolia Autonomous Region, from 2018 to 2022, and provide scientific evidence for formulating targeted prevention and control strategies.

Methods A descriptive epidemiological analysis was conducted on the spatiotemporal distribution of human brucellosis in Arong from 2003 to 2022 by using case number and incidence rate. Meanwhile, the pathogen isolation, culture, identification and multiple locus sequence typing (MLST) were carried out.

Results From 2018 to 2022, a total of 1554 cases of human brucellosis were reported in Arong banner, with an average annual incidence rate of 115.13/100 000. The case number and the incidence rate of human brucellosis fluctuated year by year, with the highest case number (466) in 2019, the cases were mainly concentrated in the age of 30 to 55 years old (67.89%);the occupation was mainly farmers (86.81%). The analysis of the data showed that human brucellosis in this area showed obvious seasonality, and farmers aged 30 to 55 years old were more likely to be affected, so targeted monitoring intervention should be carried out. In 2022, brucella was isolated from 9 patients, and the biochemical identification results showed that all the 9 strains were Brucella melitensis, including 2 B.melitensis biovar 1, 4 B.melitensis biovar 2, 2 B.melitensis biovar 3, and 1 strain of variant strain; MLST typing showed that 7 strains were MLST 8, 1 strain was MLST12, and 1 strain had a new sequence type due to gyrB gene mutation.

Conclusion At present, the epidemic of human brucellosis in Arong Banner is still very serious. Due to the lack of knowledge of animal breeding and epidemic prevention, farmers aged 30–55 years old are at high risk of brucellosis infection. We should strengthen the monitoring of brucellosis between human and livestock in this area and the intervention of high-risk groups. At the same time, we should promote the popularization of brucellosis prevention and control knowledge to curb the epidemic of brucellosis.