China CDC Weekly Preplanned Studies Serological Prevalence Survey Among the High-Risk Populations of Brucellosis-Endemic Areas — China, 2019−2020 Shenghong Lin1; Zhe Wang1,2; Xinrong Liu3; Aizhi Yu4; Muhtar·Hasan5; Jiensi·Bayidawulieti6; Haitan·Aximujiang6; Ruiqing Li7; Guoxing Zheng7; Xinwang Liang8; Xiaoling Fan8; Biqiao Hou9; Xiaolong Fan9; Dilxat·Abuliti4; Lusha Shi1; Cuihong Zhang1; Yifei Wang1; Pengjing Ning1; Caixiong Liu1; Zhongjie Li1; Liping Wang1,# Ministry of Agriculture of China and the National Summary Health Commission (NHC) and has begun being What is already known about this topic? implemented for more than 3 years (4). The purpose Timely screening of high-risk population is important of this study was to investigate the seroprevalence of to improve the early detection of brucellosis among the different high-risk occupational populations in endemic areas during the high incidence seasons, which brucellosis-endemic areas in China from 2019 to 2020 is also required by the National Brucellosis Prevention and to understand the seroprevalence of the different and Control Plan (2016–2020) (NBPCP). seasons. A cross-sectional study using an interviewed- What is added by this report? based survey was conducted in 4 total counties Seroepidemiological characteristics of brucellosis in including 3 counties (Yanggao County, Zuoyun high-risk populations were obtained and special County, and Hunyuan County) in Datong City of occupational populations were found. The Shanxi Province and 1 county (Huocheng County) in seroprevalence of brucellosis has been decreasing Yili District of Xinjiang Uygur Autonomous Region compared with that reported in the recent years due to from December 2019 to July 2020. China CDC the ongoing implementation of control measures in designed the protocol and implemented relevant endemic areas. training for local CDCs, including administering What are the implications for public health questionnaires, sampling, and testing, etc. Written practice? informed consent was obtained with face-to-face Special occupational populations could be promptly interviews before the formal inquiry, and the blood detected using routine screening, which makes it samples were collected by the staff of the county possible to initiate standardized treatment for infected CDCs. The participants were aged 18 years and above patients as early as possible. It also reminds us to pay and were working in livestock breeding, livestock attention to special occupational populations to products production and processing, as veterinarians, improve their knowledge of brucellosis and reduce the etc. The sample size is estimated according to the risk of infection. simple random sampling in the cross-sectional survey, the allowable error is 0.15p (p is the expected infection Brucellosis is a worldwide zoonotic disease with fever rate,based on other studies, p was at 7%.), and the and fatigue caused by gram-negative coccobacilli of the non-response rate is 10%. The total sample size is genus Brucella (1). Human brucellosis is usually linked initially determined to be 2,400 people, and the sample to direct contact with infected livestock or ingestion of size for each county is 600 people. unpasteurized dairy products of infected animals (2). A questionnaire was used to collect epidemiological Human brucellosis is still a severe public health data associated with brucellosis, and a blood sample challenge in most low-income and middle-income was drawn from each participant. Seropositivity was areas (1). Since the 1990s, the incidence of brucellosis defined with serum standard tube agglutination test has been increasing and reached a peak in 2014 and (SAT) approach with titer ≥ 1∶100 (+ +) or ≥1∶50 ranked in the top 10 most prevalent diseases among (+ +) if the course of disease onset lasted more than 1 the Class A and Class B infectious disease from 2008 year according to the Standard for Brucellosis to 2018 (3). To control brucellosis effectively, the Diagnosis issued by the NHC in 2019 (5). Statistical National Brucellosis Prevention and Control Plan analyses were conducted with R software (version (2016–2020) (NBPCP) was formulated by the 4.0.2, R Foundation for Statistical Computing, Chinese Center for Disease Control and Prevention CCDC Weekly / Vol. 3 / No. 6 101 China CDC Weekly Austria), and χ2 test with a significance level of significantly lower than the seroprevalence of α=0.05 was used to test the difference in proportion. brucellosis in Shanxi from 2013 to 2016 (6.15%)(6). A total of 2,411 participants were surveyed in this The seroprevalence of brucellosis among people with study, 2,384 of them completed the questionnaire and high-risk occupations in Xinjiang from 2019 to 2020 participated in blood collection, and the effective was 1.68%, which was significantly lower than the response rate was 98.88% (2,384/2,411). Of them, seroprevalence of brucellosis in Xinjiang from 2012 to 1,405 were males (58.93%) and 979 were females 2015 (16.86%)(7). All these achievements benefitted (41.07%), and the seroprevalence of brucellosis was from early screening of high-risk populations, health 3.06% among males and 1.94% among females. The education, and behavioral interventions. The seroprevalence among males (3.73%) was higher than agriculture departments also improved livestock that among females (1.95%) in Shanxi, and the vaccination and strengthened animal quarantining. At differences were significant (P<0.05). The median age the same time, the implementation of NBPCP has of high-risk populations was 54.5 years (range: 18–91), achieved good results. and the 36–59 age group contained the largest number The seroprevalence of brucellosis in Shanxi was of participants (49.54%). The seroprevalence in 18–35 2.91%, and that in Xinjiang was 1.68%, but there was age group (4.69%) was higher than that in the 36–59 no significant difference brtween them (P>0.05). These age group (1.04%) in Xinjiang, and the differences may be due to 2 reasons: 1) differing methods of were significant (P<0.05). For education level, only livestock breeding between the 2 PLADs; and 2) the 8.93% of participants had senior high school education poor knowledge of human brucellosis and the lack of or above, and the seroprevalence of brucellosis of this utilization of personal protective equipment (PPE), group was 3.76%, among which 2 participants with which was concurrently reported by Wang Z et al (8). special occupation were brucellosis seropositive (one The cohabitation between humans and their livestock was part of a local poverty-alleviation cadre in Shanxi was identified among some families during the field and the other was a rural teacher in Xinjiang) survey in Shanxi, which increased the risk of brucellosis (Table 1). transmission. The 62 participants were seropositive for Brucella Screening of high-risk populations can facilitate infection, the crude seroprevalence of brucellosis was early disease detection to provide better disease 2.60% (62/2,384), and that of Shanxi and Xinjiang incidence estimates and reduce disease complications. was 2.91% (52/1,787) and 1.68% (10/597), In this study, two special participants were identified respectively. Of the 62 seropositive individuals, 20 had among brucellosis patients, including a rural teacher ever been diagnosed with human brucellosis before and a member of the poverty-alleviation cadre. There 2019. However, when screening high-risk groups of may be two main reasons: 1) they were relatively young brucellosis, they were still seropositive for brucellosis. and came from areas where brucellosis is not endemic The seroprevalence in fall-winter and spring-summer and had no knowledge of human brucellosis; 2) they seasons were respectively 1.71% (20/1,167) and 3.45% have low awareness of brucellosis or do not know how (42/1,217) respectively and the differences were to use PPE correctly. The health education and significant (P<0.05). The serological prevalence of behavior intervention measures are vital to individuals high-risk occupational population in the spring- who are undertaking national or local poverty- summer season was higher than that in fall-winter, alleviation missions, including township or village with the same status in Shanxi province and Xinjiang officials and teachers, to properly use PPE when they uygur autonomous region (Table 2). are exposed to risk environments or engaged in high- risk occupations. DISCUSSION Considering the epidemiological characteristics of human brucellosis, the study was conducted in the fall- This study was conducted in 2 provincial-level winter 2019 and spring-summer 2020. The results administrative divisions (PLADs) with high incidence indicated that the related occupational populations had of brucellosis from 2019 to 2020. Serological a higher risk of infection during spring and summer characteristics of high-risk populations were obtained because this period is the peak lambing periods for and analyzed. In this study, the seroprevalence of cattle, sheep, and other livestock, and 90% of human brucellosis among people with high-risk occupations in brucellosis also occurs at this time (9). Furthermore, Shanxi from 2019 to 2020 was 2.91%, which was brucellosis incidence was also strongly associated with 102 CCDC Weekly / Vol. 3 / No. 6 Chinese Center for Disease Control and Prevention .000 .019* .211 .051 -value 1 0 0 0 P ) % .59 .90 .69 .04 .33 .84 .31 .85 .76 .62 .67 .71 ( 1 1 4 1 0 1 0 1 3 0 1 0 0 5 0 0 0 16 Seroprevalence Xinjiang 7 3 6 4 0 1 2 2 5 2 3 0 1 0 4 0 0 0 Seropositive 4 6 4 0 86 75 16 70 49 439 158 128 383 239 153 130 263 185 Number of participant Chinese Centerfor DiseaseControlandPrevention .026* .447 .793 .456 -value 0 0 0 0 P ) .73 .95 .89 .51 .46 .76 .64 .30 .75 .84 .00 .11 % 3 1 1 3 2 2 2 3 3 2 4 0 0 0 0 0 0 ( 11 Seroprevalence Shanxi † 1 1 3 3 0 0 0 0 0 0 36 16 28 23 12 20 17 48 Seropositive 3 2 6 2 0 1 9 53 80 75 966 821 798 936 434 758 515 1,689 Number of participant .