| ObjectsThe aim of this study is to estimate the serological prevalence of brucellosis and the proportion of brucellosis positive family in Inner Mongolia Autonomous Region, to understand the cognitive level of knowledge related to brucellosis, to explore the risk factors of brucellosis and to provide the scientific evidence for prevention. The study is also to provide scientific basis for the selection of molecular epidemiological method of brucellosis by the qualitative and quantitative evaluation of multiple locus variable number tandem repeat analysis and multilocus sequence typing.MethodsMulti-stage sampling was carried out in Siziwang Banner, the banner was divided in to pastoral area and farming area,5villages were randomly selected from each area,30families were randomly selected from each village. The family was surveyed by KAP questionnaire and the serum samples were collected for laboratory testing. All patients were collected in Center for Disease Control and Prevention of Chayouhou, Linxi, Keyouzhong banner in a certain period for the case-control study and they were carried on questionnaire survey and blood test. The risk factors of Brucellosis were analyzed by χ2test and multivariable logistic analysis. Multiple locus variable number tandem repeat analysis and multi locus sequence typing were used to typing the Brucella isolated from1953to2013in different regions. Clustering, discriminant and evolution analysis wer used to evaluate the accuracy of the two methods.Results1. A total of300households KAP questionnaire and594serum samples were collected in Siziwang banner. The brucellosis serological prevalence was9.6%(95%CI:7.2%～12.0%). Taken the household as the unit of analysis, the Brucellosis positive rate was16.67%(12.4%～20.87%).2. The prevalence of Brucellosis in Siziwang banner had significant difference between different age groups (χ2=11.556, P=0.0414). And the patients were concentrated in the30-50age group which were the working population. The prevalence had no significant difference in different regions (pastoral/farming areas).3. There were significant difference of the number of breeding sheep (t Approximation P=0.027) and goats (t Approximation P=0.0998) between the Brucellosis positive family and negative family.4. Less than50%of families knew the route of Brucellosis infection. The awareness rate of that drinking boiled milk and making dairy products with boiled milk can prevent the Brucellosis were3%and2.67%respectively.78.33%of the families got the Brucellosis prevention advice from the Banner CDC.5.872questionnaires and serum samples were collected in the case-control study. Case and control group were156and585respectively. There were significant difference in gender (χ2=20.997, P<0.0001), age (P=0.002) and occupation (x2=15.15, P=0.0005) at the baseline between the groups.6. Multivariate Logistic analysis of the case-control study showed that sex (female VS male:OR=0.421,95%CI=0.287～0.618), occupation (farmers VS other:OR=1.849,95%CI=0.974～3.509and herdsman VS other:OR=1.604,95%CI=0.409～6.296), feeding livestock (not feeding VS feeding:OR=0.512,95%CI=0.295～0.888).7. The cognition survey of case-control study showed that19.28%of the people knew that Brucellosis is an infectious disease and40.62%of the people knew that Brucellosis can be cured.11.07%of the people knew that taking protective measures when delivering the livestock can prevent Brucellosis, the awareness rate of other preventive measures was less than10%.8.212Brucella strains were divided into149MLVA types and21ST by MLVA and MLST. The simpson index of MLVA and MLST were0.990(95%CI:0.988-0.992) and0.565(95%CI:0.485-0.644) respectively. 9.9of Panel1types were founded among the143B.melitensis strains,111strains were42type, accounting for77.6%.42tpye B.melitensis strains of Inner Mongolia, Shanxi and Hebei were78.9%,97.0%and100%respectively.10. Minimum spanning tree analysis of MLVA showed the affinity among the strains isolated from Hainan province in the year2013and2010and Guangxi province in1960s. Phylogenetic tree constructed by maximum parsimony of MLST showed that B. melitensis was a highly evolved bacterium and B.suis had a close relationship with B.canis.11. The Bayes discriminant model was established to forecast the species of Brucella and evaluate the goodness of fit bwtween genotyping methods and traditional methods.Conclusions1. The real epidemic of Brucellosis in Inner Mongolia Autonomous Region is more serious than reported, the false negative rate is about20%.2. Feeding livestock is a major risk factor of Brucellosis in project banner. The adults who are labor groups are the high-risk population for Brucellosis infection. Dealing with abortion such as buring, feeding dogs and throwing to brook would increase the risk of Brucellosis infection.3. The local people has a certain perception about Brucellosis, but a lower level of knowledge.4. MLVA typing reveals that42type is the main type of Panel1in China and the B.melitensis in China may have originated in the eastern Mediterranean colony.5. Cluster analysis shows some correlation of the sporadic outbreaks in southern China caused by B.suis.6. MLST typing reveals that B.melitensis which caused the epidemic of Brucellosis in China are mainly ST8type and highly evolved.7. The discriminant of MLVA is higher than MLST and MLVA is more suitable for the investigation of outbreaks and surveillance in South of China where has sporadic epidemic. MLST can reflect the evolutionary relationship of population and is suitable for epidemiological surveillance of the northern region. |
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