apparent seropositivity using the Huddleson test of 880 (95% CI 400–1,770) per 100,000 is 11 times higher than the ofﬁcially reported number of brucellosis cases. There is no data available in the literature indicating the proportion of seroconversion that leads to clinically manifested brucel- losis in endemic areas. If 10% of the people that serocon- verted showed clinical symptoms, the incidence of clinical brucellosis would be in agreement with the reported data. However, if 50% of the people that seroconverted showed clinical symptoms, the level of under-reporting would be 5.6 (95% CI 2.5–11.4). Studies in Saudi Arabia indicate a high proportion of clinical illness among seropositive family members of acute brucellosis cases (Almuneef et al. 2004; Alsubaie et al. 2005). Further studies are needed to assess the true incidence of human cases. The estimated duration of seropositivity of 10.9 years is in agreement with Beklemishev in Kazakhstan (cited by v.Oldershausen 1968), but we were not able to estimate a conﬁdence limit, with- out time series data. In our study, the apparent seroprevalences between the Oblasts ranged from 2.2 to 18.3% in humans and between 1.3 and 8.9% in livestock species with the highest variance for both on the Rayon level. Although, the Oblast sero- prevalences of the three livestock species were comparable, we have seen a signiﬁcant correlation between human and small ruminant seropositivity on the Rayon level, thus suggesting Rayon speciﬁc clustering. This likely reﬂects the relatively localized contact networks and marketing system of Kyrgyz livestock. A sheep–cattle relationship has been conﬁrmed by the detection of a B. melitensis strains in sheep and in two cattle (data not shown). In humans, male participants were more frequently seropositive than female participants but no difference between age classes was de- tected. More data is needed to understand the frequency of brucellosis in children, where transmission may be due to both direct exposure to contaminated livestock material and consumption of raw livestock products. The higher risk of male seropositivity in human adults indicates that exposure in these rural villages may more likely be due to direct (professional) close contact with infected livestock, than by exposure through contaminated livestock products, but this hypothesis requires further investigation. In a study about risk factors of human brucellosis in Kyrgyzstan, Kozukeev et al. (2006) reported a higher, however both non signiﬁcant, odds ratio (OR) for keeping cattle (adj. OR = 4.5) followed by goats (adj. OR = 1.6). However, we ﬁnd no correlation between cattle and human seroposi- tivity (indeed, we found a negative correlation) and we only Representative Seroprevalences of Brucellosis 137 ﬁnd a signiﬁcant correlation with sheep, but not for goats. Such contradictory results, also due to different study de- signs, reﬂect the difﬁculty in determining an association of infection between humans and animals for zoonotic dis- eases. Conﬁrmation of transmission chains by molecular analysis of strains isolated from humans and different livestock species is warranted. This study was intended to inform Kyrgyz policy on brucellosis epidemiology by providing representative data using existing and new diagnostic tests. As it is important to adapt assessments to local health policy decision path- ways (Habicht et al. 1999), our analysis of human apparent seroprevalence is based on the Huddleson agglutination test, which is the ofﬁcially recognized diagnostic test in Kyrgyzstan. In a complementary analysis, we assess the test char- acteristics of all used tests using a Bayesian model for the estimation of true seroprevalence in the absence of a gold standard, which are published separately. The results will be further used to estimate the cost of brucellosis to the Kyrgyz economy analogous to Roth et al. (2003). The presented study is an example of an integrated human and animal study design under a ‘‘One Health’’ paradigm, facilitating identiﬁcation of the source of a zoonosis in the animal reservoir in a single step because of a connected study design and the ability to assess the impact of the disease in multiple sectors, notably the health and livestock production sectors. It is thus an example of the added value of a closer cooperation between human and animal health practitioners (Zinsstag et al. 2009). CONCLUSION Our study conﬁrms the high seroprevalence of brucellosis in Kyrgyzstan and suggests that the annual incidence of human brucellosis exposure, measured by serological tests, is more than ten times higher than the annual incidence of reported clinical brucellosis cases. This indicates an underreporting of human brucellosis cases even if only a fraction of the seropositive persons have clinical symptoms. Human brucellosis seroprevalence was most closely asso- ciated with brucellosis seroprevalence in sheep. Effective mass vaccination of sheep, goats, and cattle, following the guidelines by the World Animal Health Organization (OIE) are warranted to control human brucellosis at its source. Further research is needed to further conﬁrm the human– livestock linkages by molecular typing of brucella strains