One Health epidemiology of cystic echinococcosis in Bhutan: A hospital-based study with complementary abattoir surveillance data

Abstract Background : Cystic echinococcosis (CE) is a neglected zoonosis that disproportionately affects rural and economically disadvantaged populations worldwide. Although CE cases have been reported in Bhutan, epidemiology of CE remains unclear, and evidence integrating human and animal health data are scarce. This study describes the epidemiological patterns of CE and examines its concordance with routine livestock infection data using the One Health approach. Methods : We retrospectively reviewed the hospital records of patients treated for CE between January 2020 and December 2024 at three CE treating hospitals in Bhutan. Sociodemographic characteristics, temporal trends by year of treatment, and geographic distribution were analyzed descriptively. In parallel, routine post-mortem meat inspection records from the national cattle abattoir were analyzed for 2023–2025 to estimate the proportion of carcasses with hydatid-compatible cystic lesions, assess inter-annual variation, and describe the geographic origin of the slaughtered animals. Lesions were recorded based on gross inspection alone, without parasitological or molecular confirmation. Human cases and abattoir cystic lesion detections were presented in parallel for the overlapping years. Results : A total of 120 human CE cases were identified in this study. Most patients were female (60.0%), farmers (53.3%), and had no formal education (51.7%). The median age was 36 years (IQR: 21.8–53.0), with two-thirds of the patients between 15 and 64 years of age. Cases were reported from nearly all districts, with the highest numbers coming from the western and central regions. The annual case counts ranged from 14 to 33, and over 90% of the patients were treated at the national referral hospital, reflecting centralized surgical care. Among the 9219 cattle slaughtered between 2023 and 2025, 299 carcasses had hydatid-compatible cystic lesions, corresponding to an overall detection proportion of 3.2% (95% CI: 2.90–3.61). The detection proportion varied significantly by year. Presented side by side, hospital-treated cases and abattoir cystic lesion detection showed no clear temporal concordance over the overlapping years. Conclusions : CE remains a significant public health problem in Bhutan, particularly among rural populations, despite the low proportion of hydatid-compatible cystic lesions detected in routinely inspected cattle. The two data streams describe different populations over different timescales, so the contrast between them points to gaps in surveillance rather than to a measurable difference in transmission. Strengthening One Health surveillance through standardized reporting of human cases and abattoir inspection with organ location, molecular confirmation, cyst viability assessment, and expanded geographic and host coverage is needed to define transmission dynamics in Bhutan. One Health impact statement In this case series study, we report the first joint epidemiological assessment of cystic echinococcosis (CE) in Bhutan, combining five years of hospital-based human data with routine cattle abattoir inspection records. Presenting human disease and livestock inspection findings side by side reveals a surveillance gap: a persistent hospital-treated human CE burden alongside a low proportion of cattle carcasses with hydatid-compatible cystic lesions. Neither the human health nor the animal health sector can identify this gap working alone. The finding points to the need to investigate other potential intermediate hosts, including yaks and small ruminants, and to confirm detected lesions parasitologically and molecularly. Closer cooperation between the human and animal health sector is needed to interpret CE data in settings where surveillance is fragmented. These findings provide a baseline that could contribute to future transmission modeling once more comprehensive data become available.