Environmental and climatic risk factors of human cystic echinococcosis in the northeast of Iran.

Abstract

Cystic echinococcosis (CE) is a significant zoonotic helminthic disease with considerable public health and economic impact in endemic regions. We aimed to analyse the climatic and environmental factors affecting the human CE cases in North Khorasan Province, northeast Iran. Using a geographic information system, we map the addresses of 316 hospitalised CE patients from 2012 to 2022 and examined the influence of climatic variables, altitude, and land cover on CE case distribution. Data were analysed using logistic regression models. Most patients were female (58.9%) and aged 21-60 years (67.4%), with liver involvement being the most common (57.3%). The multivariate model identified urban settings, irrigated and dry farms, soil temperature, and humidity as the most important geoclimatic determinants, respectively. In contrast, gardens, moderate and excellent rangelands, minimum, maximum, and mean air temperatures, and rainfall were only found to be significant factors in univariate models. High-risk areas for CE include urban and suburban regions, surrounding fields, and pastures where stray dogs and wild canids roam, livestock husbandries are present, and residents consume unsanitised vegetables. Additionally, areas with lower soil and weather temperatures and higher humidity conditions that may enhance the survival of E. granulosus eggs dispersed by canids were identified as high-risk zones. Health managers can use these findings to prioritise control programs and allocate limited resources to these areas, ultimately reducing the future incidence of CE.