Long-Term Epidemiological Trends and Risk Factors of Crimean-Congo Hemorrhagic Fever in Kazakhstan: An Integrated Epidemiological and Entomological Analysis.

Crimean-Congo hemorrhagic fever (CCHF) remains a major tick-borne zoonotic infection and a persistent public health challenge in Central Asia. Kazakhstan is among the endemic countries, where natural foci of CCHF are concentrated predominantly in the southern regions. This study evaluated the long-term epidemiological trends, regional distribution, seasonality, and risk factors associated with CCHF in Kazakhstan. A retrospective analysis of national surveillance data from 1980 to 2023 was conducted, complemented by detailed epidemiological and entomological investigations in the Turkestan region and the city of Shymkent during 2011-2023. Laboratory-confirmed cases, tick bite-related healthcare visits, entomological surveillance data, demographic characteristics, and epidemiological risk factors were analyzed. The results demonstrated cyclic fluctuations in CCHF incidence, with epidemic peaks occurring every 4-6 years and pronounced spring-summer seasonality, with the highest incidence observed in June and July. Long-term average annual incidence in endemic southern regions exceeded the national average by 2.67-fold. A total of 50,671 tick bite-related healthcare visits were registered during 2011-2023, while their incidence declined over time. Analysis of 94 laboratory-confirmed cases identified adults aged 18-40 years as the most affected group. Tick bites and livestock-related activities were the principal risk factors. These findings support the strengthening of integrated surveillance, vector control, laboratory diagnostics, and One Health-based prevention strategies in endemic regions.