Chronic opisthorchiasis: Current situation in the Republic of Kazakhstan

Nazira N. Beisenbieva, Mazhit Shaidarov, G. Imambayeva, Dinagul Bayesheva, H.H. Johannes

International Journal of Infectious Diseases, 2016

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DOI 10.1016/j.ijid.2016.11.162
Data confidence 70 medium
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Abstract

Purpose: Aim: to investigate prevalence of human opisthorchiasis in natural foci of Kazakhstan for 2009 -2014. Objectives: 1) to study prevalence of opisthorchiasis in Kazakhstani population; 2) to perform time series analysis, considering ecological zones and administrative division of Kazakhstan. Methods & Materials: Consolidated reports 1, 2 of Ministry of Healthcare of Kazakhstan and data provided by Agency for population statistics of Kazakhstan. Statistical methods: 1) analysis of intensive values; 2) analysis of time series (average annual growth / decline rate (AAG/DR,%); 3) 95% confidence interval (CI) 1.96 × SE (CI) Results: From 2009 to 2014, average annual incidence rate was 12.24 ± 0.860/0000 (95% CI = 10.56-13.920/0000). Trends of adjusted incidence rates of helminthiasis increased in Akmola (AAGR = + 19.18%), Kostanay (AAGR = + 16.9%), Aktobe (AAGR = + 15.7%) regions. In other regions morbidity trends declined, with average annual decline of adjusted incidence rates ranging from AADR = -1.84% in West Kazakhstan to AADR = -24.5% in North Kazakhstan. Significant heterogeneity in distribution of incidence in various regions was observed, caused by specific lifecycle of Opisthorchis, prevalence of intermediate hosts of helminthiasis in reservoirs, large country area, including 9 water basins. Current investigation revealed Ural, Caspian, Irtysh, Ishim, Tobol, Turgay basins (from 18.20/0000 and 8.080/0000) to be regions with high and medium levels of morbidity of opisthorchiasis. They are located in north-western and north-eastern parts of Kazakhstan and are co-integral parts of the two world's largest natural foci of opisthorchiasis - Ob-Irtysh and Volga-Kama. Nura-Sarysu water basin and Almaty were determined to be regions with low indices (up to 0. 080/0000). However, majority of cases in Almaty were imported, with no tendency of morbidity reduction due to increase in population migration, trade and economic processes. Imported cases and infection of local population in Ishim water basin area were identified in Astana (23.250/0000). Conclusion: Uniqueness of natural environment and specificity of hydrological regime ensure stable functioning of opisthorchiasis foci. Despite the dynamic decline in morbidity during 2009 to 2014 in total population, a steady level of newly diagnosed patients with opisthorchiasis in northern and central regions of Kazakhstan remains.