Epidemiological Association Between Pathogens Detected in Open Water Sources and Acute Intestinal Infections in the Southern Aral Sea Region: The Case of Nukus City

Background:Diarrheal disease remains widespread worldwide, particularly among children under five years of age. Water is an important epidemiological factor in the transmission of enteric pathogens, and the ecological degradation of the Aral Sea basin increases the importance of studying water-associated risks in the Southern Aral Sea region. Objective. To evaluate the role of open water sources in the occurrence of acute intestinal infections (AII) and their epidemiological association with AII morbidity in Nukus city. Materials and methods. The study was conducted in the bacteriology laboratory of the Nukus City Department of Sanitary-Epidemiological Welfare and Public Health, Republic of Karakalpakstan, from January 2024 to January 2025. The source manuscript reports bacteriological examination of stool samples from 155 patients treated at the Republican Children’s Infectious Diseases Hospital and 98 water samples collected from 9 open water sources. For comparative molecular-genetic analysis, stool samples from 90 patients and 90 water samples were examined by PCR using the AmpliSens® OKI screen-FL test system. Statistical analysis included incidence measures, P, χ², φ, t, odds ratio (OR), and kappa coefficient; p<0.05 was considered statistically significant. Results. From January 2024 to January 2025, 3,645 AII cases were recorded in Nukus city. Children accounted for 2,839 cases (77.9%) and adults for 806 cases (22.1%). The lowest monthly incidence was recorded in February (37.35 per 100,000 population) and the highest in July (156.68 per 100,000). By bacteriological examination, pathogens were detected in 93/155 (60.0%) patient stool samples; the Results section of the source manuscript reports 24/107 (22.4%) bacteriologically positive water samples. PCR was positive in 81/90 (90.0%) stool samples and 64/90 (71.1%) water samples. Water and stool PCR results were significantly associated (χ²=17.52, df=1, p<0.0001; φ=0.441; OR=28.0), with overall agreement of 78.9% and κ=0.362. At the individual-pathogen level, a statistically significant association was observed only for Astrovirus (χ²=21.0, φ=0.34, t=4.58, p<0.001). Conclusion. AII morbidity in Nukus was higher among children and increased during the summer months. PCR showed a higher pathogen detection yield than conventional bacteriological testing. The findings indicate an epidemiological relationship between PCR positivity in open water and patient stool samples, with the strongest pathogen-specific association observed for Astrovirus..

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