Following WHO Guidelines to Respond to a Water Contamination Outbreak in the Edge of Hamadan, West of Iran

Background: Water and foodborne disease outbreaks continually present formidable challenges to healthcare systems, leading to morbidity, mortality, and substantial economic losses. Investigating and reporting these outbreaks play a pivotal role in effectively controlling and mitigating future occurrences. This study endeavors to scrutinize an outbreak of water contamination in Mariyanaj, Hamadan, Iran, employing the World Health Organization’s (WHO’s) comprehensive 10-step framework. Methods: In this descriptive study, we meticulously adhered to the WHO outbreak investigation and reporting guidelines, systematically progressing through each step to investigate and report the outbreak. Symptom/exposure samples, involving two samples per symptomatic individual, were collected and sent to the Center for Disease Control’s laboratory for examination. Additionally, we executed a case-control study (Step 7) to discern the root cause of the outbreak. Results: The outbreak affected 919 individuals among 12115 residents of Mariyanaj city, with a male prevalence of 57.7%. The most impacted age group was 10-14 years. Predominant symptoms included abdominal pain, nausea, and vomiting. Through meticulous field investigations and the case-control study, the contaminated water source was identified. Human samples exhibited Escherichia coli and norovirus as the most prevalent pathogens, with E. coli also detected in water samples. Conclusion: Despite advancements in outbreak investigation and reporting systems, the utilization of a standardized step-by-step approach proves more effective in identifying and managing outbreaks. The consistent monitoring of drinking water quality, particularly in times of water crises, emerges as a crucial factor in significantly preventing waterborne diseases.