CHINA – A recent study published in China CDC Weekly reveals a waterborne outbreak in China in 2021 that affected almost 1,000 people.

The outbreak involved 996 patients, predominantly students, and had two peaks over a 17-day period. Scientists identified exposure to water from a secondary water supply system as a significant risk factor through case-control studies.

The outbreak was initially identified in July 2021 when a hospital in Beijing discovered 13 patients with acute gastroenteritis in the same school.

Subsequent epidemiological investigations revealed a total of 996 patients, including 958 students and 38 staff members. Common symptoms included abdominal pain, diarrhea, nausea, vomiting, and fever.

The study identified a direct drinking water system supplied by a secondary water supply system (WSS-S) in the school building. This system offered unboiled direct drinking water (UDDW) and boiled water.

The water source for WSS-S was a groundwater well within the campus. Another hotel on the same campus had its secondary water supply system (WSS-H) using the same groundwater source well (WSW).

While WSS-H adhered to proper disinfection procedures, the water storage tank and pump of WSS-S lacked effective management. The sewage well was uncovered, and during rainfall, lacked protective facilities, making it a potential source of contamination.

Contamination source and antibiotic resistance

The study pointed to exposure to unboiled direct drinking water from the contaminated secondary water supply system as a significant risk.

The nearby garbage station and sewage well were identified as likely sources of contamination. After a rainstorm, students reported turbid water with an unpleasant odor.

Substituting drinking water with commercially bottled water resulted in a significant decrease in the number of patients.

Antibiotic resistance profiling of 17 Campylobacter coli isolates revealed co-resistance to nalidixic acid, ciprofloxacin, streptomycin, and tetracycline.

The study emphasizes the importance of ensuring the safety of drinking water, particularly in secondary supply systems, to prevent large-scale waterborne outbreaks.

Key takeaways and recommendations

The outbreak underscores the need for rigorous monitoring and management of secondary water supply systems.

Adequate disinfection, storage, and protective measures for water sources, especially during adverse weather conditions, are crucial.

The study recommends heightened vigilance and proactive measures to prevent waterborne illnesses, emphasizing the importance of a comprehensive approach to water safety.

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