Volume 8, Number 3 (12-2015)                   ijhe 2015, 8(3): 323-330 | Back to browse issues page


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Naddafi K, Beiki A, Saeedi R, Ghanbari G, Niati A, Sori L. Case Study: Norovirus Outbreak in Pardis Town in January 2014. ijhe. 2015; 8 (3) :323-330
URL: http://ijhe.tums.ac.ir/article-1-5353-en.html

1- Department of Environmental Health Engineering, School of Public Health and Institute of Environmental Research, Tehran University of Medical Sciences, Tehran, Iran
2- Center of Environmental and Occupational Health, Ministry of Health and Medical Education, Tehran, Iran , beiki@health.gov.ir
3- Department of Health Sciences, Faculty of Health, Safety and Environment, Shahid Beheshti University of Medical Sciences, Tehran, Iran
4- Office of Environmental Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
5- Operation Office of Pakdasht Rural Water and Wastewater Company, Tehran, Iran
Abstract:   (2637 Views)

Background and objectives: In the outbreak of infectious diseases, the on time epidemiological, environmental, and laboratorial investigations result in rapid diagnosis of cause and source of the outbreaks and decrease the diseases spread and public health loss. Following the outbreak of gastroenteritis in Pardis Town in January 2014, this research was conducted to identify the cause, source, and route of transmission of the outbreak.

Materials and methods: First, the descriptive epidemiological study was conducted using checklist and the stool samples were prepared and analyzed. The drinking water quality in Pardis during and before the outbreak was obtained from National Environmental Health Network. The community water supply system consisting of watershed, water resources, pipelines, storage reservoirs, disinfection systems, and distribution network were inspected and sampling and detection of thermotolerant coliforms and norovirus in water samples were performed according to the Standard Methods.

Results: There were 6,027 patients with symptoms of nausea, vomiting, cramps, mild diarrhea, and mild fever. The distribution of the disease in all age groups, gender, ethnicity, and location was uniform. Out of nine stool specimens, molecular testing of norovirus in six samples was positive. Hazards identified in the water supply system consisted of a water pipe fracture occurred two days before the outbreak, illegal connection of landscape irrigation system to the drinking water supply network, the use of unprotected Fellman wells as the resource of water supply, and discharge of domestic wastewater into the water resource upstream of the Fellman wells. The water samples taken from the Fellman wells had fecal contamination (11 out of 12 samples), but because of weakness and limited experience in identifying norovirus in water samples, norovirus was not detected in the raw water samples.

Conclusion: This study showed that the pathogen came from a single source. Clinical symptoms, epidemiological evidence, the results of analysis of human stool samples,  fecal contamination of raw water samples and norovirus resistance to the standard amounts of  free residual chlorine in water indicated that the outbreak caused by consumption of contaminated drinking water (discharge of domestic wastewater to water supply system). In order to prevent similar outbreak, resolving the observed bugs in the water supply system and implementation of water safety plan is recommended.

Full-Text [PDF 521 kb]   (923 Downloads)    
Type of Study: case report | Subject: WATER
Received: 2014/12/2 | Accepted: 2015/12/28 | Published: 2015/12/28

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