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An outbreak of Norwalk-like gastroenteritis associated with contaminated drinking water at a caravan park
J M McAnulty1, G L Rubin, C T Carvan
1Epidemiology and Health Services Evaluation Branch, New South Wales Health Department, Sydney.
Abstract:
During the 1989 Christmas holiday period, a large outbreak of gastroenteritis occurred among persons staying at a caravan park in southern New South Wales. Review of local hospital records found that 77 per cent of patients presenting with infective diarrhoea between 29 December and 3 January had stayed at the caravan park. In a retrospective cohort study we compared rates of illness among caravan park patrons exposed to different water sources. Stools were tested for pathogens and convalescent sera for viral antibodies. Rain and reticulated river water sampled from the caravan park were tested for bacteria and viruses. Of 351 persons interviewed at the caravan park, 305 (87 per cent) reported an illness characterised by diarrhoea, vomiting and abdominal pain. Of 196 persons who used reticulated river water for drinking or ablutions, 175 (89 per cent) became ill compared with 47 of 72 persons (65 per cent) who did not use this water (relative risk 1.4, 95 per cent confidence interval 1.2 to 1.6). The outbreak was probably caused by a 27-28 nm small round structured virus found in the stool from one ill person. High levels of faecal coliforms in the reticulated river water and enterovirus in sediment samples suggest that the outbreak was caused by sewage contaminating the reticulated river water through a break in the pipe directly over the underground water tanks. To prevent such outbreaks, poor water and sewerage system layouts should be avoided and nonpotable water should be clearly labelled. Where feasible, all camping-ground water should stem from town supplies.
Insights
A 1989 gastroenteritis outbreak at a caravan park was linked to contaminated reticulated river water. This outbreak highlights the need for safe water systems in public accommodations to prevent infectious disease transmission.
Area of Science:
- Public Health
- Infectious Disease Epidemiology
- Environmental Health
Background:
- A significant outbreak of gastroenteritis occurred at a caravan park in New South Wales during the 1989 Christmas holiday period.
- Hospital records indicated a high proportion of patients with infective diarrhea had stayed at the affected caravan park.
Purpose of the Study:
- To investigate the cause of the gastroenteritis outbreak among caravan park patrons.
- To compare illness rates between patrons exposed to different water sources within the park.
Main Methods:
- Conducted a retrospective cohort study comparing illness rates based on water source exposure.
- Collected stool samples for pathogen testing and convalescent sera for viral antibody analysis.
- Tested water and sediment samples from the caravan park for bacterial and viral contamination.
Main Results:
- 87% of interviewed caravan park patrons reported gastrointestinal illness (diarrhea, vomiting, abdominal pain).
- A significantly higher illness rate (89%) was observed in patrons using reticulated river water compared to those who did not (65%).
- A small round structured virus was identified in patient stool; high levels of fecal coliforms and enterovirus were found in the reticulated river water.
Conclusions:
- The outbreak was likely caused by sewage contamination of the reticulated river water supply.
- Recommendations include improved water and sewerage system design, clear labeling of non-potable water, and prioritizing town water supplies for campgrounds.