Limits...
A large waterborne outbreak of campylobacteriosis in Norway: the need to focus on distribution system safety.

Jakopanec I, Borgen K, Vold L, Lund H, Forseth T, Hannula R, Nygård K - BMC Infect. Dis. (2008)

Bottom Line: Tap water consumption was the only exposure associated with illness.Good quality source water alone is not enough to ensure water safety.Waterworks personnel should monitor the pressure regularly; reduce the leakage by upgrading the distribution network and use chlorination when conducting maintenance work.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo, Norway. irena.jakopanec@fhi.no

ABSTRACT

Background: On 7 May 2007 the medical officer in Røros (population 5600) reported 15 patients with gastroenteritis. Three days later he estimated hundreds being ill. Untreated tap water from a groundwater source was suspected as the vehicle and chlorination was started 11 May. Campylobacter was isolated from patients' stool samples. We conducted an investigation to identify the source and describe the extent of the outbreak.

Methods: We undertook a retrospective cohort study among a random sample of customers of Røros and neighbouring Holtålen waterworks. Holtålen, which has a different water source, was used as a control city. We conducted telephone interviews to gather data on illness from all household members. One randomly selected household member was asked about detailed exposure history. The regional hospital laboratory tested patients' stools for enteropathogens. Campylobacter isolates were typed by AFLP for genetic similarity at the Norwegian Institute of Public Health. Local authorities conducted the environmental investigation.

Results: We identified 105 cases among 340 individuals from Røros and Holtålen (Attack Rate = 31%). Tap water consumption was the only exposure associated with illness. Among randomly selected household members from Røros, a dose-response relationship was observed in daily consumed glasses of tap water (chi2 for trend = 8.1, p = 0.004). Campylobacter with identical AFLP was isolated from 25 out of 26 submitted stool samples. No pathogens were detected in water samples. We identified several events that might have caused pressure fall and influx of contaminated water into the water distribution system. On two occasions, pressure fall was noticed and parts of the distribution system were outdated.

Conclusion: The investigation confirmed a waterborne outbreak of campylobacteriosis in Røros. Although no single event was identified as the cause of contamination, this outbreak illustrates the vulnerability of water distribution systems. Good quality source water alone is not enough to ensure water safety. For a better risk management, more focus should be put on the distribution system security. Waterworks personnel should monitor the pressure regularly; reduce the leakage by upgrading the distribution network and use chlorination when conducting maintenance work.

Show MeSH

Related in: MedlinePlus

Cases of gastroenteritis in a sample of Røros and Holtålen household members by date of illness onset (n = 105), from April 30 to May 14, 2007 and the timeline of events, which may be relevant to the water contamination. Gray squares = Røros household members; plum squares = Holtålen household members; One case, marked with a letter R, was exposed to Røros tap water as well. IP = incubation period.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2567324&req=5

Figure 2: Cases of gastroenteritis in a sample of Røros and Holtålen household members by date of illness onset (n = 105), from April 30 to May 14, 2007 and the timeline of events, which may be relevant to the water contamination. Gray squares = Røros household members; plum squares = Holtålen household members; One case, marked with a letter R, was exposed to Røros tap water as well. IP = incubation period.

Mentions: Dates of illness onset among the cases are shown in Figure 2. The curve indicates that the outbreak started between 1–3 May and peaked between 5–9 May. The median date of illness onset was 7 May.


A large waterborne outbreak of campylobacteriosis in Norway: the need to focus on distribution system safety.

Jakopanec I, Borgen K, Vold L, Lund H, Forseth T, Hannula R, Nygård K - BMC Infect. Dis. (2008)

Cases of gastroenteritis in a sample of Røros and Holtålen household members by date of illness onset (n = 105), from April 30 to May 14, 2007 and the timeline of events, which may be relevant to the water contamination. Gray squares = Røros household members; plum squares = Holtålen household members; One case, marked with a letter R, was exposed to Røros tap water as well. IP = incubation period.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2567324&req=5

Figure 2: Cases of gastroenteritis in a sample of Røros and Holtålen household members by date of illness onset (n = 105), from April 30 to May 14, 2007 and the timeline of events, which may be relevant to the water contamination. Gray squares = Røros household members; plum squares = Holtålen household members; One case, marked with a letter R, was exposed to Røros tap water as well. IP = incubation period.
Mentions: Dates of illness onset among the cases are shown in Figure 2. The curve indicates that the outbreak started between 1–3 May and peaked between 5–9 May. The median date of illness onset was 7 May.

Bottom Line: Tap water consumption was the only exposure associated with illness.Good quality source water alone is not enough to ensure water safety.Waterworks personnel should monitor the pressure regularly; reduce the leakage by upgrading the distribution network and use chlorination when conducting maintenance work.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo, Norway. irena.jakopanec@fhi.no

ABSTRACT

Background: On 7 May 2007 the medical officer in Røros (population 5600) reported 15 patients with gastroenteritis. Three days later he estimated hundreds being ill. Untreated tap water from a groundwater source was suspected as the vehicle and chlorination was started 11 May. Campylobacter was isolated from patients' stool samples. We conducted an investigation to identify the source and describe the extent of the outbreak.

Methods: We undertook a retrospective cohort study among a random sample of customers of Røros and neighbouring Holtålen waterworks. Holtålen, which has a different water source, was used as a control city. We conducted telephone interviews to gather data on illness from all household members. One randomly selected household member was asked about detailed exposure history. The regional hospital laboratory tested patients' stools for enteropathogens. Campylobacter isolates were typed by AFLP for genetic similarity at the Norwegian Institute of Public Health. Local authorities conducted the environmental investigation.

Results: We identified 105 cases among 340 individuals from Røros and Holtålen (Attack Rate = 31%). Tap water consumption was the only exposure associated with illness. Among randomly selected household members from Røros, a dose-response relationship was observed in daily consumed glasses of tap water (chi2 for trend = 8.1, p = 0.004). Campylobacter with identical AFLP was isolated from 25 out of 26 submitted stool samples. No pathogens were detected in water samples. We identified several events that might have caused pressure fall and influx of contaminated water into the water distribution system. On two occasions, pressure fall was noticed and parts of the distribution system were outdated.

Conclusion: The investigation confirmed a waterborne outbreak of campylobacteriosis in Røros. Although no single event was identified as the cause of contamination, this outbreak illustrates the vulnerability of water distribution systems. Good quality source water alone is not enough to ensure water safety. For a better risk management, more focus should be put on the distribution system security. Waterworks personnel should monitor the pressure regularly; reduce the leakage by upgrading the distribution network and use chlorination when conducting maintenance work.

Show MeSH
Related in: MedlinePlus