Sammanfattning
BACKGROUND We describe the status of waterborne outbreaks notified in Norway and discuss this in the context of
outbreaks recorded in previous years, to gain a better understanding of their development in Norway in recent years.
MATERIAL AND METHOD We have collected information on all outbreaks notified to the Norwegian Institute of Public Health via
the surveillance system for communicable diseases in the ten-year period from 2003-2012 for which drinking water was given as
the suspected cause.
RESULTS Altogether 28 waterborne outbreaks with a total of 8 060 persons reported as ill were notified in the period. The majority
of outbreaks resulted in fewer than 100 cases of illness. There were two outbreaks with more than 1 000 cases of illness: an
oubreak of campylobacteriosis in Røros and an oubreak of giardiasis in Bergen. In more than half of the outbreaks, water was
supplied from public water distribution systems (16/28 outbreaks, 57 %). In addition, a large proportion was linked to individual
households with their own water supply (12/28 outbreaks, 43 %).
INTERPRETATION Most of the outbreaks in the ten-year period were linked to public water distribution systems, while almost half
were linked to non-disinfected water supplies to individual households. Although most of the outbreaks were small, two extensive
outbreaks were also registered in the period, resulting in more than one thousand cases of illness. This underscores the need for
good contingency planning and surveillance, so that suspicion of waterborne outbreaks is rapidly notified to the responsible
authorities, and the importance of good protection of water sources, as well as proper maintenance of water treatment plants and
distribution systems.