[The Giardia epidemic in 2004 and out-of-hours service in Bergen]

From October to December 2004, 1,300 individuals were infected with Giardia lamblia in Bergen, Norway. The aim of this study was to explore this epidemic from the perspective of an accident and emergency department in Bergen.

Patient files from 2004 were searched retrospectively in Bergen accident and emergency department, for patients with a diagnosis of infectious gastroenteritis or with the word Giardia: in the laboratory section of their files. Information from the files where Giardia tests had been done, was collected and analysed.

A total of 1,603 patients with infectious gastroenteritis were found. The number of patients with gastroenteritis more than doubled six weeks before the Giardia epidemic was recognized. 420 patients had been tested for Giardia, and 200 of them had positive tests. Most of the patients with positive Giardia tests were in their twenties. Symptoms and findings of the gastroenteritis patients with positive Giardia tests were unspecific and not very alarming.

The Giardia epidemic probably started six weeks before it was recognized as such. Giardia infection is difficult to recognize on clinical grounds alone.