[Ill after drinking untreated milk; 'die Amelander Krankheit'].

In 2012 three patients consulted their general practitioner with symptoms of gastro-enteritis with bloody stools. This was caused by drinking untreated milk infected with Campylobacter jejuni. Another patient developed reactive arthritis. He too had drunk untreated milk that had probably been infected with Yersinia enterocolitica. Between 1958 and 1995 many German children living in the region of Cologne developed gastro-enteritis after holidaying on Ameland, one of the Dutch islands. This condition was known as 'die Amelander Krankheit', and was caused by drinking untreated milk that had been infected with Campylobacter jejuni. After instructions to boil the milk before drinking were followed, the illness disappeared. These cases show that consumption of untreated milk can have negative consequences for health. Hence, if patients develop gastroenteritis symptoms after visiting a farm we recommend that the possibility that they may have drunk untreated milk is taken into account.