Food and waterborne diseases

In Portugal, listeriosis has been notifiable since April 2014, but there is no active surveillance programme for the disease. A retrospective study involving 25 national hospitals led to the detection of an outbreak that occurred between March 2009 and February 2012. The amount of time between the start of the outbreak and its detection was 16 months. Of the 30 cases of listeriosis reported, 27 were in the Lisbon and Vale do Tejo region. Two cases were maternal/neonatal infections and one resulted in fetal loss. The mean age of the non-maternal/neonatal cases was 59 years (standard deviation: 17); 13 cases were more than 65 years-old. The case fatality rate was 36.7%. All cases were caused by molecular serogroup IVb isolates indistinguishable by pulsed-field gel electrophoresis and ribotype profiles. Collaborative investigations with the national health and food safety authorities identified cheese as the probable source of infection, traced to a processing plant. The magnitude of this outbreak, the first reported food-borne listeriosis outbreak in Portugal, highlights the importance of having an effective listeriosis surveillance system in place for early detection and resolution of outbreaks, as well as the need for a process for the prompt submission of Listeria monocytogenes isolates for routine laboratory typing.

An outbreak due to the emerging monophasic Salmonella Typhimurium 4,5,12:i:- occurred in four schools in Poitiers in October 2010. Food trace-back investigation led to the identification of beef burgers as the cause of the outbreak and their subsequent withdrawal. The Institute for Public Health Surveillance conducted a retrospective epidemiological investigation to assess the extent of the outbreak and describe cases. Self-administered questionnaires were completed by students and personnel attending each of the four schools affected. Clinical cases were defined as anyone having eaten at the school when the beef burgers were served and reporting diarrhoea or fever with at least one digestive symptom (nausea, vomiting or abdominal pain), within five days after the incriminated school meal or with unknown date of onset within a 15-day period after the incriminated school meal. Of 1,559 persons exposed, 554 clinical cases were identified corresponding to an overall attack rate of 35.5%. Of 554 clinical cases, a total of 286 (53%) sought medical care and 31 (6%) were hospitalised for more than 24 hours. This multi-school outbreak is one of the biggest food-borne outbreaks of monophasic Salmonella Typhimurium 4,5,12:i:- described in France. Prompt notification of cases and rapid identification and withdrawal of the incriminated batch of beef burgers was crucial to limit the extension of this outbreak.

In June 2009, 11 outbreaks of food poisoning occurred in France, involving 45 individuals who had consumed mussels harvested in Vilaine Bay (Northwestern France). Because the toxic dinoflagellate Dinophysis spp. had been detected in the area from mid-May, okadaic acid (OA) and dinophysistoxins were suspected to be the cause of these outbreaks, although the weekly monitoring tests by mouse bioassay had been negative. With the help of the French reporting system for food-borne disease outbreaks, the detailed data on epidemiology, mussel consumption and complete product traceback, were collected for 11 individuals involved in three reported outbreaks. The batch of mussels identified as the source of these three outbreaks contained concentrations of toxins of the okadaic acid group that were approximately eight times higher than the European regulatory limit. Moreover, based on the consumption data available for the 11 cases, a lowest observable adverse effects level (LOAEL) was deduced. The LOAEL calculated from this study, although based on a very limited number of individuals, was in the same range, i.e. approximately 50 ?g OA equivalents per person, as the LOAEL established by the European Food Safety Authority in 2006.

In June 2008, three Dutch tourists participating in a mini-cruise in Turkey needed urgent repatriation for antitoxin treatment because of symptoms of botulism. Because there was a shortage of antitoxin in the Netherlands, an emergency delivery was requested from the manufacturer in Germany. An outbreak investigation was initiated into all nine cruise members, eight of whom developed symptoms. C. botulinum type B was isolated in stool culture from four of them. No other patients were notified locally. Food histories revealed locally purchased unprocessed black olives, consumed on board of the ship, as most likely source, but no leftovers were available for investigation. C. botulinum type D was detected in locally purchased canned peas, and whilst type D is not known to be a cause of human intoxication, its presence in a canned food product indicates an inadequate preserving process. With increasing tourism to areas where food-borne botulism is reported regularly special requests for botulism antitoxin may become necessary. Preparing an inventory of available reserve stock in Europe would appear to be a necessary and valuable undertaking.

Campylobacteriosis is the most common reported bacterial gastrointestinal disease in Sweden. Food-borne outbreaks of campylobacteriosis in Sweden are rather rare except for, usually rather small, family outbreaks. Water-borne outbreaks of campylobacteriosis, however, have affected several thousand persons in the past [1