Epidemiology of listeriosis in Austria.

A total of 150 human cases of listeriosis (case definition based on isolation of Listeria monocytogenes from normally sterile material) were reported in Austria between 1997 and 2007. Of these, 14 cases (9.3%) were pregnancy-associated (mother/child illness considered as a single case) with a mean age of 29.3 years (median: 26.5; range 24-36). Among the non-pregnancy-associated cases (n = 136), 75 were male (55.2%) and 61 female (44.9%); patients in this group had a mean age of 64.3 years (median: 66.2; range 1-93). The average incidence of listeriosis in Austria in the period studied was 0.168 cases per 100,000 population. The majority of cases (90.7%) were caused by systemic infection, only 9.3% of cases were local infections. Among non-pregnancy-associated cases the fatality rate was 28.7% (39/136) and among the pregnancy-associated cases 35.7% (5/14: miscarriage x3, stillbirth x1, and one death in a newborn within 15 days of birth). Serotyping results for the 150 isolates revealed serovar (SV) 4b: 54%, SV 1/2a: 31.3%, SV 1/2b: 10%, SV 1/2c: 2.7%, 4d: 1.3% and SV 3a: 0.7%. Predisposing risk factors were determined for 131 of the 150 cases: age > or = 65 years (n = 73), pregnancy (n = 14) and 44 cases of carcinoma, blood malignancies, autoimmune diseases and status post solid organ transplants (7 patients had more than one underlying illness). During the period studied, the incidence of listeriosis doubled, despite a drastic reduction in the frequency of pregnancy-associated cases.

An outbreak of febrile gastroenteritis associated with jellied pork contaminated with Listeria monocytogenes.

In September 2008, the Austrian Agency for Health and Food Safety (AGES) learned of an outbreak of diarrheal illness that included a 71-year-old patient hospitalized for gastroenteritis with a blood culture positive for Listeria monocytogenes. Three stool specimens provided by seven of 19 persons attending a day trip to a foreign city, including a final break at an Austrian tavern, yielded L. monocytogenes. All isolates were of serovar 4b and had fingerprints indistinguishable from each other. A cohort study revealed that the outbreak of gastroenteritis occurred among 16 persons who had eaten dinner at the wine tavern on September 6. Of the 15 persons who ate from platters of mixed cold-cuts, 12 (80%) developed symptoms of febrile gastroenteritis within 24-48 h. The median age of those who became ill was 62 years. A 72-year-old patient recovered from gastroenteritis but was hospitalized with bacterial meningitis on day 19 after the dinner. The epidemiological investigation identified the consumption of mixed cold-cuts (including jellied pork) at the wine tavern as the most likely vehicle of the foodborne outbreak (P = 0.0015). This hypothesis was confirmed by microbiological investigation of jellied pork produced by the tavern owner on September 3. L. monocytogenes was isolated from leftover food in numbers of 3 x 10(3)-3 x 10(4) colony forming units/g and was indistinguishable from the clinical outbreak isolates. Symptoms reported by the 12 patients included unspecified fever (12x), diarrhea (9x), headache (5x), vomiting (4x), body aches (2x) and sore throat (1x). Active case finding identified one case of rhombencephalitis (female, age 48) among another group of four guests, among whom only the patient and her asymptomatic husband had eaten jellied pork on September 6. This is the first outbreak of L. monocytogenes-associated gastroenteritis reported in Austria. The occurrence of a secondary case of meningitis (diagnosed on day 19 after consumption of jellied pork) indicates a significant risk of systemic listeriosis among elderly patients with febrile gastroenteritis caused by L. monocytogenes; antibiotic therapy should therefore be considered in such cases of documented listerial gastroenteritis.