Two consecutive outbreaks of gastroenteritis due to infections with Salmonella Typhimurium DT193 in the Austrian Armed Forces, 2009
Abstract number: P1160
Pichler J., Fretz R., Much P., Kornschober C., Mayr G., Leodolter A., Allerberger F.
In 2008, the Austrian National Reference Centre for Salmonella, AGES, reported 21 isolates of Salmonella Typhimurium definite type 193 (ST DT193) in humans. In June 2009, 99 isolates, and in September 2009, 28 isolates from members of two military caserns in the province of Upper Austria were diagnosed with ST DT193. Consequently, AGES was assigned to investigate the outbreaks. The objective was to determine the magnitude of the outbreak and to identify the chain of transmission.
Methods: A descriptive-epidemiological investigation, a cohort study of the first outbreak, and a broad microbiological investigation were carried out. An outbreak case was defined as a person who (i) fell ill with diarrhoea between May 25 and June 7, respectively between Aug 31 and Oct 2, (ii) was on military duty in the relevant time period, or (iii) had a microbiologically confirmed infection with ST DT193.
Results: The attack rates were 27% in the 1st outbreak (122/450 persons from camp A), respectively 31% in the 2nd outbreak (61/200 members of a battalion during a field exercise, formed by persons of camps A+B). A continuous common-source outbreak was assumed in the 1st outbreak, based on the findings of descriptive and analytical epidemiology. Being on military duty between May 2531 (RR 9.3; p < 0.001) and consuming several different meals in the dining hall of casern A (RRs 2.09.09; p < 0.017) in the same time period were associated with illness. However, the further conducted microbiological investigations (such as eggs from the local egg producer) were all Salmonella-negative; and the vehicle of infection was not identified. The most probable link between the two outbreaks were the use of mobile cooking units and heating boxes from camp A, which underwent inadequate cleaning and thermal disinfection due to a failure of the steamer used. Furthermore, the washing facility in camp A was in a very poor hygienic condition and a consequent resoiling of cooking utensils from the floor was very likely.
Conclusion: In spite of extensive investigations in a clearly closed setting, the vehicle of infection was not identified. However, failure in the cleaning procedure of cooking utensils and poor kitchen hygiene in the camp A may account for the 2nd outbreak.
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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