5th ASM - Orals Epidemiology

Session 1: Thursday 4 June, 09.30

The first presentation provided the results of a study leaded by Jaap Wagenaar (Utrech University) in The Netherlands in veal calf farmers. The purpose of the study was to demonstrate that the veal calf farming is a risk factor for MRSA colonization in humans. 390 farmers and their family members were investigated. MRSA prevalence was 33% in farmers and 8% in family members, results suggesting a short colonization in human directly exposed to the infected veal calf. A longitudinal approach needs to be performed.

Agnetha Hofhuis (RIVM, Biltoven) presented the results of a survey on congenital toxoplasmosis in The Netherlands. The usual protocol was suspected to under-estimate the prevalence of the infection. Working on dried blood spot filter paper cards (10008) collected in 2006, the RIVM teams concluded that in The Netherlands children were born asymptomatic, not detected and not treated, are likely to develop later in life symptoms.

Bettina Weiss, from the Robert Koch Institute (Berlin), presented the characteristics of food workers with infectious gastro-enteritis in Berlin in 2006-2007. Food workers with infectious gastro-enteritis are implicated in the spread of food-borne diseases. They analyzed the characteristics of notified food workers and estimated the length of pathogen excretion. They concluded that the case-management should consider that the period of excretion is lasting for weeks with period of intermittently negative test results.

The last presentation was related to the detection of Hepatitis E virus in wild boars in Sweden. Frederik Widen (SVA Uppsala) presented the phylogenetic analysis of positive samples collected from wild boars in different regions of Sweden. A particular phylogenetic pattern for HEV in wild boars was demonstrated and the relations with the human and swine strains discussed.

Chair: André Jestin (AFSSA)

Session 2: Thursday 4 June, 16.45

EPI24: Rene Bødker - Geographic clusters of Salmonella cases in Europe.
This was a multicentre study using data collected by the Salmonella Atlas. Three complementary statistical tests for spatial autocorrection (Global G, SaRScan and Local Gi*), combined with a measure for geographical clustering, were chosen to generate maps revealing both national and transnational clusters of high incidence rates (hot spots) and low incidence rates (cold spots). The methods identified significant clustering of the annual proportional distribution of all ten selected serotypes when screening data from 25 countries over a six year period. Hot and cold spots were the results of both stable patterns of serotype endemicity as well as temporary changes and outbreaks. It was suggested the spatial methods may be useful for future routine analysis of joint European data.

EPI02: Werner Espelage - Characteristics and risk factors for Giardia lamblia infections in Germany.
A case-control study of Giardia patients in Germany was conducted from February 2007 to January 2008. 120 cases and 240 controls were included. Cases were more likely to be male, immunocompromised and to have eaten green salad daily. It was concluded that a substantial proportion of cases in Germany was due to autochthonous infections. It was suggested that physicians should consider infections not only in patients with travel-associated diarrhoea, but also in patients without travel history especially when impared immunity was present. Green salad was an important vehicle for those infections.

EP123: Claus Stark - Trends in human Campylobacter incidence and association with climate factors, Germany, 2001-2007.
Trends in climatic factors (daily temperature and humidity) and relationship to Campylobacter incidence available from the national surveillance database were investigated. Annual data showed that incidences were highest in June-September. Temperature and humidity showed a clear association with incidence explaining 68% of the seasonal variation. Most notably an increase of 1oC in the mean temperature in the five preceding weeks was associated with an increased human incidence of 5.1%. Prevalence data for poultry (broilers) did not explain the seasonal variation as the data paralleled that of human incidence. It was suggested that high temperature might also increase prevalence in other livestock and increase environment and food consumption risks.

EPI27: Yvonne Doornduyn - Case-case comparison of Campylobacter coli and C. jejuni infections and age-, season- and degree of urbanization‑specific risk factors for C. jejuni infections. A case-control study comparing 1,315 C. jejuni cases, 121 C. coli cases and 3,409 frequency-matched controls was conducted in The Netherlands in 2002-2003. Consumption of chicken was identified as a predominant risk factor for C. jejuni infection but a variety of other risk factors e.g. barbequed meat consumption and use of proton pump inhibitors, were identified with some unique risks for the very young and elderly. Unique risk factors for C. coli infection were consumption of game and tripe, and swimming. The study confirmed that important differences in exposures exist for the two species of Campylobacter and that differences depended to some extent on age, season or degree of urbanization.

EPI25: Chris Lane - Is proximity to cattle farms an important explanatory variable for VTEC O157 infections in England and Wales? A GIS enabled analysis.
Risks of Escherichia coli VTEC O157 infection due to environmental contamination by animals, muck spreading and increased public use of the countryside were investigated by analysis of the spatial distribution of cases of infection against locations of cattle. The analysis included two control types: randomly selected control postcodes as being representative of the general population and cases of Typhoidal Salmonella as representative data for an infection with little or no relationship with cattle (that subgroup comprised travel related cases, predominantly of Indian ethnic origin). Sporadic cases of VTEC O157 were more likely the closer the residence was to a cattle holding when compared to randomly selected locations – for instance in the case-control analysis, cases were 4.5 times more likely to be within 0.5km of cattle holding than the Typhoidal controls. Proximity to cattle holdings is therefore a potential variable for analysis of VTEC O157 infections in England and Wales, particularly in the absence of epidemiological data.

Chair: Robert Owen (HPA)