No abstract

From 1992 to 1994, a prospective case-control study designed to identify preventable risk factors for Toxoplasma gondii infection in pregnancy was conducted in Norway. Case-patients were identified through a serologic screening program encompassing 37,000 pregnant women and through sporadic antenatal testing for Toxoplasma infection. A total of 63 pregnant women with serologic evidence of recent primary T. gondii infection and 128 seronegative control women matched by age, stage of pregnancy, expected date of delivery, and geographic area were enrolled. The following factors were found to be independently associated with an increased risk of maternal infection in conditional logistic regression analysis (in order of decreasing attributable fractions): 1) eating raw or undercooked minced meat products (odds ratio (OR) = 4.1, p = 0.007); 2) eating unwashed raw vegetables or fruits (OR = 2.4, p = 0.03); 3) eating raw or undercooked mutton (OR = 11.4, p = 0.005); 4) eating raw or undercooked pork (OR = 3.4, p = 0.03); 5) cleaning the cat litter box (OR = 5.5, p = 0.02); and 6) washing the kitchen knives infrequently after preparation of raw meat, prior to handling another food item (OR = 7.3, p = 0.04). In univariate analysis, travelling to countries outside of Scandinavia was identified as a significant risk factor, but this variable was not independently associated with infection after data were controlled for factors more directly related to the modes of infection.

In 1999-2000, a prospective case-control study of sporadic, domestically acquired campylobacteriosis was conducted in three counties in Norway to identify preventable risk factors and potentially protective factors. A total of 212 cases and 422 population controls matched by age, sex, and geographic area were enrolled. In conditional logistic regression analysis, the following factors were found to be independently associated with an increased risk of Campylobacter infection: drinking undisinfected water, eating at barbecues, eating poultry bought raw, having occupational exposure to animals, and eating undercooked pork. The following factors were independently related to a decreased risk: eating mutton, eating raw fruits or berries, and swimming. Results indicated that infection is more likely to occur as a result of cross-contamination from raw poultry products than because of poultry consumption per se. Drinking undisinfected water, reported by 53% of cases, was a leading risk factor in this study. Drinking water may constitute the common reservoir linking infection in humans and animals, including poultry and wild birds. Insight into the ecology of Campylobacter in freshwater ecosystems may be required to understand the epidemiology of campylobacteriosis. The possibility that certain foods confer protection against campylobacteriosis deserves exploration.

In all temperate countries campylobacter infection in humans follows a striking seasonal pattern, but little attention has been given to exploring the epidemiological explanations. In order to better characterize the seasonal patterns, data from nine European countries and New Zealand have been examined. Several European countries with weekly data available showed remarkably consistent seasonal patterns from year to year, with peaks in week 22 in Wales, week 26 in Scotland, week 32 in Denmark, week 30 in Finland and week 33 in Sweden. In Europe, the seasonal peak was most prominent in Finland and least prominent in Scotland and Austria. In New Zealand the seasonality was less consistent since the peak was more prolonged. Possible explanations for the seasonal peaks are discussed. Research into the causes of campylobacter seasonality should help considerably in elucidating the sources of human infection.