Abstract

In this exploratory investigation for determining the relative importance of transmission routes for Campylobacter, we estimated human exposure via each transmission route. Thirty-one routes were considered, of which 19 occur via ingestion of food, 9 via direct contact (e.g. pet animals) and 3 via water (e.g. swimming). The method used for calculating the number of ingested campylobacters was simple. For foods, for example, this is the product of the following parameters: the amount of food ingested per person per day, for the total population; the fraction of contaminated food in the shops; the Campylobacter concentration in contaminated food in the shops; the fraction surviving after heating. The uncertainty in the point estimates for the parameters was considered using probability distributions. The estimation of many parameters was difficult due to lack of data. Statements on differences between transmission routes are only possible to a limited extent due to the large uncertainties of the estimated exposures. The direct contact routes children's farms animals and farm animals show high exposure. Swimming in recreational water is an important water route. Raw foods (e.g. raw milk, raw chicken) also cause high exposure, usually higher than heated foods. The exposure via water, food and direct contact adds up to 0.0015, 0.050 and 0.084 campylobacters per person per day, respectively. The model parameters that most strongly determine the model output - consumption of raw food for food routes, amount of ingested faeces for direct contact routes and water purification for water routes - are important to investigate further.