Ascarids infecting carnivorous companion animals such as dogs and cats do not only rely on a direct life circle but use paratenic hosts in addition. It is well known that small rodents can maintain viable, infective larvae of Toxocara canis and Toxocara cati for considerable time periods and ingestion of such paratenic hosts can lead to patent infections with a shortened prepatent period due to direct maturation of worms in the intestine without any somatic migration (Overgaauw: 1997). However, the epidemiologic contribution of these small vertebrates as paratenic hosts to maintenance of ascarids life cycles remains to be quantified in detail. In particular for free-running cats, the risk of injection with ascarids should probably increase with increasing praying success. Although rodents can be considered to be excellent indicators for public health risks associated with zoonotic diseases (Reperant et al.: 2009). Therefore, diagnostic tools using direct detection of parasites should be preferred. In Germany, the situation is further complicated by rapidly expanding populations of neozoa, i.e. racoons and racoon dogs which can successfully use the dog as a competent definitive host and can be highly pathogenic to humans. In rodents chronically infected with Toxocara larvae, high parasite burdens can most frequently found within the musculature and the central nervous system (Cho et al.: 2007). In a recently started epidemiological survey regarding small rodents as reservoir for tick-transmitted pathogens and the influence of co-infecting gastrointestinal parasites as modulators of reservoir competence, we are currently collecting wild rodents from urban and peri-urban locations in Berlin. The tissue samples obtained within this study are ideally suited to analyze the importance of small rodents as paratenic hosts in the maintenance of the life cycle of ascarids but also of hookworms. Within this project we will analyze the same sample set as used for detection of n