| Summary: | We conducted a case-control study to investigate risk factors for acquiring autochthonous alveolar echinococcosis in Germany. Forty cases and 120 controls matched by age and residence were interviewed. Patients were more likely than controls to have owned dogs that killed game (odds ratio [OR] = 18.0), lived in a farmhouse (OR = 6.4), owned dogs that roamed outdoors unattended (OR = 6.1), collected wood (OR = 4.7), been farmers (OR = 4.7), chewed grass (OR = 4.4), lived in a dwelling close to fields (OR = 3.0), gone into forests for vocational reasons (OR = 2.8), grown leaf or root vegetables (OR = 2.5), owned cats that roamed outdoors unattended (OR = 2.3), and eaten unwashed strawberries (OR = 2.2). Sixty-five percent of cases were attributable to farming. Measures that prevent accidental swallowing of possibly contaminated material during farming or adequate deworming of pet animals might reduce the risk for alveolar echinococcosis. Human alveolar echinococcosis is caused by the larval stage (metacestode) of the fox tapeworm Echinococcus multilocularis, which usually develops in the liver of infected persons. Slow larval growth results in an asymptomatic phase of several years before diagnosis. When left untreated, the condition is lethal (1). Although modern treatments have considerably improved survival, complete cure is rare (2–4). E. multilocularis occurs worldwide in many arctic and temperate zones of the northern hemisphere (5). Its life cycle is predominantly sylvatic; several carnivorous species such as the fox, wolf, and coyote serve as definitive hosts that excrete the eggs in their feces. Several small rodent species, such as the vole, lemming, and muskrat, serve as intermediate hosts; they become infected by oral intake of the eggs, and the larvae develop in their liver. In Europe, the red fox (Vulpes vulpes) is the main definitive
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