Reappearance of human diphyllobothriasis in a limited area of Lake Como, Italy.

BACKGROUND: Very few sporadic cases of autochthonous diphyllobothriasis have been reported in Italy during the past 20 years, probably due to the drastic decrease or disappearance of some fish species, mainly Perca fluviatilis L., known as the intermediate host of the infective larval stage of this tapeworm. However, increasing consumption of raw or undercooked fish during the last years as influenced by Oriental cuisine, played an important role in a number of new single cases of the infection or microepidemics. PATIENTS: We describe six cases which were diagnosed within a period of 4 months, which all originated from the area of Lake Como (Lombardy region). All subjects had previously eaten raw perch fillets. Four individuals complained of gastrointestinal signs and symptoms, whereas two were asymptomatic. DISCUSSION: Parasitological diagnosis was achieved in four cases by recovery of typical operculated eggs in stool specimens; in two others by morphological features of proglottids recovered from feces. Treatment with niclosamide, as a single oral dose, cured the infection in all subjects. This is the first report of this infection in Italy in the last 10 years.