Double Trouble on the Lower Leg—Unique Human Coinfection with Echinococcus granulosus and Echinococcus multilocularis Without Liver Involvement

The tapeworms <i>Echinococcus granulosus</i> and <i>Echinococcus multilocularis</i> cause two different clinical manifestations in humans: cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. Both forms of echinococcosis manifest primarily in the liver, while other organs or tissues are less frequently affected. Simultaneous occurrence of CE and AE is extremely rare, and all previously reported patients exhibited affected livers, while simultaneous infection without liver involvement has not yet been described. Herein, we present an exclusively extrahepatic <i>E. granulosus</i> and <i>E. multilocularis</i> coinfection localized between the calf muscles of a patient. Due to progressive painful local swelling, an abscess was suspected, but there was no improvement after the administration of multiple courses of antibiotics. When imaging diagnostics suggested a parasitic origin of the two identified cystic lesions, positive serology for both species indicated a dual infection. Albendazole therapy was started, and extensive surgical excision was performed. Both species were confirmed using PCR and sequencing from intraoperative samples. The current case shows that coinfection without liver involvement can occur, even in patients from low-incidence regions, which should be considered in the differential diagnosis of patients with unusual clinical presentation.