The tapeworms Echinococcus granulosus and Echinococcus multilocularis 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 E. granulosus and E. multilocularis 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.

We report the first confirmed case of persistent microfilaremia in a human host infected with Dirofilaria repens. A 54-year-old woman from an endemic area in Croatia presented with peripheral eosinophilia and dermatological symptoms. Over four months, microfilariae were repeatedly detected in her blood using thick smears and Knott’s test, and the diagnosis was molecularly confirmed via COI gene sequencing and detection of Wolbachia endosymbionts. This case provides compelling evidence that D. repens can sustain a complete or near-complete life cycle in humans under specific conditions. Our findings have significant implications for clinical diagnostics, One Health surveillance, and public health interventions.

The tapeworms Echinococcus granulosus and Echinococcus multilocularis 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 had affected liver, while simultaneous infection without liver involvement has not yet been described. Hereby, we present an exclusively extrahepatal E. granulosus and E. multilocularis coinfection localized between the calf muscles of a patient. Due to progressive painful local swelling, an abscess was suspected, but there was no improvement on multiple antibiotic courses. When imaging diagnostics suggested a parasitic origin of the two identified cystic lesions, positive serology on 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 the low-incidence regions, which should be considered in the differential diagnosis of patients with unusual clinical presentation.