Not a Dead-End Host: First Confirmed Persistent Microfilaremia in Human Dirofilaria repens Infection.

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.