Detection and characterisation of hepatitis E virus in naturally infected swine in Croatia

Hepatitis E is a viral zoonotic disease infecting swine worldwide. Since pigs represent a likely animal reservoir for the hepatitis E virus, the epidemiology of naturally occurring hepatitis E was investigated in Croatian swine herds. Nearly all tested animals were seropositive for antibodies against the hepatitis E virus (55/60, 91.7%). Active infection was detected in all age groups by RT-PCR of viral RNA in serum (8/60, 13.3%) and bile samples (3/37, 8.1%), which was further confirmed by histopathological findings of characteristic lesions in the livers of the infected animals. Three new strains of hepatitis E virus were isolated from Croatian pig herds. Phylogenetic analysis using median-joining networks clustered those Croatian strains with isolates from various parts of the world, indicating their likely origin in international trade. Similarity to human isolates implies a zoonotic potential of Croatian strains, which raises a public health concern, especially in the light of the high prevalence of hepatitis E in the herds studied.