Seasonal prevalence of some zoonotic trematode infections in cattle and pigs in the north-east montane zone in India.

Seasonal variations in the prevalence of Fasciola gigantica and Eurytrema pancreaticum in cattle, and Opisthorchis noverca, Artyfechinostomum malayanum, Fasciolopsis buski and Gastrodiscoides hominis in pigs, were studied post-necropsy over a 1 year period in a humid, subtropical north-east hilly region in India. The overall prevalence rate was 53.02% in cattle (n = 960) and 12.92% in pigs (n = 960). Fasciola gigantica and E. pancreaticum occurred throughout the year with peaks during cold winter months. Both species showed a high intensity of infection in winter and a low intensity during summer and autumn. The rate of infection due to A. malayanum, Fasciolopsis buski and G. hominis rose to a peak during June-September and thereafter declined to a low level (November-March). Except for the month of February, O. noverca occurred throughout the year, with the highest rate of infection in late autumn and winter. The abundance of infection due to A. malayanum, Fasciolopsis buski and G. hominis was high during late summer and early autumn. Opisthorchis noverca showed a higher density during late autumn and winter.