Acute Eimeria tenella infection
This is the appearance of the gut of a chicken approximately 5 days after infection with a large number of infective oocysts of E.tenella. The caecae are distended and filled with blood due to the massive cell destruction resulting from the cycles of asexual reproduction (schizonts and merozoites). This form of the infection can lead to rapid mortality often characterised with bloody diarrhoea.