Changes

*Large numbers of metacercariae ingested over a short period of time leads to acute disease.

*Large numbers of metacercariae ingested over a short period of time leads to acute disease.

*Smaller numbers ingested over a longer period of time leads to chronic disease.

*Smaller numbers ingested over a longer period of time leads to chronic disease.

*'''Feed intake''' - fluke infections causes reduced food intake. Note: chronic fasciolosis occurs at a time of year when animals are on a low plane of nutrition. This combined with the reduced food intake causes significant effect on the development and severity of clinical and subclinical fasciolosis.

*'''Feed intake''' - fluke infections cause reduced food intake. Note: chronic fasciolosis occurs at a time of year when animals are on a low plane of nutrition. This combined with the reduced food intake causes significant effect on the development and severity of clinical and subclinical fasciolosis.

*'''Species susceptibility''' - the proportion of flukes that reach the bile ducts is determined mainly by the fibroplastic potential of the liver and the effectiveness of the protective immune responses (which are ineffective in sheep). Therefore, establishment rate: '''sheep>cattle>pig'''.

*'''Species susceptibility''' - the proportion of flukes that reach the bile ducts is determined mainly by the fibroplastic potential of the liver and the effectiveness of the protective immune responses (which are ineffective in sheep). Therefore, establishment rate: '''sheep>cattle>pig'''.