Changes

Chronic fasciolosis in sheep is caused by adult flukes in the bile ducts and is usually seen in February and March, 4-5 months after ingestion of metacercariae. However, cases may present in early summer if snails become infected during the winter. Progressive weight loss over weeks to months results in poor body condition, and anorexia is often seen. As adult flukes feed on blood and are capable of consuming 0.5ml each per day, anaemia and pallor frequently occur in chronic fasciolosis. Initially, this regenerative anaemia is normochromic, but becomes hypochromic as iron reserves are depleted. Hypoalbuminaemia may also result from whole blood loss, and from reduced hepatic production. This gives a reduced plasma oncotic pressure, leading to ascites and/or submandibular oedema in advanced cases.

Chronic fasciolosis in sheep is caused by adult flukes in the bile ducts and is usually seen in February and March, 4-5 months after ingestion of metacercariae. However, cases may present in early summer if snails become infected during the winter. Progressive weight loss over weeks to months results in poor body condition, and anorexia is often seen. As adult flukes feed on blood and are capable of consuming 0.5ml each per day, anaemia and pallor frequently occur in chronic fasciolosis. Initially, this regenerative anaemia is normochromic, but becomes hypochromic as iron reserves are depleted. Hypoalbuminaemia may also result from whole blood loss, and from reduced hepatic production. This gives a reduced plasma oncotic pressure, leading to ascites and/or submandibular oedema in advanced cases.

In some cases, sub-acute fasciolosis may occur if infections has occured over a prolonged period. In these instances, disease is caused by both adult flukes and larvae and ill thrift, lethargy, dyspnoea is seen from around December to March.

In some cases, sub-acute fasciolosis may occur if infection has occured over a prolonged period. In these instances, disease is caused by both adult flukes and larvae and ill thrift, lethargy, dyspnoea is seen from around December to March.

In addition to these presentations, ''[[Fasciola hepatica]]'' has subclinical effects on sheep. Fleece weight and fibre quality are affected by even small fluke burdens, and there is some evidence that lambing percentage and lamb growth rates may be negatively influenced. Condemnation of affected livers at slaughter also causes economic losses.

In addition to these presentations, ''[[Fasciola hepatica]]'' has subclinical effects on sheep. Fleece weight and fibre quality are affected by even small fluke burdens, and there is some evidence that lambing percentage and lamb growth rates may be negatively influenced. Condemnation of affected livers at slaughter also causes economic losses.