(a) With the aid of an annotated diagram, describe the life cycle of the liver-fluke (Fasciola hepatica). Explain how you will prevent the liver-fluke from completing its life cycle in the field. (c) List three effects of lice on animal production.
Explanation
(a) Life Cycle of the Liver Fluke (Fasciola hepatica)
Liver fluke: The adult fluke is found in the bile duct of animals where it feeds and reproduces. The adult fluke reproduces eggs in the bile duct of the animal which are pass out with faeces from the primary host (Cattle, sheep etc) If the eggs and faeces are passed out by the ruminant into water, they develop to a larva called miracidium which will later hatch ten days later. This larva swims in the water, looks for a snail which is its secondary host (usually Limnea truncatula). It penetrates the snails skin or the pulmonary hole. It develops to a sporocyst within the snail. Through asexual reproduction the sporocyst reproduces a larva called radial. The radial ruptures from the sporocyst and migrate to the digestive gland of the snail. Here it grows to a final larva called cercaria. After six weeks this cercaria leaves the snail through the pulmonary hole and swims to look for the final host in the water. The cercaria is ingested by the ruminant through infested pasture or water. Then in animal stomach, it makes its way to the animal liver to the bile duct through the liver tissues. It grow to an adult fluke in the animal's bile duct
(b) The life cycle of the fluke can be disrupted by: Eliminating all the snails which are its secondary host in the waters where the ruminant animals drink or feed by spraying copper sulphate solution. Provide clear uninfested waters and feed for the animals. Control weeds along river sides. Periodic burning of pasture to kill eggs in faeces
(c) The Effects of Lice on Animal Production: They cause discomfort and irritation on f animals. They blood from animals leading to anaemia. They reduce production or yield of animals. They create the wounds for secondary infection. They transmit diseases. They reduce feed and water intake. They reduce the growth of animal/cause emaciation. Weaken the animals