Liver fluke
The liver fluke is a small, flat, parasitic worm belonging to the genus Fasciola, primarily affecting the livers of various mammals such as cows, sheep, and horses. Growing to about two inches long, it is an asexual organism that feeds on the fluids of its host, particularly blood and bile. The liver fluke's life cycle is complex, involving multiple stages and different hosts, including snails, before it matures in the liver of a larger mammal. This parasite is a significant concern for livestock farmers, as it can lead to substantial economic losses, with millions of dollars reported lost annually due to liver fluke infestations. Environmental factors like rainfall and temperature can influence the liver fluke population, prompting control measures such as limiting snail hosts and administering medications to infected animals. The lifespan of a liver fluke can range from 9 to 15 years, and in some untreated cases, it may extend to 30 years. Overall, understanding liver flukes is crucial for managing their impact on livestock health and agricultural economies.
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Liver fluke
The liver fluke survives on the fluids of the livers in cows, sheep, horses, donkeys, camels, and many other such animals. It often becomes a pest to humans by infesting fields of livestock. Many countries lose millions of dollars in livestock each year to the problems caused by liver flukes.
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Echinostomida
Family: Fasciolidae
Genus: Fasciola
Species: Hepatica
The liver fluke is a small, flat, oval parasitic flatworm. It grows to about two inches (five centimeters) long. Like other parasitic flatworms, the liver fluke is bilaterally symmetrical with no definite head. Bilateral symmetry means that its body could be divided into two pieces and those pieces would be mirror images of one another. Liver flukes are not the only creatures with bilateral symmetry. Humans are also bilaterally symmetrical. If a human were to be split from top to bottom there would be two identical halves.
The liver fluke spends the majority of its life in the liver of a sheep, cow, donkey, horse, camel, or other such mammal. Like other parasitic flatworms, it feeds off of the fluids of its host. In the case of the liver fluke, the young liver fluke feeds mainly on blood and cells within the liver, while the adult feeds on fluids in the bile ducts. The liver fluke clings to its host's liver by the hooks, discs, suckers, and claws which are attached to one end of the liver fluke's body.
To reproduce, the liver fluke, which is asexual, or can reproduce independently of another organism, deposits its eggs into the waste of the host in which it lives. Up to 20,000 to 25,000 eggs go through a multitude of stages before finding hosts of their own. After leaving the body of the parent's host, the young hatch from their eggs in damp pastures. The young are now moving as miracidia larvae. During this larval stage, the young liver flukes move along the ground by moving their many cilia, or thin, fine, hairs. The larval liver flukes are searching for temporary hosts. These hosts are often snails.
Once inside these hosts, the miracidia larvae move to the snails' digestive tracks and mature into sporocysts and later into redia larvae. The redia larvae become cercaria larvae and leave the snails' bodies. Once outside the snails, the cercariae larvae roll into cysts in the grass. Sheep, cows, donkeys, horses, camels, or other mammals eat these cysts. Inside the animals' bodies, they move to the liver and mature in 10 to 14 weeks. Adult liver flukes lay eggs in their host waste, and the cycle continues.
Liver flukes are threatened by the environment when outside hosts' bodies and by the deaths of their hosts while living as parasitic flatworms. Humans often try to control the number of liver flukes in the environment to protect their livestock. In some countries, scientists can predict the yearly liver fluke population by measuring the monthly rainfall, evaporation, and temperature. In other places, the liver fluke population is controlled by limiting the number of available snail hosts. Scientists have also developed medications to give infected livestock to rid them of liver flukes.
The liver fluke's life span can be 9 to 15 years, though some untreated infections may continue for 30 years.
Bibliography
"Fasciola Hepatica – Classification." BYJU'S, byjus.com/biology/fasciola-hepatica-diagram. Accessed 15 May 2024.
"Lifecycle of Liver Fluke." SCOPS, www.scops.org.uk/internal-parasites/liver-fluke/lifecycle. Accessed 15 May 2024.
"Liver Flukes." Centers for Disease Control and Prevention, www.cdc.gov/parasites/liver‗flukes/index.html. Accessed 15 May 2024.