Liver Fluke

 

The liver fluke, or Fasciola hepatica, is a parasitic worm distributed worldwide which infects the liver of many species of mammals, including humans. The degree of disease depends on the type of host it is infecting and it has a great economic impact in cattle and other production animals, as an infected animal has impaired meat and/or milk production. Vaccination would be a desirable tool for controlling the parasite, as cases of resistance to anti-parasitic drugs are being reported from many different locations.

Cathepsin L1 (CL1) is a protein secreted by Fasciola hepatica throughout the liver infection of the host.  It is involved not only in host invasion, but also in nutrition and in preventing the immune response of the host clearing the infection. A synthetic form of this protein (FhCL1) was considered a good option for vaccination as it has conserved antigenic properties, is very stable and could be produced in vitro in large quantities (Dalton et al., 2003). In several experimental trials and one small-scale field trial, protective effects could be detected, with a decrease in fluke burden and impaired helminth development in vaccinated animals (Golden et al., 2010).

Within the PARAVAC project, that vaccination protocol is being tested now in a large scale field trial, with more than 200 commercial bulls and cows vaccinated and maintained in usual farm conditions, exposed to the natural infection.

After vaccination, blood samples are collected periodically from each animal to measure how well they are responding to the vaccine. Faecal samples are also collected, for counting of fluke eggs, and productivity data from the animals is collected.

All routine treatments are provided to the animals as usual, with exception of flukicide treatment. As these are commercial animals, and those eventually going for slaughter will have their livers collected for fluke burden analysis.




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