A DUBLIN scientist has develop a vaccine against liver fluke, a disease which costs Irish farmers some £30 million a year. If the vaccine proves successful, it could mean that this common disease will one day be eradicated.
Dr John Dalton, a biologist at Dublin City University, has spent eight years studying the parasite. The vaccine he developed has been patented around the world and is now being commercially developed by the Irish arm of a multinational firm, Mallinckrodt Veterinary. It could be on sale by 2000.
Although vaccines against bacteria and viruses are common, vaccines against larger parasites like liver fluke and malaria have been less successful, Dr Dalton - who claims the DCU vaccine may be one of the first against a veterinary parasite, says he and his team were successful because they started by trying to understand the parasite.
Dr Dalton is convinced that the DCU approach will be successful and already he's working on a possible vaccine against liver fluke in humans, and on a similar tropical disease, bilharzia.
The liver fluke is a small parasitic flatworm that must spend part of its complex life in a fresh water snail - and so the disease mostly occurs on wet and poorly drained land - and part in the liver of a mammal. "It eats its way through the liver, puncturing holes in it", Dr Dalton said.
A badly infected animal can be weakened by the blood loss, or die from liver failure. Sheep are, especially susceptible, but cattle and other animals are also vulnerable, while an estimated 17 million people are infected, mostly in South America and China.
In Ireland, farmers dose animals twice a year with drugs. But the new vaccine, Dr Dalton told The Irish Times, should be cheaper and safer: it would actually protect the animal against the disease, not leave any residue in the animal or on the pasture, and there is no problem of drug resistant forms of the disease developing.
Dr Dalton said that on average the numbers of parasites found in vaccinated animals during clinical trials were less than 30 per cent of the levels seen in other animals, and that vaccinated animals did not have any signs of disease. These results have now been submitted to a scientific journal.
And, because of the way the vaccine was designed, any eggs produced by parasites that survive the vaccine don't hatch.
Dr Dalton says that this breaks the vicious cycle of infection and reinfection and means it should be possible to eradicate the disease in the long term.
Dr P.J. Quinn, professor of parasitology at UCD's Veterinary College, said yesterday that he could not comment on Dr Dalton's work, as he was not familiar with the research. However, he added that "if there is an effective vaccine against liver fluke it would be enormously important".