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Beyond the Bale : Apr 07 - May 07
PROFILE Dr David Piedrafita Parasitologist and AWI postdoctoral fellow The parasitologist and the vampire worm When AWI recruited Dr David Piedrafita to the SheepGenomics Parasite Sub-program, they brought on board a passionate advocate for animal health and a researcher who somehow manages to genuinely admire the parasite he studies.The enthusiasm can seem a touch eccentric, given that the subject of Dr Piedrafita's intrigue and admiration is a bloodsucking worm. Nonetheless, as he enthusiastically describes its lifecycle he leaves you in no doubt that the barber's pole worm is something of a nightmare.The larvae squirm their way onto pasture where they are eaten by sheep, which allows the female worms to develop into an army of stomach-lacerating, bloodsucking, egg-laying aliens. Even the worm's scientific name is enough to make you squirm: Haemonchus contortus. Yet to hear Dr Piedrafita tell it, these worms are a high point of evolution.Their intricate behaviours and ingenious biochemical trickery makes them an opponent worthy of deep Australian Wool Innovation Limited AWI, GPO Box 4177, Sydney NSW 2001 production traits. Even so, given precedents in other hosts battling other parasites, Dr Piedrafita does think they stand a good chance of succeeding. In Dr Piedrafita's 'dirty lab', where larvae are harvested and cultured, it is easy to get caught up in the logic and his passion for AWI's biotechnological vision. So it takes a moment to register that somewhere along the line, the scientist has actually used the word "cute" in reference to the vampiric worms. He attempts to justify the description: "If you hold the adults in your hand you can actually feel them trying to burrow in," he says with deadpan congeniality. "It's like a massage, and rather nice." I remind him the worm's goal is to suck blood. "Which they can't do through human skin, " he quickly qualifies. After a pause, he feels obliged to add: "But I like worms ... everybody has their peculiarity." For the wool industry, that is a good thing. Internal parasitic worms, in particular Haemonchus contortus, cost the Australian wool and sheepmeat industry more than $200 million a year through production losses and treatment costs.With no new drugs on the horizon, since investment in sheep anthelmintics has been declining, the work of worm- loving researchers like Dr Piedrafita has become crucial. In 2004, Dr Piedrafita was awarded a three-year postdoctoral fellowship to assist him with his research. His ability to mentor and support students who are just beginning their research career is also evident, as he is the supervisor of an AWI-funded PhD student, Nick Robinson, at Monash University. Dr Piedrafita has also been involved with the annual AWI postgraduate conference. -- GIO BRAIDOTTI understanding: "With bacteria or viruses you only have to contain or kill one cell," he explains. "But worms are like a big battleship.You can hit it several times but that doesn't mean it will sink.You have to hit the engine room and that means understanding what drives the parasite. And then, of course, the driver is a biological mechanism -- it can change.The way they do that is pretty clever." This adaptability is precisely what is causing the sheep industry concern.The worm is steadily developing resistance to chemical drenches.While land-management practices can help, Dr Piedrafita is convinced that researchers need to start working on alternatives. "Some growers are already giving up farming because of parasites -- they have sheep that either don't grow or produce, or they lose too many animals." The numbers he quotes make for a disturbing snapshot. A sub-clinical infestation (with no visible signs of worms) can reduce wool growth by 10 per cent and weight gain by 30 per cent. A burden of 1000 worms can remove 50 millilitres of blood a day. If present in larger numbers, the worms can kill. "So what we are trying to do with SheepGenomics is mount a national effort over 10 years to bring biotechnology to bear on the problem," Dr Piedrafita says. "We know sheep can develop natural resistance to barber's pole worm, which means there are natural cellular, immunological and genetic responses that can tell us how to beat the worm.We should be able to use that knowledge to develop new drugs, vaccines, genetics, even markers for breeding programs." However, on the animal-breeding front the strategy comes with one catch. Most of the resistant sheep breeds are not very productive, and the SheepGenomics team is unsure whether worm resistance can be separated from the low PHOTO: BRAD COLLIS
Jun 07 - Jul 07
Feb 07 - Mar 07 Supplement