New War on Parasites
Giardia. Not many Australians had heard of the parasitic organism before the contaminated water scares of Sydney and Adelaide hit news headlines around the country earlier this year.It is not that Giardia is uncommon. Millions of people around the world regularly fall sick from this parasitic organism which invades the human gut. Giardia can also cause disease in animals.But the disease is far more prevalent in under-developed countries where the lack of modern hygiene and sanitation facilities exacerbate the parasite's faecal-oral mode of transmission. Giardia causes severe diarrhoea in its victims, making for an unpleasant and uncomfortable illness which can prove very debilitating.In developed countries like Australia, Giardia rears its head in the less common instance of infection through water supplies and swimming pools - as in the case of Sydney and Adelaide. Roughly another four per cent of the Australian population come down with Giardiasis through food poisoning, most often in the form of "traveller's diarrhoea" picked up while on holiday. Giardia is also a common cause of diarrhoeal outbreaks in day care centres in Australia.Those who have had the misfortune to be struck down with Giardia may also have found out that the treatment can be as unpleasant as the cure. Flagyl is the most common drug used -- it tastes terrible and is often vomited, especially by children.But there is an alternative -- albendazole -- and the use of this drug to treat Giardia was pioneered by Murdoch's Division of Veterinary and Biomedial Sciences-based Institute for Molecular Genetics and Animal Disease (IMGAD) at Murdoch University.IMGAD began its research into albendazole almost ten years ago. At that time the unit had already established a reputation with the in vitro cultivation of Giardia -- no mean feat since cultivation of parasites outside a host is often difficult.This research came to the attention of international pharmaceutical company SmithKline Beecham, which asked the University if it was interested in testing the effects of albendazole on Giardia.IMGAD successfully demonstrated the efficacy of albendazole on Giardia in research funded by SmithKline Beecham.
Today the company markets albendazole as a relatively mild-tasting chewable tablet called "Zentel" which is registered and available in Australia."It was a rather serendipitous collaboration," recalls Andy Thompson, Professor of Parasitology at Murdoch University's Division of Veterinary and Biomedical Sciences. "SmithKline Beecham got a new lease of life for one of their old drugs and Murdoch University expanded its capability in an area in which it already had expertise." But that is not the end of the story. "We thought that if this drug worked for Giardia then why don't we try it against other protozoan parasites?" said Professor Thompson.Subsequent research showed that albendazole was also efficacious against protozoa like Cryptosporidium and Microsporidia which are common parasites of humans and animals but which are also significant in causing opportunistic infections in HIV positive patients. Albendazole is also effective against malaria, although not as potent as some other drugs currently used to treat the disease. However the discovery is still significant in terms of mass treatment. In places like Africa and Asia, where most of these tropical parasites thrive, clinicians may find it useful to administer one drug for various parasites rather than several different drugs.
The section of SmithKline Beecham that Murdoch University deals with is their "Tropical" diseases section.In the past ten years, this section of the company has funded IMGAD with more than $1.2 million to carry out research into protozoan parasites. Professor Thompson is quick to point out that the company is getting value for its money."IMGAD is particularly good at what it does because of the multidisciplinary approach it employs," said Professor Thompson. In addition to himself, other key players are Associate Professor of Pharmacology and Chemotherapy, Professor Jim Reynoldson and Biochemist, Dr Anthony Armson. The men are further backed up by a team of almost 20 scientists, consisting of post doctoral fellows, research assistants, graduate and undergraduate research students.IMGAD also benefits from its close association with Murdoch's State Agricultural Biotechnology Centre (SABC), where it conducts forms of specialised research such as genetic sequencing and other molecular biological aspects of the research.IMGAD also works closely with the State Government Chemistry Centre."A lot of the work we have done for SmithKline Beecham has paid off for them," emphasised Professor Thompson.On its part, SmithKline Beecham has been generous in terms of the latitude it has allowed IMGAD in conducting its research."A lot of other companies are very specific about what they want you to do for them," said Professor Thompson, "But we find that with SmithKline Beechham it's a really good relationship with sufficient flexibility to accommodate new directions in research."This leeway has been conducive to further serendipitous discoveries by IMGAD. Professor Reynoldson explained that another use for albendazole was in the treatment of hydatid cysts -- nasty tumour-like cysts caused by tapeworms which often have to be removed by surgery.Albendazole can sometimes treat the cysts, although it is more typically used peri-operatively -- meaning that the surgical area is flooded with albendazole to prevent further infection as the cyst is surgically excised, explained Professor Reynoldson.Research currently underway looks at improving the efficacy of albendazole to treat hydatid cysts by improving the uptake of the chemical into the body and the cysts.There is also research focusing on the target site for drugs since it was discovered that albendazole hits a target site in Giardia and other related protozoan parasites not previously explored.Research is focusing on improving the delivery of drugs to the target site, as well as modification of the drugs to fit the target site more precisely."It is a bit like a lock and key analogy," explained Professor Reynoldson "and what it means is that we may be able to produce new and better compounds for the treatment of protozoan parasites."IMGAD's work on protozoan parasites has also spawned work in related areas. The unit was recently commissioned by the National Pig Research and Development Corporation (PRDC) to investigate protozoa causing diarrhoea in piglets.The total funding of $160,000 provided by the PRDC includes a matching component of funds from the Pig Industry Compensation Fund of WA and will involve collaboration with clinician Dr Ross Buddle, epidemiologist Associate Professor Ian Robertson and molecular biologist Dr Una Morgan.According to Professor Thompson, IMGAD is developing an edge over its competitors because the unit is building up an extensive range of protozoan parasites which can be used for models in research, thus providing excellent opportunities for new research projects. |
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Dr Anthony Armson Institute for Molecular Genetics and Animal Disease Telephone (08) 9360 2457 email armson@numbat.murdoch.edu.au |
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Associate Professor Jim Reynoldson Institute for Molecular Genetics and Animal Disease Telephone (08) 9360 2227 email reynolds@numbat.murdoch.edu.au |
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Associate Professor Andy Thompson Institute for Molecular Genetics and Animal Disease Telephone (08) 9360 2466 email andrew_t@numbat.murdoch.edu.au |