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A goat is not just for Christmas
Animal health in the developing world.
Goats were the surprise hit of last year’s Christmas present-giving season. A longer-term challenge, though, is to keep them healthy.
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Two of the greatest problems facing the world are hunger and poverty. Domestic animals are inextricably linked to both. One-quarter of the world’s poor depend on animals, not just as a source of food, but as a source of income. For farmers in developing countries, animal ownership is the route to prosperity and wellbeing. Imagine, then, the fallout that an outbreak of livestock disease has on the rural poor. It can devastate whole families, local communities and affect a nation’s economy.
The
Animal Health in the Developing World initiative focuses on livestock diseases in the developing world and their impact on human health and wellbeing. Awards for this £25 million Wellcome Trust grant scheme have just been made. The projects supported combine high-quality research with a focus on issues directly relevant to livestock owners in impoverished countries.
What exactly are livestock keepers’ needs? Their main preoccupation is to maintain the health of their livestock. In practice, this means stopping, or at the very least controlling, the diseases that frequently sweep through their herds. But vaccines, diagnostics or treatments also have to be affordable and applicable to difficult climates. Practicalities are crucial.
The projects funded address the development of vaccines, drugs and diagnostics. On the ‘wanted’ list are contagious bovine pleuropneumonia, peste de petits ruminants, sleeping sickness, African swine fever, theileriosis, and schistosomiasis. Nematode parasites affecting sheep and goats, as well as the tapeworm Taenia solium in pigs, are also targets.
But the initiative’s remit is not simply about finding new interventions – it is also about local capacity building. The Trust is keen to encourage collaborations between scientists and the local communities – livestock keepers, animal health practitioners and policy makers – to help identify their real needs and research priorities. There will be an emphasis on practical help: on educating and training animal health practitioners to ensure knowledge transfer and the uptake of the newly emerging technologies.
To guarantee people’s opinions are heard and communities become aware of animal health issues, the Wellcome Trust has set aside a further £3 million for the
Livestock for Life scheme to be launched in June 2005. As part of the Animal Health in the Developing World initiative, the goal of this scheme is to strengthen links between livestock keepers, practitioners, researchers, policy makers and other stakeholders working in the field of international animal health.
Small animals, big problems
What could be more appetising than an edible vaccine?More than a tasty morsel for goats and sheep, it could become a cheap, much-needed solution for the poorest farmers in developing countries.
Molecular biologist Professor Michael Baron, at the
BBSRC Institute for Animal Health at Compton, UK, has pioneered a plant-based vaccine to tackle the peste des petits ruminants, a debilitating disease of sheep and goats which kills between 20 and 60 per cent of infected animals.
“The problem with peste des petits ruminants is that it is spreading such a lot,” Professor Baron points out. In the last 15 years, this virus has spread throughout the Middle East and the Indian subcontinent, and there have even been a few outbreaks in Turkey. Goat and sheep owners tend to be the poorest of the poor since those who cannot afford to keep cows choose small animals instead. As a result, it is the poorer farmers that are worst hit by this disease.
Although there are vaccines, they are out of people’s reach: the cost of the vaccine often exceeds the value of the sheep or goat. Instead, an edible vaccine that does not need cold storage or experts to administer it would be cheap to make and easy to swallow.
Professor Baron began a collaboration with scientists based in Bangalore, India, who genetically modified the peanut plant, Arachis hypogea, to make a new type of viral protein in its leaves. They chose the H protein, which is on the outside of the virus and is known to be recognised and targeted by the host immune system.
When fed to animals, these plants provoked the host’s defence mechanisms. In mice, sheep and goats, animals fed the leaves of the plant produce the right kind of antibodies. But do these antibodies actually stop the virus?
The only way to find out is to expose the animals to the live virus. This cannot be done without the appropriate containment facilities. The Wellcome Trust funding is allowing Professor Baron to work with the Bangalore-based scientists to test their vaccine further. Because the necessary facilities are not available in Bangalore, those trials will be run in the UK.
If the vaccine proves effective, its big advantage will be low cost. And livestock keepers will be able to feed the vaccine to the animals themselves. “My hope is that a disease that is troublesome to a lot of people who have far more troubles than they need will be controlled or at the very least suppressed,” says Professor Baron.
Theileria trickery
A taste for milk could be partly to blame for the epidemic of Theileria, a single-celled parasite, which is killing cattle in North Africa, the Middle East and India.
To meet a growing demand for milk, many of these countries imported animals with superior milk-producing characteristics. “The problem is that these introduced animals are much more susceptible to Theileria than indigenous species,” says Professor Ivan Morrison, an immunologist at the University of Edinburgh. As a result, some 240 million cattle in these areas are at risk of infection.
Professor Morrison’s project, which has recently been awarded funding through the Animal Health in the Developing World initiative, is aimed at exposing the parasite’s trickery and understanding its epidemiology to deliver better prevention methods. The parasite hijacks the host’s white blood cells, forcing them to divide. “It has a clever mechanism: when the host cell divides, the parasite divides too,” says Professor Morrison. The result is an acute lymphoproliferative disease known as tropical theileriosis that kills its victim.
Although 240 million cattle are at risk of infection, it is smallholders that are by far the worst hit. The only existing chemotherapeutic agent, buparvaquone, is far too expensive for small farmers. And in areas where it has been used extensively, there have been reports of emerging drug resistance.
Fortunately, the Theileria annulata genome has been fully sequenced by the
Wellcome Trust Sanger Institute in collaboration with Professor Andy Tait’s team at the University of Glasgow, which will no doubt speed the development of a new vaccine.
Professor Morrison plans to use this genetic information to identify molecules that are involved in the host–parasite interaction. “It would provide us with ways of producing attenuated parasites,” he says – a key step towards effective vaccines.
In addition to the research, Professor Morrison will be engaged in a substantial training programme with collaborators in Tunisia and Turkey. Researchers and technicians working on the project will have opportunities to interact with the partner institution to acquire expertise in various areas. The idea is to strengthen local capability – to train researchers who, in the long term, will be able to take the work forward within their own institution. “It is important to get the balance right,” says Professor Morrison. “The research and the training, both are important objectives of the project.”
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