Gone but not forgotten

 
 

The imminent eradication of rinderpest represents a significant scientific achievement, writes Alison Lee

The list of diseases successfully eradicated by mankind is by no means an extensive one. Until recently, the list consisted of just one item – smallpox, which was eradicated in 1979. However, smallpox may soon be joined by another disease: rinderpest.

Also known as ‘cattle plague’, rinderpest is a disease of domestic cattle and some wildlife. There are records of its existence from as far back as 3000BC and its devastating effects on livestock in Europe motivated the foundation of the first college of veterinary medicine in the world in Lyons in 1761. More recently, in 1924, the World Organisation for Animal Health was established in order to combat the disease.

You may wonder why such effort was put into eradicating an infection of livestock when there are so many human diseases out there to be combated. However, it must be remembered the huge impact livestock diseases can have on a country’s economic and food production capabilities.

Even though many of us were in primary school back in 2001, most people can remember horrific scenes of Britain’s foot and mouth outbreak of enormous pyres of dead cattle, JCBs digging mass graves and devastated farmers robbed of their livelihood. International sporting events were cancelled and travel to and from England was strictly controlled, as the nation was plunged into a state of emergency.

So imagine what the situation would be like if an even more deadly disease like rinderpest was still rampant. In severe outbreaks, rinderpest has an almost 100 per cent mortality rate. Vets nickname its symptoms the three Ds, discharge, diarrhoea and death. Even though rinderpest can’t infect humans, one third of the human population of Ethiopia died in the famine that resulted after the disease ravaged the cattle population there in the 19th century.

Yet rinderpest was not infallible, due mostly to the development t of an effective vaccine. Walter Plowright, an English veterinarian, pioneered viral vaccine research in the 1950s and developed the TCRV (Tissue Culture Rinderpest Vaccine). He grew, or ‘passaged’ the virus in cell culture, until he obtained a harmless strain of the disease that could safely be administered to animals, promoting an immune response.

Henceforth, animals that are naturally infected can effectively overcome the virus and don’t experience clinical disease. This vaccine was cheap, effective and easily administered. In fact, the cost of the eradication of rinderpest is estimated to be a mere $3 million. This has been money well spent, with over 70 million tonnes of meat and one billion tonnes of milk produced in the developing world since the introduction of the vaccine. Sadly, Plowright passed away on February 19th 2010, before the official announcement of rinderpest’s eradication.

That official announcement hasn’t been made just yet, but delegates at the Global Rinderpest Eradication Symposium held in Rome this October, were confident that eradication would be officially announced in May 2011. Until then, disease status reports from various countries involved will be reviewed to confirm that the disease is really gone.

But can we ever be certain that a disease has been completely eradicated? In the 1970s, the Inter-African Bureau for Epizootic Diseases commenced a plan (entitled JP15) to completely eradicate rinderpest from Africa.

Between 1967 and 1972, cattle were regularly vaccinated and it seemed that rinderpest had indeed been pushed to extinction on the African continent. However as former colonies gained independence, new governments refused to implement follow up vaccinations and the disease broke out all over again thanks to war and disorganisation. There is no guarantee that this won’t happen again.

In addition, rinderpest doesn’t just infect cattle: it can be maintained in reservoir wildlife populations such as gazelle, wildbeest, buffalo and even giraffes and hippos which can then spread it back to farm animals. So although the disease may be declared officially eradicated, follow-up monitoring will continue for years to confirm that rinderpest, which hasn’t broken out since an episode in Kenya in 2001, is really gone for good.

Eradication of a disease with such a vast global distribution was no mean feat, especially considering most of the affected nations don’t possess much in the way of veterinary, agricultural or scientific infrastructure. These include notoriously dangerous, war-torn countries such as Iraq, Afghanistan and Pakistan. Yet vets, NGOs and agricultural scientists managed to co-ordinate and implement disease testing, surveillance and vaccination, co-operating with local farmers and governments.

Let us not omit praise where it is due: the Irish government’s financial management hasn’t received much praise in the press recently, but not all the money spent over the last decade went to waste. Our government created a trust fund, which supported the rinderpest eradication campaigns in Brunei, Belarus, Serbia and Armenia. In fact, Ireland donated a huge amount of aid to the Global Rinderpest Eradication Programme; hence a little Irish flag is displayed on official GREP documentation.

It is rare to hear a success story these days (much less one that involves money and Ireland), but readers should take heart at the news of rinderpest eradication. It is a huge step forward for the developing world, for global food production and for medicine. It is also a great achievement for science – one that all involved should be proud of.

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