National Pig Association THE VOICE OF THE UK PIG INDUSTRY NPA is active on members' behalf in Brussels & Whitehall, and with processors, supermarkets & caterers – fighting for the growth and pros-perity of the UK pig industry.

And there are promising indications, from trials at Bishop Burton, that treatment of young pigs can significantly improve herd health and growth rates.

The principle behind the so-called "dirt vaccine" has been understood for several decades, ever since microbiologist Dr John Standford, and his wife Cynthia, worked among Ugandans afflicted with leprosy and tuberculosis.

Their experiences caused Stanford to argue that if children (and young animals) are not exposed to a wide range of bacteria, their immune system cannot learn which organisms to fight and which are beneficial.

He believes it is this absence of immune system learning in an increasingly clean world that has contributed to the current dramatic rise of allergic illnesses (such as asthma) in the developed world.

It is not suggested that pig producers throw away everything they have learned about biosecurity and deliberately expose young pigs to harmful organisms.

But it is thought that vaccination with mycrobacterium vaccae - now cultured in Britain from the original handful of mud taken from a specific site in Uganda - could play an important role in educating the immune system of young pigs.

So far in the Bishop Burton trials, the weight gain advantage has been in the region of 30 percent and none of the vaccinated pigs has shown signs of PMWS, whilst in the control group there have been six cases.

Professor Stanford's team has been in talks with potential commercial partners - but the frustrating aspect from producers' point of view is that getting a vaccine to market will take several years.

Mycrobacterium vaccae seems to unlock the body's power to fight a wide range of diseases. John Stanford began his research into the microorganism after noticing the incidence of diseases such as leprosy was different in different parts of Uganda. He found BCG (the vaccine usually used to fight tuberculosis and which sometimes also worked against leprosy) was effective in one particular region, where mycrobacterium vaccae was present.

Further investigation showed mycrobacterium vaccae shares many of its proteins with tuberculosis and leprosy. Research has been continuing since the 70s and the research team now believes - and its theory is increasingly accepted by other scientists - that we in the developed world are wrong to equate all bugs with disease; the majority are helpful and some are essential to our wellbeing.

According to immunologist Graham Rook, our desire to reduce contact with bugs has gone too far and may now be causing diseases in humans. He argues that if your immune system has not met sufficient germs during its development phase it will subsequently overreact when it does meet them, causing allergic illness, such as asthma.

Mycrobacterium vaccae was cultured at Middlesex Hospital and added to a vaccine, and in trials with animal proved more effective. In an extended prophylactic trial children in Iran were vaccinated and 12 years later none had contracted leprosy or tuberculosis. Therapeutic trials in a Spanish hospital for leprosy patient have also been positive.

Mycrobacterium vaccae, which is now cultured at Portland Down, is being trialled with asthma sufferers at Southampton Hospital and the indications are that symptoms can be reduced by 30 percent.

It has also being trialled with cancer patients receiving chemotherapy. Results give hope that in larger phase three trials around Europe it will be shown that survival can be improved by a statistically significant amount.

Meanwhile London University College trials with young pigs at Bishop Burton College continue and Professor Stanford and his colleagues continue to be encouraged by the results being achieved.

John Stanford is confident that as the trials progress it will become evident that PMWS can be prevented by using the mycrobacterium vaccae immunology treatment.

Source: National Pig Association - 21st July 2004