Thursday, February 04, 2010

BCG - how it works

From Dr. Ueli Zellweger we have received the following explanation of how BCG vaccination - the live attenuated strain of Mycobacterium bovis known as Bacillus Calmette-Guérin (BCG) - works.

Defra are keen to use this in hotspot areas (where badgers are known to have endemic tuberculosis) The vaccine may or may not work, they really do not know, but are on record as hoping 'it won't make matters worse'. The jabs will need to be repeated at least every twenty months. And that, together with advice on bio security, constitutes Defra's 'eradication policy' for tuberculosis in England..
Why BCG does not perform like other Vaccines

In any normal infection the body defence works by production of vast amounts of antibodies. Such antibodies can also be stimulated by ordinary vaccines for all kinds of bacteria and virus diseases and they can be traced in blood which makes diagnosis with various techniques fairly easy.

But this does not work for Tuberculosis – it never did and it never will do – because the tubercle bacteria have a waxy coat to which antibodies cannot attach. Tuberculosis therefore causes a so called humoral body defence; that means the very slowly multiplying bacteria are attacked by enzymes and white blood cells mainly. These are killing or even digesting the bacteria by a method called phagocytosis resulting in crumbly pus in the so called tubercles – whole heaps or lumps containing several 1000 to billions of bacteria.

This defence is much more unspecific and slower than the usual one by antibodies.

Any BCG vaccine stimulates this humoral defence only but never prevents an infection; it may keep it on a low scale maybe. There is no other vaccine available and there most probably will never be another one.

No matter how many millions more DEFRA invests ( I hear of some 30 so far for the Vaccine only ) this is nature - which cannot be forced by politics.
Dr. Ueli Zellweger
More on Defra's badger vaccine scoping project, it's progress and time scale here.

We have added the following link to an email sent to by virologist Dr. Ruth Watkins who explains how BCG works when injected and also points out:
BCG is not effective if given after infection with M bovis or M tuberculosis.

All those queueing up to 'vaccinate' badgers endemically infected with TB, please note....

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