A Western-blot test will determine if our white blood cells can recognize a bacterium that cause Lyme disease. If they can, it means that we had contact with such bacteria (or still do). Sounds great, huh? Bad news. There is no way to determine with 100% accuracy if our white blood cells can recognize Lyme.

Let me explain why. The test will check if our defence system can react against specific antigens. Now, what is the antigen? It's a protein at surface of - in this case - a bacterium. As soon as such protein is detected, white blood cells will attack. Now sounds complicated? Ok, here comes simple picture:

Let's say that Lyme spirochete is an elephant. White blood cells - our hunters - are like blind ones, they need to touch elephant before they recognize him. Ok, here comes... a tail... um.. trunk.... it got 4 legs... Where is problem? They cannot judge how big this trunk is and if it really belongs to the elephant.

Our white blood cells cannot react against "An animal that got 4 legs, a tail and trunk". They must attack everything that got trunk, every animal with 4 legs etc.

See problem? Not only elephants got - for example - trunks. Some other animals too, for example an elephant seal or anteater.

In other words, the Western Blot detects if our body had contact with animals which:

- have grey skin
- have trunk
- have tail
- have 4 legs
See now, why a single band (let's say p 17) does not judge if one had Lyme? Simple as this, the single band can be inducted by thousand of causes. Usually it was a contact with spirochetes, but not always.

Let's go back to normal language. The single band, for example 41, means that our body had contact with the bacterium that use a flagellum to movement. Lyme spirochetes use such device, but at least hundred of others bacteria use it too.

I suppose there is no single human being without at least single "positive" band in an IgG Western Blot test.

Of course there are more and less specific antigens, for example the 39th band is known as one of most specific ones (nearly always means that it was Lyme bacteria), some others are 31, 34 and 93

Ok. now let's talk about differences between the IgG and IgM test. It's really simple, IgM means that our body had the contact with such "elephant" just now. It's far more sensitive, because only few animals got the grey skin, trunk and tail and 4 legs. The positive IgM test (3 or more bands) nearly always means active Lyme.

The positive IgG test means that our body had contact with such animal long time ago, sometimes it detects even 10 years old ones. It's pretty possible that our body saw a turtle 5 years ago and an elephant seal 2 years ago, they give together the animal with 4 legs, trunk, grey skin and tail.

Now time for a trick - antibiotics usually kill some spirochetes, so they become "visible" to our defence system (alive ones very often can trick our immunoglobulins). It means that after the antibiotic treatment we should expect the positive IgM test result. Once this method was used to detect syphilis - another disease that might be "invisible" while spirochetes are alive.

Now two other facts - one, that there is NO specific antigen for Lyme. It means, we can get a lot of positive bands without even single contact with bacterium. Another fact - Lyme can change shape, so neither known test can detect it. It might change from elephant to an animal with wings, yellow skin and 6 legs.

Keep in mind that blood for the western-blot must be tested quickly, otherwise it might give a completely false (false negative) result.