Side note: If you are really worried because 6 out of who knows how many barbecued in 2011–2012 (and two before that), you might have a fear issue. This is not very likely to happen to you looking at it from a statistically point of you.
However regarding your question, your best bet is simply to change away from using something with bristles to clean it. Opt for scrubs, cloths or other washing products.
If you have to use a wire brush, use one of good quality and replace it when it shows significant signs of wear and tear. After using the brush on the grill, if you rinse the grill rist with running water, you will further reduce the risk of bristles. You could even dry it off with cloths.
But please don't go paranoia on something which has a rather slim chance of happening.