1.. The majority of Hanafi, Shafa`i and Hanbali scholars, and some of the Malikis, are of the view that if worms come out of the back passage, that invalidates wudu.
2.. Although it is proven that if worms come out of the back passage, that invalidates wudu, it does not make it obligatory to clean oneself, because the reason for cleaning oneself (istinja’) is the presence of impurity, and the purpose behind cleaning oneself with water or stones is to remove the substance of impurity from the surface of the body, except in the case where they contaminate the anus and the surrounding area with impurity. But if they do not contaminate the anus, then there is no requirement to clean oneself if they come out.