Hello. My friend has 4 chinchillas, two pairs in two different cages. The last 2 times we cleaned one pair 's cage, it had worms in it!!!! Many of them!!!!! We clean their cages once a week, the other cage has no problem. We put the same hay and food in both cages, but the one has worms and the other not.. Any possible reasons?? Note, it 'summer here in Greece.