There is no evidence to suggest that millipedes carry diseases that can harm humans or pets. Although some species of millipedes can produce a secretion that may cause skin irritation or discoloration, these incidents are rare and typically not severe. However, it's always a good practice to avoid handling millipedes with bare hands and wash thoroughly if you come into contact with them. Overall, although millipedes may look creepy and crawly, they are generally harmless creatures.