Blood cancers: Cancers like leukemia, myeloma, and lymphoma occur when blood cells start to divide uncontrollably with out dying off at the end of their life cycle. Ticks, leeches, feminine mosquitoes, vampire bats, and an assortment of other purely natural creatures do take in the blood of other animals, https://www.youtube.com/watch?v=buIHtQY7fCU