Known as babesiosis, the disease is caused by a microscopic parasite that attacks blood cells, causing flu-like symptoms that can make it difficult to accurately diagnose. Like Lyme disease, which is caused by bacteria, babesia microti parasites are carried by deer ticks.
http://yourlife.usatoday.com/health/story/2011/07/A-deadly-new-reason-to-avoid-deer-ticks/49212700/1