Expansion of zoonotic Babesiosis and Lyme Disease and comparison with human cases in Connecticut, 2001-2010

We analyzed reservoir host sera for seroreactivity to Borrelia burgdorferi and Babesia microti and reviewed Connecticut human surveillance case data collected during 2001-2010. While seroprevalence to B. burgdorferi and Lyme disease is widespread in the state, the highest human babesiosis and rodent seroprevalence rates were still in New London County, where this protozoan disease was first documented in the state. Nevertheless, human cases and reservoir host infection for babesiosis increased significantly from 2001-2005 to 2005-2010 and in other parts of the state. Babesiosis is not confined to long established endemic areas of Connecticut.