Table 1. Summary of nymphal Ixodes scapularis infection with Babesia microti, Borrelia burgdorferi ,and both, Nantucket Island, Massachusetts, and Connecticut, 2007 and 2010.

Region	Year became disease endemic	Year tick sample collected	B. burgdorferi infection prevalence (no. positive/no. tested)	B. microti infection prevalence (no. positive/no. tested)	Tick ratio*	Co-infection prevalence (no. positive/no. tested)
Nantucket, MA	1969	2010	0.21 (18/87)	0.09 (8/87)	2.33	0.01 (1/87)
Southeastern CT
Lyme	1996	2007	0.13 (23/182)	0.15 (28/182)	0.82	0.04 (8/182)
Old Lyme	1992	2007	0.20 (13/65)	0.20 (13/65)	1.00	0.06 (4/65)
Combined sites			0.15 (36/247)	0.17 (41/247)	0.88	0.05 (12/247)
Northeastern CT
Hampton	2007	2010	0.29(43/147)	0.10 14/147)	2.90	0.05 (8/147)
South Mansfield	2002	2010	0.11 (12/111)	0.09 (10/111)	1.22	0.01 (1/111)
North Mansfield	2002	2010	0.13 (18/139)	0.01 (1/138)	13.00	0.00 (0/138)
Willington	Not endemic	2010	0.36 (51/142)	0.03 (4/142)	12.00	0.02 (3/142)
Eastford	Not endemic	2007	0.31 (93/298)	0.03 (10/298)	10.33	0.03 (10/298)
Combined sites			0.26 (217/836)	0.05 (39/836)	5.20	0.03 (24/828)

*Ratio of I. scapularis ticks infected with B. burgdorferi and that of ticks infected with B. microti.