Table 3. Comparison between the ratio of Lyme disease and babesiosis incidence in humans and the ratio of Borrelia burgdorferi and Babesia microti infection in ticks (‘tick ratio’), New England, 2007 and 2010*.

Data source, y	Lyme disease†	Babesiosis†	Human ratio‡	B. burgdorferi§	B. microti§	Tick ratio¶	Human/tick ratio
Private practice
Nantucket, 2010	7,500	1,250	6.0	0.21	0.09	2.33	2.6
Northeastern CT, 2010	660	70	9.4	0.26	0.05	5.20	1.8
Reported to CT DPH or MA DPH
Nantucket, 2010	194	56	3.5	0.21	0.09	2.33	1.5
Northeastern CT, 2010	211	7	30.0	0.26	0.05	5.20	5.8
Southeastern CT, 2007	191	85	2.3	0.15	0.17	0.88	2.6

*CT DPH, Connecticut Department of Public Health; MA DPH, Massachusetts Department of Public Health.
†Annual incidence rates of Lyme disease and human babesiosis calculated for the towns and years for which tick assessments were conducted by using private practice or state-reported cases and mid-year population estimates from CT DPH (23) and MA DPH (24).
‡Ratio of human Lyme disease incidence rates to babesiosis incidence rates.
§Nymphal Ixodes scapularis tick infection prevalence with Borrelia burgdorferi and Babesia microti.
¶ Ratio of I. scapularis ticks infection prevalence with B. burgdorferi and infection prevalence with B. microti.