Table 1.

Prevalence of infection with Borrelia mayonii in nymphal Ixodes scapularis ticks fed as larvae on Peromyscus leucopus mice with active infections

Mouse number	No. fed B. mayonii-infected nymphs recovered from the mousea	Outcome for molted nymphs resulting from uninfected larvae fed at different time intervals after mice were exposed to infected nymphs
		4 wk after infection					12 wk after infection
		Detection of B. mayonii spirochetes from mouse ear biopsyb	No. fed larvae recovered	Detection of B. mayonii DNA in molted nymphs		Detection of B. mayonii spirochetes from molted nymphsb	Detection of B. mayonii spirochetes from mouse ear biopsyb	No. fed larvae recovered	Detection of B. mayonii DNA in molted nymphs		Detection of B. mayonii spirochetes from molted nymphsb
				No. positive nymphs/no. tested nymphs	Infection prevalence (95% CI)c				No. positive nymphs/no. tested nymphse	Infection prevalence (95% CI)c
42	10	+	175	32/50	0.64 (0.50–0.76)	+	+	129	12/50***	0.24 (0.14–0.37)	+
45	7	+	97	28/50	0.56 (0.42–0.69)	+	+	144	11/49***	0.22 (0.13–0.36)	+
48	3	+	146	44/50	0.88 (0.76–0.94)	+	+	77	6/50***	0.12 (0.06–0.24)	NT
49	4	+	136	36/50	0.72 (0.58–0.83)	+	+	45	17/41**	0.41 (0.28–0.57)	NT
51	1	+	81	36/50	0.72 (0.58–0.83)	+	+	52	1/49***	0.02 (0.00–0.11)	NT
52	4	+	125	47/50	0.94 (0.84–0.98)	+	+	115	7/50***	0.14 (0.07–0.26)	NT
56	9	+	200	49/50	0.98 (0.90–1.00)	+	+	162	26/50***	0.52 (0.39–0.65)	NRf
59	8	+	129	31/50	0.62 (0.48–0.74)	+	+	79	15/50**	0.30 (0.19–0.44)	+
60	8	+	75	16/24	0.66 (0.47–0.82)	+	+	75	28/50NS	0.56 (0.42–0.69)	+
84	7	+	87	39/50	0.78 (0.65–0.87)	+	+	51	4/41***	0.10 (0.04–0.23)	NT
41	4	+	32	17/29	0.59 (0.41–0.74)	NTd	NT	NT	NT	NT	NT
65	6	+	49	38/47	0.81 (0.67–0.90)	NT	NT	NT	NT	NT	NT
78	4	+	27	18/23	0.78 (0.58–0.90)	NT	NT	NT	NT	NT	NT
79	3	+	38	28/34	0.82 (0.66–0.92)	NT	NT	NT	NT	NT	NT
81	3	+	16	12/16	0.75 (0.51–0.90)	NT	NT	NT	NT	NT	NT
83	6	+	52	30/50	0.60 (0.46–0.72)	NT	NT	NT	NT	NT	NT
86	8	+	33	30/32	0.94 (0.80–0.98)	NT	NT	NT	NT	NT	NT
87	3	+	42	18/37	0.49 (0.33–0.64)	NT	NT	NT	NT	NT	NT
94	7	+	54	39/50	0.78 (0.65–0.87)	NT	NT	NT	NT	NT	NT
95	6	+	31	27/28	0.96 (0.82–0.99)	NT	NT	NT	NT	NT	NT
98	10	+	24	13/22	0.59 (0.39–0.77)	NT	NT	NT	NT	NT	NT
Subset of 10 mice examined at both time points				358/474	0.76 (0.71–0.79)				127/480***	0.26 (0.23–0.31)
All examined mice				628/842	0.75 (0.72–0.77)

^aTwenty potentially infected nymphs were placed on each mouse. Fed infected nymphs recovered from the mice may have included nymphs infected via cofeeding during the bloodmeal.

^b+, live B. mayonii spirochetes detected by culture.

^cPrevalence of B. mayonii infection in tested nymphs; 95% confidence intervals computed using score confidence intervals.

^dNT, not tested.

^eComparison between proportions of B. mayonii-infected nymphs resulting from larvae fed at 4 versus 12 wk after mice were infected; likelihood ratio test:

^NSP ≥ 0.05,

^*P < 0.05,

^**P < 0.01,

^***P < 0.001.

^fNR, no result due to contaminated culture.