Utility of Borrelia burgdorferi sensu stricto C6 Peptide for Serologic Confirmation of Erythema-Free Ixodid Tick-Borne Borrelioses in Russia

Table 2

Sensitivity of B. burgdorferi C6 peptide based PHOSPHAN tests for serum IgM and IgG antibody detection in samples from ITBB patients prior to treatment (N = 391).

Patient Group	Number (%) of positive serum samples at the baseline in ITBB patients as a function of disease duration
	<7 days				≥ 7 days
	No. of patients	C6 IgM	C6 IgG	C6 IgM/IgG	No. of patients	C6 IgM	C6 IgG	C6 IgM/IgG
EM patients	133	16 (12.0)	50 (37.6)	56 (42.1)	58	16 (27.6)	30 (51.7)	35 (60.3)
EM/HGA patients	42	13 (31.0)	21 (50.0)	23 (54.8)	43	19 (44.2)	31 (72.1)	34 (79.1)
EM/TBE patients	11	2 (18.2)	2 (18.2)	3 (27.3)	6	1 (16.7)	1 (16.7)	2 (33.3)
EMF patients	24	5 (20.8)	5 (20.8)	8 (33.3)	7	2 (28.6)	2 (28.6)	4 (57.1)
EMF/HGA patients	31	3 (9.7)	4 (12.9)	6 (19.4)	9	6 (66.7)	5 (55.6)	7 (77.8)
EMF/TBE patients	19	7 (36.8)	8 (42.1)	11 (57.9)	8	1 (12.5)	5 (62.5)	5 (62.5)

EM = erythema migrans, EMF = erythema migrans-free, EM/HGA = EM patients coinfected with HGA agent, EM/TBE = EM patients coinfected with TBE virus, EMF/HGA = EMF patients coinfected with HGA agent, and EMF/TBE = EMF patients coinfected with TBE virus. Statistically significant differences (Fisher’s exact test, p < 0.05) were observed for comparison of pairs: C6 IgM versus C6 IgG in EM patients at EM duration <7 days and ≥7 days; C6 IgM versus C6 IgG in EM/HGA patients at EM duration ≥7 days; C6 IgM at disease duration <7 days versus C6 IgM at disease duration ≥7 days in EMF/HGA patients; C6 IgG at disease duration <7 days versus C6 IgG at disease duration ≥7 days in EMF/HGA patients. All other comparisons were not statistically significant.