TABLE 2.

Genetic sequencing of PVs (n = 252), isolated from wastewater samples, by surveillance site and study period

Site	No. of isolates for which data are available	No. of strains with mutations (%)	Among strains with mutation							No. of isolates with intertype recombination (%)
			Median no. of mutations per strain (range)	No. of strains with ≥5 mutations (%)	Median % divergence from Sabin strain (range)	Median no. of transversions (range)	Median ratio of no. of transversions/total no. of mutations (range)	Median no. of silent mutations (range)	Median ratio of no. of silent mutations/total no. of mutations (range)	Total	S1/S2	S1/S3	S2/S1	S2/S3	S3/S1	S3/S2
All sites and periods combined	252	194 (77)	2 (1, 7)	6 (3)	0.22 (0.11, 0.77)	0 (0, 3)	0 (0, 1)	1 (0, 3)	0.50 (0, 1)	50 (20)	2 (4)	1 (2)	3 (6)	4 (8)	10 (20)	30 (60)
Córdoba City
Initial IPV period (May-10 August 2005)	5	4 (80)	2 (1, 5)	1 (25)	0.22 (0.11, 0.56)	0 (0, 0)	0 (0, 0)	1 (0, 2)	0.35 (0, 1)	1 (20)	0	0	0	0	0	1 (100)
From first OPV reintroduction (11 August 2005-April 2006)	129	104 (81)	2 (1, 5)	1 (1)	0.22 (0.11, 0.55)	0 (0, 3)	0 (0, 1)	1 (0, 3)	0.50 (0, 1)	26 (20)	2 (8)	0	0	2 (8)	3 (12)	19 (73)
Rio Cuarto	37	30 (81)	2 (1, 7)	2 (7)	0.22 (0.11, 0.77)	0 (0, 2)	0 (0, 1)	1 (0, 3)	0.50 (0, 1)	7 (19)	0	0	1 (14)	0	3 (43)	3 (43)
Villa Maria	39	29 (74)	2 (1, 5)	1 (3)	0.11 (0.11, 0.56)	0 (0, 1)	0 (0, 1)	1 (0, 3)	0.20 (0, 1)	9 (23)	0	0	2 (22)	0	3 (33)	4 (44)
San Francisco	42	27 (64)	2 (1, 7)	1 (4)	0.22 (0.11, 0.77)	0 (0, 1)	0 (0, 1)	1 (0, 3)	0.29 (0, 1)	7 (17)	0	1 (14)	0	2 (29)	1 (14)	3 (43)