Lymphatic filariasis elimination endgame in an urban Indian setting: the roles of surveillance and residual microfilaremia after mass drug administration

Table 2 Filarial test strips (FTS) findings among primary school children (6–7 years) of Surat City in transmission assessment survey (TAS) (2016)

Name of the Evaluation Unit	Central & East Zone (EU1)	West, South-West & North Zone (EU2)	South & South-East Zone (EU3)
Estimated number of 6–7 years children in EU	71 969	67 435	72 576
Total number of 6–7 years enrolled in schools	53 982	51 065	54 432
Total number of primary schools in EU	333	340	368
Average number of 6–7 year students per school	162	150	147
Sample size for cluster design	1692	1692	1692
Number of clusters	30	30	30
Sampling fraction	0.41	0.44	0.45
Sampling Interval	2.44	2.26	2.21
Critical cut off	20	20	20
Total FTS done	1850	1865	1849
Total FTS positive	6	10	12
FTS positive born outside Surat	5	10	11
FTS positive in areas with poor sanitation	6 out of 6	10 out of 10	12 out of 12
Total FTS negative	1691	1715	1702
FTS invalid^a	153	140	135
Antigenemia %	0.35	0.58	0.7

^aOf these 428 invalid tests, approximately 258 (60%) occurred on the first day (of four) of the TAS survey

ISSN: 2049-9957