[Field application of antibody detection in a low transmission area of Schistosoma japonicum].

Objective: To evaluate the field application of IHA and ELISA for schistosomiasis japonica detection at low transmission status.
Methods: 728 and 799 persons were examined by Kato-Katz's method, IHA and ELISA for schistosomiasis in an endemic village in the year of 2008 and 2010, respectively. The results of IHA and ELISA was evaluated in comparison to that of Kato-Katz (27 slides with 3 stool specimens) used as gold standard.
Results: The positive rate of Kato-Katz's method, IHA and ELISA were 10.3% (75/728), 40.0% (291/728) and 40.1% (292/728) in 2008, and 3.8% (30/799), 31.5% (252/799) and 40.1% (320/799) in 2010 respectively, in which significant difference was observed for the result between Kato-katz's method (chi2 = 26.92, P < 0.05) and IHA (chi2 = 11.82, P < 0.05). The consistency between the result of antibody detection and that of Kato-Katz's method was poor, lower than 0.2 (P < 0.01). If routine screening diagnosis mode was adopted, namely, population screened with IHA or ELISA first and confirmed with Kato-Katz's method, correlation analysis showed that the positive rate of Kato-Katz's method increased with the number of stool specimens and slides (rIHA2008 = 0.922, rELISA2008 = 0.908, rIHA2010 = 0.749, rELISA = 0.798; P < 0.05) . Those with egg positive but missed by IHA or ELISA mainly were cases with low infection intensity. When EPG < or = 40, the rate of detection ranged from 66.1% (39/59) to 87.0% (20/23) with IHA, and 62.7% (37/59) to 100% (23/23) with ELISA. When EPG > 40, however, all cases could be detected with ELISA, but some missed with IHA.
Conclusion: In low transmission areas, the determination of target population for chemotherapy should be based on the examination of nine slides per stool specimen by Kato-Katz's method after serological screening.