Concurrent comparison of three water contact measurement tools in four endemic villages of the Philippines. The schistosomiasis transmission ecology in the Philippines project (STEP).

BACKGROUND

Schistosomiasis japonica is a chronic helminthic infection contracted through contact with water infested with Schistosoma japonicum. The infection is associated with severe disease and is an important public health concern in Philippines.

OBJECT

To estimate the agreement in the frequency of water contact between bimonthly interviews, self-administered diaries and observations.

METHODS

A total of 286 individuals were followed over either a 4 or a 6 months period. Agreement between direct observation and both the bimonthly and diary methods were estimated.

RESULTS

The agreement between the observation and the bimonthly interview was 71.8% when days without any water contacts were considered, but decreased to 23.3% when only days with at least some water contact were considered. The agreement between the observation and the diary was 78.7% when days without any water contacts were considered and 40.8% when only days with some water contacts were considered.

CONCLUSIONS

Agreement about the degree of water contact is poor between the different measurement tools. This has important implications for future research, since a high degree of measurement error can severely bias any results from studies involving water contact.