RESUMEN
Passive surveillance on the burden of disease due to diarrhoea will underestimate the burden if families use healthcare providers outside the surveillance system. To study this issue, a community-based cluster survey was conducted during October 2001 in the catchment area for a passive surveillance study in Zhengding county, a rural area of northern China. Interviews were conducted at 7 randomly-selected households in each of 39 study villages. The respondents indicated where they sought initial care for cases of diarrhoea or dysentery among children or adults. In the absence of diarrhoea and dysentery cases in the household in the preceding four weeks, the respondents were asked about healthcare use for a hypothetical case. Overall, 80% (95% confidence interval [CI] 67-93%) would chose the village clinic, 11% village pharmacy (95% CI 1-22%), 4% township hospital (95% CI -1-10%), 4% self-treatment (95% CI 1-8%), and 1% county hospital (95% CI 0-2%). Approximately, 84% of patients would seek treatment for diarrhoea and dysentery at centres participating in passive surveillance, suggesting that passive surveillance will provide a relatively accurate assessment of burden of diarrhoea in Zhengding county.