All questions of the interview that was based on the vignette referred to the diarrhoeal illness of the person described in the vignette. Selected socio-demographic sellekchem variables were recorded at the outset before enquiring about illness-related experience, meaning and behaviour operationalised as categories denoting patterns of distress (referring to additional somatic symptoms not mentioned in the vignettes and psycho-social problems), perceived causes, self treatment at home, and outside help seeking. The selection of the most relevant locally valid categories of distress, perceived causes, and help-seeking behaviour required for a meaningful description of the insider’s perspective was based on discussions with local researchers, fieldworkers and focus group discussions among purposively selected community residents.

Study design and participant selection This cross-sectional survey was conducted prior to a mass oral cholera vaccination campaign to provide baseline data on community views of diarrhoeal illness in areas of Zanzibar at high risk for cholera among unaffected adults [21]. A simple random sample of 180 houses per site was drawn based on enumerated houses from an existing geographic information system for the peri-urban and a census database for the rural site. Sampled peri-urban houses were approached with the help of aerial photographs and a global positioning system device. Sampled houses in the rural community were located through census house numbers nailed on doorframes. If the house selected for sampling did not contain dwellings (e.g.

if it was a business place, mosque or under construction), then the field teams would move on to the house which was closest to the front door of the originally selected house. If the second house was not inhabited either, then a third house was identified following the above procedure, and so forth until a household with eligible participants was found. A household is defined by people sharing the same kitchen or pot. Eligible participants had to be 18 years or older and willing enough to give time for an interview of approximately one hour duration. Three field teams plus a coordinator on both islands were recruited by the MoHSW and trained in a ten-day workshop to conduct this survey. Each team consisting of an interviewer and a note taker completed on average two interviews per day.

Written informed consent was obtained from all participants prior to the interview and no compensation was offered to them. Data management and analysis strategy For cholera, the categories related to illness Cilengitide experience, meaning and help-seeking behaviour were coded for their prominence with a value of 2 after a spontaneous response, a value of 1 after a probed response and a value of 0 if not considered at all to reflect the response style.