During August 2015, a boil water notice (BWN) was issued across parts of North West England following the detection of Cryptosporidium oocysts in the public water supply.
Using prospective syndromic surveillance, we detected statistically significant increases in the presentation of cases of gastroenteritis and diarrhea to general practitioner services and related calls to the national health telephone advice service in those areas affected by the BWN.
In the affected areas, average in-hours general practitioner consultations for gastroenteritis increased by 24.8% (from 13.49 to 16.84) during the BWN period; average diarrhea consultations increased by 28.5% (from 8.33 to 10.71). Local public health investigations revealed no laboratory reported cases confirmed as being associated with the water supply. These findings suggest that the increases reported by syndromic surveillance of cases of gastroenteritis and diarrhea likely resulted from changes in healthcare seeking behaviour driven by the intense local and national media coverage of the potential health risks during the event.
This study has further highlighted the potential for media-driven bias in syndromic surveillance, and the challenges in disentangling true increases in community infection from those driven by media reporting.
The potential impact of media reporting in syndromic surveillance: An example using a possible Cryptosporidium exposure in north west England, August to September 2015
Euro Surveill. 2016;21(41):pii=30368. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.41.30368
AJ Elliot, HE Hughes, J Astbury, G Nixon, K Brierley, R Vivancos, T Inns, V Decraene, K Platt, I Lake, SJ O’Brien, GE Smith