Increased stool sampling during a waterborne outbreak of cryptosporidiosis does not increase the detection of other faecal pathogens

Aims: To ascertain the effect of enhanced surveillance following an outbreak of waterborne cryptosporidiosis on the number of faecal specimens submitted to the local microbiology laboratory and the number positive for common enteric pathogens. The outbreak provided an opportunity to estimate the extent of routine under ascertainment of common enteric pathogens. Method: Retrospective search of the computerised microbiology system database for details of faecal examination requests for the period 26 April to 6 June in 1998 and 1999 (period of outbreak). Results: Specimens were received from 378 community patients during the six week period 26 April to 6 June 1999. This was double that for the same period in 1998 (a non-outbreak year). Oocysts of Cryptosporidium parvum were detected in 59 patients, an eightfold increase compared with the same period in 1998. Despite the greater number of patients tested, the detection of other pathogens in patients with gastroenteritis was not altered when compared with the same period in the previous year. Conclusion: This study found no evidence of under ascertainment of gastrointestinal infection (common bacterial pathogens and rotavirus) by local general practitioners.