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Objective: To establish the incidence and aetiology of infectious
intestinal disease in the community and presenting to general
practitioners. Comparison with incidence and aetiology of cases
reaching national laboratory based surveillance.

Setting: 70 general practices throughout England.

Participants: 459 975 patients served by the practices. Community
surveillance of 9776 randomly selected patients.

Results: 781 cases were identified in the community cohort, giving an
incidence of
19.4/100 person years (95% confidence interval 18.1 to 20.8). 8770
cases
presented to general practice (3.3/100 person years (2.94 to 3.75)).
One case
was reported to national surveillance for every 1.4 laboratory
identifications, 6.2 stools sent for laboratory investigation, 23
cases presenting to general practice, and 136 community cases. The
ratio of cases in the community to cases reaching national
surveillance was lower for bacterial pathogens (salmonella 3.2:1,
campylobacter 7.6:1) than for viruses (rotavirus 35:1, small round
structured viruses 1562:1). There were many cases for which no
organism was identified.

Conclusions: Infectious intestinal disease occurs in 1 in 5 people
each year, of
whom 1 in 6 presents to a general practitioner. The proportion of
cases not recorded by national laboratory surveillance is large and
varies widely by microorganism. Ways of supplementing the national
laboratory surveillance system for infectious intestinal diseases
should be considered.

Key messages
Infectious intestinal disease is common, with 9.4 million estimated
cases each year in England. In 1.5 million cases (1 in 6) patients
present to their general practitioner.
Only a fraction of these cases are reported to national laboratory
surveillance.
A greater proportion of cases due to common bacterial pathogens are
reported than cases due to common viral pathogens. Ways of
supplementing the national laboratory surveillance system for
infectious intestinal diseases should be considered.

Reference: Wheeler, J., Sethi, D. et al. 1999. Br. Med. J.
318(7190):1046-1050.
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[log in to unmask] (Liza May)