Longitudinal study of infectious intestinal disease in the UK (IID2 study): incidence in the community and presenting to general practice

Abstract

Objectives: To estimate, overall and by organism, the incidence of infectious intestinal disease (IID) in the community, presenting to general practice (GP) and reported to national surveillance.

Design: Prospective, community cohort study and prospective study of GP presentation conducted between April 2008 and August 2009.

Setting: Eighty-eight GPs across the UK recruited from the Medical Research Council General Practice Research Framework and the Primary Care Research Networks.

Participants: 6836 participants registered with the 88 participating practices in the community study; 991 patients with UK-acquired IID presenting to one of 37 practices taking part in the GP presentation study.

Main outcome measures: IID rates in the community, presenting to GP and reported to national surveillance, overall and by organism; annual IID cases and GP consultations by organism.

Results: The overall rate of IID in the community was 274 cases per 1000 person-years (95% CI 254 to 296); the rate of GP consultations was 17.7 per 1000 person-years (95% CI 14.4 to 21.8). There were 147 community cases and 10 GP consultations for every case reported to national surveillance. Norovirus was the most common organism, with incidence rates of 47 community cases per 1000 person-years and 2.1 GP consultations per 1000 person-years. Campylobacter was the most common bacterial pathogen, with a rate of 9.3 cases per 1000 person-years in the community, and 1.3 GP consultations per 1000 person-years. We estimate that there are up to 17 million sporadic, community cases of IID and 1 million GP consultations annually in the UK. Of these, norovirus accounts for 3 million cases and 130,000 GP consultations, and Campylobacter is responsible for 500,000 cases and 80,000 GP consultations.

Conclusions: IID poses a substantial community and healthcare burden in the UK. Control efforts must focus particularly on reducing the burden due to Campylobacter and enteric viruses.

Figure 1

Recruitment in the cohort study, Infectious Intestinal Disease 2 Study, UK 2008–9.

Figure 2

Recruitment in the general practice presentation study, Infectious Intestinal Disease (IID) 2 Study, UK 2008–9.

Figure 3

Age-specific rates of infectious intestinal disease general practice (GP) consultations—estimates from the cohort and general practice presentation studies, Infectious Intestinal Disease 2 Study, UK 2008–9.

Figure 4

Patterns of reporting to national surveillance for all infectious intestinal disease (IID), UK 2008–9. Black numbers represent the rates (with 95% CIs) in the community, presenting to general practice and reported to national surveillance. Red numbers represent the ratios of incidence in the community and presenting to general practice respective to the incidence of infectious intestinal disease reported to national surveillance (with 95% CIs).

Figure 5

Patterns of reporting to national surveillance for Campylobacter, Salmonella, norovirus and rotavirus, UK 2008–9. Black numbers represent the rates per 1000 person-years (with 95% CIs) in the community, presenting to general practice and reported to national surveillance. Red numbers represent the ratios of the incidence rates in the community and presenting to general practice compared with infectious intestinal disease reports to national surveillance (with 95% CIs).