Clostridium difficile-associated disease – a newly notifiable disease in Ireland

Background: In May 2008, all new cases Clostridium difficile-associated disease (CDAD) became notifiable in Ireland. Recurrent cases are not notifiable. Since the 1^st August 2009, national collation of C.difficile enhanced surveillance commenced on a voluntary basis in Ireland.
Objective: To review the data from the above two national surveillance initiatives to 30^th September 2009 and provides an overview of the epidemiology and burden of CDAD in Ireland.
Methods: Notification of new CDAD cases occurs within the disease category acute infectious gastroenteritis (AIG). Information on case type, origin and onset of CDAD is collected in the enhanced surveillance scheme. CDAD case definitions proposed by the European Centre for Disease Control are employed.

Results: From 4^th May 2008 – 30^th September 2009, 3134 CDAD cases were notified; 1624 cases in 2008 (weeks 19-53) and 1510 cases in 2009 (weeks 1-39), giving an estimated annual national crude incidence rate of 57.8 cases per 100,000 population in 2008 and 48.3 cases per 100,000 in 2009. There has been a gradual decline in national CDAD notifications, however it is difficult to determine the statistical significance because of the relatively short lifespan of the surveillance system.  Notified cases were more likely to be female (59%) and older (mean age 74 years [range 2-110 years]). Cases were commonest among hospital inpatients (( 62.2% ) with  7.5% classified as GP patients, 2.8% hospital outpatient, 1.5% ‘other’, 0.2% hospital day patient and 25.8% either “not specified” or “unknown”. No  seasonal trend was evident due to an incomplete annual data set.

Twenty seven hospitals have submitted enhanced CDAD data on 128 cases since August 2009.  The majority of cases were in females (57.8%) and in the over 65 age group (68.8%). Nineteen percent were recurrent CDAD - 33% of these were classified as being of community origin and onset. The majority of all cases were healthcare-associated (74.2%); 53.9% from hospital, 5.5% from nursing homes and 9.4% from other hospitals. Community associated cases accounted for 22.7% of all cases, 90% of whom had symptom onset in the community. The onset of CDAD occurs predominantly in healthcare settings (71.1%); 57% in hospital, 5.5% in nursing homes and 5.5% in other hospitals. However, a large proportion of all cases have symptom onset in the community (27.3%).

Conclusions: The collation of national data on C.difficile through both surveillance systems has provided a valuable insight into the burden of CDAD in Ireland, including the incidence of recurrent CDAD and the burden of CDAD outside acute hospitals. Moreover, the collection of data on the origin and onset of CDAD will help to direct appropriate preventative and control programmes at a national level.