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• Norovirus outbreaks in England and Wales : 2003 and 2004
• Increase in RSV activity in England: prophylaxis with palivizumab appropriate for 'at risk' infants
  

 

Norovirus outbreaks in England and Wales : 2003 and 2004

 

 

The Health Protection Agency's Communicable Disease Surveillance Centre (CDSC) has collected standardised data on general outbreaks of infectious intestinal disease (IID) since 1992 (1).   Norovirus is the most common cause of IID in England (1,2).   The number of outbreaks of IID due to norovirus varies, but is generally between 130 to 250 outbreaks each year.   Two distinct peaks of norovirus activity occurred in England and Wales since 1992: one   in 1995-96 with 368 outbreaks, and in 2002 there was an unusually high number of outbreaks (686) that coincided with the emergence of a new variant genogroup II 4 (3) (figure 1).  

Figure 1 Norovirus outbreaks in England and Wales: 1992 to 2004

Provisional data*

Seventy-nine per cent of all outbreaks reported have occurred in healthcare settings, either in hospitals or residential care homes.   Hotels (7%) and schools (5%) are the next most frequent settings.   Table 1 shows the mode of transmission and setting of norovirus outbreaks in England and Wales between 1992 and 2004.

Table 1 Mode of transmission for norovirus outbreaks England and Wales : 1992 to 2004

Outbreak setting	Number of Foodborne outbreaks (%)	Number of person-to-person outbreaks (%)	Number of other/unknown outbreaks (%)	Total
Food outlets	89 (58.2)	38 (24.8)	26 (17.0)	153
Hospitals	12 (0.9)	1222 (93.2)	77 (5.9)	1311
Residential homes	32 (2.7)	1066 (91.0)	74 (6.3)	1172
Schools	4 (2.8)	129 (89.0)	12 (8.3)	145
Hotels	51 (23.8)	140 (65.4)	23 (10.7)	214
Other	39 (28.3)	88 (63.8)	11 (8.0)	138
Total	227 (7.3)	2683 (85.6)	223 (7.1)	3133

Outbreaks in the healthcare sector show a marked seasonality with peak occurrence in the winter months (figure 2), although other settings do not appear to show this seasonal pattern.   Outbreaks in healthcare settings are also associated with higher rates of mortality and last longer than outbreaks in other settings, but tend to involve fewer people and are less likely to be foodborne (1).   A recent study in the South West of England examining the impact of IID outbreaks in healthcare settings, showed norovirus to be the predominant cause and was identified in 63% of outbreaks.   The cost to the health service in England was estimated to be £115 million after extrapolating the cost of bed days lost plus staff absence.   Outbreaks were seen to be shorter when control measures were implemented quickly, such as closing wards to new admissions within four days of the beginning of the outbreak (4).

Figure 2 Seasonality of norovirus outbreaks in England and Wales by outbreak setting: 1992 to 2004

In 2003 there were 220 outbreaks of IID due to norovirus and by October 2004 148 outbreaks had been reported to CDSC. The regions with the highest number of outbreaks in 2003 are the North West and Yorkshire and Humberside. To date, the North East and Yorkshire and Humberside have the highest number of outbreaks reported in 2004 (table2).

Table 2 Norovirus outbreaks in England and Wales : 2003 to 2004

Region	Year
	2003	2004*
North East	36	37
Yorkshire And Humberside	46	30
East Midlands	2	2
East of England	38	15
London	10	12
South East	10	10
South West	7	13
West Midlands	12	6
North West	52	23
Wales	7	-
Total	220	148

*Data provisonal.

Seventy-eight per cent of norovirus outbreaks identified in 2003 were in the healthcare settings and 74% in 2004 (table2).  

The most common mode of spread is person-to-person.   Of all outbreaks identified since 1992, 86% occurred via this route of transmission, 4% through contaminated food, and 3% through food followed by person-to-person.   Table 3 shows the setting for outbreaks in 2003 and 2004.  

Table 3 Norovirus outbreaks in England and Wales by setting: 2003 to 2004

Setting	Year
	2003	2004*
Hospital/residential care home	171	110
Hotel	11	6
School	20	18
Restaurant	4	3
Club/centre	6	3
Other	8	8
Total	220	148

*Provsional data.

The majority of outbreaks are spread from person-to-person with 88% in 2003 and 87% in 2004 spread in this manner (table 4)

  Table 4 Norovirus outbreaks in England and Wales by mode of spread: 2003 to 2004

Mode of spread	Year
	2003	2004
Person-to-person	183	125
Foodborne	5	2
Foodborne then person to person	4	1
Water	-	1
Other	-	2
Unknown	28	17
Total	220	148

*Provsional data.

From September to mid November 2004 there have been 33 reports of outbreaks of IID due to norovirus, similar number of outbreaks to that seen in the same period in 2003.   The number of outbreaks in 2004 will rise as further reports are received and all data for 2004 are provisional at this time.

 

References

 

1. Lopman BA, Adak GK, Reacher MH, Brown DWG.   Two epidemiologic patterns of norovirus outbreaks: surveillance in England and Wales , 1992-2000.   Emerg Infect Dis 2003; 9(1): 71-7.

2. Food Standards Agency.  Report of the study of infectious intestinal disease in England . London : The Stationery Office, 2000.

3.Lopman B, Vennema H, Kohli E, Pothier P, Sanchez A, Negedro A et al . Increase in viral gasrtoenteritis outbreaks in Europe and epidemic spread of new norovirus variant.   The Lancet 2004; 363 :682-8.

4. Lopman BA, Reacher MH, Vipond IA, Hill D, Perry C, Halliday T et al .   Epidemiology and cost of nosocomial gastroenteritis, Avon, England, 2002-2003.   Emerg Infect Dis 2004; 10(10): 1827-34.

 

 

Increase in RSV activity in England: prophylaxis with palivizumab appropriate for 'at risk' infants

 

Levels of respiratory syncytial virus (RSV) activity have increased markedly over recent weeks, as expected around late autumn/early winter.   The number of laboratory reports made to the Health Protection Agency Centre for Infections are higher than the same time last season (2003/04), but are at a lower level than seen during the last substantial RSV season in 1999/00 (figure).  

The largest increase in the number of laboratory reports continues to be among children aged under 1 year, indicating that prophylaxis with palivizumab is now considered appropriate for 'at risk' infants, as outlined on the Health Protection Agency website, available at < http://www.hpa.org.uk/infections/publications/pdf/RSVpaper.pdf >

Influenza activity in the United Kingdom , and across Europe continues to remain low. Further information is available at < http://www.eiss.org/index.cgi >.

Figure Laboratory reports of RSV received by HPA Centre for Infections from NHS and HPA microbiology laboratories, by date of specimen: 2004 and recent years

Please note, reports may not have been received for specimens taken in recent weeks, therefore these data are provisional. Caution should, therefore, be exercised in the interpretation of the trend for the most recent weeks.