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Volume 6 No 15; 13 April 2012

Confirmed pertussis in England and Wales continues to increase

A national increase in laboratory-confirmed cases of pertussis in England and Wales has been observed from the second quarter of 2011, predominantly in adolescents and adults, and has continued into 2012. The HPA has therefore declared a level 3 incident [1] to facilitate coordination of its response to the ongoing, increased pertussis activity. Escalation of the response primarily aims to prevent infant deaths and minimise morbidity in older children and adults.

Pertussis can affect individuals of all ages but young infants are at highest risk of severe complications, hospitalisation and death. Although adolescents and adults tend to display milder symptoms, they can be an important source of infection for very young infants, too young to be fully protected through vaccination.

Pertussis is a cyclical disease with increases occurring every 3-4 years. The increase in 2011 has previously been reported [2], with the last peak occurring in 2008. During 2011, numbers of confirmed cases were high in age groups under 15 years, but in line with anticipated cyclical increases. For example, the incidence of laboratory-confirmed cases in infants <3 months was 103 per 100,000 in 2011 compared with 101 per 100,000 in 2008. The number of confirmed cases in the 15-and-over age group, however, exceeded expected levels; cases in this age group were nearly 50% higher in 2011 (with an incidence of 1.6 per 100,000) than those in 2008 (with an incidence rate of 1.1 per 100,000).

The provisional total of confirmed cases of pertussis in 2012 in England and Wales to the end of March has reached 665, compared to 175 in the same period in 2008 (table 1). High numbers of cases continue to be confirmed in individuals aged 15 years or older with 474 cases in the first quarter of 2012, compared to 86 cases in 2008. This may be in part due to increased awareness amongst health professionals improving case ascertainment in older age groups. This is reflected by the increased demand for serology testing which is the predominant method of confirmation in adolescents and adults who typically present with milder features late in the course of the illness. However, waning immunity following vaccination and /or natural infection is also likely to be an important contributory factor [3]. Activity is also high in infants under 3 months with 65 cases in this period in 2012 compared to 34 cases in 2008. Three pertussis-related deaths in infants were reported in the first quarters of 2012 and 2008.

The increase in pertussis activity has been observed in Wales and across all regions in England with some areas reporting clusters in educational settings and incidents linked to healthcare settings. The highest numbers of confirmed cases in the first quarter of 2012 have been in the South East and the South West regions (table 2).

Table 1. Provisional number of confirmed cases of pertussis in 2008 and 2012 by age group: quarter 1 (January to March), England and Wales

Age group

<3 months

3-5 months

6-11 months

1-4 years

5-9 years

10-14 years

15+ years

Total cases

2008

34

7

2

7

5

34

86

175

2012

65

10

3

6

14

93

474

665

 

Table 2. Provisional number of confirmed cases of pertussis in 2008 and 2012 by region: quarter 1 (January to March), England and Wales

Region

2008

2012

East Midlands

19

72

East of England

15

33

London

20

53

North East

10

57

North West

18

50

South East

38

154

South West

29

131

Wales

5

16

West Midlands

13

25

Yorkshire and the Humber

8

74

References/notes

1. A level 3 incident is the third of five levels of alert under the HPA's Incident Reporting and Information System according to which public health threats are classified and information flow to the relevant outbreak control team is coordinated. A level 3 incident is defined as one where the public health impact is significant across regional boundaries or nationally.

2. Laboratory-confirmed cases of pertussis reported to the enhanced pertussis surveillance programme (England and Wales): annual report for 2011. Health Protection Report 2012; 6(8): immunisation. Available online at: http://www.hpa.org.uk/hpr/archives/Infections/2012/immunisation12.htm

3. Campbell H, Amirthalingam G, Andrews N, Fry NK, George RC, Harrison TG, et al. Accelerating control of pertussis in England and Wales. Emerging Infectious Diseases 2012; 18(1): 38-47.

Confirmed measles cases in England and Wales: update to end-March 2012

The provisional total of laboratory-confirmed cases of measles this year in England and Wales with onset dates to the end of March 2012 has reached 253, compared to 200 in the same period in 2011. The majority of cases with onset in February and March were diagnosed in the North West region where there is an on-going outbreak (see table) [1, 2]. More than 60% (86/136) of the cases in the North West are in unvaccinated children under 10 years, of which 26 are infants less than a year of age, and the genotype is B3. In comparison, an outbreak in North Wales which began in February has primarily been linked with one secondary school with spread to younger unvaccinated children within families in the locality. The genotype associated with this outbreak is D8. Letters were sent to local schools and general practitioners to remind them of the need to ensure children have received two doses of MMR vaccine. Immunisation sessions were organised in schools in the affected area [2, 3]. The South East and London regions have consistently reported cases throughout this period and the predominate genotype is D4.

The latest UK MMR vaccine coverage data published last month for children reaching their second or fifth birthday in October to December 2011 quarter shows 91.9% of 2 years olds have received their first dose and 86.7% of five years olds completed the two dose course [4]. These are the highest levels recorded since combined UK data were first produced in 1995.

Number of confirmed cases of measles with onset in 2011 and number by month of onset and region, January to March 2012: England and Wales

Month

London

East Mids

East of England

North East

North West

South East

South West

West Mids

Wales

York & Humber

Total

Total 2011

421

16

42

15

40

344

87

40

19

62

1086

 

 

 

 

 

Jan-12

11

-

-

-

3

21

2

1

1

-

39

Feb-12

7

-

2

-

61

9

2

2

24

-

107

Mar-12

11

-

1

-

72

14

-

-

8

1

107

Total 2012

29

-

3

-

136

44

4

3

33

1

253

Number of confirmed measles cases by month of onset, England and Wales: January 2007 to January 2012


Across Europe, 2012 data from the twenty-nine EU and EEA countries is only available to the end of January; nearly 600 measles cases were reported for this month of which 63% were identified in Romania [2]. In addition, a large measles outbreak, nearly 4,500 cases between 1st January and 3rd March, is ongoing in the west of Ukraine which borders Hungary , Poland and Slovakia . There have been vaccine shortages in the Ukraine since 2010 and without effective control measures the epidemic is expected to accelerate and spread geographically during the measles peak transmission season from February to June. The European Football Championship will be jointly hosted by Ukraine and Poland in June 2012 and visitors to the event are encouraged to ensure they are fully vaccinated [5].

References

1. "Measles on Merseyside - latest", HPA press release, 26 March 2012.

2. European Centre for Disease Prevention and Control (ECDC). European measles monthly monitoring (EMMO), March 2012.

3. Public Health Wales. "Porthmadog measles outbreak update". 19 March 2012.

4. HPA. Quarterly vaccination coverage statistics for children aged up to five years in the UK (COVER programme): October-December 2011. Health Protection Report 2012; 6(12): immunisation.

5. NaTHNaC. " UEFA European Football Championship 2012 - information for health professionals advising travellers", 20 March 2012.

The changing pattern of listeriosis cases in England and Wales: 1990-2011

Listeriosis is a rare but serious food-borne disease caused by the bacterium Listeria monocytogenes. The elderly, the immunocompromised, pregnant women, unborn and newborn infants are disproportionately affected. The clinical signs of disease in these populations include septicaemia, encephalitis, meningitis, miscarriage and still birth. It has been estimated that the case fatality rate for listeriosis in non-pregnancy related cases in England and Wales is 41% [1] and in the UK, L. monocytogenes is recognised as being the leading cause of death due to a foodborne pathogen [2].

Between 1990 and 2000, cases of listeriosis in England and Wales reported to the HPA national surveillance system were relatively stable at an average of 109 cases per year. However, from 2001 to 2009, there was an increase in the number of cases reported with an annual average of 191 cases (figure 1). The increase has been seen particularly in patients aged 60 years and over presenting with bacteraemia.

In 2010, there was a 13.6% decrease in the number of reported cases of listeriosis with a total of 159 cases reported in England and Wales. This decline continued in 2011 with a further 7.5% decrease resulting in 147 reported cases. In 2011, 82% of cases were non-pregnancy related while 16% were pregnancy related; this represents a 6.4% increase in pregnancy related cases from the previous year. However, the number of pregnancy related cases is within observed levels and this proportional difference is likely in part, to be a result of fewer non pregnancy-related cases. Nevertheless, the number of pregnancy related cases is higher than previous years with the exception of 2009 (figure 1). An increase in pregnancy related listeriosis cases amongst ethnic minorities since 2006 in England and Wales has also been reported [3].

Being above 60 years of age has been noted as a risk factor for developing listeriosis [4] and presenting with bacteraemia in the absence of CNS involvement. But, recent data show a decline in the number of cases of listeriosis and bacteraemia presentation in those aged 60 years and over since 2007(figure 2). Conversely in 2011, a slight increase in the number of cases below 60 years of age presenting with listeriosis was observed (11%; 62 cases) and with bacteraemia involvement (34%; 47 cases) (figure 2).

Microbiological characterisation data (serotyping and Amplified Fragment Length Polymorphism typing [SerofAFLP]) were available for majority of the cases. Serotype 4 has consistently been the predominant serotype and in 2011 it accounted for 60% of all cases of known serotype (73/120) (Figure 3), of which AFLP 4V was the most predominant subtype.

Table 1. Number of Listeria cases by type in England and Wales, 1990-2011

Table 2. Distribution of listeria cases by presentation in E&W

 

Table 3. Serotype distribution of listeriosis in E&W

 

References

1. Mook P, Patel B and Gillespie IA (2011). Risk factors for mortality in non-pregnancy-related listeriosis. Epidemiology and Infection. 2011; 140: 706-715.

2. Food Standards Agency. Listeria factsheet, Friday 14 October 2011. Available at: http://www.food.gov.uk/safereating/microbiology/listeria.

3. Mook P, Grant KA, Little CL, et al. Emergence of pregnancy-related listeriosis amongst ethnic minorities in England and Wales. Euro Suveill. 2010; 15(27).

4. Gillespie IA, Mook P, Little CL, et al. Listeria monocytogenes infection in the over-60s in England between 2005 and 2008: A retrospective case-control study utilizing marker research panel data. Foodborne Pathogens and Disease 7(11): 1373 - 1379.