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Volume 7 No 39; 27 September 2013

Laboratory confirmed pertussis in England: data to end-July

Whilst pertussis activity in England and Wales continues at raised levels compared to recent years, overall laboratory-confirmed cases fell in November 2012 and the decrease continued into June 2013. A slight increase in the number of laboratory confirmed cases has been observed in July 2013 in line with seasonal trends. This news report presents current pertussis activity to 31 July 2013, updating the previous report that included data to the end of May 2013 [1]. Provisional data for the immunisation programme in pregnancy suggests that coverage is falling: immunisation of pregnant women continues to be important in the face of persisting raised levels of infection.

A level 3 incident was declared in April 2012 to coordinate the response to the ongoing increased pertussis activity observed in the third quarter of 2011 and extending into 2012 [2]. In response to this ongoing outbreak, the Department of Health announced on 28 September [3,4] that pertussis immunisation would be offered to pregnant women from 1 October 2012 to protect infants from birth whilst disease levels remain high. It has been confirmed that this programme will be continued in 2013/2014 until further notice, pending further advice from the Joint Committee on Vaccination and Immunisation [5].

In England pertussis activity has fallen each month from November 2012 but continued at high levels in all age groups aged one year or older compared to equivalent periods in previous years (figure 1). Provisional data show that in June and July, 333 and 355 cases respectively were newly confirmed, compared with 380 cases in May (figure 1). In July, for the first time since November 2012, the monthly total was higher than confirmed pertussis cases in the previous month. Whilst the overall number of cases has fallen, large numbers of cases continue to be confirmed in individuals aged 15 years or older with 296 cases reported in July 2013, compared to 843 in July 2012 and 55 in July 2008, the previous peak year (table 1). In those aged 10-14 years, there were 39 cases confirmed in July 2013; 91 in July 2012; and 19 in July 2008.

High pertussis activity has been observed across all regions in England and Wales. The highest numbers of confirmed cases in June and July 2013 have been in the South of England and Midlands and East of England PHE regions (table 2). In Wales 10 laboratory confirmed cases were reported in June and 17 in July 2013, compared to 25 cases in June and 38 in July 2012.

All infants under 11 months are now in the cohort born to mothers who were eligible for pertussis-containing vaccine in pregnancy. In England there was a fall in confirmed cases of pertussis from July/August 2012 through to December 2012 in infants under one year (figure 2) in whom low numbers of cases have been sustained through to July 2013. In infants under three months there were nine confirmed cases in June and seven in July 2013; these numbers are lower than the equivalent period in 2012 with 52 in June and 49 cases in July. Disease incidence does, as expected, continue to be highest in this age group. There were no pertussis-related infant deaths reported in June and July 2013.

Whilst cases were lower in all age groups in June/July when compared to these months in 2012, the impact was greatest in infants <3months. This specific effect on infants covered by the maternal immunisation programme is consistent with a programme effect. Between January and July 2013 there were 86 confirmed cases in infants under 1 year of age compared to 288 in the first 7 months of 2012. The situation will continue to be monitored but an increase in pertussis disease in infants <1 year has not yet been observed in the current third quarter of 2013 (July-September) when pertussis activity is usually at its highest.

Information on the uptake of pertussis immunisation in pregnant women has been published for women giving birth up to the end March 2013 [6]. New provisional data suggests that coverage has fallen on a monthly basis since that time and was estimated at 49.8% for women giving birth in June 2013. A report on UK vaccine coverage statistics for children aged up to five years (April-June 2013) is due to be published by PHE next week.

Current high levels of reporting may, in part, be due to increased awareness amongst health professionals leading to improved case ascertainment in older age groups. This is reflected in 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, it is considered that the increases that have been observed reflect a real change in pertussis activity with waning immunity following vaccination and/or natural infection likely to be important contributory factors [7]. This is supported by the high number of confirmed cases in infants under three months of age in whom ascertainment has been more consistent through time.

Table 1. Provisional number of confirmed cases of pertussis in England, 2008 to 2013 by age group: June and July

Age group

<3 months

3-5 months

6-11 months

1-4 years

5-9 years

10-14 years

15+ years

All ages

2008 June
18
2
2
1
3
15
62
103

July

27
5
1
4
1
19
55
112
2009 June
14
2
1
1
5
13
55
91

July

8
2
7
8
13
43
81
2010 June
6
1
1
1
1
2
22
34

July

7
2
1
3
3
3
25
44
2011 June
24
2
1
1
2
7
49
86

July

9
2
1
2
12
47
73
2012 June
52
6
5
9
12
72
503
659

July

49
13
4
6
17
91
843
1023
2013 June
9
6
3
1
3
30
281
333

July

7
1
3
1
8
39
296
355

 

Figure 1. Provisional number of confirmed cases of pertussis in England, by month: January 2011 to July 2013

 

Figure 2. Monthly distribution of laboratory confirmed cases in 2012, and January to July 2013, England, by age group based on provisional data

 

Table 2. Provisional number of confirmed cases of pertussis, England and Wales: June and July 2013, 2012 and 2008 by region

Region

2013 2012 2008

June

July

June

July

June

July
London
35 31 43 63 13 9

Midlands and East of England

108 95 199 368 29 25
Anglia and Essex
33 24 56 112 10 5
East Midlands
38 33 72 135 11 4
South Midlands and Hertfordshire
8 16 29 50 1 4
West Midlands
29 22 42 71 7 12

North of England

74 98 143 239 22 30
Cheshire and Merseyside
8 16 9 18 5 6
Cumbria and Lancashire
6 10 6 23 2 3
Greater Manchester
12 15 18 25 3 8
North East
14 9 26 38 3 4
Yorkshire and Humber
34 48 84 135 9 9

South of England

116 131 274 353 39 48
Avon, Gloucestershire and Wiltshire
32 34 92 113 9 17
Devon, Cornwall and Somerset
27 25 30 49 6 10
Kent, Surrey and Sussex
33 46 89 104 11 5
Thames Valley
8 3 22 38 9 8
Wessex
16 23 41 49 4 8
England Total
333 355 659 1023 103 112
Wales
10 17 25 38 1 6
England and Wales Total
343 372 684 1061 104 118

 

References

1. Confirmed pertussis cases in England and Wales: update to end-May 2013. HPR 7(29): news, 19 July 2013.

2. A level 3 incident is the third of five levels of alert under the HPA's Incident Reporting and Information System (IERP) 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. An IERP level 3 incident was declared in April 2012 in response to the ongoing increased pertussis activity (HPR 6(15), http://www.hpa.org.uk/hpr/archives/2012/news1512.htm).

3. “Pregnant women to be offered whooping cough vaccination”, 28 September 2012. Department of Health website, http://www.dh.gov.uk/health/2012/09/whooping-cough/.

4. "HPA welcomes introduction of whooping cough vaccination for pregnant women as outbreak continues”, HPA press release, 28 September 2012, HPA website: Home › News Centre › National Press Releases › 2012 Press Releases.

5. Department of Health, Public Health England NHS England. Continuation of temporary programme of pertussis (whooping cough) vaccination of pregnant women”, https://www.gov.uk/government/publications/whooping-cough-vaccination-programme-for-pregnant-women-extension-to-2014.

6. Public Health England, https://www.gov.uk/government/publications/pertussis-vaccine-uptake-in-pregnant-women-march-2013

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

New HIV diagnoses and numbers accessing HIV care in the UK: 2012

New HIV diagnoses

In 2012, 6,364 people (4,559 men and 1,805 women) were newly diagnosed with HIV in the United Kingdom, a slight increase on 6,219 new diagnoses the previous year. The overall trend shows a decline since a peak of 7,928 new diagnoses in 2005. Most of this decline is a decrease in the number of diagnoses among heterosexuals born abroad. Over the past five years, where country of birth data were reported, the number of new diagnoses among persons born in Africa declined from 35% (2,540/7,273) in 2008, to 22% (1,413/6,364) in 2012. The numbers of AIDS cases, and deaths of HIV-infected persons, have remained low in 2012 at 390 and 488 deaths, respectively.

Over the last decade, there has been a steady increase in the number of new HIV diagnoses among men who have sex with men (MSM), which surpassed the number among heterosexuals for the first time in 2011 (figure 1). After adjusting for missing data, there were 3,250 new diagnoses among MSM in 2012, the highest number ever reported, and a 10% increase from 2,960 in 2011. In London, this increase was 14%, with 1,400 diagnoses in 2011 and 1,600 in 2012. The rise in new diagnoses among MSM may be partially explained by an increase in HIV testing. The number of MSM having an HIV test in the UK increased from 64,270 in 2011 to 72,706 in 2012 (a 13% increase), while in London the increase was 19% (from 28,640 in 2011 to 34,000 in 2012). Nevertheless, there is compelling evidence that HIV transmission among this group is staying high; a back calculation analysis of reported HIV infections indicates that HIV transmission remains high among MSM [1] . A recent modelling study suggests that the large majority of new infections stem from MSM unaware of their infection [2].

Persons who acquired their infection through heterosexual contact were the second largest group reported in 2012 and accounted for 45% (2,880/6,364) of all new diagnoses. Infections acquired through injecting drugs and other routes have remained low, with 120 and 110 new diagnoses in these categories respectively in 2012.

Figure 1. New HIV diagnoses by exposure group: United Kingdom, 2003–2012 (observed and adjusted for missing information)

Persons accessing HIV-related care

Overall, 77,614 diagnosed persons were seen for care in 2012. Where exposure group data were reported (97%, 75,451), 50% were men (14,165) and women (23,548) who acquired their infection through heterosexual sex and 45% (33,964) were MSM (figure 2). The remainder accessing HIV-related care acquired their infection though injecting drug use (2%, 1,617), mother-to-child transmission (2%, 1,603) or blood products (0.7%, 554).

Antiretroviral therapy (ART) coverage is continuing to rise, with 85% (66,057/77,309) of persons seen for care in 2012 prescribed treatment compared to 68% (24,090/35,285) in 2003. The British HIV Association (BHIVA) guidelines recommended in 2008 that ART treatment should start when a person's CD4 count falls below <350 cells/µl; the coverage of treatment in HIV-infected persons with a CD4 count <350 cells/µl has increased from 81% (13,246/16,297) in 2008 to 89% (11,945/13,431) in 2012.

Figure 2. HIV-diagnosed persons seen for HIV care by exposure group and ethnicity: United Kingdom, 2003–2012*

* Excludes 823 of 77614 persons seen for care with ethnicity not reported.

With the increase in the number of new diagnoses among older persons (497 diagnoses among persons aged 50 and over in 2003 compared to 990 diagnoses in 2012), and the effect of an ageing cohort, the number and proportion of people accessing HIV-related care aged 50 and over will continue to increase. In 2012, one in four (19,123/77,614) adults living with diagnosed HIV were aged 50 and over, compared with one in eight in 2003 (4,361/35,971)(figure 3).

Figure 3. HIV-diagnosed persons seen for HIV care by age group: United Kingdom, 2003–2012

There is geographical heterogeneity among persons living with diagnosed HIV in the UK, with 42% (32,499/77,184) residing in London. In England, over the past 10 years, the Public Health England Centre areas that had the largest proportional increases in the number of HIV-diagnosed persons seen for HIV care were Yorkshire and The Humber (from 1,305 in 2003 to 4,026 in 2012) and the West Midlands (from 1,675 in 2003 to 5,118 in 2012). London saw the lowest proportional increase although numbers were highest (18,516 in 2003 to 32,499 in 2012). There is increasing movement of HIV-diagnosed persons across geographical boundaries from where they live to where they were seen for HIV care. Where information was available, 11% of those who used London HIV services were non-London residents (3,770/35,912).

National testing guidelines recommend that, where the prevalence of diagnosed HIV infections is two or more per 1,000 among persons aged 15-59, an HIV test should be offered to persons newly registering in general practice and being admitted to a general medical ward. In 2012, 64 Local Authorities (LAs) had a diagnosed prevalence above the two per 1,000 threshold, half of which were in London (32/64). All but one of the 33 London LAs have prevalence above this threshold. Outside London, the five LAs with the highest prevalence and which are above the two per 1000 threshold are: Brighton and Hove, Salford, Manchester, Blackpool and Luton.

References

1. Birrell PJ, Gill ON, Delpech VC, Brown AE, Desai S, Chadborn TR, et al. HIV incidence in men who have sex with men in England and Wales 2001–10: a nationwide population study. The Lancet Infectious Diseases: 13(4): 313-318, 2013.

2. Phillips AN, Cambiano V, Nakagawa F, Brown AE, Lampe F, Rodger A, et al. Increased HIV incidence in men who have sex with men despite high levels of ART-inducted viral suppression: analysis of an extensively documented epidemic. PLOS One: 8(2), 2013.e55312.