Surveillance of antenatal infections HIV, hepatitis B, syphilis and rubella susceptibility in London SR Anderson, A Righarts, H Maguire Summary: London has relatively high rates of HIV, hepatitis B and syphilis, and has the potential for undiagnosed infection in pregnancy. As part of a drive to improve HIV testing in pregnancy, surveillance of a number of antenatal infections has been carried out in London s 30 maternity units since 2000. Infection screening rates rose from 89% in 2000 to 94% in 2002, and HIV screening rates increased from 66% to 86%. During 2002, 115,230 women booked for antenatal care; 998 were HBsAg positive (about ten in 1000), 452 were HIV positive (five in 1,000), 412 tested positive for syphilis (four in 1000), and 3,929 were susceptible to rubella (36 in 1000). The main burden of infection was concentrated in a few geographic areas. Worryingly the majority of women found to be HIV positive were diagnosed by antenatal screening and not before. Key words: antenatal hepatitis B HIV London rubella surveillance syphilis Commun Dis Public Health 2004; 7(4): 251-57 Introduction Early detection of infections such as HIV, hepatitis B, syphilis and rubella in pregnancy can lead to health gains for both mother and child 1,2. Effective treatment and intervention can be offered to prevent onward transmission of HIV 1 and hepatitis B 3-7 and reduce the risk of congenital syphilis 2. London has relatively high rates of HIV, hepatitis B and syphilis when compared to the rest of the UK 8, and therefore an increased potential for undiagnosed infection in pregnancy. Little information was available in 1999 to describe the rates of hepatitis B and syphilis infection or rubella susceptibility in London s antenatal population. Rates of HIV infection were available from the Unlinked Anonymous Survey (unpublished data from Health Protection Agency, Communicable Disease Surveillance Centre: SR Anderson, H Maguire Health Protection Agency London Regional Epidemiology Unit A Righarts Communicable Disease Surveillance Centre Health Protection Agency, London Address for correspondence: Dr Sarah R Anderson Health Protection Agency 6th Floor, New Court 48 Caney Street London WC2A 2JE tel: 020 7492 0475 fax: 020 7492 0482 email: sarah.a@virgin.net www.hpa.org.uk) but rates of HIV screening uptake were not. Knowing how to improve care for both mothers and their unborn child was therefore difficult. In 1998 the Department of Health asked health authorities in England and Wales to ensure that all antenatal women were screened for hepatitis B and that at-risk infants were fully immunised against the virus 9. In addition, it requested all health authorities to test at least 50% of their pregnant women for HIV by the end of 2000 10 and 90% by the end of 2002. No clear monitoring process was recommended for hepatitis B or HIV and so the Communicable Disease Surveillance Centre (CDSC) London, now part of the Health Protection Agency (HPA) initiated its own surveillance system. In 2003 a set of antenatal screening standards were published by the Department of Health to reinforce existing policy that all pregnant women in the UK should be offered screening for rubella susceptibility, syphilis, HIV and hepatitis B as an integral part of their antenatal care 11. A review of the London surveillance system for antenatal infections is therefore timely. Methods The London surveillance system for antenatal infections was set up following a six-month pilot in 2000. Data is collected by nominated antenatal screening coordinators at 30 maternity units across London. On a six-monthly basis it is summarised and sent on a one page pro forma to the local consultants in communicable disease control (CCDC) and to the HPA London who enter it into a database. The pro-forma requests information on: the size of the booked antenatal population (available from COMMUNICABLE DISEASE AND PUBLIC HEALTH VOL 7 NO 4 DECEMBER 2004 251
antenatal clinic data); the uptake of screening for HIV, hepatitis B, syphilis and rubella immune status in the study cohort; and the numbers testing positive for each infection and susceptibility to rubella (available from laboratory data). Each hospital tests their own specimens, the majority use the Abbot AxSYM system for HIV, Hepatitis B and rubella and a microelisa assay made by Newmarket for syphilis. Using this dataset we assess the success of London s surveillance for antenatal infection. Results In London, surveillance data for antenatal infections has been collected since the year 2000. Over the last three years there has been a progressive rise in the proportion of pregnant women screened at London s 30 maternity units, from 89% in 2000 to 94% in 2002. Trends in antenatal surveillance data 2000-02 Since 2000, over 90% of maternity units in London have achieved over 90% uptake for hepatitis B, syphilis and rubella antibody screening. Uptake for HIV screening has risen from 66% to 86% but is still below the national standard of 90% (see figure 1). Since the year 2000 surveillance data for HIV, hepatitis B and syphilis infections shows: a static rate of syphilis infection and apparent small rises in hepatitis B carriage (from nine to 10 per 1,000 women screened) and HIV prevalence (from four to five per 1,000 women screened). For rubella, a drop in the susceptibility of pregnant women has been seen from a maximum of 42 to 36 per 1,000 women (see figure 2). Surveillance data for 2002 In 2002, 115,230 women were booked for antenatal care at 30 London maternity units. Ninety-one per cent of units returned data. Ninety-six per cent of women were tested for hepatitis B, 86% for HIV and 96% for syphilis; 96% reportedly had rubella immunity/susceptibility recorded. Testing for each infection varied by unit from 60-100%. For hepatitis B, 23 of 30 units tested over 95% of women and for HIV 22 of 30 units tested over 80% of women and 13 of 30 over 90%. Hepatitis B In 2002, 998 pregnant women tested positive for hepatitis B carriage in London, a rate of one in 100 pregnant women screened. Rate of carriage varied by maternity unit ten fold, from 2/1,000 at Queen Mary s Hospital (Southeast London) to 21/1,000 at the North Middlesex Hospital. Nearly a third of maternity units have rates of hepatitis B carriage over 1% (see figure 3); with North Middlesex, Guy s/st Thomas s and King s having rates nearer 2%. The national prevalence of Hepatitis B has been estimated as 152 per 100,000 (0.15%) 12,13, with a less than 1% prevalence of HBsAg in the antenatal population 14,15,16. In a large UK study of over 72,000 antenatal women the estimated prevalence of chronic HBV infection ranged from 0.03% to 1.75% 17. The highest prevalence 1.75% was reported in London with an average of 0.98%. HIV In 2002, 452 pregnant women in London were HIV positive, a rate of five in 1,000 of the 86% tested. In 2000, 71% had been tested and there were 364 women HIV positive. The rate of HIV positivity among the tested women varied by maternity unit from one/1,000 in Kingston to 14/1,000 at the North Middlesex Hospital (see figure 4). At the North Middlesex Hospital, over 50% of the 42 HIV positive women were first diagnosed by antenatal screening. In London as a whole, 69% (312 of 452) of HIV positive pregnant women were apparently not known to be infected prior to pregnancy. Preliminary 2002 estimates from the national Unlinked Anonymous survey of HIV in pregnant women shows that at least 75% of HIV positive women in London were diagnosed prior to delivery 8. FIGURE 1 Uptake of antenatal testing across London, 2000-02 252 VOL 7 NO 4 DECEMBER 2004 COMMUNICABLE DISEASE AND PUBLIC HEALTH
FIGURE 2 Antenatal infection rates/susceptibility across London, 2000-02 Syphilis In 2002, 412 pregnant women tested positive for syphilis, a rate of four/1,000 (range from one/1,000 to 12/1,000) (see figure 5). Three maternity units in London, accounting for over 10% of the total antenatal population, have nearly 1% of their pregnant population infected with syphilis; these were North Middlesex, Guy s/st Thomas s and King s. Rubella susceptibility In 2002, 3,929 pregnant women in London were known to be susceptible to rubella, a rate of 36 in 1,000 or 3.6% of London s pregnant population. The range of patients susceptible to rubella varied by maternity unit from 0.03% (one in 3,062) at the Royal Free Hospital to 14.3% (143 in 1,000) at Newham Hospital (see figure 6). FIGURE 3 Burden of hepatitis B in antenatal patients by London maternity units, 2002 COMMUNICABLE DISEASE AND PUBLIC HEALTH VOL 7 NO 4 DECEMBER 2004 253
FIGURE 4 Burden of HIV in antenatal patients by London maternity units, 2002 FIGURE 5 Burden of syphilis in antenatal patients by London maternity unit, 2002 254 VOL 7 NO 4 DECEMBER 2004 COMMUNICABLE DISEASE AND PUBLIC HEALTH
FIGURE 6 Rubella susceptibility in antenatal patients by London maternity unit, 2002 Discussion Antenatal surveillance in London Surveillance is, the continuous analysis, interpretation and feedback of systematically collected data, generally using methods distinguished by their practicality, uniformity and rapidity rather than accuracy or completeness 18. Surveillance for the prevalence of antenatal infection in London has met most of this definition. It is a simple, practical system based on a single reporting form returned every six months. It is relatively representative with 91% coverage, and it generates yearly reports in a timely fashion. It relies entirely on the goodwill and hard work of dedicated midwives and other professionals across the city. Limitations to London s antenatal surveillance A number of limitations have been noted. Data was incompletely available from some maternity units, limiting coverage to 91%. This was mostly due to laboratory-data retrieval problems. Although the conclusions drawn from the results may be limited by the data coverage, no information of greater accuracy is available. Data collection by each trust has differed; issues that have arisen from this include: discrepancies in data depending on where the data has originated (antenatal records or lab records) and the interpretation of the reporting form depending on who completed the form (head of midwifery or antenatal screening coordinator). These problems have largely been overcome as most trusts have appointed an antenatal screening coordinator (or named individual responsible for antenatal surveillance) and now most have good audit trails in place. Trends in antenatal surveillance data 2000-02 Changes in government policy and the setting of standards for antenatal screening have led to increased levels of screening in the last three years. The London antenatal infection surveillance system confirms standards are rising. This has occurred most noticeably in HIV screening, where coverage has risen from 66% to 86%. In the last three years at least 90% of London s maternity units have screened over 90% of their pregnant women for hepatitis B, syphilis and rubella susceptibility, though the majority have failed to reach the government s target for HIV screening of 90%. This may be because hospitals are using opt-out policies for hepatitis B, syphilis and rubella but an opt-in policy for HIV screening. A more detailed review is needed of HIV screening. Although there has been an apparent increase in infections detected by antenatal screening, the changes are small (a rise in hepatitis B carriage from nine to 10 per 1,000 women tested) and so the full significance of these findings is difficult to assess. Over the last three years there has been a decrease in the number of women susceptible to rubella in London (figure 2). This reinforces a trend seen by Tookey et al. in North West London 19. However, COMMUNICABLE DISEASE AND PUBLIC HEALTH VOL 7 NO 4 DECEMBER 2004 255
numbers remain high in certain areas of London such as Newham, where 14.3% of women are not protected against rubella. This is likely to reflect the ethnic diversity of this area and confirms work by Miller that showed that Asian women are more susceptible to rubella due to the lower levels of vaccination 20. Discussion of antenatal surveillance data for 2002 In 2002, 96% of maternity units screened women for hepatitis B, syphilis and rubella susceptibility; however this percentage hides the fact that for hepatitis B, only three quarters (23 of 30 units) tested over 95% of women. For HIV less than half the maternity units tested over 90% of pregnant women (the government s target). The majority of HIV positive patients found during antenatal screening were not previously diagnosed. This is worrying and suggests that more needs to be done to encourage London s sexually active population to consider voluntary HIV testing and counseling and to practise safe sex. However, the HPA estimates that the rate of trans-mission of HIV from mother to child in London has reduced from 19% of pregnancies in 1997 to 8% in 2002 8. The London wide surveillance system for antenatal infections reveals that a high burden of infection appears to be concentrated in a few geographic areas: in the North Central Sector - North Middlesex hospital; in the South East Sector - Guy s/st Thomas s and King s College; and in the North West Sector - Central Middlesex Hospital (see figure 7). This may partly be a reflection of the ethnic minority population living locally who have higher prevalence rates. The 2001 census showed that around 40% of Londoners belong to an ethnic minority, but the population of Brent, served by Central Middlesex Hospital, has a substantially higher ethnic minority population at 66%; it is also possible that higher infection rates reflect deprivation as assessment of indices of deprivation are found to be higher in these areas of London 21. In North East London, the Homerton Hospital has one of the highest HIV rates at 14/1,000 but data on hepatitis and syphilis are currently lacking. It seems likely that this is also a high burden area. Newham has substantially higher rates of rubella susceptibility than other areas, and this might be explained by the high proportion of newly arrived ethnic minorities from countries where immunisation against rubella is not routine (63% of Newham s population is from an ethnic minority 22 ). The future Overall London s antenatal surveillance shows that London s maternity units are meeting government targets in most areas, but improvements can still be made. Testing is important so that mother and baby can receive treatment and intervention such as therapy or vaccine. Infections in pregnancy should not go unrecognised. In London the next steps are to further increase the uptake of screening, particularly HIV screening, and in addition link surveillance to the uptake of preventive measures such as hepatitis B vaccination for infants at risk and antiretrovirals for HIV positive mothers and their infants. It is intended also to audit the system during 2004 with colleagues across London. Other UK regions may be interested in the London experience and may find it useful to use a standard proforma, a named antenatal screening coordinator for each maternity unit and a central point of reference to receive surveillance data and issue reports. Acknowledgements Thanks to Mandy Wright, HPA London Regional Epidemiology Service, and to midwives, antenatal screening coordinators, and microbiological colleagues across the city who provided the data. We are very grateful. Also thanks to Suzanne Truttero, London Supervising Midwife, who helped instigate the surveillance system. References 1. Henderson SL, Lindsay MK, Higgins JE, Clark WS, Bulterys M, FIGURE 7 London Rates of hepatitis B, HIV and syphilis in selected London trusts during 2002 compared to the average for 256 VOL 7 NO 4 DECEMBER 2004 COMMUNICABLE DISEASE AND PUBLIC HEALTH
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