|
 |
|
|||||||
|
|||||||||
© 2003 American Public Health Association
RESEARCH AND PRACTICE |
At the time of the study, Barbara H. Francis was with Mercy Hospital for Women, Melbourne, Australia, and Swinburne University of Technology, Melbourne. Adrian K. Thomas is with Mercy Hospital for Women, and the Rubella Committee, Deafness Foundation, Victoria, Melbourne. At the time of the study, Catherine A. McCarty was with the University of Melbourne.
Correspondence: Requests for reprints should be sent to Barbara Francis, National Serology Reference Laboratory Australia, 41 Victoria Parade, Fitzroy, Victoria, 3065, Australia (email: bfrancis{at}bigpond.net.au).
 |
INTRODUCTION |
|---|
 TOP INTRODUCTION METHODSRESULTSDISCUSSIONReferences |
|---|
This study assessed the impact of rubella immunization, which commenced in Australia in 1971, on the serological status of women of childbearing age over a 25-year time period and identified the risk factors for ongoing rubella susceptibility.
|
METHODS |
|---|
|
TOPINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
|---|
The source materials were the computerized records of all 74 753 rubella tests performed on patients and staff at Mercy Hospital for Women between 1976 and 2000. Mercy Hospital for Women is a public teaching hospital on the outskirts of central Melbourne and has similar patient demographics to the Melbourne metropolitan area from where the majority of patients come.1 Included in the final database were all routine test results from pregnant and nonpregnant patients merged with separately extracted demographic and parity data (the number of previous pregnancies continuing for more than 20 weeks of gestation, available from 1995 onward).
Between 1976 and July 1990, hemagglutination-inhibition (HAI) was the sole test used; in 1990 it was replaced by enzyme immunoassay for routine rubella immunoglobulin G (IgG) screening, the HAI test being retained as a reference method. Rubella antibody status was classified as negative (IgG 
14 IU/mL or HAI 1:8), low positive (IgG = 15–34 IU/mL or HAI = 1:16), or positive (IgG 
35 IU/mL or HAI 1:32).
SPSS (SPSS Inc, Chicago, Ill) version 10.1 was used for all analyses: logistic regression was used for univariate, multivariate, and stratified analyses; mean ages were compared by analysis of variance; and parity differences were assessed using the Pearson’s 
2 statistic. A P value < .05 was considered statistically significant.
|
RESULTS |
|---|
|
TOPINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
|---|
Table 1
shows that 65 227 patient results were eligible for the study, representing 159 countries of birth, 75 languages, and 43 religions. Between 1976 and 2000, the proportion of seronegative women decreased from 9.4% to 2.5%, but those with low antibody titers increased from 2% to 5.7%, having peaked at 11.6% in 1992 (Figure 1). For Australian women younger than 30 years, the proportion who were seronegative was higher for parous than for nulliparous women, whereas the reverse was true for young Asian women (22 = 6.47, P = .01). There was no significant difference for women older than 30 years.
|
|
The mean age increased significantly from 25.8 years in 1976–1985 to 30.4 years in 1996–2000 (F2 = 2898.3, P < .001); 44% of women were born overseas, and country of birth was the most significant predictor of rubella susceptibility of those tested (Table 1
).
For each time period, all Asian and Other women born overseas had significantly increased odds of being seronegative compared with those born in Australia. In 2000, the last year of our study, women born in Asia, sub-Saharan Africa, and South America (Africa and South America are included under Other in Table 1) had 5 times the odds of being seronegative compared with all other women (odds ratio [OR] = 4.98; 95% confidence interval [CI] = 3.33, 7.44).
Other significant factors in seronegativity were language spoken and religion. Non–English-speaking women were 1.5 times as likely as English speakers to be seronegative in 1996–2000, and during 1996–2000, Australian-born Muslim women had 3 times the odds of being seronegative as Australian-born women of all other religions combined (OR = 3.02; 95% CI = 1.31, 6.93).
|
DISCUSSION |
|---|
|
TOPINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
|---|
This study shows that although rubella vaccination has produced a significant reduction in rubella seronegativity in women of childbearing age, susceptibility has remained at 2% to 3% since 1995, and full protection seems unlikely. The increase in low titers is also of concern, as reinfection in pregnancy, with a slight risk to the fetus, occurs more often in these women.2
Country of birth was the major factor associated with seronegativity. For the entire 25 years of the study, women born in developing countries, particularly nulliparous Asian women younger than 30 years, had significantly increased odds of being susceptible to rubella compared with Australian-born women. A Vietnamese rubella education program in Melbourne during 1989–19913 probably accounts for the slight improvement since 1996; however, a threefold difference between Vietnamese and Australian women remains, and there were similar findings in a British follow-up study of selective rubella immunization programs in Asian communities.4
Despite comprehensive vaccination programs in industrialized countries including Australia and the United States, congenital rubella syndrome, although significantly less prevalent, still occurs,5–8 particularly among unvaccinated women from developing countries.8,9 Consequently, except for Finland,10 the goals of eliminating indigenous cases of congenital rubella syndrome and rubella in pregnant women in Europe and the United States by 2000 have not been met.7,11
Our study shows that current rubella immunization programs in Australia,12 although effectively providing protection for most Australian-born women, are not adequately serving immigrant women from developing countries where rubella vaccination is not widely practiced and where susceptibility to rubella is still very high.13,14 A World Health Organization meeting in 2000 reported that only 105 of 214 (49%) countries and territories that report to the organization use rubella vaccine, and an estimated 100 000 cases of congenital rubella syndrome still occur each year.15 Until developing countries have the means to introduce comprehensive vaccination programs of their own, industrialized countries including Australia that have large immigrant populations need to maintain specifically targeted programs for their immigrant women, ideally on entry to the country, where public health messages are more easily delivered.
|
Acknowledgments |
|---|
This study was supported by grants from the Medical Research Foundation for Women and Babies, Melbourne, Australia, and Deafness Foundation, Victoria.
We gratefully acknowledge the valuable contribution of the following people: David Clarke and Nick Mountford for data entry; Darren Smith, Bill Dingle, and Peter Coventry for data extraction; Jenny Kox, Slava Marich, and Sue McLean for their scientific expertise; Dr Leon Taft, Dr James Scurry, and numerous other medical, pathology, nursing, technical, computer, medical records, and office staff involved at various stages of the study over the past 25 years.
Human Participant Protection
This study was approved by the Mercy Hospital for Women health and aged care research ethics committee.
|
Footnotes |
|---|
Contributors
This study formed part of the research requirements for a doctor of philosophy degree at Swinburne University of Technology, undertaken by B. H. Francis, who was responsible for all the rubella antibody tests performed over the entire 25 years of the study and who conducted all the statistical analyses. A. K. Thomas provided clinical guidance and direction for the study. C. A. McCarty was Francis’ PhD supervisor and provided statistical consultation and guidance. All 3 authors contributed to the writing of the brief.
Accepted for publication September 11, 2002.
|
References |
|---|
|
TOPINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
|---|
1. 1996 Census of Population and Housing Melbourne (Statistical Division)—Victoria. Melbourne, Australia: Australian Bureau of Statistics; 1996.
2. Burgess MA. Rubella reinfection—what risk to the fetus? Med J Aust.1992;156:824–825.[Medline]
3. Yeates K. Vietnamese Rubella Education Program: 1989–1991. Melbourne, Australia: Deafness Foundation (Victoria); 1992.
4. Miller E, Waight P, Rousseau SA, et al. Congenital rubella in the Asian community in Britain. BMJ.1990;301:1391.
5. Cheffins T, Chan A, Keane RJ, Haan EA, Hall R. The impact of rubella immunisation on the incidence of rubella, congenital rubella syndrome and rubellarelated terminations of pregnancy in South Australia. Br J Obstet Gynaecol.1998;105:998–1004.[Medline]
6. Sullivan EM, Burgess MA, Forrest JM. The epidemiology of rubella and congenital rubella in Australia, 1992 to 1997. Commun Dis Intell.1999;23:209–214.[Medline]
7. Miller E, Tookey P, Morgan-Capner P, et al. Rubella surveillance to June 1994: third joint report from the PHLS and the National Congenital Rubella Surveillance Programme. Commun Dis Rep Rev.1994;4:R146–R152.
8. Reef SE, Frey TK, Theall K, et al. The changing epidemiology of rubella in the 1990s. On the verge of elimination and new challenges for control and prevention. JAMA.2002;287:464–472.
9. Sheridan E, Aitken C, Jeffries D, Hird M, Thayalasekaran P. Congenital rubella syndrome: a risk in immigrant populations. Lancet.2002;359:674–675.[Web of Science][Medline]
10. Peltola H, Davidkin I, Paunio M, et al. Mumps and rubella eliminated from Finland. JAMA.2000;284:2643–2647.
11. Centers for Disease Control and Prevention. Measles, rubella, and congenital rubella syndrome—United States and Mexico, 1997–1999. MMWR Morb Mort Wkly Rep.2000;49:1048–1051.[Medline]
12. Heath TC, Burgess MA, Forrest JM. Moving the second dose of measles-mumps-rubella vaccine to school entry: implications for control of rubella. Commun Dis Intell.1998;22:157–158.[Medline]
13. Banatvala JE. Rubella—could do better. Lancet.1998;351:849–850.[Medline]
14. Action needed now to stop the rubella tragedy. Child Vaccine Initiative Forum.1998;15:2–8.
15. World Health Organization (WHO). Report of a Meeting on Preventing Congenital Rubella Syndrome: Immunization Strategies, Surveillance Needs. Geneva. Switzerland: Department of Vaccines and Biologicals, WHO; 2000.
This article has been cited by other articles:
|
|
 |
|
  Ai Theng Cheong and Ee Ming Khoo Prevalence of Rubella Susceptibility Among Pregnant Mothers in a Community-Based Antenatal Clinic in Malaysia: A Cross-Sectional Study Asia Pac J Public Health, October 1, 2008; 20(4): 340 - 346. [Abstract] [PDF]
|
|
|
|
 |
|
 W. Dimech, L. Panagiotopoulos, B. Francis, N. Laven, J. Marler, D. Dickeson, T. Panayotou, K. Wilson, R. Wootten, and E. M. Dax Evaluation of Eight Anti-Rubella Virus Immunoglobulin G Immunoassays That Report Results in International Units per Milliliter J. Clin. Microbiol., June 1, 2008; 46(6): 1955 - 1960. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. M. Wilson, C. Di Camillo, L. Doughty, and E. M. Dax Humoral immune response to primary rubella virus infection. Clin. Vaccine Immunol., March 1, 2006; 13(3): 380 - 386. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Dimech, L. Panagiotopoulos, J. Marler, N. Laven, S. Leeson, and E. M. Dax Evaluation of Three Immunoassays Used for Detection of Anti-Rubella Virus Immunoglobulin M Antibodies Clin. Vaccine Immunol., September 1, 2005; 12(9): 1104 - 1108. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |