Oral Fluid Testing and Rubella, England and Wales | CDC EID

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Volume 16, Number 10–October 2010
Research
Oral Fluid Testing during 10 Years of Rubella Elimination, England and Wales

Gayatri Manikkavasagan, Antoaneta Bukasa, Kevin E. Brown, Bernard J. Cohen, and Mary E. Ramsay Comments to Author
Author affiliation: Health Protection Agency Centre for Infections, London, UK

Suggested citation for this article

Abstract
Surveillance of rubella in England and Wales has included immunoglobulin M testing of oral (crevicular) fluid from reported case-patients since 1994. The need for laboratory confirmation to monitor rubella elimination is emphasized by poor sensitivity (51%, 95% confidence interval 48.9%–54.0%) and specificity (55%, 95% confidence interval 53.7%–55.6%) of the clinical case definition. During 1999–2008, oral fluid from 11,709 (84%) of 13,952 reported case-patients was tested; 143 (1.0%) cases were confirmed and 11,566 (99%) were discarded (annual investigation and discard rate of clinically suspected rubella cases was 2,208/100,000 population). Incidence of confirmed rubella increased from 0.50 to 0.77/1 million population when oral fluid testing was included. Oral fluid tests confirmed that cases were more likely to be in older, unvaccinated men. Testing of oral fluid has improved ascertainment of confirmed rubella in children and men and provided additional information for assessing UK progress toward the World Health Organization elimination goal.

In 1970, rubella vaccination was introduced in the United Kingdom for prepubertal girls and nonimmune women of childbearing age to protect them from the risks for rubella during pregnancy. Although this selective vaccination policy effectively reduced the number of cases of congenital rubella syndrome (CRS) and terminations of pregnancy, rubella during pregnancy continued to occur (1). In 1988, measles, mumps, and rubella (MMR) vaccine was introduced for universal vaccination at 13–15 months of age with the goal of eliminating circulating rubella.

A considerable decrease in rubella in young children followed, but in 1993, clinically diagnosed and laboratory-confirmed rubella increased; the increase occurred predominantly in older men who had previously not been offered a rubella-containing vaccine (2). Therefore, in November 1994, rubella vaccine was included in a school catch-up campaign to prevent a predicted measles epidemic (3). Approximately 92% of children 5–16 years of age received combined measles–rubella vaccine. In 1996, to maintain measles control, a second dose of MMR was recommended for children 5 years of age.

For any disease in the elimination phase, accurate surveillance is necessary to identify reservoirs of infection and susceptible groups (2). In 2005, the World Health Organization (WHO) European Region adopted a resolution to eliminate indigenous rubella by 2010 (elimination goal of confirmed rubella incidence <1 per 1 million population) (4). WHO has developed a clinical case definition for rubella (5), but identification of cases based on clinical suspicion alone becomes less reliable as disease incidence decreases. Therefore, for countries trying to eliminate rubella, laboratory confirmation of all suspected cases is recommended (4). Before 1994, surveillance of laboratory-confirmed rubella in England and Wales was based mainly on detection of immunoglobulin (Ig) M against rubella in serum. However, because rubella infection is usually mild, physicians are reluctant to obtain blood samples for serum confirmation, especially from young children. There is also some reluctance to obtain serum from men because the diagnosis is not of major clinical significance. Oral or crevicular fluid is a noninvasively obtained clinical specimen that is likely to be more acceptable, especially for children, and is safe and easy to obtain (6–9). Transudates from the capillary bed situated beneath the margin between the tooth and gum are obtained by rubbing an absorptive device between the gum and the cheek. These samples, which are distinguishable from saliva samples, contain mucosal cells that enable detection of the rubella virus by PCR. Methods for obtaining, extracting, and storing oral fluid samples are well established (7,10–13). Detection of rubella IgM in oral fluid has been validated and shown to be »90% sensitive and 99% specific compared with detection in serum (2). Samples are also suitable for genome detection (14,15). Therefore, since late 1994, the enhanced surveillance program in England and Wales has relied on oral fluid testing to provide laboratory confirmation for clinically diagnosed cases of measles, mumps, and rubella (however, serum testing is still recommended for confirmation of infection during pregnancy). An additional increase in rubella incidence occurred during 1995–1998. Reports of rubella peaked in 1996 (a total of 9,081 clinically diagnosed cases were reported) (16). This situation offered an opportunity to evaluate the sensitivity and specificity of the WHO clinical case definition for rubella. In addition, we describe the added value of oral fluid testing during the subsequent 10 years of rubella elimination (1999–2008). full-text: Oral Fluid Testing and Rubella, England and Wales | CDC EID

Suggested Citation for this Article

Manikkavasagan G, Bukasa A, Brown KE, Cohen BJ, Ramsay ME. Oral fluid testing during 10 years of rubella elimination,England and Wales. Emerg Infect Dis [serial on the Internet]. 2010 Oct [date cited]. http://www.cdc.gov/EID/content/16/10/1532.htm

Oral Fluid Testing during 10 Years of Rubella Elimination, England andWales

DOI: 10.3201/eid1610.100560

Comments to the Authors

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Address for correspondence: Mary E. Ramsay, Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency Centre for Infections, 61 Colindale Ave, London NW9 5EQ, UK; email: m.ramsay@hpa.org.uk