A critical component of laboratory surveillance for measles is the genetic characterization of circulating wild-type viruses. The World Health Organization (WHO) Measles and Rubella Laboratory Network (LabNet), provides for standardized testing in 183 countries and supports genetic characterization of currently circulating strains of measles viruses. The goal of this report is to describe the lessons learned from nearly 20 years of virologic surveillance for measles, to describe the global databases for measles sequences, and to provide regional updates about measles genotypes detected by recent surveillance activities. Virologic surveillance for measles is now well established in all of the WHO regions, and most countries have conducted at least some baseline surveillance. The WHO Global Genotype Database contains >7000 genotype reports, and the Measles Nucleotide Surveillance (MeaNS) contains >4000 entries. This sequence information has proven to be extremely useful for tracking global transmission patterns and for documenting the interruption of transmission in some countries. The future challenges will be to develop quality control programs for molecular methods and to continue to expand virologic surveillance activities in all regions.

Rubella virus infection is typically diagnosed by the identification of rubella virus-specific immunoglobulinSymptomatic rubella is characterized by a mild fever and a maculopapular rash of short duration. The clinical diagnosis of rubella is unreliable, and many rash illnesses, such as those caused by measles virus and parvovirus B19, mimic rubella (2). Therefore, laboratory confirmation is essential for the diagnosis of rubella and is typically done by testing serum samples for rubella virus (RV)-specific immunoglobulin M (IgM) antibodies. Serum IgM and IgG responses to RV develop rapidly in the first few days after the onset of rash. However, approximately 50% of samples collected on the day of rash onset test negative for RV-specific IgM antibodies (1, 9, 17). Often, only a single serum sample taken near the time of rash onset is available, resulting in the lack of serologic confirmation of many rubella cases. Thus, the development of a rapid laboratory diagnostic tool for the confirmation of rubella within the first few days of symptom onset would improve the ability to confirm rubella.The isolation of virus in cell culture or the detection of viral RNA by reverse transcription-PCR (RT-PCR) also provides reliable evidence of RV infection (26). Unfortunately, blood is not a good sample for use for the detection of RV, because the highest viral titers in blood typically occur before the onset of rash and virus is undetectable in blood by 2 days after rash onset (6). The virus titer in throat swabs, however, usually reaches a peak titer on the day of rash onset and the titers in throat swabs decline more slowly than those in blood, so that virus can be detected for up to 5 to 7 days after rash onset (6). Several RT-PCR assays for the detection of the RV genome in clinical samples have been described (3,7,15,16,20,25). Templates for the determination of viral sequences for molecular epidemiology can also be made by using RT-PCR.The use of alternative specimens could help reduce the obstacles to specimen collection, storage, and transport in the field (22). Oral fluid (OF), which is collected by rubbing an absorptive device between the gum and the cheek, can be obtained by a method that is relatively noninvasive, is easier to obtain than blood, and has the advantage that it can be used for both RVspecific antibody detection and RV genome detection (12,19,20). Currently, in the United Kingdom, OF samples from notified clinically diagnosed cases are collected between 1 and 6 weeks after the onset of symptoms and are transported by mail to the Central Public Health Laboratory, where they are tested for specific antibody and viral RNA by RT-PCR. By the use of this strategy, specimens from 54.6% of rubella notifications from 1995 through 2001 were obtained for laboratory testing and specimens from 12.7% of the rubella notifications were confirmed to represent rubella cases (20,21).

In 2003, the Pan American Health Organization (PAHO) adopted a resolution calling for rubella and congenital rubella syndrome (CRS) elimination in the Americas by the year 2010. To accomplish this goal, PAHO advanced a rubella and CRS elimination strategy including introduction of rubella-containing vaccines into routine vaccination programs accompanied by high immunization coverage, interruption of rubella transmission through mass vaccination of adolescents and adults, and strengthened surveillance for rubella and CRS. The rubella elimination strategies were aligned with the successful measles elimination strategies. By the end of 2009, all countries routinely vaccinated children against rubella, an estimated 450 million people had been vaccinated against measles and rubella in supplementary immunization activities, and rubella transmission had been interrupted. This article describes how the region eliminated rubella and CRS.

Data from the regional measles surveillance system have documented widespread rubella virus circulation in many different countries in the Americas. In response to the ongoing endemic incidence of the disease and the potential for a major rubella epidemics in the region, the Pan American Health Organization Technical Advisory Group on Vaccine Preventable Diseases recommended the implementation of a regional initiative to strengthen rubella and congenital rubella syndrome (CRS) preventive efforts in 1997. This article summarizes and highlights the progress toward accelerated rubella control and CRS prevention in the English-speaking Caribbean and in Chile, Costa Rica, and Brazil. Useful knowledge is being generated for the adaptation of similar rubella strategies elsewhere. The findings also document the feasibility of implementing the recommended strategies and their rapid impact on disease burden.Rubella, usually a mild febrile rash illness in children and adults, can produce devastating consequences when a woman becomes infected in early pregnancy. The sequels of infection during pregnancy include miscarriage, stillbirth, and a series of birth defects known as congenital rubella syndrome (CRS). Since 1969, rubella-containing vaccines have been shown to be safe and effective in preventing rubella and CRS.Data generated by a regional measles surveillance system developed by the Pan American Health Organization (PAHO) document widespread rubella virus circulation in many countries in the Americas. Some countries also have CRS cases. In the Western Hemisphere, an estimated 20,000 infants with CRS are born annually-even in the absence of major epidemics [1].In response to the ongoing rubella virus circulation and the potential for major rubella epidemics in the region, the PAHO Technical Advisory Group on Vaccine Preventable Diseases recommended in 1997 that a regional initiative be implemented to strengthen rubella and CRS prevention efforts. To achieve this initiative, PAHO developed a rubella control and CRS strategy [2] that includes the introduction of rubellacontaining vaccines into routine childhood immunization programs, vaccination of women at childbearing age, development of specific vaccination strategies for accelerated rubella control and CRS prevention, support to countries in the development of integrated surveillance systems for measles and rubella, implementation of a CRS surveillance system, and rubella virus isolation. Here we summarize the progress made toward rubella control and CRS prevention with emphasis on experience gained in the accelerated control of rubella in the English-speaking Caribbean and in Chile, Costa Rica, and Brazil. METHODSData from an integrated measles-rubella surveillance system and a CRS surveillance system were analyzed to assess the burden of rubella and CRS disease. Coverage

Rubella and congenital rubella syndrome (CRS) continue to be important health problems in many countries. In June 2004, the World Health Organization Steering Committee on Research Related to Measles and Rubella Vaccines and Vaccination met to evaluate data from research and operational activities and to identify critical scientific issues and gaps in knowledge that need to be addressed to improve the global control of rubella and CRS. Information about surveillance for rubella, natural and vaccine-induced immunity to rubella, laboratory diagnosis, the molecular epidemiological profile of rubella virus, and mathematical modeling to assess the burden of CRS and the impact of rubella vaccination was reviewed. This report summarizes the presentations and recommendations for future research.