Perspectives on the role of surveillance in eliminating rubella and ...

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Perspectives on the role of surveillance in eliminating rubella and congenital rubella syndrome in the Americas Expert Rev. Vaccines 12(9), 989–993 (2013)

Jon Kim Andrus*1 and Ciro A de Quadros2 1 Pan American Health Organization, 525 23rd Street, NW, Washington, DC 20037, USA 2 Sabin Vaccine Institute, Washington, DC, USA *Author for correspondence: [email protected]

Effective management and coordination in regions currently lacking surveillance capacity will require significant increases in existing human resources to manage vitally needed expanded national surveillance systems. An adequate investment in human resources and infrastructure capacity is essential for ensuring surveillance functions well. This was the experience in the Americas, particularly with the recent elimination of rubella and congenital rubella syndrome. By taking this path, other benefits to the overall public health of the nations will occur. The purpose of this paper is to present perspectives on the role of surveillance in the elimination of rubella in the Americas and to share related perspectives on capacity development in developing countries. Hopefully, these perspectives will aid efforts to strengthen surveillance and advance rubella elimination in other regions of the world. KEYWORDS: rubella elimination • surveillance

Surveillance is a core function of good public health practice. When linked with an effective public health intervention like the elimination of rubella and congenital rubella syndrome (CRS), surveillance functions to define trends in disease burden so appropriate action or adjustments in the interventions can be made [1]. The aggressiveness of the intervention will influence the quality of surveillance, and ultimately the human resource capacity development. If control of a disease is the strategy, experience demonstrates surveillance typically is supported with only enough resources to limit extensive spread or to respond to the inevitable outbreaks [2]. Unlike control of endemic disease, elimination aims for zero cases with no endemic transmission. Endemic transmission at any level is obviously not acceptable. The continuum of the commitment going from control and to the elimination of a disease requires a concomitant expansion in the investment in human resources working in a strengthened systems www.expert-reviews.com

10.1586/14760584.2013.841435

environment for surveillance. Well-trained public health staff detecting and responding to the occurrence of cases is absolutely essential regardless whether the approach is control or elimination of the disease [3]. The purpose of this paper is to present perspectives on the role of surveillance in the elimination of rubella in the Americas and to share related perspectives on capacity development in developing countries. As the experience suggests, the authors believe rubella could not have been eliminated if it had not been for the previous successes of polio and measles elimination initiatives [1]. In all cases, the investment in human resources and capacity development remained an essential guiding principle. For purposes of this article, the term elimination, rather than eradication, will be used. The surveillance challenge & opportunity

Rubella is a rash illness caused by a highly infectious Rubivirus of the Togaviridae family. Among children the severity of illness is

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Perspective

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generally less than measles. Unfortunately, many think of rubella as a benign disease because the disease is less severe compared with measles and some people are asymptomatic transmitters of the rubella virus. But, rubella infection in older people can cause more severe outcomes, such as a self-limiting, but at times debilitating arthritis. More importantly, when a pregnant mother becomes infected within the first 10 weeks of her gestation, the risk of her giving birth to a baby with CRS approaches 90% [4]. The CRS outcome of rubella infection wreaks havoc on families. Like with polio, the debilitating sequelae of CRS are devastating and life-long. CRS poses substantial challenges for the subsequent care of these babies, particularly for vulnerable families already living on the margins of poverty. Previous studies using modeling methodologies attempted to estimate the global burden of CRS [5]. Other retrospective hospital record reviews attempted to supplement previous disease burden estimates, particularly at the national levels [6]. These studies focused on collecting hospital data on children with cataracts or hearing disorders consistent with CRS. Other CRS sequelae, namely mental retardation and autism, are extremely difficult to measure, let alone associate causality to rubella. Most often the cause of mental retardation or autism remains unknown, and can be a significant factor in underestimating the true disease burden of CRS. From a public health perspective, this problem can be solved by focusing on surveillance of wild rubella virus transmission, coupled with a vaccination elimination strategy. Simply put, elimination is achieved with rapid reduction of the susceptible population to infection and with surveillance of wild virus transmission for determining when the target has been achieved. Once wild virus transmission is interrupted, the occurrence of CRS cases ceases. The challenge of improving surveillance of rubella virus transmission becomes an opportunity to improve rash fever surveillance and to achieve ultimately elimination of the CRS burden of disease. The measles link

Prior to efforts to eliminate measles from the Americas, there was no clear understanding of rubella disease burden for reasons mentioned above [7]. For all practical purposes, the probable case definition used for measles was a person with rash and fever that the health provider thought was consistent with measles. The protocol required that a blood specimen be taken for laboratory testing for the presence of IgM against measles virus. As more children were investigated, and vaccination efforts to eliminate measles were successfully implemented, fewer children meeting the probable case definition were found to be infected with measles virus. The surveillance recommendation was modified to test for rubella if the IgM for measles proved negative. Field workers also targeted specimen collection for virus isolation so genotyping could be performed. Over time, it became very clear as the program matured, more rubella cases were identified that would have been missed previously. Measles elimination has unmasked the hidden burden of rubella [7]. In addition, the molecular epidemiology of endemic rubella transmission began to emerge [8,9]. 990

Additionally, as much better information was being collected, it became apparent that rubella and CRS could also be potentially eliminated, particularly if the routine immunization program and the measles vaccination campaigns continued to administer measles–rubella combined vaccine. Operationally, measles- and rubella-related diseases are ‘conjoined at the hip’. This relationship was not a challenge, but an incredible opportunity to eliminate multiple conditions at once, with tremendous cost-savings. Studies initially conducted in the Caribbean and then confirmed in other Latin American countries, consistently demonstrated that for every dollar spent on CRS elimination, ministries of health generally save approximately US$12–13 in the treatment of these children with their lifelong disabilities [10]. What became hugely rewarding was that CRS eradication was operationally easier to achieve than either polio or measles [1]. The experience demonstrates that when the rubella mass vaccination campaigns are done well, only one campaign is required to interrupt endemic rubella transmission and ultimately eliminate CRS. Therefore, to understand the role of surveillance in the eradication of rubella and CRS, one must also appreciate the vaccination strategies inextricably linked to surveillance. The vaccination and surveillance strategies to eliminate measles and rubella transmission are described elsewhere, but essentially they all aim to rapidly reduce susceptible populations, taking advantage of the community immunity effects of these vaccines [1]. The vaccination strategies start with the routine program, aimed to raise coverage as high as possible, while simultaneously implementing the supplemental mass immunization campaigns. To achieve equity in the interventions – to insure that risk groups and vulnerable populations are reached – surveillance serves to identify risk groups so that mass vaccination campaigns can be reinforced in risk areas. Specifically, the epidemiology of measles directed a one-time vaccination campaign in every country to target children aged