Academic journal article Bulletin of the World Health Organization

Burden of Disease from CRS

Academic journal article Bulletin of the World Health Organization

Burden of Disease from CRS

Article excerpt

Introduction

Rubella is a common cause of childhood rash and fever; its public health importance relates to the teratogenic effects of primary rubella infection in pregnant women (1). The worldwide pandemic of rubella in 1962-65 highlighted the importance of congenital rubella syndrome (CRS); and in the USA alone, more than 20 000 cases of CRS were estimated to have occurred (2).

Table 1 summarizes the clinical manifestations of congenital rubella. After infection in the first trimester, there is an approximately 50% increase in risk of spontaneous abortion (3). CRS manifestations in surviving infants may be transient (e.g. purpura); permanent structural manifestations deafness, congenital heart disease, cataract); or late-emerging conditions (e.g. diabetes mellitus). Sensorineural deafness may occur following maternal infection up to the 19th week of pregnancy, while cataract and heart disease only occur after infection prior to the ninth gestational week (4).

Table 1: Main clinical manifestations of congenital [rubella.sup.a]

General
   Fetal loss (spontaneous abortion and stillbirths)
   Low birth weight
   Micrognathia

Ears and central nervous system
   Sensorineural deafness: unilateral or bilateral
   Central auditory deafness
   Mental retardation
   Speech defects

Cardiovascular system
   Patent ductus arteriosus
   Pulmonary arterial stenosis
   Ventricular septal defects

Eyes
   Retinopathy
   Cataracts: pearly, dense, nuclear; 50% [bilateral.sup.b]
   Micropathalmos

Transient neonatal [manifestations.sup.c]
   Thrombocytopenia, +/- purpura
   Hepatospenomegaly
   Meningoencephalitis
   Bony radiolucencies
   Adenopathies

Late-emerging or developmental
   Late-onset interstitial pneumonitis, age 3-12 months
   Chronic diarrhoea
   Insulin-dependent diabetes mellitus

(a) Adapted from ref. 4 and 99.

(b) Cataract is always accompanied by retinopathy.

(c) Extensive infection; high mortality.

The absolute risk of CRS among children born to mothers infected during pregnancy varies widely in different studies; in part, this reflects the age at follow-up of children, as deafness is most easily detected after 2 years of age (5). Among a series of 269 infants born to mothers with rubella infection during pregnancy, Miller et al. (6) found that the risk of congenital infection was 81% and that of malformations was 69% after confirmed maternal rubella with rash in the first trimester. The risk of malformation detected by 2 years of age fell rapidly from 90% of nine infants infected prior to 11 weeks' gestation to 33% of four infants infected at 11-12 weeks' gestation. No defects were detected among 63 infants born to mothers infected after 16 weeks' gestation. A study in the USA, however, found a small risk of CRS even among infants born to mothers infected after the 16th week of pregnancy (7).

Interest in the burden of disease and global rubella vaccination policies has increased recently for a number of reasons. Rubella outbreaks leading to CRS were documented in Panama (8) in the mid-1980s, and in Oman (9) and Sri Lanka (10) in the 1990s. Measles vaccine coverage of infants is now [is greater than] 80% in many developing countries; thus effective rubella control programmes are feasible. Many countries have introduced rubella-containing vaccines to their national programmes, using a variety of different schedules. In addition, measles-mumps-rubella (MMR) vaccine is distributed in the private sector, even in countries without a national rubella control programme (11). There is thus a need to review the principles and practice of control of rubella and CRS.

In this review article, the first of two parts on control of rubella and CRS in developing countries, we present information on the burden of disease related to CRS and make recommendations for surveillance of rubella and CRS. In part 2, we present information on the current use of rubella vaccine in different WHO regions, and summarize the lessons learned from different rubella vaccination policies (12). …

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