Background
Rubella is now rare because of widespread compliance with childhood immunization programs. The disease is usually a benign and inconsequential viral illness unless exposure occurs in utero.
Congenital rubella syndrome is associated with clinically significant congenital malformations. The live-attenuated virus vaccine has decreased the incidence of rubella significantly, thereby decreasing congenital disease.
Image in a 4-year-old girl with a 4-day history of low-grade fever, symptoms of an upper respiratory tract infection, and rash. Courtesy of Pamela L. Dyne, MD. Pathophysiology
The causative organism is a single-stranded RNA togavirus that is transmitted by means of respiratory droplets. The virus replicates in the nasopharynx and regional lymph nodes, resulting in viremia. The virus then may spread to the skin, CNS, synovial fluid, and transplacentally to a developing fetus.
Epidemiology
Frequency
United States
Before the rubella vaccination became available in 1969, epidemics occurred every 6-9 years and pandemics every 10-20 years. In 1977-1981, 20,395 cases of rubella were reported in the United States. According to Statistical Handbook on Infectious Disease regarding historical trends of rubella in the United States, the incidence has significantly decreased since that time.[1] In 1990, 1124 cases of rubella occurred, and, in 1999, only 267 occurred. In the last decade, the rate has been less than 10 cases of congenital rubella syndrome per year. These cases mostly affected mothers born outside of the United States in Latin American countries with lower vaccination rates.
In 2004, the Centers for Disease Control and Prevention (CDC) reported that, since 2001, fewer than 25 cases of rubella have occurred each year in the United States.[2] The CDC estimates 95% vaccination coverage among school-aged children and 91% immunity in the population.[2]
During the 1990s resistance to the MMR vaccine developed. An earlier (since discontinued) version in the United Kingdom was associated with aseptic meningitis. As a result of this, vaccination rates in the United Kingdom fell from an earlier level of 92% to 79% in 1998; they have since rebounded.[3] Moreover, a correlation between autism and MMR use was later postulated. Subsequent epidemiologic studies have shown no significant association between the vaccine and either condition. Inadequate vaccination rates have led to an ongoing outbreak in Austria.[4]
A recent case control study, presuming it to be a random variation, found a correlation between early rubella vaccination (before age 10) and later development of multiple sclerosis.[5] Another recent study shows that immigrant women in Canada had surprisingly low vaccination rates; this highlights the risk of epidemics in areas with significant immigrant populations.[6] Vaccination rates remain very high in the United States; should this change in the future, the frequency of rubella could change dramatically.
International
The rubella vaccination is given to only about half the world's population. Congenital rubella syndrome remains a major problem in some areas. In Russia, for instance, congenital rubella syndrome causes 15% of all birth defects.
Mortality/Morbidity
Infection in healthy children or young adults is generally self-limited and without sequelae.
- The most common complications are arthropathies of the fingers, wrists, and knees that can persist for a year or more.
- Thrombocytopenia with purpura and hemorrhage is a rare complication of rubella.
- Congenital rubella syndrome is associated with malformations of multiple organ systems including the CNS and cardiac, ocular, and skeletal systems. Infants with congenital rubella syndrome who survive into adulthood may be plagued by autoimmune disorders and dysgammaglobulinemia.
- Damage to the fetus is most likely when maternal infection occurs during the first 2 months of pregnancy, although there is risk associated with infection up to 5 months.
Race
- The highest risk is among members of racial or ethnic groups who are unvaccinated and who may be exposed to persons traveling from areas where rubella vaccination is not routine.
- Recent outbreaks have occurred among persons of Hispanic ethnicity. Consequently, Hispanic persons and persons from countries without rubella vaccination programs should be considered susceptible to rubella unless they have documentation of vaccination or serologic evidence of immunity.
Sex
Rubella affects men and women equally.
Age
Before vaccination, the peak incidence occurred in children aged 5-14 years. However, at present, most cases occur in teenagers or young adults.
Watstein SB, Jovanovic J. Statistical Handbook on Infectious Diseases. Westport, CT: Greenwood; 2003:5.
CDC. Elimination of rubella and congenital rubella syndrome--United States, 1969-2004. MMWR Morb Mortal Wkly Rep. Mar 25 2005;54(11):279-82. [Medline].
Elliman D, Bedford H. MMR: where are we now?. Arch Dis Child. Dec 2007;92(12):1055-7. [Medline].
Schmid D, Kasper S, Kuo HW, Aberle S, Holzmann H, Daghofer E. Ongoing rubella outbreak in Austria, 2008-2009. Euro Surveill. 2009;14(16):[Medline].
Ahlgren C, Toren K, Oden A, Andersen O. A population-based case-control study on viral infections and vaccinations and subsequent multiple sclerosis risk. Eur J Epidemiol. Jul 26 2009;[Medline].
McElroy R, Laskin M, Jiang D, Shah R, Ray JG. Rates of rubella immunity among immigrant and non-immigrant pregnant women. J Obstet Gynaecol Can. May 2009;31(5):409-13. [Medline].
CDC. CDC. Centers for Disease Control and Prevention: Morbidity and Mortality Weekly Report. Achievements in Public Health: Elimination of Rubella and Congenital Rubella Syndrome—United States, 1969-2004. JAMA. 2005;293:2084-6.
Fisher RG, Boyce TG. Prenatal infections. In: Moffet's Pediatric Infectious Disease: A Problem-Oriented Approach. Lippincott Williams & Wilkins; 2005:631-2.
Maldonado Y. Rubella. In: Behrman RE, Kliegman R, Jenson HB, eds. Nelson Textbook of Pediatrics. Philadelphia, PA: WB Saunders; 2004:1032-4.
Mercurio MG, Elewski BE. Cutaneous manifestations of systemic viral, bacterial, and fungal infections and protozoal disease. In: Dermatologic Signs of Internal Disease. 2nd ed. 1995:254.
Palacin PS, Castilla Y, Garzon P, Figueras C, Castellvi J, Espanol T. Congenital rubella syndrome, hyper-IgM syndrome and autoimmunity in an 18-year-old girl. J Paediatr Child Health. Oct 2007;43(10):716-8. [Medline].
Sanchez PJ. Viral infections of the fetus and neonate. In: Feigin RD, Cherry J, Demmler GJ, Sheldon S, eds. Textbook of Pediatric Infectious Diseases. Philadelphia, PA: Saunders; 2004:881-5.
Smith A, Yarwood J, Salisbury DM. Tracking mothers' attitudes to MMR immunisation 1996-2006. Vaccine. May 16 2007;25(20):3996-4002. [Medline].
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