Updated: Abril 14, 2004
Rubella in childhood is usually a mild illness and its major cause of harm is when infection occurs during pregnancy, especially during the early months of pregnancy.
The risk of women contracting rubella infection has been greatly reduced in the United States by the universal immunization of young children and women with rubella vaccine.
However, some people, confused about the possible risks of the measles-mumps-rubella (MMR) vaccine, have opted to not vaccinate their children against those diseases. Instead, some have sought to expose them in gatherings with other children that they believe have rubella as a way to protect their daughters before their childbearing years.
Unfortunately the child that is thought to have rubella may not have it. In fact, rubella is impossible to distinguish from many other common infections that produce a rash without special laboratory tests. Indeed, experienced physicians can be incorrect in their diagnosis of rubella when lacking those tests—sometimes calling other illnesses with a rash “rubella” and sometimes not recognizing rubella at all. Thus children who are thought to have rubella at a “rubella party” may not really have rubella. Some of these infections may cause serious risks to health.
If the “host” at such a party truly has rubella, not all children will become infected and thus will remain susceptible. Although rubella like measles is caused by a virus that is transmitted from person to person in mucus droplets coughed or sneezed into the environment, rubella doesn’t spread as effectively as measles in this type of setting.
Children infected with rubella at the “party” may or may not develop a rash, so there is no way to know which children have become immune without laboratory testing. This is because rubella usually is a mild illness; about half of infected persons will have no symptoms.
Anyone infected with rubella at the “party” becomes a hazard in the community for the unborn fetuses of women who may be susceptible to rubella and who are pregnant. Thus not only may the child who gets rubella not have symptoms they may be contagious for 3 to 4 weeks.
When rubella symptoms occur, they may include low-grade fever and swollen lymph nodes in the back of the neck followed by a generalized rash.
Complications of rubella are uncommon in children but may include joint pain, a temporary decrease in platelets, and encephalitis (inflammation of the brain). Temporary arthritis may also occur, particularly in adolescents and adult women.
So why is rubella a problem? Rubella in expectant women often leads to congenital rubella syndrome (CRS) in their fetuses. This is a devastating disease characterized by deafness, mental retardation, cataracts and other eye defects, heart defects, and diseases of the liver and spleen that may result in a low platelet count with bleeding under the skin.
The incidence and severity of congenital defects are greater if infection occurs during the first month of gestation. Up to 85% of expectant mothers infected in the first trimester will have a miscarriage, fetal death (stillbirth), or a baby with CRS.
The World Health Organization estimated that, in 1999, 110,000 infants were born with CRS worldwide. Although most CRS occurs in developing countries, it also continues to occur in the U.S., mostly among the infants of unimmunized women.
The first vaccines for rubella were licensed in 1969. Today rubella vaccine is generally given in combination with measles and mumps vaccines (MMR).
Before a vaccine was available, there was a rubella outbreak in the U.S. (1963 to 1964), during which it is estimated that about 12 million people developed the infection. Because some of those infected were expectant mothers, 11,000 fetuses died and 20,000 babies were born with permanent disabilities as a result of exposure to the virus during pregnancy. The number of cases of rubella fell very sharply once the rubella vaccine was licensed in 1969; today there are fewer than 10 cases of congenital rubella syndrome in the U.S. each year.
Persons exposed to infants with congenital rubella syndrome, particularly post-pubertal women for whom rubella immunity is critical, should be aware that infants with CRS may shed rubella virus for at least one year.
Researchers estimate that about one in every 22,000 MMR vaccinations could result in a child developing a temporary bleeding disorder called idiopathic thrombocytopenic purpura (ITP). ITP following MMR immunization is rarely dangerous — generally much less serious than measles, mumps, or rubella — and is easily treated. A recent study found that children who had ITP from other causes who then later received the MMR vaccine had no vaccine-associated recurrences. ITP can also occur as a result of rubella infection.