Hearing Conditions and Auditory Disorders, Causes of

Rubella

One of the most common causes of congenital deafness is rubella infection in utero. Rubivirus is a single-stranded virus that results in an exanthematous illness, which often presents with nonspecific symptoms such as a pruritic rash, lymphadenopathy, as well as low-grade fever. According to the Centers for Disease Control, rubella infections are highly contagious and could be transferred from one individual to another through droplets emanating from an infected individual. Although rubella vaccines are currently available for immunization, infections continue to occur around the world, particularly in developing countries. One of the greatest concerns regarding rubella infections is associated with its teratogenic effects on the developing fetus during pregnancy. Studies have shown that the most severe effects of a rubella infection are observed when the virus is contracted during the first trimester. A global pandemic infection involving the rubella virus occurred in the 1960s, which emphasized the importance of screening and/or administering vaccines as a preventive measure against the occurrence of congenital rubella syndrome (CRS). In the [Page 462]1980s, at least 20,000 cases of rubella infections were diagnosed in the United States, whereas in other countries, the prevalence was higher, affecting 1 in 1,000 babies. Surveillance studies conducted in developing countries have shown that rubella epidemics reoccur at 4- to 7-year intervals, regardless of the economic status of a particular country. The implementation of mass immunization is thus essential to prevent the occurrence of CRS in 10 percent of pregnant women who are susceptible to the infection.

Aside from hearing conditions, rubella infections may also cause cardiac defects, vision loss, and disorders involving the central nervous system, including mental retardation and microcephaly. Infants diagnosed with CRS often develop features of growth retardation. Despite the wide range of effects of rubella infections, changes to hearing levels is considered as the most common effect of this viral disease. Serological screening of infants with intermediate levels of congenital auditory impairment has shown that 50 percent of the cases harbored antibodies specific to the rubella virus. Studies have also shown that the most severe effects of this virus are often observed in infections that have occurred during the second month of pregnancy. During this stage of gestation, the developing fetus acquires sensorineural functions, which are targeted by the presence of the microbe.

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