Seroepidemiology of rubella virus infection among female residents on the offshore islets of Taiwan.

Although rubella vaccination was introduced in Taiwan in 1986 several outbreaks have occurred since then. In order to examine the epidemiological characteristics of rubella virus infection on the offshore islets of Taiwan, the Pescadore (Penghu) Islets and Orchid (Lan-Yu) Islet, the female residents of the islets aged 2-83 years were chosen as the study population. A community-based survey was carried out in three townships randomly selected through stratified sampling. Serum specimens of 677 healthy girls and women randomly sampled from the study areas were screened for the rubella antibody by a latex agglutination test and confirmed by a solid-phase immunoassay. A total of 415 subjects were antibody-positive giving a prevalence of 61.3%. The mean +/- standard deviation of rubella IgG index was 2.84 +/- 0.32. The seropositive rate increased with age in all three townships. The age pattern indicated that the regular ten-year rubella epidemic cycle ceased after 1978. A higher prevalence was observed in Orchid Islet than in the Pescadores. The overall seronegative rate was 48.7% (191/392) for females less than 20 years of age and 32.0% (48/150) for reproductive women between the ages of 20 and 35 years. With such a high proportion susceptible among females of child-bearing ages on the offshore islets of Taiwan, a mass rubella vaccination programme should be enforced in order to prevent possible outbreaks of congenital rubella syndrome in the future.