Rubella and Congenital Rubella Syndrome -- New York City

In 1985, a provisional total of 630 cases of rubella (0.26/100,000 population) was reported in the United States. This is the lowest annual total since rubella became a nationally notifiable disease in 1966. It represents a 16% decrease from the 1984 total of 752 cases and a 99% decline from 1969, the year of rubella vaccine licensure and the year with the greatest number of reported cases (57,686). Reported rubella activity for the first 46 weeks of 1986 was 22% below that reported for the same time period in 1985. In spite of this high degree of rubella control, outbreaks of rubella in New York City (NYC) in 1985, and subsequently of congenital rubella syndrome (CRS) in 1986, raise concern about the potential for similar outbreaks in other areas of the United States. Rubella

NYC experienced outbreaks of rubella each spring during the period 1983-1985 (1-3). These outbreaks primarily involved adults, and spread occurred in the workplace. Heightened rubella activity in 1985 (Figure 1) was associated with the recognized occurrence of outbreaks in a prison (50 cases), as previously reported (3); in a factory (45 cases); and in five hospitals (18 cases). Altogether, NYC* reported 184 cases of rubella to the Centers for Disease Control (CDC) in 1985. Age was reported for 173 of the patients involved; 91% of them were greater than or equal to 20 years old.

Forty-five cases of rubella occurred in a population of predominantly Hispanic female workers at a factory in the South Bronx. Onsets of rash occurred between February 8 and April 8, 1985. The estimated attack rate for this facility was 7.5%. Patients ranged from 19 to 56 years of age (median = 40 years). Six pregnant women were identified among the employees; all were found to have prior immunity to rubella. Exclusion of the ill employees and of the pregnant women, pending serologic determination of immunity, resulted in 100 missed person-days of work.

During the spring of 1985, eighteen cases of rubella occurred in hospital workers from five medical facilities. Fourteen of these cases occurred in one large hospital located in the South Bronx. Ten of 14 cases were serologically confirmed by demonstration of enzyme-linked immunosorbent assay (ELISA) rubella-specific IgM. The three first-generation cases were epidemiologically linked to the rubella outbreak occurring in the factory described above. Workers from this factory had gone to the hospital's dermatology clinic, where transmission to the medical staff occurred. This hospital outbreak continued for three generations and involved four physicians, five nurses, two laboratory workers, two clerical workers, and one x-ray technician. All of the patients had a rash that lasted from 1 to 7 days. Onsets of rash occurred between March 22 and May 6, 1985. Patients ranged from 24 to 37 years of age (median = 28 years).

Methods used to control the outbreaks included determining the rubella status of all employees, vaccinating susceptibles, and improving active surveillance. In addition, exclusion of employees during their infectious periods was recommended. The protocol used for controlling the outbreaks was similar to that used in previous outbreaks of rubella in the workplace (4). Congenital Rubella Syndrome

During the first 5 months of 1986, eight suspected cases of CRS were reported to the NYC Department of Health. The diagnosis of CRS in all infants was based on clinical and laboratory data. CRS was serologically confirmed in five cases by demonstration of ELISA rubella-specific IgM; three cases were classified as CRS compatible by CDC criteria (Table 1) (5).

All eight of these births occurred in major NYC medical centers between January 5 and March 11, 1986, which was 8 to 10 months after the peak of the rubella outbreak (Figure 1). All eight infants had congenital heart disease: five of them had patent ductus arteriosus; four, peripheral pulmonary artery stenosis, and one, an atrial septal defect. In addition, six of the infants had cataracts; three, hearing loss; two, purpura; one, hepatosplenomegaly; one, congenital glaucoma; and one, microcephaly. Four (50%) of the mothers reported a rubella-like illness with a rash during the first 2 months of pregnancy. However, even though two were evaluated by physicians, none were diagnosed as having rubella. None of the seven mothers interviewed were linked to any other known cases of rubella.

In an effort to determine how this outbreak might have been prevented, information on the mothers of infants with CRS was obtained from hospital records and from personal interviews with seven of the eight women (Table 2). Information on race and ethnicity was available for all eight women: four (50%) were Hispanic, two were black, one was Asian, and one was a non-Hispanic white. In contrast, Hispanics accounted for only 28.4% of total live births in NYC in 1985 (NYC Department of Health, Bureau of Health Statistics and Analysis, unpublished data, 1985). Four of the women were immigrants: two were from the Dominican Republic (year of immigration, 1983 and 1985, respectively); one was from Guyana (1981); and one, from Poland (1976). One woman lived in a welfare hotel. The women ranged from 18 to 29 years of age (median = 24 years), and they had received from 8 to 12 years of formal education (mean = 9.6 years). Five of the women were married; none were employed. Only one lived in the South Bronx. Five of them had previously delivered live infants in NYC hospitals; two of the women had each had two previous live births. At least one woman had undergone rubella screening during a previous pregnancy and was found to be susceptible, but had not been immunized postpartum. None of the seven women interviewed had attended family planning clinics prior to conception.

Five of the seven women interviewed reported receiving prenatal care at clinics affiliated with major medical centers, beginning in the first or second trimester. Two women reported no prenatal care. Based on their ages and personal histories, only two of the eight women (ages 18 and 19) could have been enrolled in NYC schools at a time when rubella vaccine was required by law. The 18-year-old reported rubella vaccination in 1970, but investigators were unable to obtain provider verification. The 19-year-old, an intravenous drug abuser, could not be located. In addition, a 29-year-old woman reported having previously received rubella vaccine in a public clinic prior to entering school. This claim was discounted because the reported immunization would have occurred before the licensure of rubella vaccine. None of the other seven women who were interviewed reported previous rubella vaccination. Reported by A Kaul, MD, I Luten, MD, Lincoln Medical and Mental Health Center, New York City, B Fedun, St. Luke's-Roosevelt Hospital, New York City, LA Pizzurro, A Van Buskirk, SM Wright, EE Taylor, PA Thomas, MD, S Schultz, MD, New York City Dept of Health; Surveillance, Investigations, and Research Br, Div of Immunization, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: This is the first reported cluster of CRS cases in the United States since the occurrence of outbreaks in Chicago (1978-1979, 30 cases) (6) and the San Francisco Bay area (1979-1980, 13 cases) (7). So far in 1986, nine cases of CRS have been reported to the National Congenital Rubella Syndrome Register, a passive surveillance system maintained at the Division of Immunization, CDC (5). The outbreak in NYC accounts for eight of these and underscores two serious concerns. First, 10% to 20% of postpubertal women still lack serologic evidence of immunity to rubella (8-10), and, second, the continued occurrence of rubella in the childbearing-aged population means that potentially preventable CRS cases will occur during the next 10 to 30 years until highly immune cohorts of persons vaccinated as children make up the entire childbearing-aged population.

Since the spring of 1985, the NYC Department of Health has maintained a pregnancy log to follow prospectively the outcomes of pregnant women with serologically confirmed rubella. Nine such women were enrolled for followup in 1985; seven of them elected to carry their pregnancies to term. No CRS cases have been identified from these pregnancies. None of the mothers of the infants with reported cases of CRS were included in this pregnancy log. This observation and the failure to directly link any CRS cases with recognized outbreaks of rubella in NYC emphasize the fact that reported rubella cases monitored only the trend in rubella activity in NYC and did not include all rubella cases that occurred in 1985.

To increase levels of rubella immunization in the childbearing-aged population, a multifaceted approach is necessary. Rubella vaccine should be offered to susceptible postpubertal women whenever they have contact with the health care system. Specific settings where immunization of hard-to-reach adult populations might be accomplished include colleges, family planning clinics, health care institutions, and places of employment. There should also be both followup immunization of women found to be susceptible by premarital rubella screening and postpartum and postabortion immunization of susceptibles identified by screening during pregnancy.

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