Epidemiologic Notes and Reports Varicella Outbreak in a Women's Prison -- Kentucky
During January and February 1989, three cases of varicella (chickenpox) occurred among inmates at the Federal Correctional Institution in Lexington, Kentucky. This all-women prison is a 1200-bed facility with an onsite hospital. At the time of the outbreak, 1276 inmates were housed in the facility; approximately one fourth were Hispanic (primarily from Central and South America); 36 (3%) were pregnant. Thirty-two (3%) inmates were seropositive by enzyme-linked immunosorbent assay (EIA) and Western blot for human immunodeficiency virus (HIV) infection, including six persons with acquired immunodeficiency syndrome (AIDS). The first case of varicella developed on January 8 in a 25-year-old U.S.-born black woman who had been on furlough in New Jersey with her 8-year-old daughter who had chickenpox. The second case occurred on February 1 in a 23-year-old Central American woman; she had given a hair permanent to the first case-patient within 24 hours before the first patient developed a rash. The third case was identified on February 19 in a 19-year-old U.S.-born Hispanic woman who also has severe juvenile rheumatoid arthritis. The latter two women attended the same class during late January.
The third case-patient lived in the chronic-care unit of the prison hospital with 17 other women, including two with AIDS and one receiving low-dose steroids for treatment of systemic lupus erythematosis. She potentially exposed two groups of contacts. The first group comprised other inmates in the chronic-care unit, the unit's medical staff, and inmate workers. To prevent further transmission, persons with uncertain histories of previous chickenpox infection were not permitted to enter the unit. Three nurses who were uncertain of their histories were excluded from the unit pending results of their varicella-zoster (VZ) antibody titer tests. In addition, 12 patients and four inmate workers from the chronic-care unit were identified from histories as possibly not immune.
The second group of contacts comprised all other identifiable social and classroom contacts of the third case-patient and included greater than 200 inmates who attended the same programs or classes during the 3 days before she developed symptoms. Of this group, 100 were uncertain about histories of previous varicella infection, including 40 with self-identified risk behaviors for HIV infection and one who may have been pregnant. Serum specimens were obtained from 116 of these inmates and three staff members to measure VZ antibody titers. Because of the time required to process the specimens, all potentially susceptible inmates in this second group of contacts were quarantined in a separate unit within the prison until their serologic results became available.
Overall, 115 (99%) of the 116 persons with evaluative results* were immune to VZ (immunity defined as titers greater than or equal to 1:8 by immunofluorescent antibody (IFA) measurement); the one person who was confirmed susceptible to VZ after duplicate IFA testing remained asymptomatic. All pregnant women, AIDS patients, and staff were immune. In addition, all 40 persons reportedly at risk for HIV infection were negative for HIV antibody on EIA testing. No cases of varicella have occurred since the third case. Reported by: JB Williams, S Fawkes, Federal Correctional Institution, Lexington, Kentucky. Div of Immunization, Center for Prevention Svcs, CDC.
Editorial Note: In the United States, exposure to and infection with the highly communicable VZ virus is virtually unavoidable (1). VZ virus causes both varicella (the manifestation of primary infection in a susceptible person) and zoster (the result of reactivation of latent virus); patients with either disease may transmit the virus to susceptible persons (1-3). An estimated 3.5 million cases of varicella and 300,000 cases of zoster occur in the United States annually (2).
Varicella can be life threatening, particularly in adults, pregnant women, neonates, and immunocompromised persons. VZ infection in pregnancy may also produce fetal infection and an array of congenital abnormalities characterized as "congenital varicella syndrome" (4). Zoster occurs and can be severe in HIV-infected persons (5). Persons from rural tropical and subtropical regions are less likely than persons from temperate zones to be infected as children, leaving them susceptible as adults (6). Thus, in this prison population, increased risk existed for transmission and severe health effects.
In this investigation, the estimated level of immunity for the inmate population was at least 99%. Based on this nonrandom sample from the population of 1267 inmates, at most, 13 persons were possibly susceptible to varicella before the onset of disease in the first case-patient. Nonetheless, the close confines and extensive socialization in a prison maximize the potential spread of a highly contagious disease, such as varicella, despite high levels of immunity.
Introduction and subsequent transmission of the VZ virus among patients and staff can be reduced in health-care settings such as in this prison. CDC has developed isolation precautions for hospitalized patients who either have active disease or have been exposed to varicella or zoster (7). CDC has also issued recommendations to minimize virus transmission to and from hospital personnel (8); in institutions where varicella is prevalent or where there are many high-risk patients, it may be useful to screen those personnel who have a negative or equivocal history of varicella for the presence of serum antibodies to VZ virus to document susceptibility or immunity (persons with a positive history can be considered immune). In the absence of a licensed vaccine against VZ, efforts should be taken to maximize the effectiveness of existing recommendations for control of VZ virus infections.
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8. Williams WW. Guideline for infection control in hospital personnel. Infect Control 1983;4(suppl 4):326-49. *Three women had "interfering substances" in their serum preventing a determination of VZ antibody presence, but subsequent interviews with family members established a childhood history of chickenpox in all three cases.
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