Cytomegalovirus transmission in child care homes

Background: Children attending child care centers have high rates of cytome galovirus (CMV) excretion. Women exposed to such children have an increased risk of acquiring CMV infection, and primary infection places the offsprin g of such women at risk of congenital CMV infection. We studied family chil d care homes to determine if this child care alternative might represent a safe haven from CMV. Methods: One hundred thirty-two women providing care in their homes were st udied using a latex agglutination method to determine the rate of CMV serop ositivity at baseline. Women who were seronegative for CMV were then sample d prospectively at 6-month intervals between March 1991 and August 1994 to determine the annual, rate of CMV acquisition. A point prevalence of CMV ex cretion in family homes was determined by sampling 106 children from 25 ran domly selected homes. Cytomegalovirus isolates were compared by molecular a nalysis using-polymerase chain reaction-based methods to identify transmiss ion. Results: At baseline, 57.6% of the 132 providers were se seropositive for C MV. Seropositive providers were more likely to be caring for toddlers (aged 1-2 years) (67% vs 46%; P=.02) and had worked in child care somewhat longe r (median of 28.5 a 21.5 months; P=.ll). Using stepwise logistic regression , the strongest predictors of seropositivity at baseline were caring for ch ildren aged 1 to 2 years (odds ratio [OR]=2.37; P=.02) and number of months as a child care provider (OR=1.17 for an increase of 24 months as provider ; P=.08). Six or more years as a provider was highly associated with seropo sitivity (OR=3.27; P=.02). During follow-up, 5 of 51 seronegative providers seroconverted, yielding an annual infection rate of 6.8%. The point preval ence survey of children from the 25 homes (14 had seropositive providers) i dentified 8 CMV-excreting children. Three children in 1 home had indistingu ishable isolates by polymerase chain reaction mapping. The provider serocon verted and excreted an isolate with a molecular profile indistinguishable f rom that of the children. Conclusions: The prevalence of CMV excretion is low among children attendin g child care homes (8% vs 15% in prior studies of child care centers; P=.07 ), and only I (20%) in 5 of the homes had CMV-excreting children. However, the overall CMV seroconversion rate of home child care providers was compar able to the rate observed among providers in child care centers. Families w ho use family home child care as an alternative to large child care centers are exposed to a low and unpredictable risk of CMV infection.