Varicella prevalence in day-care centers

Occupational risk for cytomegalovirus, but not for parvovirus B19 in child-care personnel in France

BACKGROUND

Studies assessing the risk of cytomegalovirus (CMV), parvovirus B19 (B19V), rubella and varicella infections in female child-care personnel may help define appropriate preventive strategies during pregnancy.

METHODS

Serologic testing for all four viruses and a self-administered questionnaire to identify risk factors were conducted on child-care staff aged 20-50 years old and on a reference group of women.

RESULTS

In 395 exposed and 382 reference women, CMV, B19V, rubella and varicella seroprevalence were 69.4, 79.4, 98.7, 100% for exposed women, and 41.1, 68.0, 98.2, 99.7% for reference women, respectively. For CMV, the adjusted seroprevalence ratio (PR) of exposed versus reference workers, (PR, 1.43 [95% IC, 1.22-1.69]) was observed as of the first year of exposure. The risk attributed to occupation was 30.1%. Identified risk factors included exposure duration, past employment in maternity hospital, and participation in cleaning tasks. The risk attributable to personal factors ranged from 14.5% to 32.4%. The adjusted B19V PR was not significant (PR, 1.05 [95% IC, 0.94-1.16]).

CONCLUSIONS

French female child-care staff runs an occupational risk for CMV infection, but not for B19V infection. The fraction attributable to this CMV occupational risk was not higher than the risk associated with personal factors.

Consensus: varicella vaccination of healthy children--a challenge for Europe

The seriousness of varicella-zoster virus (VZV) infection as a public health issue is becoming clearer as country-specific epidemiologic and pharmacoeconomic data become available. In Germany, for example, studies have shown that >5.5% of immunologically healthy individuals develop varicella-related complications such as bacterial superinfections, acute neurologic disorders, pneumonia, bronchitis and otitis media; whereas in Italy, 3.5 to 5% of childhood cases of varicella cause complications such as upper respiratory tract and cutaneous infections. Varicella vaccines are now available. These live attenuated Oka strain vaccines have been shown in extensive studies to be highly immunogenic and well-tolerated in immunocompetent and immunocompromised children, with seroconversion rates ranging from 94 to 100% and 53 to 100%, respectively. These vaccines are also highly effective against clinical disease. These considerations led to a reevaluation of varicella vaccination policies. A routine varicella vaccination program targeting healthy children has already been implemented in the US, and data produced are encouraging and valuable. Similar strategies have not yet been adopted across Europe. The European Working Group on Varicella (EuroVar) was formed in 1998 to address the issues surrounding varicella epidemiology in Europe. After a series of meetings, the EuroVar members prepared a consensus statement recommending routine varicella vaccination for all healthy children between 12 and 18 months and to all susceptible children before their 13th birthday, in addition to catch-up vaccination in older children and adults who have no reliable history of varicella and who are at high risk of transmission and exposure. However, such a policy is recommended only if a very high coverage rate can be achieved. This could be reached with a measles-mumps-rubella-varicella combined vaccine.

Infection control challenges in child-care centers

The child-care environment predisposes young children to infection with a variety of pathogens. Factors contributing to increased incidence of certain infections include age-specific hygiene behaviors, immunologic immaturity of young children, and exposure to pathogens with high infectivity. Respiratory tract and enteric pathogens are responsible for most illnesses, but a number of other agents are also important. Hygienic interventions, especially handwashing, remain important in infection control, but maintenance of appropriate immunization levels plays a crucial role in disease prevention in the child-care setting. Future interventions will center on development of new vaccines to eliminate susceptibility of young children to as many infectious agents as possible and continued evaluation of other preventive measures.

Community impact of childhood varicella infections

OBJECTIVES

To assess age-specific incidence rates, health care utilization, and lost parental work associated with varicella infection in a population-based cohort of children, and to validate parent-reported health care utilization data.

STUDY DESIGN

We conducted a telephone survey of a population-based cohort of 4557 households with children aged birth to 13 years. Medical chart abstraction was used to validate health care utilization information.

RESULTS

We report varicella incidence rates in preschool children that are 2 to 2.5 times higher than previous studies. Rates of varicella-related serious complications, hospitalizations, parental work leave, and medication use are comparable with rates reported elsewhere. However, health provider visits occurred only 0.3 to 0.5 times as frequently as estimated in other studies. One hundred percent of reported hospitalizations and serious complications and 92% of provider visits were validated to be within the study time frame through medical chart audits.

CONCLUSIONS

Parents are an accurate source of varicella-related health care utilization data. Parent-reported incidence data indicate that varicella infections are increasing in preschool children. This shift to infections in younger children may be related to the increased use of out-of-home care for infants and young children. Furthermore, the shift may after the community burden of varicella because of the observed increased parental work loss and decreased frequency of health care visits in the preschool children.

The epidemiology of varicella-zoster virus infections

Historically, varicella has been a disease predominantly affecting preschool and school-aged children in the United States. The live attenuated varicella vaccine was licensed in this country in 1995 and has been recommended for routine use in immunization of children 12 to 18 months of age. As an increasing proportion of the children in the United States are protected from varicella by vaccination, changes in the current epidemiology of the disease are anticipated. This article reviews the current epidemiology of VZV infection and outlines issues related to possible changes in varicella epidemiology that may follow widespread use of the live varicella (Oka) vaccine.

Modified varicella-like syndrome

After incidental exposure to natural varicella, up to 18% of vaccinees reported a breakthrough infection known as modified varicella-like syndrome (MVLS) over up to 10 years of postvaccination follow-up, compared with natural varicella occurring in similarly aged unvaccinated children at the rate of 9% per year. Children with MVLS are frequently asymptomatic, and their disease is characterized by having fewer lesions, less fever, and lasting fewer days than natural varicella. When a case of MVLS occurs there are few secondary cases, suggesting that it is infrequently transmitted. Sequelae such as secondary bacterial infection, cerebellar ataxia, encephalitis, and pneumonia occur infrequently.