Biology Reference
In-Depth Information
program - is the early childhood population, in particular infants and toddlers
attending group daycare. Although primary HCMV infection may occasionally
cause mild disease in the toddler, a far greater concern is that the child may serve
as a vehicle for subsequent infection of a parent. Should a pregnant mother become
infected, the resulting newborn would then be at significant risk of HCMV disease
and its attendant sequelae. Such child-to-parent transmission of HCMV has been
well documented: daycare workers are in particular at increased risk for primary
HCMV infection (Pass et al. 1990; Murph et al. 1991). Thus, interruption of HCMV
transmission in the daycare environment could serve as an important efficacy end-
point for vaccine programs. Behavioral interventions and improved education about
the risks of transmission can also likely play a role in decreasing the likelihood of
this mode of transmission (Cannon and Davis 2005), but behavioral interventions
alone are unlikely to completely eliminate the risk of transmission in this setting.
Development and implementation of HCMV serologic screening programs for
women of child-bearing age may be of benefit in identifying those women and
families who might benefit most from behavioral and vaccination strategies aimed
at interrupting this type of transmission.
Clearly, immunization of infants and toddlers prior to acquisition of primary
HCMV infection is a strategy that should be considered for HCMV disease control.
Immunization of the infant or toddler could result in secondary benefits for adult
subjects, particularly mothers, who would be at decreased risk for acquiring infec-
tion from their child. Such an immunization approach has been utilized for rubella
vaccine, which is routinely administered to young children; in this setting, the
primary benefit of vaccination is not the prevention of rubella per se in the child,
but the prevention of rubella transmission to young women, with the secondary
benefit of prevention of congenital rubella syndrome in subsequent pregnancies.
This occurs, in part, through herd immunity, which ultimately benefits all women
of child-bearing age. Use of mathematical modeling suggests that such an approach
for a HCMV vaccine would produce benefits similar to those realized by rubella
vaccination (Griffiths et al. 2001). Thus, the strategy of universal immunization of
young children against HCMV deserves further consideration.
Moreover, universal immunization against HCMV in early life may confer health
benefits that extend ultimately to men as well as women of child-bearing age.
Increasingly, HCMV infection has been tied to an increased lifetime risk of illnesses
such as atherosclerosis, malignancies, inflammatory and autoimmune diseases, and
the phenomenon of immune senescence in later life (Soderberg-Naucler 2006).
Prevention of HCMV infection, and conceivably elimination of infection through
herd immunity, could provide widespread benefits for human health.
Adolescent HCMV Infections
Adolescents acquire primary HCMV infections at a high frequency. In a prospective
study of HCMV-seronegative adolescents, an annual HCMV infection rate of
13.1% was observed (Zhanghellini et al. 1999). Onset of sexual activity and
