Anna,

Some time back I printed off from the internet  Ruth Lawrence's 'A Review of
the Medical Benefits and Contraindications to Breastfeeding in the United
States' October 1997, which comes from HRSA  Maternal & Child Health Technical
Information Bulletin.  Not sure if I wrote down the url for this, I will have
a dig around my papers and see if I can find it, unless another lactnet can
tell us quickly.  Anyway, it says:

<<CMV causes systemic infections that vary with the age and immunocompetence
of the host but are predominantly asymptomatic.  Although infections acquired
postnatally can be similar to those found in infectious monuculeosis,
infection is rarely significant except in immunocompromised individuals who
are being treated for malignancies, infected with HIV, or receiving
immunosuppressive therapy for transplant.  Infections acquired
transplacentally, during the intrapartum period, or in early infancy may be a
problem.  Congenital infections usually are asymptomatic but can result in
later hearing loss or learning disability.  About 5 percent of infected
infants have profound involvement with growth retardation, jaundice,
microcephaly, intracerebral calcifications, and chorioretinitis.  Infections
acquired at birth from maternal cervical secretions or breastmilk usually are
not associated with symptoms.  Infants with congenital or acquired infections
usually do better if they are breastfed, because of the continuing supply of
maternal antibodies provided in their mother's breastmilk.  Infants, usually
premature infants infected through CMV seropositive blood, have developed
lower respiratory tract infections. Blood products for neonates are now
specifically screened for CMV and irradiated.

CMV, though not highly contagious, is ubiquitous.  For infants, the birth
process and child care exposure are the common sites.  Effects on the infant
are greatest when the mother develops a primary infection during pregnancy.
CMV is usually acquired during late adolescence.  Young mothers are at greater
risk for developing the disease during pregnancy.  In a random study of
postpartum women, 39 percent had CMV in their milk, vaginal secretions, urine,
and saliva.  Of the infants who were breastfed, 69 percent developed
infections while the antibodies were present in the milk.  The infants shed
the virus, developed immune responses to the virus, but did not develop
disease.  Transmission of CMV from breastmilk is related to the duration of
breastfeeding.  Reactivation of CMV in the breastmilk peaks between 2 and 12
weeks, a time when transplacental antibody is waning.  Infants who continue to
receive antibody or associated protective factors via the milk rarely manifest
any symptoms.  Non-breastfed infants can be infected via other secretions,
including saliva; they do not receive protective anibodies or other host
resistance factors present in breastmilk and may have significant residuals of
the disease (e.g., microcephaly and mental retardation).

Term infants can be breastfed when the mother is shedding virus in her milk
because of the passively transferred maternal antibodies.  Premature infants
with low concentrations of transplacentally acquired maternal antibodies can
develop disease from fresh breastmilk containing the virus.  Freezing destroys
the virus, and breastmilk can be frozen at minus 20 degrees centigrade for
seven days before feeding it to the infant for the first few weeks, until the
titer of antibody received via the milk increases.  (Some experts consider
storage for three days at minus 20 degrees centigrade adequate.)>>

Dworsky M, Yow M, Stagno S, Pass RF, Alford C. 1983.  Cytomegalovirus
infection of breast milk and transmission in infancy. Pediatrics 72:295-299

Yeager AS, Palumbo PE, Malachowski N, Ariagno RL, Stevenson DK. 1983.
Sequelae of maternally derived cytomegalovirus infections in premature
infants.  Journal of Pediatrics 102:918-922

American Academy of Pediatrics, committee on Infectious Diseases. 1997.  1997
Red Book: Report of the Committee on Infectious Diseases. Elk Grove Village,
IL; American Academy of Pediatrics.

Regards
Helen Woodman, NCT Breastfeeding Counsellor, Storrington, West Sussex, UK