YELLOW FEVER VACCINE, BREASTFEEDING TRANSMISSION SUSPECTED - CANADA

********************************************************
A ProMED-mail post

ProMED-mail is a program of the
International Society for Infectious Diseases


Date: Mon 7 Feb 2011
Source: EurekAlert! [edited]



A 5-week-old infant most likely contracted a vaccine strain of yellow
fever virus [YFV] through breastfeeding, according to a case report
published in CMAJ (Canadian Medical Association Journal). "Until
recently, avoidance of vaccination of breastfeeding women with yellow
fever vaccine had been based on theoretical grounds only," writes Dr
Susan Kuhn, with coauthors. [In fact, previously there have been one
confirmed and one probable case of breast milk transmitted YF vaccine
to infants. See below. - Mod.TY] "We report the probable transmission
of vaccine strain of yellow fever virus from a mother to her infant
through breastfeeding," which supports current recommendations for
breastfeeding mothers to avoid the vaccine.

The yellow fever vaccine is a live-virus vaccine that has been used
since the 1940s.

When the infant was 10 days old the mother received pre-travel advice
and travel vaccinations, including one for yellow fever. Subsequently,
they traveled to Venezuela for one week and breastfeeding was
continued. The infant did not receive vaccinations.

"The previously healthy 5-week-old infant male presented to the
hospital with a 2-day history of fever and irritability," write the
authors. "The day before his admission, he had been noted to have
focal seizures on alternating sides." Testing of the spinal fluid
revealed evidence of recent infection with the yellow fever virus.
Given that the travellers elected to stay in urban Venezuela where
yellow fever is not known to be a risk, the authors concluded that the
likely explanation was transmission of the yellow fever vaccine strain
through breastfeeding. The baby showed no sign of insect bites, had
not been in contact with sick people, was not exposed to animals in
Canada or elsewhere, had no history of herpes infections in family
members, and had not had any vaccinations prior to his symptoms.

"This probable case of yellow fever virus further supports the
current recommendations for avoidance of yellow fever vaccination in
lactating mothers of infants under 9 months of age," write the
authors. "While there may be situations in which the mother will have
unavoidable and significant risk of yellow fever exposure, the risk to
the infant due to maternal vaccination must be weighed against the
risk of wild-type virus infection."

The authors conclude that travelling women should adjust their plans
to reduce or limit their risk of exposure, or postpone their trip
entirely until their infant is no longer breastfeeding or is old
enough to be vaccinated.

--
Communicated by:
ProMED-mail Rapporteur Mary Marshall

[The recommendation to avoid YF vaccination of breastfeeding mothers
of very young infants is prudent. The case above underscores that
recommendation. The following is taken from the CDC Morbidity and
Mortality Weekly Report cited below:

Following YF vaccine administration, primary vaccine recipients often
develop a low-level viremia with the vaccine virus. The viremia
usually occurs within 3-7 days and persists for 1-3 days, abating as
YFV IgM antibodies are developed.

One probable and one confirmed case of YEL-AND (YF vaccine-associated
neurologic disease) have been reported in infants whose mothers were
vaccinated with YF vaccine. Both infants were breastfed exclusively,
were younger than 1 month at the time of the exposure, and had not
received the vaccine themselves. YF vaccine virus was recovered from
the CSF of the confirmed case patient, and YFV-specific IgM antibodies
were detected in the probable case-patient's CSF. Testing was not
performed on the breast milk in either case to confirm the presence of
vaccine virus.

Reference
---------
Staples JE, Gershman M, Fischer M: Yellow Fever Vaccine.
Recommendations of the Advisory Committee on Immunization Practices
(ACIP). Recommendations and Reports, Morbidity and Mortality Weekly
Report (MMWR) Recomm Rep. 2010 Jul 30; 59(RR-7): 1-27; available at
. - Mod.TY

The full article from CMAJ is available at
.
- Sr.Tech.Ed.MJ]

.................................................dk/ty/mj/dk
*##########################################################*
************************************************************
ProMED-mail makes every effort to verify the reports that
are posted, but the accuracy and completeness of the
information, and of any statements or opinions based
thereon, are not guaranteed. The reader assumes all risks in
using information posted or archived by ProMED-mail. ISID
and its associated service providers shall not be held
responsible for errors or omissions or held liable for any
damages incurred as a result of use or reliance upon posted
or archived material.
************************************************************
Donate to ProMED-mail. Details available at:

************************************************************
Visit ProMED-mail's web site at .
Send all items for posting to: promed@promedmail.org (NOT to
an individual moderator). If you do not give your full name
name and affiliation, it may not be posted. You may unsub-
scribe at .
For assistance from a human being, send mail to:
.
############################################################
############################################################