Karen's questions were very pertinent.

>Since the time between HIV exposure and the time the host tests positive
>can be several months, how can we be *sure* the viral exposure for the baby
>is not during labor/delivery rather than breastfeeding?

Well, that's the problem - we *can't* be sure.  In l997 John et al in
Nairobi discovered viral shedding in cervical secretions of 32%, and in
vaginal secretions of 10%, of HIV+ pregnant mothers during the last
trimester of pregnancy. Others have said that the baby's skin is not an
effective barrier against the virus, and that transmission can occur as a
result of the virus coming into contact with the baby's skin, eyes, mouth
and mucous membranes.
But maybe it's more fashionable to blame breastfeeding.

>When a young child who is breastfed by his HIV+ mother turns from HIV- to
>HIV+, it is because of breastfeeding.
>When a young child who is NOT breastfed seroconverts, it is considered
>"late onset HIV".  Huh?

Yes. Bryson et al proposed definitions for in utero vs intrapartum
transmission. Between 0 - 90 days the baby could be considered to have
intrapartum transmission.  Apparently non-breastfed babies can test negative
on PCR at birth and any time up to 90 days and then test positive.  When you
add this to the window period for the mother, anything up to 14 months
(Riordan) it certainly does raise some questions.

>And wasn't there some study (maybe reported in a JHL?) where researchers
>inoculated beakers of human milk with the HIV virus and went they went back
>to isolate it, couldn't find it?  Seem to remember they looked for it down
>to very improbable parts per million.  (My old JHLs are out on loan.)

Yes, Orloff et al, JHL, 1993.  They did some work trying to innoculate EBM
with the virus and were unable to recover it unless they did it in a very
special way.  They also discussed the antiviral effects of lipids in human
milk; lipase breaks down the fats, the fatty acids disintegrate the viral
envelope. Some of the research was done in the 60s and 70s, so it's been
known for decades.  Yet no-one seems to have take this further for HIV.  Why
not???

Still on the subject of lipids, Dr Paul Lewis and others (also Nairobi, same
group of people, about six of them) have isolated HIV in cell-free
breastmilk, and Nduati and others have found HIV in milk cells, but in both
the studies the lipid portion of the milk was discarded first. Both these
research articles give quantities of the virus that the infant would ingest
in the milk (in the cells, in the cell-free portion, vast numbers). The same
group did the studies on cervical/vaginal secretions, but I haven't found
anything which lets us know if the babies of the mothers that shed the virus
are the same babies who show higher rates of transmission. I'd just love to
know.

One more coincidence.  Dr Nduati wrote the first draft for the UNAIDS HIV
and Infant Feeding Guidelines, the Review of HIV transmission through
breastfeeding. The final copy says that the longer the duration of
breastfeeding the greater the additional risk of HIV transmission through
breastmilk.  Yet in her study on HIV-infected cells in breastmilk it was
found that "the prevalence of high virus load was greatest at 8 - 90 days
and then declined to zero after 9 months."

All this research is so contradictory, and the conclusions don't always
correlate with the findings.  For instance the Leroy multi-centre pooled
analysis (Lancet, August l998) described the risk of transmission of HIV
through breastfeeding as "substantial", yet only 5% of the babies who were
not infected at birth and were shown to be infected at  2.5 months could
have been assumed to have been infected via breastfeeding.  This still
leaves a window of 2 weeks when other reviewers think transmission could
have occurred during delivery. The duration of breastfeeding for the babies
in that review was 3 - 36 months (ie at least one of them only breastfed for
3 months).

The cases of transmission through blood transfusion etc. have shown pretty
conclusively that yes, a newly infected mother has a much higher chance
(29%)  of passing HIV on to her baby (high viral load with a new infection)
so the baby of a mother newly infected during the breastfeeding period is at
greatest risk of infection.  As is the baby of a mother who has active AIDS.
But there may be a window period, after the initial infection and before Sx
of AIDS when we don't seem to know what the risk to the breastfed baby is
because no-one has thought to study this.  Why not?

If we don't know the timing of the mother's infection, Anne's figures of 25%
transmission if not breastfed and 30% transmission if breastfed tie in with
the Leroy review, and there have been other studies which showed similar
figures (Simonon, 4.9%). There have been still more which show a lower rate
of transmission when babies are breastfed than when they are not.  So are we
over-estimating the risk at 14% or 15%?  Lastly, these statistics are
meaningless when we talk to the invididual HIV-infected mother - the baby
will not become 4% or 5% or 15% infected - either he will be infected, or he
will not.  And, at the present time, we have *absolutely* no way of knowing
whether he is already infected, or if he will become infected, and if so
how?  Even if he tests positive straight after delivery when you would think
we could be sure he had been already-infected in utero, and definitely
should be breastfed - even then you can't trust the tests - some 8% of
newborns born to *un*-infected mothers have have tested positive at delivery.

But, if in doubt, let's just blame breastfeeding. Makes you want to open a
bookstore, doesn't it?

Pamela Morrison IBCLC, Zimbabwe

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