| Abstract |
Recent publications have challenged the
idea that the vast majority of human immunodeficiency virus
(HIV) infections in children are contracted through vertical
transmission. For example a South African paper published
last year found that 132 (5.6%) of 2348 children aged 2-14
were infected with HIV. Only 20 of the children infected with
HIV had a biological parent who had also been tested for HIV,
and 15 (75%) of these parents were HIV-negative. The numbers
were small and there may have been problems with misattribution
of motherhood but already these data are affecting the allocation
of funds for prevention of infection. It is, therefore, crucially
important for more data to be gathered on this subject. The
objective of this pilot study is to determine the prevalence
of horizontally transmitted HIV infections in children aged
18 months to 14 years in rural South Africa. We hypothesise
that HIV prevalence in children of HIV negative mothers is
less than 1%.
The Africa Centre is currently conducting a large population
based adult HIV surveillance study. We will recruit 1500 children
of mothers who have been tested as part of that study into
the current study.
The children will be evenly divided among 3 groups defined
by age (18m-4y, 5-9y, 10-14y). Participating children will
undergo anonymous linked HIV testing. A questionnaire will
be administered to gather information about risk factors for
horizontal transmission of HIV. In the cases when children
are HIV positive and their mothers are HIV negative, maternity
testing using short tandem repeat loci will be done to establish
the biological relationship. We estimate that 30% of mothers
will be HIV positive. Recruiting 545 mother/child pairs into
each age group, therefore, will allow us to find 380 pairs
with HIV negative mothers in each group. This sample size
is sufficient to identify 1% HIV prevalence among children
of HIV negative mothers with 95% confidence interval of 0.5-2.0%.
If HIV prevalence amongst children of HIV negative mothers
is greater than expected we will apply for further funds to
conduct large case-control study to determine risk factors
for such horizontal transmission of HIV. If the prevalence
rate is <1% this study will have contributed important
evidence on the true nature of HIV transmission to children.
It will also, regardless of the prevalence result, provide
an important, cohort of discordant mother-child pairs, on
whom further prospective studies of the impact of such discordance
on paediatric morbidity and mortality, and the socio-economic
well-being of the family, in contrast to concordant mother-child
pairs.
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