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Infection of the baby
   Last updated: 18.06.04
 
The detection of HIV infection in children born to HIV–positive mothers is complex, and testing methods are changing rapidly. All babies born to women with HIV acquire maternal antibodies, and it is not easy to differentiate their own from their mother's. All babies have HIV antibodies from their mother's bloodstream, irrespective of whether they are HIV infected themselves. These maternal antibodies persist for approximately ten months, and may last as long as eighteen months. HIV antibody tests on these young babies will only show if the mother is infected, and are not helpful in differentiating between infected and uninfected infants. Many parents want to have an early definitive diagnosis, as repeated observation and testing can be distressing and disruptive. Many doctors would like to be able to diagnose truly HIV infected infants earlier in order to start treatment. There is an increasing availability of prophylaxes and therapies, and it is known that about 25% of babies who are HIV infected develop clinical symptoms of AIDS or die within the first year of life.

When it is known that a child is at significant risk of HIV infection (e.g. when the mother is known to be HIV-positive), a number of measures should be employed to try to ascertain if the baby is HIV infected as quickly as possible, and before maternal antibodies clear. These more sensitive tests are carried out routinely at major centres experienced in dealing with children at risk of HIV infection. Most of these centres will be happy for less HIV experienced centres to contact them for advice and assistance with care.

An accurate early diagnosis of HIV infection in infants depends on tests which establish the true presence of HIV virus, as opposed to HIV antibodies, in the baby. These tests are:
  • p24 antigen or acid–dissociated p24 antigen tests

  • Virus culture

  • HIV DNA Polymerase Chain Reaction tests (PCR).


PCR and virus culture tests should be performed at repeated intervals: within 48 hours of birth (testing at this point identifies about 40% of infected children), at about 4–8 weeks, and at 3–6 months. US guidelines on testing state that if two or more IgG antibody tests (see below) are negative at least six months after birth, with a one month interval between the two tests, it is reasonable to assume that the child is not infected.

In addition, tests of the infant's immune system may help to make an early diagnosis. These tests are:
  • High immunoglobulin levels (IgG, IgA, IgM)

  • Inverted CD4:CD8 ratio

  • Persistent HIV antibody after 18 months.


Finally, many infants have some clinical manifestations of HIV infection by 6 months of age. In the USA, researchers suggest that the majority of children can be identified with currently available technology by 3–4 months old.

All infants born to HIV-infected mothers should ideally receive a six week course of oral AZT, and should not be breast-fed.

Health care workers should not treat a recently delivered mother who knows she is HIV positive differently from any other mother. For some women (and families), this will be a time for planning for the future, despite the fact that the HIV status of the baby will not be known for some time. This will include decisions about any measures which might lower the chances of post natal HIV transmission, such as not breast-feeding. It will also be important to consider how to cope with the uncertainty and monitoring of the baby in the first few months. This will also be a time to plan who needs to know about the baby's risk of HIV infection. Most women will find it helpful to inform their GP and Health Visitor, but only if these professionals are sympathetic to the woman's HIV status. Knowing that the baby might be HIV infected can mean that appropriate care can more quickly be offered.

Although the majority of babies born to women with HIV are not infected, health care workers will understandably usually treat the baby as HIV infected until their HIV status is clarified. The baby may be offered prophylaxis against PCP before a definite diagnosis is made. The prophylaxis is known to be relatively safe in infants, and PCP is a significant risk to the baby in the first few months of life if she or he is HIV infected.

HIV disease in children is different from adults and different criteria are used to diagnose AIDS. About 25% of babies who are HIV infected develop clinical symptoms of AIDS or die within the first year of life. Babies who survive the first year of life have a slow progression to AIDS comparable to adults. Out of all those children truly infected at birth, 70% are alive at 6 years and 50% at 9 years old. There may be considerable psychosocial issues for children born HIV infected when they reach their teens. These issues range from adolescent reactions to taking so many drug treatments to wanting to experiment sexually. Until recently, the life expectancy of children with HIV was not high. With combination therapy, it is now extended and these psychosocial issues are becoming more urgent.

See Children, adolescents and families for further discusssion.

References


BMJ vol 316, 24 Jan 1998 Special issue devoted to HIV antenatal testing in the UK.

Intercollegiate Working Party for Enhancing Voluntary Confidential HIV testing in pregnancy, May 1998.

Kim L et al. Evaluation of sperm washing as a potential method of reducing HIV transmission in HIV-discordant couples wishing to have children. AIDS 13: 645-651, 1999.

Lorraine Sherr Of Mice and Women, http://iapac.org/clinmgt/women/mice.html.Summer 1997 DemiMondaine.

Semprini et al: Insemination of HIV–negative women with processed semen of HIV–positive partners, Lancet 340: 1317–19, 1992.

The National HIV Prevention Information Service has published a Resource Guide on Antenatal HIV testing policy. This can downloaded from http://www.hea.org/uk/nhpis