The HIV epidemic in South Africa has progressed rapidly over the past eighteen years. It is estimated that by 2007, 5.5 million people in South Africa were living with HIV/AIDS (ASSA model 2003). The annual Antenatal National HIV and Syphilis Prevalence Survey, conducted since 1990, shows an exponential growth in prevalence, with the national HIV sero-prevalence rate peaking at 30.2% in 2005, but declining to 29.1% in 2006 and 28% in 2007. Despite all its inherent limitations, this is currently the most reliable form of HIV surveillance in South Africa.
The various provinces have different prevalence rates in 2007 the Western Cape had the lowest prevalence at 12.6%. However, in some areas in the Western Cape the prevalence exceeds the national average. There is also variation in prevalence by age group, with the highest prevalence in 2007 in the 20-39 year age groups. In the 30-34 year age group the prevalence was as high as 40.2%. The national prevalence in the 15-29 year age group has declined from 2005 to 2007.
In the Western Cape, from 2004 to 2006, the prevalence in pregnant women less than 25 years of age has reduced each year possibly suggesting a reduction in incidence in this age group. In 2006, 21.1% of pregnant women in the 25-29 year age group were HIV-infected. This still constitutes a considerable disease burden for women in their reproductive years. By 2003, non-pregnancy related infections (NPRI) were found to be the most common primary cause of maternal death. Of these NPRIs, AIDS was the most common sub-category, and TB and pneumonia the most common causes of death in this group of women.
An estimated 60,000 to 70,000 children are newly infected with HIV each year. In 2006 there were approximately 257,900 HIV-infected children under 14 years of age in this country. Mother-to-child transmission (MTCT) is the overwhelming source of HIV infection in young children.
HIV infection is currently one of the leading direct and indirect causes of morbidity and mortality amongst South African mothers and children, and is a threat to the country's ability to meet the Millennium Development Goals.
Prevention of Mother-to-Child Transmission of HIV
In the absence of any interventions to prevent MTCT, an estimated 25-45% of HIVinfected mothers will pass the virus to their infants. HIV may be transmitted during pregnancy, labour and delivery or during breastfeeding.
Since the mid-1990s, clinical trials have shown the effectiveness of antiretroviral drugs in lowering the rate of transmission of HIV from infected mothers to their newborn infants. In 1994, the findings of the PACTG 076 study showed a two thirds reduction of MTCT with antenatal oral Zidovudine and intrapartum continuous Zidovudine infusion. In 1999 a study from Thailand showed a 50% reduction in MTCT with antenatal oral AZT and 3 hourly oral AZT during labour. Shortly thereafter the HIVNET 012 study showed a 47% reduction in MTCT with single dose NVP to mother and infant.
Subsequently the problem of rapid emergence of viral NNRTI resistance after such limited exposure to NVP and its negative impact on maternal and neonatal ART became a major concern, particularly as the national ART program rolled out.
In 2004, the Thailand group published a study showing that intrapartum and early neonatal NVP added to their AZT regimen (including 1 week of neonatal AZT) reduced early MTCT to a startlingly low 1 - 2%. With dual therapy and a restriction of maternal NVP to only a single dose, NNRTI resistance was less evident, but still of concern.
Prevention of mother to child transmission of HIV (PMTCT) with maternal HAART and replacement feeding in the developed world has been shown to be almost 100% effective. There is also evidence that elective caesarean section, safe obstetric practices and safe infant feeding practices reduce MTCT of HIV. However, in developing countries with resource constraints, HAART may not always be deliverable to pregnant women. In these settings where infectious diseases are common replacement feeding (or lack of breastfeeding) may also be associated with an increase in morbidity and mortality due to malnutrition and infections. |
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