The diagnosis and management of perinatal HIV infection

Assessment of mother-to-child HIV-1 and HIV-2 transmission: an AIDS reference laboratory collaborative study

OBJECTIVE

A prospective study was carried out to assess HIV-1 and HIV-2 mother-to-child transmission (MTCT) rates in Portugal between 1999 and 2005 by analysing the proportion of diagnosed infected children born to HIV-positive mothers.

MATERIALS AND METHODS

Serial blood samples were collected from 1315 children at risk of HIV-1 infection, 131 children at risk of HIV-2 infection and six children at risk of both HIV-1 and HIV-2 infections attending 25 Health Institutions. HIV proviral DNA was detected by nested polymerase chain reaction (PCR) and statistical analysis was performed using spss.

RESULTS

DNA PCR using HIV-1 and HIV-2 long terminal repeat (LTR) primers amplified 92.5% and 75% of maternal HIV infections, respectively. Overall, MTCT occurred in 3.4% [95% confidence interval (CI) 2.5-4.6%] of HIV-1 and 1.5% (95% CI 0.2-5.4%) of HIV-2 mother-child pairs. A significant decrease in HIV-1 MTCT was observed with time, from 7.0% (95% CI 2.6-14.6%) in 1999 to 0.5% (95% CI 0.0-2.5%) in 2005. HIV MTCT was associated with an absence of antiretroviral therapy in infected pregnant women (P<0.0001). Of the 48 infected children (46 with HIV-1 and two with HIV-2), the schedule of blood sample collection was followed for only 26 children. In 14 (53.8%) of those 26 children the infections were diagnosed in the first sample collected before they were 48 h old, suggesting in utero transmission. Despite the national recommendations for antenatal HIV testing, a high overall proportion (22.2% for HIV-1 and 44.3% for HIV-2) of mothers did not access any MTCT prevention measures, mostly because of late diagnosis in pregnancy. A small but significant proportion of HIV-2 infection was found in mothers with no identifiable link with West Africa.

CONCLUSION

HIV-2 transmission rates are low (1.5% in this study), and this may have led to a lower uptake of interventions, but in the absence of interventions transmission does occur. HIV-1 transmission was also associated with a lack of intervention, mostly as a result of late presentation. Use of primers restricted to a single sequence led to false-negative maternal results in a significant proportion of cases. In part this may have been attributable to very low HIV DNA loads as well as primer template mismatches. HIV infection was not documented in children born to mothers with negative HIV DNA PCR results.

The impact of expected HIV transmission rates on the effectiveness and cost of ruling out HIV infection in infants

OBJECTIVE

To quantify the costs and effectiveness of different strategies for ruling out HIV infection in infants born to HIV-infected mothers in the United States.

METHODS

The authors assessed 4 different testing strategies that incorporated serial HIV DNA polymerase chain reaction (PCR) testing with or without enzyme-linked immunosorbent assay (ELISA) antibody testing. Testing costs, false reassurance rates, and incremental cost-effectiveness ratios were compared for the 4 strategies.

RESULTS

In HIV-exposed infants, HIV DNA PCR testing at birth, 1 month, and 4 months of age results in a false reassurance rate of 21 per million (at a 2% transmission rate). Adding an ELISA test lowers the false reassurance rate to 0.052 per million at a cost of $570,000 per additional case detected; adding another PCR lowers the false reassurance rate to 1.49 per million at a cost of $720,000 per additional case detected compared with the 3-PCR strategy. At a high transmission rate (20%), there would be substantially more erroneously negative results (false reassurance rate is 256 per million with PCR testing at birth, 1 month, and 4 months) and consequently more favorable cost-effectiveness ratios with additional testing: $47,000 per additional case detected by adding 1 ELISA test and $59,000 per additional case detected by adding another PCR test.

CONCLUSIONS

False-negative HIV results after serial testing in exposed infants are rare, and the incremental cost-effectiveness ratios of additional tests are substantial at low transmission rates. However, the false reassurance rate increases considerably with a 3-PCR strategy and additional testing becomes more cost-effective at greater transmission rates; therefore, additional testing may be warranted in infants at greater risk of infection.

Health care industries' perspective of viral load assays: the VERSANT HIV-1 RNA 3.0 assay

This article will compare the VERSANT HIV-1 RNA 3.0 (bDNA 3.0) assay with other HIV-1 viral load assays, particularly the AMPLICOR HIV-1 MONITOR (Amplicor 1.5), the industry standard. The discussion will cover the history of viral load assay development and challenges to the field. It will finish with a description of the evolving markets for viral load assays in the developing world and the impact of variations in the different assays on their ability to reach those markets and patient populations.

HIV in pregnancy

Pregnancy in individuals infected with HIV has become an important problem because of a fourfold rise of infection in women of childbearing age in the developed world. The incidence of vertical transmission varies in different continents and is highest in Africa. Transmission may occur in utero (antepartum), during delivery (intrapartum), or after birth (postpartum), occurring during the latter period, in many cases, through breastfeeding. Maternal viral burden around the time of delivery is the strongest determinant of the risk of disease transmission. While breastfeeding may account for up to one-third of cases of vertical transmission in Africa, the benefits of breastfeeding outweigh its risks, even in HIV infection, and breastfeeding is recommended in those areas. Treatment of the mother with antiretroviral agents significantly decreases the risk of vertical transmission.