HIV This Week

A Case Series of 104 Women Infected with HIV-1 via Blood Transfusion Postnatally: High Rate of HIV-1 Transmission to Infants through Breast-Feeding.

Liang K, Gui X, Zhang YZ, Zhuang K, Meyers K, Ho DD. J Infect Dis. 2009; 200:682-6.

Liang and colleagues investigated transmission of human immunodeficiency virus type 1 (HIV-1) via breast-feeding by 104 Chinese mothers who acquired the infection through blood transfusion postnatally. Of 106 children, 38 (35.8%) were infected. All children survived to age 5 years, and their survival curve was similar to that of their mothers. These findings suggest a high rate of HIV-1 transmission via breast-feeding when mothers were infected postnatally via blood transfusion, perhaps because of the higher viremia expected during the acute phase of infection. The course of disease among infected children was significantly less rapid than that among newborns infected perinatally, suggesting that a brief window of HIV-1-free life often enables the immune system of an infant to stave off rapid disease progression.

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Editors’ note: Although blood-selling practices were officially prohibited in China by 1995 and the Blood Transfusion Law was passed in 1998, some of the women in this cohort were infected by blood transfusions as late as 2000. This emphasises the importance of concrete local plans to reduce the time between the announcement of policies and their implementation. In this case study series of acutely infected, breastfeeding women, the HIV transmission rate of 35.8% was considerably higher than previous estimates of 9 to 16% for post-natal transmission through breast milk. The risk of HIV transmission rose significantly to 62.5% (95%CI, 35.4-84.9%) if mastitis or cracked nipples were reported. The low mortality rate of 13.2% in these children after a mean of 9.1 years in the absence of antiretroviral treatment suggests rapid evolution in the immune system capacity over the initial weeks and months of life leading to better viral control.

Lehman DA, Chung MH, Mabuka JM, John-Stewart GC, Kiarie J, Kinuthia J, Overbaugh J. J Acquir Immune Defic Syndr. 2009;51:522-9

Antiretroviral resistance after short-course regimens used to prevent mother-to-child transmission has consequences for later treatment. Directly comparing the prevalence of resistance after short-course regimens of highly active antiretroviral therapy and zidovudine plus single-dose nevirapine (ZDV/sdNVP) will provide critical information when assessing the relative merits of these antiretroviral interventions. In a clinical trial in Kenya, pregnant women were randomized to receive either ZDV/sdNVP or a short-course of highly active antiretroviral therapy through 6 months of breastfeeding. Plasma samples were collected 3-12 months after treatment cessation, and resistance to reverse transcriptase inhibitors was assessed using both a sequencing assay and highly sensitive allele-specific polymerase chain reaction assays. No mutations associated with resistance were detectable by sequencing in either the ZDV/sdNVP or highly active antiretroviral therapy arms at 3 months posttreatment, indicating that resistant viruses were not present in >20% of virus. Using allele-specific polymerase chain reaction assays for K103N and Y181C, the authors detected low levels of resistant virus in 75% of women treated with ZDV/sdNVP and only 18% of women treated with highly active antiretroviral therapy (P =0.007). Y181C was more prevalent than K103N at 3 months and showed little evidence of decay by 12 months. The study finding provides evidence that compared with ZDV/sdNVP, HAART reduces but does not eliminate nevirapine resistance.

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Editors’ note: This small Kenyan trial is the first study to compare directly the prevalence of HIV resistance after short-course antiretroviral treatment with standard prophylactic regimens. Of 58 women initially randomised, 40 women had plasma samples for analysis by sequencing assay and highly sensitive polymerase chain reaction. One study arm received zidovudine twice daily for 6 weeks before delivery, single-dose nevirapine during labour, and for the babies, single dose nevirapine. The women in the other study arm received twice-daily zidovudine, nevirapine, and 3TC for 6 weeks before and 6 months after delivery. The big difference seen in the levels of resistant virus 3 months or more after ceasing to take drugs may well be due to the fact that in the first arm, nevirapine was not accompanied by any other antiretroviral drug during labour. Antiretroviral treatment for 6 months did not eliminate nevirapine resistance, suggesting that after nevirapine is stopped, treatment cessation strategies should include temporarily continuing zidovudine and 3TC to prevent single drug pressure caused by nevirapine’s longer half-life.