An investigation of hepatitis B virus in antenatal women tested for human immunodeficiency virus, in the Western Cape Province of South Africa

Maponga, Tongai Gibson (Stellenbosch : Stellenbosch University, 2012-03)

Thesis (MScMedSc)--Stellenbosch University, 2012.

ENGLISH ABSTRACT: Hepatitis B virus (HBV) immunisation protocols in much of Africa are based on data from the pre-human immunodeficiency virus (pre-HIV) era that indicated that HBV transmission occurs predominantly horizontally between siblings and play-mates rather than vertically from mother to child. The immunosuppression associated with HIV infection however may release HBV from immune control resulting in higher HBV viral loads, which may increase the risk of perinatal mother to child transmission of HBV. The aim of this study was to determine the prevalence and characteristics of chronic HBV infection in HIV-infected pregnant women compared to HIV-uninfected pregnant women in the Western Cape province of South Africa. Ethical approval was obtained to conduct a retrospective, matched case-control, unlinked anonymous study using residual plasma samples from the 9355 pregnant women included in the Western Cape's 2008 National HIV and Syphilis Antenatal Survey. Samples were tested for HBsAg on the AxSYM (Abbott, Chicago, IL) and confirmed by neutralization. Confirmed HBsAg-positive samples were tested for HBeAg, anti-HBe and anti-HD (Diasorin, Saluggia, Italy) and had HBV viral load and genotyping done. In addition, HBsAg-negative samples were tested for anti-HBc. Samples from 1549 HIV-infected pregnant women were included and matched to the same number of samples from age- and race-matched HIV-uninfected women. Median age of 26 years, parity and education were similar in the two groups. The prevalence of HBsAg was 3.4% for the HIV-infected group and 2.9% for the HIV-uninfected group. HBV DNA loads of greater than 104 IU/ml were detected in 32.1% of HBsAg-positive, HIV/HBV co-infected women, and in 14.3% HBsAg positive, HBV mono-infected women. Among the HIV-infected group 18.9% of HBsAg-positive were HBeAg positive, with a median viral load of 7.93 log10 IU/ml; whilst 15.5% HIV-uninfected women were positive for HBeAg with a median viral load of 6.07 log10 IU/ml. Genotype A was seen in 92.6% of the isolates while 7.4% of the isolates were genotype D. Serum total anti-HBc antibodies that are a marker of past infection were detected in 42.2% of HIV-infected and in 24.1% of HIV-uninfected women that were negative for HBsAg. No positive sample for anti-HD was seen among all HBsAg-positive samples. This data indicates that there is increased exposure to HBV in HIV-infected pregnant women than in HIV-uninfected women and that a greater proportion of HIV-infected pregnant women compared to HBV mono-infected pregnant women may be at increased risk of transmitting HBV to their infants. Further studies are needed to determine the rate of vertical transmission of HBV in the HIV era.

AFRIKAANSE OPSOMMING: Hepatitis B virus (HBV) immunisasie protokolle vir meeste dele van Afrika is gebaseer op data versamel in die era voor MIV. Die data dui aan dat HBV oordrag hoofsaaklik deur horisontale transmissie tussen broers, susters en speelmaats eerder as vertikale transmissie van moeder na kind plaasvind. Die onderdrukking van die immuunstelsel as gevolg van MIV infeksie kan egter lei tot 'n verhoogde risiko van perinatale HBV oordrag van moeder na kind. Die doel van hierdie studie was om die voorkoms en karakter van chroniese HBV infeksie in MIV-positiewe swanger vroue te vergelyk met die van MIV-negatiewe swanger vroue. Etiese goedkeuring is verkry om 'n retrospektiewe, deursnee-, ongekoppelde anonieme studie uit te voer wat gebruik maak van oorblywende plasma monsters van 9355 swanger vroue wat ingesluit is in die Wes-Kaap 2008 Nasionale MIV en Sifilis Voorgeboortelike Opname. Die monsters was getoets vir HBsAg antiliggame (AxSYM, Abbott, Chicago, IL) en bevestig deur neutralisasie toetse. Positiewe monsters was getoets vir HBeAg en anti-HBe (Diasorin, Saluggia, Italië). HBV viruslading en genotipering was ook op HBsAg positiewe monsters gedoen. Die HBsAg negatiewe monsters was getoets vir die teenwoordigheid van anti-HBc. Monsters van 1549 MIV-positiewe swanger vroue was ingesluit in die studie. Dieselfde aantal monsters van MIV-negatiewe vroue, met ooreenstemende ouderdom en etnisiteit, was ingesluit as kontroles. Die gemiddelde ouderdom van albei groepe was 26 jaar. Pariteit en opvoeding was dieselfde in albei groepe. Die voorkomssyfer van HbsAg was 3.4% in die MIV-positiewe groep en 2.8% in die MIV-negatiewe groep. HBV DNS ladings van meer as 104 IU/ml was waargeneem in 32.1% van die MIV-mede-geinfekteerde vroue en in 14.3% van die MIV-negatiewe groep. In die MIV-positiewe groep was 18.9% vroue HBeAg positief, met 'n gemiddelde virale lading van 7.93 log10 IU/ml, terwyl 15.5% MIV-negatiewe vroue positief was vir HBeAg met 'n gemiddelde virale lading van 6.07 log10 IU/ml. In ons studie was 92.6% van die monsters genotipe A en 7.4% genotipe D. Toatale anti-HBc antiliggame, 'n merker van vorige infeksie, was gevind in 42.2% van MIV-mede-geïnfekteerde vroue en 24.1% van MIV-negatiewe vroue wat negatief was vir HBsAg antiliggame. Data van ons studie dui op 'n verhoogde risiko vir vertikale HBV transmissie van MIV-positiewe moeders na hul babas. Verdere studies word benodig om vas te stel of vertikale transmissie van HBV van MIV-positiewe vroue na hul babas plaasvind.

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