Red Hot Tips Point: Infection with Hepatitis C Virus among HIV-Infected Pregnant Women in Thailand

Wednesday, July 1, 2009

1Division of Reproductive Health, Centers for Disease Control and Prevention, Atlanta, GA 30341-3717, USA
2Thailand MOPH-U.S. CDC Collaboration, CDC, Nonthaburi 11000, Thailand
3Faculty of Medicine Siriraj Hospital, Mahidol Univeristy, Siriraj, Bangkoknoi, Bangkok 10700, Thailand
4Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
5Queen Sirikit National Institute of Child Health, Department of Medical Services, Ministry of Public Health, Bangkok 10400, Thailand
6Department of Public Health Sciences, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
7Department of Medical Services, Rajavithi Hospital, Ministry of Public Health (MOPH), Bangkok 10400, Thailand
8Global AIDS Program, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA

Received 5 March 2008; Revised 28 June 2008; Accepted 3 November 2008

Recommended by Daniel Landers

Abstract

Objective. The purpose of this study was to describe the epidemiology of coinfection with hepatitis C virus (HCV) and HIV among a cohort of pregnant Thai women. Methods. Samples from 1771 pregnant women enrolled in three vertical transmission of HIV studies in Bangkok, Thailand, were tested for HCV. Results. Among HIV-infected pregnant women, HCV seroprevelance was 3.8% and the active HCV infection rate was 3.0%. Among HIV-uninfected pregnant women, 0.3% were HCV-infected. Intravenous drug use by the woman was the factor most strongly associated with HCV seropositivity. Among 48 infants tested for HCV who were born to HIV/HCV coinfected women, two infants were HCV infected for an HCV transmission rate of 4.2% (95% 0.51–14.25%). Conclusions. HCV seroprevalence and perinatal transmission rates were low among this Thai cohort of HIV-infected pregnant women.

1. Introduction

Worldwide, the hepatitis
C virus (HCV) seroprevalence rate among pregnant women is approximately 1% [1]. This is similar to the 1.6% prevalence of HCV
antibody in the general population in the United States
[2]. Among HIV-infected pregnant women, much
higher prevalences of HCV positivity have been reported, ranging from as high
as 30 to 50% in some settings [3, 4], particularly in populations with high
rates of injection drug use.

Although the
perinatal transmission rate of HCV is estimated to be less than 5% among
HIV-uninfected women, it is generally higher in HIV-infected women [1]. Not all studies, however, have found
increased HCV transmission rates among HIV-infected women [5] and a wide range
of estimates of the risk of vertical transmission of HCV among coinfected women
has been reported with wide geographic variation [6, 7].

The purpose of this study was to
describe the epidemiology of coinfection with hepatitis C virus and HIV among a
cohort of pregnant Thai women.
2. Materials and Methods

The current study
population includes 1771 women previously enrolled in three vertical
transmission studies in Bangkok,
Thailand [8–10] who had
specimens available for HCV testing.
From the first study (peri-1), 342 HIV-uninfected women and 293 HIV-infected
women are included. From the second
(peri-2) and third studies (peri-3), 391 and 745 HIV-infected women are
included, respectively. Women in these
studies were either enrolled during antenatal care (peri-1 and 2) or at
delivery (peri-3). All children born to
HIV-infected women were followed
for 4–18 months and
their mothers did not breastfeed. No
follow-up information is available for infants born to HIV-uninfected women in
peri-1. Peri-1 was an observational prospective
cohort study without treatment interventions, peri-2 was a randomized
placebo-controlled clinical trial assessing the efficacy of short-course
zidovudine prophylaxis antenatally and
intrapartum, and peri-3 was an observational
study of short-course zidovudine and single-dose nevirapine propylaxis. All three studies were conducted jointly by
the Thailand Ministry of Public Health and the U.S. Centers for Disease Control
and Prevention (CDC) at two large Bangkok
hospitals from 1992 to 2004. The three
perinatal studies (peri-1,2,3) and this current retrospective laboratory study
were all approved by the institutional review boards at the CDC in Atlanta and
the Ethical Review Committees for Research in Human Subjects at the Thailand
Ministry of Public Health and Siriraj Hospital in Bangkok.

In the original
studies, specimens were collected and tested for HIV, HIV viral load, CD4 count
as previously described [8, 9]. Stored
plasma specimens from pregnancy or delivery were screened for antibodies to HCV
(anti-HCV) using enzyme immunoassay (EIA; Abbott Murex version 4.0, Abbott Laboratories, Abbott Park, Ill USA).
All positive EIAs were tested with qualitative reverse transcriptase
polymerase chain reaction (RT-PCR; Ampliscreen, Roche Diagnostic Systems, Branchburg, NJ,
USA). If the qualitative RT-PCR was negative, the
plasma specimen was retested with recombinant immunoblot assay (RIBA 3.0,
Chiron Corporation, Emeryville,
Calif, USA). All women who were EIA positive and either
qualitative RT-PCR or RIBA positive are considered HCV infected (either current
or past); all other women are considered HCV uninfected. All specimens with detectable virus were
tested with quantitative PCR (COBAS Amplicor HCV Monitor Test, version 2.0,
Roche Diagnostic Systems) with a lower limit of detection of <600
copies/mL. All women with detectable
virus are considered to have active HCV infection. Specimens with detectable HCV were genotyped
using the Trugene HCV 5′NC genotyping kit (Bayer HealthCare LLC, Berkeley, Calif,
USA) and
sequence analysis with the OpenGene DNA sequencing system. Results were then confirmed using sequence analysis (ABI
PRISM 310 Genetic Analyzer, Applied Biosystems, Calif,
USA)
methods. In 8 cases where the results from
the two techniques were discordant, the 715 nt E1-E2 region at position
883-1597 nt was directly sequenced.

Stored plasma from
infants born to women coinfected with HIV and HCV was also tested for HCV. An HCV-infected infant was defined as an
infant who was anti-HCV positive (i.e., EIA-positive with confirmatory RIBA) at
18 months of age or older or who had positive HCV RNA on two occasions. Several serial samples from infants were
tested, depending on availability of samples and testing results, since HCV
infection often cannot be excluded in infants by one-time testing [11]. However, due to limited availability infant
specimens, 18/48 (37.5%) of infants tested had testing at only one time point.

Statistical analyses
were performed using SAS software version 9.1 (SAS Institute, Cary, NC, USA). Odds ratios with 95% confidence intervals
were estimated using unconditional logistic regression, adjusting for the three
perinatal studies. Ninety-five percent confidence intervals for HCV
transmission rates were estimated using exact binomial
methods.
3. Results

There were low rates of intravenous drug use
(1.5%) among the 1771 women included in this study (Table 1). A higher proportion of women reported several
other risk factors for hepatitis C acquisition, including having an injection
drug-using partner (10.2%) and ever having been a commercial sex worker
(7.8%). HIV-infected women had
moderately high CD4 counts at delivery (mean 428 cells/mm3); the
mean viral load at delivery was 10 000 copies/mL.
tab1
Table 1: Demographic and clinical characteristics of
1771 women enrolled in 3 vertical transmission HIV studies
in Bangkok, Thailand, 1992–2004 (n (%)).

Among 1429 HIV-infected pregnant women 62 (4.3%)
were found to have HCV antibodies by EIA.
Of those, 54 had positive confirmatory testing by either RT-PCR
(n=43) or by RIBA (n=11). Thus, 3.8%
(54/1429) of HIV-infected pregnant women were found to be coinfected with HCV
and 3.0% (43/1429) had evidence of
active infection. Among 342
HIV-uninfected women, 2 (0.6%) were found to have HCV antibodies by EIA. Of those, only one of the women had positive
confirmatory testing by RT-PCR. Thus, 0.3% (1/342) of HIV-uninfected
pregnant women were found to be infected with HCV.

Among the 54
HCV-seropositive women, 22 did not receive any antiretroviral prophylaxis, 22
received 4 weeks of antenatal zidovudine and intrapartum zidovudine, and 10
received 4 weeks of antenatal zidovudine and intrapartum zidovudine and
nevirapine. Of the 43 HIV-infected women with quantifiable HCV, the serum
levels of HCV RNA were as follows: 12 women with <100 000 copies/mL, 17
women with 100 000–850 000
copies/mL, and 13 women with >850 000 copies/mL. One woman who was HCV RNA-PCR positive on the
qualitative assay had undetectable virus (<600 copies/mL) on the
quantitative assay. The HIV-uninfected
woman with quantifiable HCV had a serum level of HCV of 62 000 copies/mL. The HIV-infected women in later cohorts
(peri-2 and peri-3) were more likely to be HCV infected (4.1 and 4.4%, resp.)
compared with HIV-infected women in the earlier cohort (1.7%) (see Table 1). Among the 35 HCV-infected women with
confirmed HCV genotyping results, 14 (40%) were genotype 3a, 14 (40%) were
genotype 1a, 4 (11.4%) were genotype 1b, 2 (5.7%) were genotype 6a, and 1 (2.9%)
was genotype 4a.

In unadjusted
analyses, factors associated with pregnant women being HCV infected included more
education, intravenous drug use, having a partner with a history of injection
drug use, ever having been a commercial sex worker, and having received a blood
transfusion. These risk factors remained significant when
adjusting for perinatal study (Table 2).
In a multivariate model adjusted
for all covariates in Table 2, only three factors remained significant: intravenous drug use (adjusted odds ratio
70.5; 95% CI 24.8–201), having a partner with a history of injection drug use
(adjusted odds ratio 3.4; 95% CI 1.5–7.4), and having received a blood
transfusion (adjusted odds ratio 6.7; 95% CI 1.9–23.9). Since HIV-uninfected women were only included
in peri-1, we included only women in peri-1 when estimating the odds of HCV
infection by HIV status. This study did
not find an association between HIV infection status and HCV infection (adjusted
odds ratio 5.9; 95% CI 0.7–51.0).
tab2
Table 2: Odds of
being HCV-infected among 1771 pregnant women enrolled in 3 vertical transmission HIV studies in Bangkok, Thailand, 1992–2004.

For peri-1, all 5 infants born to HIV/HCV-infected
women had samples tested for HCV RNA at 2, 4, and 6 months and no infants were
found to be HCV infected. For peri-2,
12/16 infants had 6-month samples available which were tested for HCV RNA and 13/16
infants had 18-month samples available which were tested for HCV
antibodies. All infants had testing from
at least one time point and 10 infants were tested at more than one time point. From peri-2, one infant was HCV-RNA positive
at 6 months; additional testing of a 4-month sample from this infant confirmed
that this infant was HCV-RNA positive.
In addition, three infants were anti-HCV positive by EIA at 18
months. However, only one of these
infants had positive confirmatory testing by RIBA. For peri-3, 15 infants had serial testing at
both 2 and 4 months and 27 infants had testing performed for at least one time point.
No infants were found to be HCV infected.

In summary, among 48 infants tested for HCV
who were born to HIV/HCV coinfected women, two infants were HCV infected for an
HCV transmission rate of 4.2% (95% 0.51–14.25%). One of these infants was born to a woman who was
infected with HCV genotype 3a and had an HCV viral load of 764 323 copies/mL
and an HIV viral load of 2092 copies/mL.
The mother of this infant received zidovudine for 4 weeks antenatally and
during labor; this infant was HIV uninfected.
The other infant was born to a woman who was infected with HCV genotype
1a and had an HCV viral load of >850 000 copies/mL and an HIV viral load of
20 342. The mother of this infant did
not receive any antiretroviral prophylaxis; this infant was HIV infected.

The HIV vertical transmission rate among
infants born to the 1429 HIV-infected women was 12.9% (Table 3). There was a 9.4% (5/53) HIV transmission rate among
HCV-infected mothers and a 13.0% (170/1306) HIV transmission rate among HCV-uninfected
mothers (P=.445). The odds of an
infant being HIV infected did not differ significantly by the mother’s HCV
status neither in unadjusted
analyses (odds ratio 0.70; 95% CI 0.27–1.77), nor in analyses adjusted for perinatal
study (adjusted odds ratio 0.82; 95% CI 0.32–2.12).
tab3
Table 3: HIV/HCV status and clinical characteristics
of infants born to 1429 HIV-infected women enrolled in 3 vertical transmission of HIV
studies in Bangkok, Thailand, 1992–2004 (n (%)).
4. Conclusions

HCV infection in pregnancy is
emerging as an increasingly important issue.
Due to improved HCV blood screening, mother-to-child transmission of HCV
has now replaced transfusion-associated transmission as the predominant mode of
spread in children [1]. In this retrospective
analysis of more than 1700 pregnant women in Thailand, most of whom were HIV infected,
we found relatively low hepatitis C seroprevalence rates. Among the HIV-infected pregnant women, HCV
seroprevalence was 3.8% and active HCV infection was 3.0%. Among HIV-uninfected pregnant women, HCV
seroprevalence was 0.3%. The low rate of
injection drug use in the population (1.5%) likely accounts for this relatively
low HCV seroprevalence, which is only slightly higher than many general
populations of pregnant women who are HIV uninfected. (1) In a study conducted in Thailand
from
1993-1994 among a
convenience sample of 120 HIV-infected women, 6.7% were anti-HCV positive by EIA
[12]. In another study in Thailand
in
1991, 2.7% of 883 women admitted to the hospital with gynecologic abnormalities
had HCV antibodies [13]. Among Thai
women reporting injection drug use, higher HCV prevalence rates have been
reported, with 15% of 200 female injection drug users HCV infected in a recent
study [14].

The risk factors for HCV infection identified, which included more education,
intravenous drug use, having a partner with a history of injection drug use,
ever having been a commercial sex worker, and having received a blood
transfusion, were similar to risk factors associated with HCV in prior studies
[15]. Although the number of
HIV-uninfected women was small in this study, we did not find HIV infection to
be a significant risk factor for HCV infection. As expected, a history of
injection drug use was the strongest predictor of HCV infection (adjusted OR
126; 95% CI 48.6–326), similar to other studies among blood donors which have also
identified injection drug use as a strong risk factor for HCV infection [15]. There are six major HCV genotypes, which are
numbered 1–6 and subtyped a, b, and
c. Type 1b is the most common genotype
worldwide. Types 1a and 3a, which were
the predominant genotypes in the present study, are largely associated with
injection drug use [16, 17].

In the United States,
routine HCV screening is recommended for persons with certain high-risk
characteristics (e.g., history of injection drug use or blood transfusion) and
for children born to HCV-infected women [18].
However, routine screening is not recommended for pregnant women without
other risk factors [19]. U.S.
guidelines
also recommend that HIV-infected persons be routinely screened for HCV [20]. In Thailand, although current national
guidelines do not address routine HCV screening or hepatitis testing for
HIV-infected patients, most physicians provide hepatitis testing for
HIV-infected adults with symptoms or risk factors, and pediatric providers in
tertiary care centers often test HIV-infected children who are at risk. Pregnant women in antenatal clinics are also
routinely screened for hepatitis B, but not HCV. HCV treatment is available in Thailand
at cost to patients
or to patients with private health insurance.

The HCV perinatal
transmission rate among infants born to HIV/HCV coinfected women in this study was
4.2%. However, due to the small number
of HCV-infected women in our sample, the confidence interval was wide. The estimated frequency of HCV transmission
in this current study is similar to those of two recent multicenter studies conducted among
mostly HIV-uninfected women in the United States [21] and Europe [22] which reported
transmission rates of 3.6% and 6.2%, respectively. Since HIV-infected women in
this cohort had relatively high CD4 counts at delivery, it is not clear how
generalizable these findings are to other cohorts of HIV-infected pregnant
women. Although the published literature
has shown a correlation of maternal HCV viral load and the risk of HCV vertical
transmission [4, 23], there were too few HCV mother-to-child transmission in
our study to draw conclusions. However, both
HCV-infected infants born to HIV-infected women had high HCV viral loads.
Acknowledgments

The authors wish to thank the TUC laboratory staff for their
outstanding work processing and testing all the specimens, and Daniel Newman
for his extensive assistance with data management for the study. This study
received funding from the Opportunistic Infections Working Group at the Centers
for Disease Control and Prevention. The findings and conclusions in this
article are those of the authors and do not necessarily represent the official
position of the Centers for Disease Control and Prevention.