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Prevalence of maternal hepatitis C infection according to HIV serostatus in six Spanish regions (2003–2006)

Teresa Seisdedos, Asunción Díaz, María José Bleda, Marta Ortiz, Alfredo García, Mercedes Díez
DOI: http://dx.doi.org/10.1093/eurpub/ckq085 643-645 First published online: 16 July 2010

Abstract

The objective of this article is to describe the prevalence of maternal Hepatitis C infection globally and by HIV serostatus. Unlinked anonymous testing on 474 539 samples from newborn babies was carried out, selected through stratified sampling by year and HIV status, in six Spanish Autonomous Regions, from 2003 to 2006. Results were 0.15% for global anti-hepatitis C virus (HCV), 29.69% and 0.10% for HIV(+) and HIV(−) women, respectively. Anti-HCV prevalence rate is low in these regions compared to Hospital cohorts. Although a high prevalence rate in HIV co-infected women is found, it tends to decrease along the period studied.

  • co-infection HIV–HCV
  • hepatitis C
  • pregnancy
  • unlinked anonymous studies

Introduction

The extent of hepatitis C virus (HCV) infection is not well known. In its acute phase is usually asymptomatic, but it is a major public health concern due to the frequency and severity of its sequelae. In Europe, the average prevalence was 1.03% in 20011 but several factors limit comparison between countries. First, surveillance systems are uneven with different case definition, many of them reporting prevalent cases along with incidents ones.1 Secondly, due to the large proportion of asymptomatic cases, there was an unknown proportion of undiagnosed cases—later diagnosed—and subnotification.2 Third, population under surveillance variability also contributes to the complex picture, and, although the mode of transmission is not recognized in almost half the cases, the prevalence of infection is 10 times higher in subpopulations such as injecting drug users or patients in haemodyalisis.2 Finally, recent data suggest that simultaneous epidemics, produced by different HCV genotypes, unequally affect population according to age, sex and risk groups.3

HCV infection is very prevalent among HIV-infected persons because both viruses share routes of transmission, and a greater morbi-mortality due to the HCV in co-infected patients is noted. HCV vertical transmission is estimated at 5%, and mainly depends on the HCV viral load of the mother, but is up to three times higher in situation of co-infection with HIV.4

This article aims to contribute to the knowledge of the HCV epidemic situation in Spain, presenting data on prevalence of antibodies against HCV in newborn, reflecting their mothers’ situation, globally and by HIV serostatus, in six autonomous regions, from 2003 to 2006.

Methods

An unlinked anonymous study was conducted using dried blood samples collected for congenital metabolic disorders detection of infants born between 2003 and 2006. Balearic Islands, Canary Islands, Castilla-La Mancha, Castilla y León, Valencia and Galicia were the participating regions. Initially, all samples were analyzed to detect antibodies to HIV by ELISA (Genscreen HIV1/2, Bio-Rad France). Positive results were confirmed through western blot recombinant test (Chiron RIBA HIV-1/HIV-2 CIS, Ortho Diagnostic Systems, Inc., USA). In order to estimate anti-HCV prevalence, samples were stratified according to HIV situation and year. In the stratum of HIV infected mothers, all viable blood stains were analysed to detect anti-HCV using ELISA (Monolisa HCV plus v.2, Bio-Rad, France), being positive those doubly reactive. Finally, in the stratum of HIV-negative mothers, a random sample was chosen, calculating its size for each year, for an expected prevalence of 1%, assuming 95% confidence level and 0.4% error. It was also corrected by finite populations.

Statistical analysis estimates prevalence of anti-HCV, global and according to HIV status, and their respective 95% confidence intervals (95% CI), per year and for the whole period. Estimates were calculated taking into account the sample design. Chi-squared test was used for assessing temporary changes on trends.

Results

During the whole period of study, 474 539 samples were analysed for HIV, which accounted for 88% of the total number of births of the participating Autonomous Regions registered by the Spanish National Institute of Statistics, and for 35% of the total number of births in the country. A total of 714 samples were identified HIV positive (HIV prevalence of 0.15%; 95% CI: 0.14–0.16%). Of these, 681 were tested for HCV. Prevalence rate of HCV infection in HIV(+) mothers resulted in 29.69% (95% CI: 28.02–31.36%). The highest prevalence was 41.61% in 2003 and the lowest 23.65% in 2006 (table 1), with a statistically significant decreasing trend (P = 0.0001). To estimate the prevalence of HCV infection in HIV(−) mothers, a sample of 8555 specimens were analysed, reflecting a prevalence for the period of 0.10% (95% CI: 0.03–0.17%), with a range of variation between 0.05% and 0.19% (table 1), without presenting a significant trend.

View this table:
Table 1

Maternal anti-HCV prevalence (%) of newborn babies, globally and by HIV serostatus (2003–2006)

YearAntibody anti-HCV prevalence rates
GlobalMothers without HIV infectionMothers with HIV infection
Prevalence (%)95% CIPrevalence (%)95% CIPrevalence (%)95% CI
20030.110.02–0.210.050.00–0.1441.6137.99–45.24
20040.230.04–0.420.190.01–0.3825.9522.16–29.74
20050.090.00–0.180.050.00–0.1428.9325.38–32.48
20060.170.03–0.310.130.00–0.2723.6521.28–26.01
Total0.150.08–0.220.100.03–0.1729.6928.02–31.36
  • Baleares, Canarias, Castilla-La Mancha, Castilla y León, C. Valenciana y Galicia

In all women, the anti-HCV prevalence was 0.15% (95% CI: 0.08–0.22%). The lowest prevalence rate was found in 2005 (0.09%) and the highest in 2004 (0.23%) (table 1), although the differences were not significant.

Discussion

This article presents HCV infection prevalence among mothers of newborn babies from Balearic Islands, Canary Islands, Castilla-La Mancha, Castilla y León, Valencian and Galician Autonomous Regions, globally as well as according to HIV status.

HCV prevalence in women have been informed with a wide range of values in Europe: from 0.19% to 0.2% of an unlinked anonymous study in newborn babies in UK (2000)5 up to 2.4% in pregnant women treated at an hospital in Italy (1999).6 Data are also uneven in Spain. In 2004, antibodies to HCV were detected in 0.4% of women who attended his first antenatal visit in Salamanca,7 and 1.4% in pregnant women attended in two hospitals, in Asturias8 and Catalonia.9

The anti-HCV seroprevalence rate found in this study is lower than any of the ones mentioned above except that of the UK study, where the same methodology was used. This method avoids the selection bias that present the results derived from hospital samples or cohorts that tend to overestimate prevalence in the general population, because they usually involve selecting groups with greater probability of having the infection. In addition, the coverage of newborns of this study is approaching 100% of the participating communities, and includes more than one-third of the total Spanish population.

Due to these characteristics, this study offers powerful, valid information for the participant regions, representing optimally the mothers of newborn babies and conveniently enough women of reproductive age. Nevertheless, the study may underestimate the prevalence for the whole of Spain, since the cities included are not among the largest in the country, where risk factors such as intravenous drug abuse are greater.

Obviously, the study shows that the prevalence of anti-HCV in negative HIV mothers is greatly lower than in women with HIV infection, of which about 30% had HCV antibodies. This proportion is lower than that of a hospital-cohort study of Spanish pregnant women HIV(+) in 2006.10 Moreover, it is important to stress that the study findings suggest that prevalence rate in women co-infected with HIV tend to decrease.

Nowadays, paediatric HCV infections are almost exclusively due to vertical transmission, and are more frequent when the mother is co-infected with HIV. This has a considerable potential impact among children. Acknowledging the prevalence of both infections in mothers allows estimating the magnitude of infection in infants.

In conclusion, the information presented in this article is useful because: (i) allows to know the real magnitude of maternal HCV infection in the six studied regions, its variation according to HIV, the potential of transmission to neonates and trends in these parameters, and; (ii) helps to understand the information about HCV infection and HCV–HIV co-infection in Spain, since unlinked anonymous methodology prevents common selection biases. Considering these results, the convenience of continuing and expanding this information system in our country, including information on mother’s age and nationality, is of utmost importance.

Acknowledgements

Unlinked Anonymous Study in Newborns working group:

  1. Autonomous programmes of HIV/AIDS and early detection of metabolic disorders:

    • Balearic Islands: Rosa Aranguren and Francisca González.

    • Canary Islands: Domingo Núñez, Eduardo Domenech and Flora Barroso.

    • Castila – La Mancha: Juan Atenza, Gonzalo Gutiérrez and Carmen Eva Pérez.

    • Castilla y León: Carmelo Ruiz, Alfredo Blanco, Henar Marcos, Juan José Tellería and Isabel Fernández.

    • Galicia: José Antonio Taboada, Ramón Vizoso y José R. Alonso-Fernández.

    • Valencian Community: Mercedes Pons, Manuel Moya, Cristina Aguado and Sonia Alcover

  2. Reference laboratory: National Centre of Microbiology (ISCIII): Marta Ortiz and Alfredo Garcia.

  3. Design, coordination and analysis: National Centre for Epidemiology (ISCIII) / Secretariat of the National Plan on AIDS: Teresa Seisdedos, Asunción Díaz, María José Bleda and Mercedes Díez.

Conflicts of interest: None declared.

Key points

  • Global prevalence of antibodies. Anti-HCV among mothers of newborn babies in Spain was 0.15%; HCV prevalence rate in HIV(+) mothers was 29.69%, and 0.10% in HIV(−).

  • HCV prevalence rate in HIV(+) mothers has decreased from 2003 to 2006.

  • Unlinked anonymous methodology prevents common selection biases, helping to better understand the epidemic situation of HCV infection and HCV-HIV co-infection in Spain.

  • It is of utmost importance continuing and expanding this information system in our country, including information on mother’s age and nationality.

References

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