Sexual transmission of HCV not seen in US women's HIV cohort

Michael Carter
Estimated reading time 5 minutes
This article is more than 21 years old.

A large US study has found that very few HIV-positive women become coinfected with hepatitis C virus (HCV) after an HIV diagnosis. Writing in the November 15th edition of Clinical Infectious Disease, which is now available online, investigators also note that past or current drug use is by far the strongest risk factor for infection with HCV, and that a sizeable minority of women who do contract HCV will naturally clear the virus. Although several recent studies involving HIV-positive gay men have suggested that HCV may be more readily transmitted during sex than previous thought, the US investigators found no evidence of the sexual transmission of HCV in the women enrolled in their study.

This retrospective study involved a total of 2059 HIV-positive women and 569 HIV-negative women who were enrolled in the Women’s Interagency HIV Study (WIHS). Stored blood samples obtained between 1994 – 99 were used for the study. On entry into the study women were tested for HCV and answered questions about drug use and their sexual behaviour. Follow-up was every six months.

At baseline, HCV antibody tests were negative for 55% of the HIV-positive women and 69% of the HIV-negative women.

Glossary

acute infection

The very first few weeks of infection, until the body has created antibodies against the infection. During acute HIV infection, HIV is highly infectious because the virus is multiplying at a very rapid rate. The symptoms of acute HIV infection can include fever, rash, chills, headache, fatigue, nausea, diarrhoea, sore throat, night sweats, appetite loss, mouth ulcers, swollen lymph nodes, muscle and joint aches – all of them symptoms of an acute inflammation (immune reaction).

person years

In a study “100 person years of follow-up” could mean that information was collected on 100 people for one year, or on 50 people for two years each, or on ten people over ten years. In practice, each person’s duration of follow-up is likely to be different.

p-value

The result of a statistical test which tells us whether the results of a study are likely to be due to chance and would not be confirmed if the study was repeated. All p-values are between 0 and 1; the most reliable studies have p-values very close to 0. A p-value of 0.001 means that there is a 1 in 1000 probability that the results are due to chance and do not reflect a real difference. A p-value of 0.05 means there is a 1 in 20 probability that the results are due to chance. When a p-value is 0.05 or below, the result is considered to be ‘statistically significant’. Confidence intervals give similar information to p-values but are easier to interpret. 

retrospective study

A type of longitudinal study in which information is collected on what has previously happened to people - for example, by reviewing their medical notes or by interviewing them about past events. 

syphilis

A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.

Over a mean of 3.5 years of follow-up, a total of 22 (1.5%) women seroconverted for HCV. However, the weakness of HCV antibody response in eight women led the investigators to conclude that only 14 of the women were true incident HCV infections (ten HIV-positive, four HIV-negative).

These 14 cases were used to calculate the incidence of HCV infection in the study population. Amongst HIV-positive women, the incident rate was 2.7 per 1000 person years, and amongst HIV-negative women 3.3 cases per 1000 person years. The difference in incidence between HIV-positive and HIV-negative women was not statistically significant (p=0.76).

Women with a history of drug use of any kind, either during the study period or before enrollment, were significantly more likely to become infected with HCV than women who never used drugs (5.3 cases per 1000 person years versus 0.7 cases, p=0.01).

When the investigators looked at the drug use patterns of the 14 women with new HCV infection they found that six had a history of crack, cocaine or heroin use during the study period, and that six other women reported the use of these drugs before entry to the study. In total 86% of women who acquired HCV reported current or prior drug use, compared to 22% of the 1517 HCV-negative women at enrollment (p

Birth in Puerto Rico was the only other significant risk factor for HCV infection(p=0.02).

Of particular note, the investigators found no association between acute HCV infection and the total life-time number of sexual partners, frequency of condom use, or history of sexually transmitted infection.

The CD4 cell counts of women who contracted HCV were comparable to those who remained HCV free (433 cells/mm3 versus 385 cells/mm3. There were no readily identifiable trends in the HIV viral loads of women after their infection with HCV, although in the HAART treated women HIV viral load did decline by an average of 50,000 copies/mL to an average of 6000 copies/mL, which the investigators attribute to the effects of anti-HIV therapy.

HCV viraemia was detected in 12 of the women, with HCV viral load measuring from

The investigators comment “the incident rate of HCV infection in this large group of women with or at risk of HIV-1 infection was low.” However, given the high risk of HCV infection from injecting drug use and the high prevalence of HCV infection in the study cohort at baseline, the investigators add, “it is likely that those in the WIHS cohort at highest risk of HCV acquisition had already acquired infection before enrollment.”

Investigators also note that 42% of women who became viraemic for HCV appeared to clear infection. This is substantially higher than the current estimate that 15% of infected individuals will not develop chronic infection. They note, however, that the women in this study who cleared the infection had low HCV viral peaks.

”Conclusions about HCV acquisition and acute infection are limited by the relatively few cases of seroconversion detected”, caution the investigators. Nevertheless, they suggest that some important observations should be noted, in particular that acute HCV was almost exclusively seen in women with current or past drug use. Furthermore, an antibody response may not develop for some time in some HCV-exposed individuals. In addition, many HCV infected individuals will clear the infection, particularly if they are not immunosuppressed, and will do so soon after infection.

Further information on this website

Hepatitis C - overview

The liver and hepatitis C - factsheets

HIV and hepatitis - booklet in the information for HIV-positive people series (pdf)

Fisting, drug use, syphilis; risk factors for hepatitis C transmission in HIV-positive gay men - news story

References

Augenbraun M et al. Incident hepatitis C virus in women with human immunodeficiency virus infection. Clinical Infectious Diseases 37 (on-line edition), 2003.

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