 Hepatitis C virus |
Despite increasing reports of sexual transmission of hepatitis C (HCV), particularly among gay men with HIV, exactly how it is transmitted remains mysterious. Some kind of exposure to blood appears to have to be involved, however.
A study of people attending STD clinics in Miami recently found that injecting drugs remains by far the biggest risk factor for HCV (it did not, contrary to other studies, find that been being tattooed or pierced were HCV risks). However, sexual contact with an HCV-infected person was the second-highest risk factor.
Nonetheless, a 10-year Spanish study of 171 couples where one partner had HCV found not a single case of transmission among an estimated 40,000 instances of anal or vaginal sex - despite condoms being used only 56 per cent of the time. 31 of the women became pregnant during this time and one person caught HIV from their partner.
The importance of blood as a factor was underlined by another strange case in which HCV was passed between two gay men who used the same needle for the erection drug, Caverject, which is injected with a fine needle into the penis.
Whatever the transmission method, HCV is an increasingly serious health problem, with 120-180 million people infected worldwide - four times as many as HIV. It is particularly bad for people co-infected with HIV, who develop severe and often fatal liver damage two to three times faster. Current treatments are expensive and difficult to tolerate - though they can cure. A recent study of US army veterans who had both HIV and HCV found that out of 300 patients only 65 (22 per cent) were judged as being 'eligible' for anti-HCV therapy. 13 per cent of the rest seemed to be controlling HCV well enough not to need treatment, but the others were deemed ineligible due to current alcohol or drug use, or psychiatric problems (major depression is a side effect of current anti-HCV therapy).
It is good news, therefore, that an increasing number of anti-HCV drugs are in the pipeline and could be available within two to three years. Among drugs currently in lab trials are ISIS 14,803, a gene-therapy drug which reduced the HCV viral load tenfold in those to whom it was given, and two HCV protease inhibitors made by the drug firms Eli Lilly and Boehringer Ingelheim.
A vaccine for HCV could be on the market by 2010, a researcher told the recent International Symposium of Viral Hepatitis in Sydney. Dr Michael Houghton of Chiron Pharmaceuticals, who co-discovered the hepatitis C virus in 1987, said that experimental vaccines had protected nine out of 10 chimpanzees against HCV infection. Gus Cairns
Anal cancer is known to be 35 times more common in gay men and 70 times more common in both women and gay men with HIV. It is caused by certain varieties of the human papilloma virus (HPV), which also causes genital and anal warts.
This high risk has led for calls for regular anal smear tests to detect cancer in the same way as women have tests for cervical cancer (which is caused by the same virus).
However a survey of 26 HIV positive gay men with pre-cancerous test results has shown a much lower than expected rate of cancer and, in over a third of cases, spontaneous remission.
The 26 patients were all infected with cancer-causing HPV and had 'High-Grade Anal Intra-epithelial Neoplasia' (HGAIN), which means that smear tests detected pre-cancerous changes in cells. They had been studied from 1995 till 2001. On average six of the 26 would have been expected to develop anal cancer over the six years of the study, but in fact none did. Furthermore, 37 per cent reverted to the low-grade version of neoplasia or stopped having any abnormal cells at all.
The study authors warned that anal cancer may take longer than six years to develop and that current tests only pick up 60 per cent of HGAIN cases. But they conclude the low cancer rate is real, and may mean that antiretroviral drugs are having a protective effect. They suggest cancer screening may not need to be done as often as previously suggested.
Vaccines against cancer-causing HPV are in development and are predicted to be available within a few years.
Heterosexual
couples where one partner has HIV are finding it hard to get NHS help to have
babies in ways that avoid unsafe sex. The 9th British HIV Association (BHIVA)
Conference in Manchester heard that despite the risk of HIV transmission only
nine per cent of couples who apply for safe-fertilisation services get them paid
for by the NHS. And of the 74 Assisted Conception Clinics in the UK offering services
to couples with fertility problems, only 14 have helped HIV positive men and nine
helped positive women.
Dr Carole Gilling-Smith of the Chelsea and Westminster (C&W) Hospital in London told the conference that 38 couples had been through the hospital's 'sperm-washing' procedure. In this the sperm are separated from the seminal fluid - it is the latter that contains HIV, both as free viral components and inside lymph cells. Sperm cells are not usually infected but are HIV-tested to make sure before being added to a nutrient fluid and introduced via artificial insemination (AI) into the women. For men with fertility problems (nucleoside HIV drugs can damage the viability of sperm) IVF - test-tube fertilisation - and the sophisticated ICSI technique where a sperm is injected directly into an egg cell are possible.
However only nine per cent of patients have had the C&W's service paid for by the NHS, as hospital trust managers are reluctant to pay for HIV positive couples to conceive. Others have to pay £625 for sperm-washing, £2,080 for IVF or over £2,800 for ICSI.
94 inseminations have been performed on the 38 couples, with a conception success rate of one in five and a live birth rate of one in 10 - this is average for AI services. 15 babies, none with HIV, have so far been born.
Dr L Frodsham of the same hospital said that 45 per cent of the UK's 294 GUM clinics said they had received requests from HIV positive patients about conception and that one in six of all female patients make this enquiry.
She said the Assisted Conception Clinics (ACCs) have yet in the main to cater for patients with HIV. Of the 14 who treated HIV positive men only seven performed sperm washing and only two of those HIV-tested the washed sperm. Whereas half of GUM clinics offer pre-conception counselling to ensure positive parents understood the implications of having a child, only three of the 14 ACCs did so. Gus Cairns
Previous studies have indicated that women with HIV tend to have lower HIV viral loads compared with men with similar CD4 counts.
But a new study at the 9th BHIVA Conference suggests it's not so simple. Analysis of 13,000 European HIV patients, of whom 2,100 were women, indicated that women did tend to have a viral load around 20 per cent lower than men.
However, this depended on their CD4 count. Women with high CD4 counts had lower viral loads than men. Around the 250 CD4 count level, women had the same viral loads, however. And at CD4 counts under the Aids-defining limit of 200, women tended to have slightly higher viral loads.
Researchers have suggested previously that women's lower viral loads could mean faster progression to Aids relative to men, but this appears not to be the case.. Nonetheless, the researchers reiterated a plea for HIV treatment guidelines to include recommendations specifically for women.
