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Blood-borne viral STIs

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Martin Jones, MSC, RGN, CNS.

Coordinator, Sexual Health, Eastbourne Downs Primary Care Trust

This third and final Factfile in the series on sexually transmitted infections concerns viral STIs that are blood-borne: human immunodeficiency virus (HIV), hepatitis A, hepatitis B and hepatitis C. Sexual contact is not their only mode of transmission but is the focus here.
This third and final Factfile in the series on sexually transmitted infections concerns viral STIs that are blood-borne: human immunodeficiency virus (HIV), hepatitis A, hepatitis B and hepatitis C. Sexual contact is not their only mode of transmission but is the focus here.


HIV (human immunodeficiency virus)
An estimated 41 200 cases of HIV infection exist in the UK, of which about a third are undiagnosed. Since AIDS was first identified in the early 1980s, there have been 15 000 UK deaths associated with HIV (PHLS, 2003).


Sex between men has been the cause of most cases to date, with 28 835 reported to the Public Health Laboratory Service to the end of 2002. However, in recent years, sex between men and women has overtaken sex between men as the route of infection for most newly diagnosed cases.


In 2002, 55% of new cases resulted from sex between men and women, compared with 32% from sex between men. In 1998 this was 48% and 41% respectively, and before 1987, 4% and 79% respectively. Between two-thirds and three-quarters of heterosexually acquired HIV infections in the UK are likely to have been acquired in Africa (PHLS, 2003) (see panel for scale of global crisis).


Different types of sexual activity are associated with different risks of HIV transmission: unprotected receptive anal intercourse, whether between men or between men and women, is associated with a higher risk than insertive anal intercourse. A number of co-factors will affect the risk, including rectal bleeding, the presence of other sexually transmitted infections, viral load (the level of HIV in blood and body fluids) and so on. Similarly, in unprotected vaginal intercourse, the receptive female is at greater risk than the male, with similar co-factors affecting the risk (NAM, 2002).


Between around 1-3% of cases of HIV in UK have been caused by oral sex. Receptive fellatio (when a man or a woman takes a man's penis in the mouth) is the only established route of HIV transmission from oral sex, although disputed reports exist for insertive fellatio and for cunnilingus, and there is one case report of HIV infection from oral-anal contact (rimming). There are no reports of HIV transmission through kissing (NAM, 2002).


The advent of highly active antiretroviral therapy (HAART), using combinations of three or more antiretroviral drugs together, has dramatically reduced HIV mortality rates. The use of these drugs for post-exposure prophylaxis following sexual exposure is not established practice, but may be available in some HIV treatment centres for patients presenting within 24-48 hours of exposure.


Primary HIV infection occurs 2-12 weeks after infection and is described as a flu-like illness. Table 1 shows the association of certain symptoms with a later diagnosis of HIV infection. As in post-exposure prophylaxis, the usefulness of HAART in primary HIV infection has not been established. British HIV Association guidelines recommend referring patients with primary HIV infection to a clinical trial (BHIVA, 2001).


Hepatitis A
The main route of hepatitis A transmission is faeco-oral - via food, water and close personal contact. Sexual transmission has been reported in gay men via oral-anal (rimming) and digital-anal (fisting) contact (AGUM/MSSVD CEG, 2002) and rarely in other groups. Up to 50% of those infected with hepatitis A are asymptomatic, or have mild, non-specific symptoms.


There are two phases to acute hepatitis A infection (see panel overleaf). It is worth offering vaccination against hepatitis A to men who have sex with men. (AGUM/MSSVD CEG, 2002).


Hepatitis B
Hepatitis B may be transmitted through blood-to-blood, mother-to-child or sexual contact. It is estimated to be 100 times more transmissible than HIV. This means that sexual activities such as oral sex and deep kissing, considered to be 'safer' sex in the context of HIV transmission, probably carry a higher risk of hepatitis B transmission.


Hepatitis B testing and immunisation should be offered to: men who have sex with men, sex workers of either sex, injecting drug users, HIV-positive patients, sexual-assault victims, people from countries where hepatitis B is common, victims of needlestick injuries and the sexual partners of any of these people. The serological tests for hepatitis B are summarised in Table 2.


Of those who acquire hepatitis B through sexual contact, 90-95% develop natural immunity within six months. Acute symptoms are similar to hepatitis A (see panel) but may be more severe. Those at risk of acquiring hepatitis B and not found to have naturally acquired immunity should be offered vaccination (AGUM/MSSVD CEG, 2002, PHLS, 2003).


Hepatitis C
The main route for hepatitis C transmission in the UK is through use of contaminated needles by injecting drug users. Sexual transmission rates are thought to be rare (about 0.2-2% per year of relationship, or 2-11% of partners in long-term relationships). These rates increase if the index patient is HIV infected.


Partners should be notified and tested for hepatitis C. The use of condoms should be advised.


In the UK, seroprevalence of hepatitis C is estimated to be 0.4%, making this a low prevalence area of the world; and 15-20% of those who acquire hepatitis C clear the virus within six months. The other 80-85% develop chronic hepatitis C infection, which may lead to liver disease later in life (PHLS, 2003).


THE GLOBAL AIDS CRISIS
- Sub-Saharan Africa is the most affected region of the world, with high rates of infection in some countries


- In Botswana a 15-year-old male has a 90% chance of dying with AIDS and the risk is similar in South Africa and Zimbabwe (BBCi, 2003)


- Worldwide, to the end of 2001, there were estimated to be 40 million cases of HIV, with rapidly developing epidemics in Eastern Europe and Central Asia


HEPATITIS A
There are two phases to acute hepatitis A infection, prodromal illness and icteric illness.


PRODROMAL ILLNESS
- This phase lasts for three to 10 days.


- Symptoms are flu-like (malaise, myalgia and fatigue), often with right upper abdominal pain


- There are no specific signs


ICTERIC ILLNESS
- Jaundice (mixed hepatic and cholestatic) associated with anorexia, nausea and fatigue


- This usually lasts for one to three weeks


- It can persist for 12 or more weeks in a few patients who have cholestatic symptoms (itching and deep jaundice)


- Fever is not found in this phase


- Signs: jaundice with pale stools and dark urine. Liver enlargement/ tenderness and signs of dehydration are also common.


Source: Signs and symptoms of Hepatitis A, AGUM/MSSVD CEG, 2002

Association for Genitourinary Medicine and Medical Society for the Study of Venereal Diseases Clinical Effectiveness Group. (2002) National Guideline for the Management of the Viral Hepatitis A, B and C. Available at: www.agum.org.uk

BBCi. (2003) Botswana's boys' bleak future. Available at: http://news.bbc.co.uk/1/hi/world/africa/2801187.stm (accessed on May 8, 2003)

British HIV Association (BHIVA) Writing Committee. (2001) BHIVA Guidelines for the Treatment of HIV-infected Adults with Antiretroviral Therapy. Available at: www.bhiva.org

Hecht, F.M. (2002) Use of laboratory tests and clinical symptoms for identification of primary HIV infection. AIDS 16: 1119-1129.

National AIDS Manual (NAM). (2002) AIDS Reference Manual (25th edn). London: NAM Publications.

Public Health Laboratory Service (PHLS). (2003) HIV and sexually transmitted infections. Available at: www.phls.org.uk
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