Health: A question of health

WHAT IS the statistical risk of contracting HIV infection after unprotected vaginal intercourse with an HIV-infected partner?

The risk of being infected by the HIV virus following one episode of unprotected vaginal intercourse with an infected partner is extremely difficult to predict, with estimates ranging from between 0.1 per cent (1 in 1,000) and 20 per cent (1 in 5). The risk is higher following anal intercourse between male partners. This raises the question of whether someone who is exposed to the risk of HIV infection should be given anti- HIV drugs, in the hope of preventing an infection developing. Health workers who accidentally prick themselves with needles that are potentially infected with HIV are recommended to have a month's treatment, with a cocktail of drugs, in order to reduce their risk of becoming infected. It is possible that this same cocktail may reduce the risk of infection for someone who has been exposed to HIV through sexual contact. You could think of this as the HIV equivalent of the "morning after pill". A big difference, however, is that treatment consists of two or three powerful drugs that must be taken for a month, starting within hours of exposure. Seek urgent advice from an STD clinic if you think you may have been exposed to HIV infection.

IS IT possible to catch genital herpes from someone who has cold sores around the mouth?

There are two related herpes simplex viruses - HSV-1 and HSV-2. HSV-1 is the virus that usually causes cold sores around the mouth, and HSV- 2 usually causes genital herpes, but either form can infect either area of the body, so it is possible to catch genital herpes from cold sores.

Please send questions to A Question of Health, `The Independent', 1 Canada Square, Canary Wharf, London E14 5DL; fax 0171-293 2182; or e-mail to health@independent.co.uk - Dr Kavalier cannot respond personally