Mohammed Dica is the first person to be successfully prosecuted in England and Wales for passing on the Aids virus, HIV, through sex.

Though the case is a landmark, the prosecution followed a decision by the Home Office some years ago that there were enough powers under the Offences against the Person Act 1861 to secure convictions in such cases.

In 1998, following a recommendation from the Law Commission, the official law reform body, ministers issued a consultation paper proposing a new offence of "intentional transmission of a disease with intent to cause serious harm."

 

But they eventually concluded that the 140-year old act gave them enough powers.

Dica's conviction of causing grievous bodily harm under the act has proved them right, and is likely to mean more prosecutions in the future.

The conviction is the second in the UK for transmitting HIV.

In February 2001 Stephen Kelly, 33, was convicted under Scottish common law of culpable and reckless behaviour in having unprotected sex with his girlfriend, Anne Craig, knowing he was infected with the virus.

A heroin user, he later told her he had picked up the infection through needle-sharing in Glasgow's Glenochil prison. He had been advised to practice safe sex and alert partners to his HIV status.

Kelly's prosecution sparked controversy because the scientific evidence that secured his conviction came from confidential information from a research study on HIV which was obtained by a police warrant.

The problem of what to do about HIV-positive men - and, potentially, women - who recklessly or deliberately infect sexual partners first hit the headlines in 1992.

Then, the Crown Prosecution Service was said to be "powerless to act" over the case of Roy Cornes, a 24-year-old haemophiliac from Birmingham who picked up the virus through a contaminated blood transfusion and was accused of infecting four women.

One had died and another had borne an HIV-positive baby.

Debate raged among legal experts as to whether a prosecution could succeed and what the possible charge might be.

New Zealand example

In the end, Cornes died before any prosecution could be brought. It was his case which sparked off the Law Commission proposals.

There have been other similar cases around the world.

In 1995 the New Zealand court of appeal upheld a conviction for causing grievous bodily harm against a man who had infected two women with HIV.

 

Two years later a fisherman, Paul Georgiou, was jailed for 15 months after a court in Cyprus judged that he was aware he was carrying the HIV virus when he had sex with a British woman, Janette Pink.

To succeed in any prosecution for passing on HIV or herpes, prosecutors would have to prove that the defendant knew he or she was infected with the virus.

They would also have to show that the victim had been infected by the defendant rather than someone else.

Last year prosecutors in England invoked the 1861 act to charge a 33-year-old doctor, Richard Sullivan, with causing grievous bodily harm by infecting a 32-year-old solicitor with the genital herpes virus through sex.

But the case against him was dropped after the judge heard there was no evidence he knew he had the sexually transmitted disease.

The court also heard the woman had gone to hospital with symptoms 10 months before having sex with him.