A man who contracted HIV after receiving treatment for haemophilia has said he was not told that he had the virus for months.
Haydn Lewis was HIV positive for eight months before he was told
Haydn Lewis, from Cardiff, said he thought it was during this time that his wife also became infected with HIV.
An independent inquiry has begun into how patients with haemophilia were given contaminated NHS blood products in the 1970s and 1980s.
More than 1,700 patients have since died, and many more are terminally ill.
It is thought nearly 5,000 people were exposed to hepatitis C and, of these, more than 1,200 were also infected with HIV.
Mr Lewis, who now helps a campaign group called Tainted Blood, is raising concerns about the procedures followed in his treatment.
He said that when he checked his medical records, it transpired that he had contracted the virus a year before he was told by his doctor.
"I was first tested for HIV in 1984 but not informed or consulted and then finally told I was positive for HIV in February 1985," he said.
"There was no mention that I was positive by my consultant and, through that period, I could have infected my wife or my children."
Indeed, Mr Lewis believes it was during this period that his wife Gaynor became affected.
"I can only assume that because I know from the moment that I was told I was positive, there wasn't any chance that I was going to infect my wife," he said.
Gaynor Lewis is now HIV positive as well
"Celibacy is quite easy when you are told you have a life-threatening condition."
Tony Calland, the chair of the British Medical Association's Ethics Committee, said the case was "completely unacceptable".
"The whole basis of the relationship between a doctor and their patient is one of trust," he said.
"It is certainly in current guidelines that as soon as a doctor knows something about a patient's condition that he informs the patient about the difficulties he may face with that condition and the risks and benefits of the various types of treatment that are available."
The inquiry which starts on Wednesday is studying the contamination of NHS blood products, but Mr Lewis urged that a "wider remit" including the contamination of commercial blood products should be considered.
A spokesperson for the Department of Health said they had been open and transparent about the issue and had "great sympathy for those who were infected with Hepatitis C and HIV".
Another family, from Newport, have also revealed that they were only told that their son Colin had Aids just before he died aged seven.
Colin had been given his first treatment the day before his first birthday in 1983 and had contracted HIV by the time he was two.
Mr and Mrs Smith said they had suspicions there was more to their son's ill-health when doctors reacted to an incident when Colin he was sharing a bed with his brother Daniel.
"Both boys were covered in blood," said Janet Smith, who rang the hospital to seek advice in the middle of the night.
"And they just said 'Clean Daniel up, don't worry about Colin, just clean Daniel off - did it go in his mouth?'.
"That was the first time that the alarm bells rang and then they said 'Burn the mattress'."