The BBC's Mike McKay: 'The Doncaster case worries the health experts'

The helpline has received 430 calls since it set up this week.

The callers are seeking advice on whether they should take an Aids test.

Doncaster Health Authority has had to call on the NHS for extra support to man the phonelines and they are being handled through a London office. Around 120 staff are taking calls.

All have been given training in counselling people about taking tests.

The health authority is advising anyone who had unprotected sex in the past five years to consider a test.

Ten people have contracted the condition through heterosexual sex in the last two years - after virtually no such cases in the previous decade.

The majority of those infected are women, and health officials say the most common factor has been unprotected sex between people who met at pubs and nightclubs.

Doncaster has five nightclubs and a high concentration of pubs.

John McIvor: Young people should use a condom

John McIvor, health authority chief executive, said: "We would urge all young adults in Doncaster entering new sexual relationships to use a condom.

"We would wish to reinforce the message that anyone having sex without a condom with a new casual partner is putting themselves at risk."

Mr McIvor said young people had probably become complacent about the risk of contracting HIV, as heterosexual transmission had been relatively rare.

He said: "It is a long time since the major Aids campaigns. Doncaster has a vibrant nightclubbing scence and it may be that once young people have maybe had a drink or two they get a bit blase."

Early treatment vital

HIV infection often presents as an acute flu-type illness and then remains hidden for several years until serious infections and Aids develop.

Aids and HIV publicity material is being circulated in Doncaster

Early treatment can significantly prolong a healthy life, so an early diagnosis is very important.

HIV positive women can transfer the infection to their babies through childbirth. If a pregnant woman is known to be positive, treatments can be offered which reduce the risk of the baby developing the virus.