Eleven states that once required special consent for HIV testing have changed their laws, a key step to making an HIV test part of the standard battery that patients expect.

But HIV specialists meeting on Thursday said other barriers include physician confusion about the ease of today's rapid tests, which can cost as little as US$15 (S$23), even though many patients seem to accept them.

No more than 100 of the nation's 5,000 emergency rooms routinely test for HIV in patients who are not critically ill, said Dr John Bartlett of Johns Hopkins University, who co-chaired the Forum for Collaborative HIV Research meeting. Yet because so many HIV patients are poor or uninsured, ERs are the health care setting most likely to find them.

And while every pregnant woman is supposed to be tested so her fetus can be protected if the mother is found to have Aids, about 40 per cent are not tested, he said.

'Those are what we call missed opportunities,' Dr Bartlett said.

Today, the test is 'much better, it's much easier, it's much cheaper. The treatment is really great now.' Just over 1.1 million Americans are estimated to have HIV and 232,000 do not know it, according to the Centres for Disease Control and Prevention (CDC).

The CDC for years recommended routine testing mainly for people at high-risk, such as injecting drug users. Then, finally, came drugs potent enough to keep HIV patients healthy for years, postponing the slide into full-blown Aids. Yet nearly half of new infections still were being discovered too late for patients to benefit. Not to mention that people who don't know they're infected unwittingly spread the virus.

So in September 2006, the CDC recommended routine testing for everyone ages 13 to 64, whether they think they're at risk for HIV or not.

There is no nationwide data yet on the new guidelines' impact, CDC's Dr Bernard Branson told The Associated Press.

But Dr Branson listed encouraging signs: