When it comes to testing people for HIV, health officials have often had to choose between taking a blood test that can screen for the virus soon after infection, which few people volunteer for, or give patients a convenient saliva test that is not as reliable during early stages of the disease.

Stanford chemists in the US, collaborating with the Alameda County Public Health Laboratory in California, have now developed a test that gives the convenience of a saliva sample, but allows for reliable results, the scientific journal Proceedings of the National Academy of Sciences reported in its January 22 edition.

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"The earlier you can detect, the better, because people can infect other people," chemistry professor Carolyn Bertozzi, Stanford's Anne T. and Robert M. Bass Professor in the School of Humanities and Sciences, said of the new test. "Every day that goes by that a person's behavior is not modified based on their HIV status is a day that they could be infecting other people, especially young people."

Testing for HIV

Up until now, the most common means of testing for HIV infection has been to take a blood sample and check for antibodies, proteins the immune system has built up to attack the infection in a bid to fight the virus.

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But this form of screening has its downside — needles. Health officials and researchers needing to test large numbers of people quickly in order to contain the spread of the disease say needles inhibit their work, reports Cheng-ting "Jason" Tsai, the lead author on the new paper.

"There's a lot of populations you just can't reach out to by blood tests," Tsai said.

"But if you were to do oral fluid, then all of a sudden you open up a brand new population that was not otherwise accessible to you."

All of this, the researchers say, can be done without requiring a blood sample or much technology to process the samples that are taken. "It is purposefully low tech," Bertozzi says.

The team behind the find say more studies are needed to substantiate the results, but add that the first experiments suggest that the saliva test works well. Their test accurately detected 22 people who took part in the Alameda County screening trial.

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Both Tsai and Bertozzi hope that the same principles can be used to create tests that are useful for allergy testing and screening for typhoid and tuberculosis.