From VOA Learning English, this is the Health Report.

December 1 marked World Aids Day. People around the world join together to celebrate progress in fighting acquired immune deficiency syndrome, better known as AIDS.

A new device aims to make identification of AIDS easier and to lower the cost of testing in developing countries. The device is used to count a disease-fighting white blood cells called the CD4 cell.

The human immunodeficiency virus -- HIV attacks and destroys CD4 cells making patients unable to fight off infection. Doctors often suggest patients use antiretroviral drugs to help strengthen the body's natural defences for fighting disease. A CD4 cell count can help doctors decide if the drug treatment is necessary or not.

The count requires a blood sample and a laboratory equipped to study the cells. This can be difficult to do in some African nations where many people have AIDS but where testing laboratories are in short supply.

Rashid Bashir heads the bioengineering department at the University of Illinois at Urbana-Champaign. He and his team have developed the new device which they call "lab on a chip". It is a 3-centimeter-by-4-centimeter cartridge with all the equipment and chemicals needed to perform a CD4 cell count.

"The promise is to bring the lab to the patient rather than the patient to the lab," he said.

The device uses just a drop of blood. It separates the white cells from the red cells which carry oxygen. It then counts the CD4 cells immediately.

Rashid Bashir has a financial interest in a business called Daktari Diagnostics. The company is working to market the "lab on a chip" and develop a hand-held device to read the results.

Xuanhong Cheng is a bioengineering professor at Lehigh University in Pennsylvania. She is not involved in Mr Bashir's research, but she says combining processing and identification in one chip is more helpful than other CD4 counters in development.

"A lot of people just look at the detection side. But if the sample has to be processed using very complicated methods, then it's still not quite applicable in resource-limited settings," she said.

Ms Cheng says it will be at least a few years before any of those devices is available on the market. She is also working on developing a CD4 counter.

"The way that we make a device in a lab is very different from industrial manufacturing processes. So, the process is not as straightforward as some people would think," she said.

There is an urgent need for better CD4 tests, and she says she is happy about the competition.

And that's the Health Report from VOA Learning English. I'm Milagros Ardin.