Focus is on cheaper and quicker tests

Of the estimated 33.4m people living with HIV in the world today, the largest number is in developing countries. Research in HIV diagnostics has therefore had to focus on cheaper technology to identifying quickly those who need treatment most.

Accompanying that is a move towards earlier treatment of HIV-infected patients in areas with limited medical resources.

A clinical trial in Haiti this year indicated that starting HIV treatment earlier than current practice produces a higher rate of survival. And early treatment with anti-retroviral (ARV) drugs has also been shown not only to save lives but cut overall costs.

Current World Health Organisation guidelines for treatment suggest as a trigger point for ARV treatment a patient’s count of CD4 cells (specialised white blood cells that fight infection) dropping below 200 per cubic millimetre of blood.

At this level, however, patients are vulnerable to developing Aids-related complications that can lead to death.

New WHO guidelines, announced on Monday, suggest a trigger point of 350 CD4 cells. (A CD4 value for a healthy person can range from 400 to 1,700.)

The new level is in line with recent studies conducted by Massachusetts General Hospital and the University of Cape Town’s Desmond Tutu HIV Centre. These found that starting anti-retrovirals when CD4 levels fall below the 350 level, instead of the 200 level, could prevent about 76,000 deaths and 66,000 opportunistic infections over the next five years in South Africa.

“The question of when to start treatment is critical to improving patient outcomes.” Dr Rochelle Walensky, one of the leaders of the Harvard study, told the FT. “The risk of TB, and other severe infections, at higher CD4 counts warrants earlier treatment.”

But the need to increase HIV testing in developing countries brings with it a host of challenges. Most pressing is the development of cheaper point-of-care CD4 tests. In many countries such testing is not financially feasible.

In response, the Bill and Melinda Gates Foundation has since 2005 made two grants worth more than $1bn to the CD4 Initiative at Imperial College London to develop a $2 point-of-care CD4 kit.

It is in China, where HIV awareness is low, that US-registered company SemiBio, backed with funding from a leading Asian private equity fund, claims to have developed already the technology for a point-of-care, easy-to-use CD4 test priced at $1.80 per kit.

SemiBio’s founder, Tom Cao, says he cannot sell the kit in the Chinese market but is currently in discussions with the Johannesburg Health Ministry about introducing his kit in South Africa, where the government has instituted a nationwide campaign to promote HIV testing and awareness.

Another issue is the appropriateness of testing measures for at-risk populations. Despite the existence of oral and urine rapid tests, the most widely used rapid tests require drawing blood, which often deters people from voluntarily taking the test.

“Don’t overestimate [the ordeal of] the process of taking blood,” warns Dr. John Nkengasong, head of the International Laboratory Branch of the US Centers for Disease Control and Prevention, and co-chair of the US President’s Emergency Plan for Aids Relief (Pepfar). He argues that greater use of oral tests would increase the number of people willing to take the test in rural areas.

Teguest Guerma, acting director of the HIV/Aids department at the WHO, says one of the main issues that needs to be addressed in rural areas is the role of laboratory monitoring.

To meet this challenge, Dr Nkengasong and Pepfar are joining forces with a number of African countries to link up lab networks.

Pepfar’s first five-year plan, which ran up to last year, put 3m HIV-infected patients on ARV globally, the majority in African countries. According to Dr Nkengasong, the estimated number of HIV-infected Africans being treated beforehand was only 50,000.

One of the most promising areas of HIV diagnostic research has been carried out in Tanzania. The work on early infant diagnosis, by the Division of Infectious Diseases and International Health at Duke University in the US, has determined that dried blood specimens yield results comparable with conventional methods that involve transporting frozen plasma samples packed in dry ice. Sending dried blood specimens to a lab in the local postal system costs $6. Transporting the same number of frozen plasma samples costs $515.

While a host of challenges lie ahead in the field of HIV diagnostics, progress looks promising. The 2009 UN Aids report shows that, globally, a rising number of people with Aids are surviving. The next step is to ensure that this rise is matched in the developing world.

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