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The three biggest myths about viral load monitoring in resource-limited settings

Through my work I’ve understood that there are many different perspectives on viral load monitoring (VLM). All of them are understandably products of their environment. Many of the beliefs people have regarding viral load monitoring were formed over a decade ago when there were only RNA-based HIV viral load testing platforms available.  In 2002 a new platform based on reverse transcriptase (RT) was introduced that made viral load monitoring more accessible without sacrificing reliability.

To those of you who are familiar with both platforms these myths may sound quite out of step with the times. But these opinions are widely held in many parts of the world, particularly in those parts of the world defined as resource-limited.


  1. You don’t need viral load monitoring when you have CD4 testing
    HIV viral load tests and CD4 tests measure different things (see: What’s the difference between HIV viral load tests and CD4 tests). CD4 is an excellent test to see what condition the immune system is in. Viral load, on the other hand, detects how active the HIV virus is. Both these pieces of information are important for doctors to use when managing HIV.  That’s why in most developed nations, both tests are given as a routine part of HIV management.


  3. Viral load monitoring is too expensive
    This was the impression made when viral load testing was introduced into Sub-Saharan Africa in the 1990’s.  The costs of the tests and equipment have come down significantly since then but the perception remains.  What people often fail to consider is the cost of not testing. A recent study(1) has suggested that frequent viral load and CD4 monitoring has the potential not only to add three quality-adjusted life years to patients’ lives, but save billions of dollars for struggling economies in Africa and elsewhere.


  5. Viral load monitoring is impractical for resource-limited regions
    RNA-based platforms introduced in the 1990’s required delicate instruments and advanced laboratory conditions that are rare to find in resource limited settings. That all changed in 2002 when tests using reverse transcriptase (RT) as a marker where introduced. Today there is a test that can work in the resource limited settings but in many instances this perception remains an obstacle.


1. Vijayaraghavan A et al. Cost effectiveness of alternative strategies for initiating and monitoring highly active antiretroviral therapy in the developing world. Journal of Acquired Immune Deficiency Syndrome. 2007 Sept 1;46(1):91-100.


The difference between HIV viral load and CD4 tests

CD4 and viral load are two of the key tests doctors use to manage HIV. But the tests themselves, what they measure, and how doctors use them are quite different. Below is a brief overview of how the two tests work.

CD4 tests measure the number of CD4 T-cells in the blood to gauge the strength of the immune system in the presence of HIV infection. CD4 is an excellent test in this respect and has been the primary indicator doctors have used to monitor the overall condition of the patient’s immune system. It is most useful in determining when an untreated patient needs to begin taking ARVs. The test is usually simple to perform and relatively cheap to administer which has lead to its widespread use.

The test has two main limitations with regard to HIV management. First, there are many factors, other than HIV activity, that can affect the amount of CD4 T-cells present in the blood at any given time. So the doctor cannot be sure if the CD4 value is caused by HIV activity or other factors. Second, it can take up to 6 months for HIV activity to be reflected in the CD4 count.

While CD4 measures the body’s reaction to the virus, the viral load test measures the number of virus particles in the blood directly. A low viral load indicates that HIV is not actively reproducing and that the immediate risk of disease progression is low. A high viral load means the virus is active and the infection will progress. The viral load test is a more reliable indicator of viral activity than the CD4 test and, as such, a more reliable indicator of disease progression. It is the most useful tool in determining whether or not antiretroviral drugs are working since treatment failure is first manifested by a rise in viral load. In virtually all cases, this rise in viral load occurs within a month or two of the cause of treatment failure. 

Historically, the viral load test has had one main drawback: While a mainstay of treatment in developed nations, it has been more difficult to perform in resource-limited settings. That’s because tests introduced in the mid 1990’s are developed around platforms that measure RNA. These tests are made with delicate equipment and require laboratory conditions that are uncommon in resource-limited clinics. The introduction of the world’s first viral load test that measured reverse transcriptase (RT) in 2002 changed all that. The RT platform now provides equivalent results with simple equipment and lower demands on the laboratory running the test.


Three reasons viral load monitoring matters

  1. Patients. First and foremost, viral load monitoring (VLM) helps doctors manage HIV better, thus increasing the patients’ length and quality of life.  This not only makes their lives better, but that of their families as well. It also helps the community by keeping them productive and working longer.
  2. Budgets. VLM helps makes the supply of ARVs go further.  Many nations have a limited supply of ARVs, so ensuring none of the drugs are wasted is a top priority. VLM is the most accurate way to detect treatment failure, and as such gives the best indication of when to stop using medication that is no longer working for a patient. It also helps determine the best time to begin treatment, so it isn’t initiated earlier than necessary.
  3. Society. Stemming the spread of ARV resistance.  When treatment stops being effective and a patient continues taking the same ARVs, HIV can become resistant to the drugs. And if the patient passes on their infection, their resistant strain goes with it. With VLM to help detect treatment failure, the development of drug resistance can be minimized and treatment options for patients can be kept open.

Those are my top three. If you have other reasons, please feel free to share your view with a comment.


CNN raises awareness for viral load testing

Imagine a guy calls you up and says: “Hi I’m a reporter with CNN and I’d like to interview you about your company”.  I did what any of you would do. Put the phone down and started planning my revenge on the mate who I thought was responsible for such a practical joke.

However, lo and behold, it was true. CNN did want to know how we were helping create access to HIV monitoring in resource limited settings and highlight the immense importance of the subject.  OK, now, what shirt to wear?

If you want to see the interview you can take a look at the video below.


What’s a blog? Oh, right, a blog…

“Martyn you gotta have a blog” advised a US colleague. Blog…hmmm…blog. Yes well…BLOG. The mind boggled. I thought for a few minutes, could this be a new toothpaste, another way of saying I had a cold or just some new terminology to describe market share. I was stuck. Luckily, before I could make a twit of myself a friend came to the rescue. “Yes, your personal thoughts about viral load testing published on the web".

Ok, so here goes. I will attempt to share my views on HIV monitoring, provide information and possibly help stimulate some debate. I´ll try to post twice a week, depending on the weight of my inbox, and hope that the information I post creates comments and feedback. The editorial views will be mine and not necessarily those of my employees or our partners around the world. I hope the information provided will be a useful resource to those of you who want to learn more about HIV monitoring and how we can make this test more accessible to HIV patients around the globe.

Either way I hope you find this blog a useful resource. If you don’t, please let me know how I can improve it.



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