March 4, 2015

March 4, 2015
CD4 Counts

Welcome to another day in my life. Today is Wednesday and we have almost made it through the middle of another work week. I hope you are having a beary safe and great week so far. Dab the AIDS Bear and I are still recovering from pneumonia and flu.

I get a ton of questions from people living with HIV (and some from negative folks) about CD4 (t-cell) counts and viral load. Which is more important, which do I pay attention etc... so I thought I would blog about this issue today.

There is a radical change of understanding – and thus methodology – that is occurring in the field of HIV transmission reduction, popularly termed HIV prevention. Essentially, transmission-reduction methods based upon a new paradigm – the biology of transmission – are replacing methods based upon the current paradigm which is based upon modifying sexual behaviour. In developed countries, this shift has already occurred. However, in developing countries such as those in Southern Africa, we appear to be in limbo, largely due to the costs of the new methodologies, such as viral load testing. In this article we examine some of the potential benefits of this new approach, and integrating the old with the new. We also highlight what we consider to be an astonishing oversight in transmission-reduction approaches, namely Primary HIV Infection (PHI).

Biomedical Methods of reducing HIV transmission

For at least a decade in Southern Africa, public messaging concerning reducing the risk of transmitting HIV from one person to the next has been static, namely the ever-present Abstain-Be Faithful-Condomise (ABC) behavioral risk-reduction approach, in addition to the screening of blood and reducing mother-to-child transmission. Most ‘HIV prevention’ programs are based upon one or more of these methods.

However, there have been significant biomedical transmission-reduction developments in the area of reducing HIV transmission over the last few years, such as the recognition that male circumcision reduces forward transmission of HIV from women to men by up to 60%, and strong evidence that ART is a highly effective means for serodiscordant couples to have babies with significantly reduced risk (between 92% and 100%) of transmitting HIV from one partner to the other.

In some developed countries the concept of PEP (Post Exposure Prophylaxis) has been extended to a ‘morning after pill’ application, where unprotected sex is dealt with in the same way as rape, using a course of ART medications commencing no less than 72 hours after possible exposure to HIV. There are even rumblings of PrEP – commencing ART before possible exposure to HIV - in order to remove the risk of infection from unprotected sex. Thus far, these interventions are limited and controversial, and the implications are being hotly debated. However, it appears that the discourse on reducing transmission of HIV from one person to another has quietly shifted from behavioral risk-reduction methods towards biological risk-reduction methods, at least in developed nations.

Viral load levels and HIV transmission

This paradigm shift is based upon the undeniable biological fact that the amount of HIV in the sexual fluids (viral load) at the time of sex is the main determinant of the probability of transmission. If the person has an undetectable viral load at the time of sex, the chances are very small of HIV being transmitted to the other person. ART reduces viral activity and viral replication. It is logical – and demonstrated in several large studies – that HIV-positive people taking ART have a much lower forward transmission rate than those not taking ART.

An additional biological fact is that any untreated co-infection – including STIs, tuberculosis, malaria, gastrointestinal infections, flu, etc – will cause spikes (sharp increases) in viral loads. This is because these co-infections cause the immune system to strengthening the TH2 system to deal with these co-infections, at the expense of the mechanisms that keeps HIV under control (TH1 System)5. Therefore, in viral reduction approaches, access to prompt and effective primary health care treatment is a fundamental requirement for effective viral load control, and consequently, HIV transmission reduction.

It goes without saying that an increase in the frequency of unprotected sex increases the probability of transmission. However, the viral load at the time of sex far outweighs sexual frequency in determining the probability of transmission. Advocates for viral load reduction methodology say “It’s about the virus, stupid! No virus, no transmission.”

This understanding of the importance of viral load levels in determining HIV transmission is widespread in developed countries with significant HIV-infected populations. However, in developing countries, this concept is rarely discussed in the public discourse of HIV transmission reduction, for the simple reason that most developing countries do not have the necessary finances to apply the viral load detection technology on a wide scale in national health systems. We argue that, even if we cannot measure viral loads in a given population with significant HIV prevalence, we can certainly introduce measures that are likely to lower viral loads in those infected, and thus impact transmission rates.

Resistance to the Viral Load approach

A repeated argument in developing countries against introducing concepts such as the viral load in HIV/AIDS education materials - let alone mentioning fluctuating viral load levels at different periods of infection – is that many people do not have a basic understandings of biology and germ theory. The argument continues that discussions regarding viral activity will create undue confusion, and jeopardize behavioral risk-reduction messaging and practices. For this same reason many developing countries rely heavily upon simplistic public explanations of HIV transmission, mainly ABC prevention methods.

Despite a decade or more of evidence showing how sporadic the success of these simplistic messages are in terms of reducing the number of new infections – if at all – we valiantly reiterate and advocate this approach. Why? Perhaps it is because we don’t know what to replace it with, or because, logically, it should work, and we are somewhat perplexed about why it doesn’t. For many agencies, this has resulted in a paralysis of analysis: We don’t quite know why the ABC approach doesn’t work, but we need to keep promoting it until we figure out what else to do.

It is our belief – and experience – that low literacy has no connection to intelligence. Instead, the desire to learn more about the body, biology, and germ theory is strong, regardless of literacy. People are perfectly capable of learning new concepts and terminology: Let us teach them what they need to know to understand exactly how HIV transmission occurs. Perhaps it is time to uncover the details?

Integrating behavioural and biological approaches

To be clear: We do not oppose the ABC approach. On the contrary, we are quite certain that the ABC methods can have a significant impact when promoted within a meaningful context of understanding exactly how HIV transmission occurs. When people understand how HIV transmission actually occurs – including fluctuating viral levels due to co-infections - then targeted ABC methods suddenly make sense to many people who otherwise view such methods as a failure. Furthermore, the authors advocate a systematic top-down dissemination of the necessary information and appropriate messaging and applications, commencing with clinicians, then educators, and finally the general public.

For example, very rarely does one hear in a public forum that for the majority of HIV infection that the person has a very low viral load. This refers to the asymptomatic period after the Window Period and before the immune system weakens to the pre-AIDs and AIDS stages. Consequently, the probability of transmitting HIV is very low (approximately 1 in 500 to 1 in 10,000 sexual acts) during this asymptomatic stage of HIV infection. This phenomena results in the perplexing situation – serodiscordant couples - where one partner is HIV-positive, the other partner is HIV-negative, and the partner without HIV remains uninfected despite repeated exposure through unprotected sex. However, with a single co-infection of, for example an untreated STI, the viral load can spike sufficiently to permit transmission during unprotected sex between serodiscordant couples.

Given this understanding, is it not probable that there is a much higher chance of persuading a person living with HIV to either abstain or wear a condom during any period of co-infection (illness), and thus reduce the risk of transmitting HIV to his or her partner? Simplistically, if seeking rapid medical treatment for illness plus abstinence or condoms were the recommended courses of action when a person living with HIV is ill in any way, the ABC methods would be more easily accepted, and - dare we say - more effective because they are being used in a targeted fashion when they are needed most: During periods of high viral loads.

Viral load reduction in developing countries

When the notion of reducing viral load becomes the primary goal of HIV transmission-reduction programs, the importance of effective primary health care becomes evident, as does the importance of ensuring, for example, clean water supplies to a community to prevent co-infections with gastrointestinal infections. Government and other agencies involved in housing development, sanitation, agriculture, poverty alleviation, trade and industry, transportation, and water supply and quality – to name a few – become necessary partners in the drive to lower HIV transmission by contributing towards healthier communities with greater access to medical care. It is no coincidence that previous pandemics in Europe, such as the Black Death and the Bubonic Plague, were largely eradicated due to macro social infrastructural changes, not medical interventions.

Also, methods of supporting those living with HIV can become more focused upon viral-load reduction methods, such as recommending specific nutritional elements (e.g., selenium) that appear to lower viral load, or those that support immune function and control of HIV (e.g zinc, and Vitamin A), versus the current generic ‘eat well’ guidelines. Also, other methods of reducing HIV viral load levels – such as deworming – and the prevention of other common co-infections can be promoted.

It is for similar reasons that the recent change in the criteria for qualifying for ART by the South African Department of Health, from a CD4 count of 200 to 350, will have a significant impact upon reducing the number of HIV transmissions. The simple fact of the matter is that sick people – people with weak immune systems and opportunistic infections – have much higher viral loads, and are thus a high risk population in terms of transmitting HIV. Reported transmission probabilities are between 1 in 100 and 1 in 1,000 sexual acts. If we place people on ART before AIDS illnesses develops, they have lower viral loads, and transmission is less likely.

Hope this helps you understand the difference and what to look at on your lab results and hope you have a beary safe and great Wednesday!

Until we meet again; here's wishing you health, hope, happiness and just enough.

big bear hug,

Daddy Dab