Thursday, June 9, 2011

HIV Treatment Has Come a Long Way, Prevention Has a Long Way to Go

South Africa, apparently, has a plan to "eliminate HIV in the next 30 years". The plan is based on a mathematical model, which assumes very high HIV prevalence and a population that will be tested once a year. Those found positive will be given antiretroviral drugs immediately, to take for the rest of their lives. The model says that this will eliminate the epidemic.

It would be interesting to know what figures they used in their model. South Africa has indeed tested many millions of people in the last twelve months, perhaps 12 million or more. But it has been estimated that people might need to be tested more frequently than once a year, perhaps twice or even four times a year. Will once a year be feasible, even if it turns out to be enough?

Sure, plenty of research has shown that a lot of people responding to antiretroviral treatment have a very low viral load and are unlikely to transmit the virus to their sexual partners. But that doesn't mean that 'test and treat', as it's called, will eradicate transmission altogether.

Recent research which gave rise to a lot of the hype about test and treat involved discordant couples. These are couples where only one person, the 'index case', is infected. It is believed that the index case will, sooner or later, infect their partner if they continue to have unprotected sex. The rate of transmission in discordant relationships is, indeed, very high. Putting the infected partners on drugs, assuming that they are found to be HIV positive early enough, could significantly reduce the risk to the HIV negative partner.

But that doesn't answer the question of how the index partner was infected. They would probably not have been protected by a test and treat policy, unless that policy was able to ensure that a huge percentage of new infections were discovered and treated very early on. But, while you can see the motivation for putting the HIV positive partner on drugs to protect the negative partner in discordant couples, in a couple where neither is positive there is no such motivation.

The South African plan doesn't deal with the issue of whether all HIV positive people will agree to or adhere to treatment. It doesn't even ask if putting people on treatment immediately is the best thing for those people's health. Leaving treatment till too late is clearly bad for people's health. But treating them too early, as well as being expensive and more likely to result in non-adherence and consequent resistance, may not be ethical.

It certainly won't be ethical if people are compelled to take the drugs, regardless of whether they need them or not. But there's also the question of whether people should take drugs for the benefit of others, or for the benefit of public health. [There's an interesting discussion of patient autonomy by Dr Joseph Sonnabend on his POZ blog.]

Treating more people, if and when they need treatment, is a good thing. Testing more people and testing them regularly is also good, especially if the results of such widespread testing are used to figure out why so many people become infected in South Africa. But test and treat alone is very unlikely to eliminate any epidemic in any country in 30 years, or even in 100 years.

No matter what any model (or 'expert') tells you, treating as many HIV positive people as possible is not the same as developing strategies to ensure that people don't become infected in the first place. Public health is a lot more complicated than any mathetical model can show. That's why so few diseases have ever been eradicated.

Diseases that have been virtually eradicated in some countries were not eradicated merely because of some powerful technology, either. They were eradicated because the conditions under which the disease is transmitted were also addressed. Water, sanitation and hygiene in the case of many diseases, air quality and habitation in the case of others, food and nutrition, living conditions, working conditions, etc. Test and treat remains relatively blind to the conditions under which HIV is transmitted (as has the HIV industry).

Alarmingly, research has shown that test and treat alone will not even come close to eradicating HIV in the US, where transmission is many times lower than in South Africa and the amount per head spent on healthcare is the highest in the world. And this is not because the universal testing part of the strategy is not in operation but because only 1 in 5 people on treatment have the undetectable viral load requried to ensure that they don't infect their partner through unprotected sex.

Test and treat is neither a miracle nor something that is impossible to effect. But it will not eradicate HIV epidemics, ever, anywhere. And public health experts should know that there is no such precedent for eradicating a disease that is transmitted in a number of ways (some of which are adequately acknowledged and some of which are not). It is wholly irresponsible to make the implicit promises that one hears constantly about test and treat.

There is a lot we don't yet know about HIV transmission and, apparently, a lot we are not very anxious to discuss. So let's not get distracted from HIV prevention by what is just one in a long line of hyped technical fixes. Test and treat, treatment as prevention, whatever you want to call it, will only ever be part of an effective strategy to eradicate HIV.


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