What Viral Load is Uninfectious?

posted: 23/11/2009

A new study has found more evidence that people with low viral loads are less infectious.
 

US researchers found that very few HIV transmissions come from people with a viral load below 1000 copies/ml. The rate of transmission more than doubles when the viral load reaches 10,000 copies/ml.
 

There’s been a lot of debate about HIV treatment, viral load and infectiousness. Evidence is mounting up to show that successful HIV treatment significantly reduces infectiousness.

'The Partners' study recruited 3408 people and monitored HIV sero-discordant (= mixed HIV status) couples every three months to look for new HIV infections and to measure viral load in the HIV-positive partner. If HIV infection was found in previously HIV-negative partners, viral sequencing of both partners was carried out to check that the partner was the source of HIV. This analysis revealed 108 linked infections, people who had infected their partners.

Viral load logs
Viral load figures are often given on a logarithmic scale, because viral load rises so very steeply. A ‘one log increase’ means that viral load has increased by ten times. A viral load of 10,000 copies/ml is therefore one log higher than a viral load of 1000 copies/ml. Similarly, a viral load of 1,000,000 copies/ml is one log higher than a viral load of 10,000 copies/ml, and so on.

Transmission halves as log falls
Researchers found that a fall in viral load of 0.74 log reduced the risk of HIV transmission by 50%.
It’s hoped that the findings of this study will assist further research into the use of HIV treatment in prevention.
 

Viral load is not the only thing which affects whether HIV is transmitted. If either partner has any sexually transmitted infection (often these show no symptoms), these STIs make HIV transmission far more likely, even with a low viral load. Recent Swiss, German and French statements have broadly confirmed that an undetectable viral load usually means HIV cannot be transmitted. But where there are STIs, HIV transmission becomes likely.  

Viral Load information

There is more information on viral load in NAM’s new patient information booklet CD4, viral load & other tests. You can download it here, or order it free from NAM's online bookshop. 

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Swiss Court Frees HIV+ Man

posted: 10/03/2009

In the first ruling of its kind in the world, the Geneva Court of Justice has freed a man given 18-months prison for exposing someone to HIV.The court ruled that the risk of HIV transmission while the man was on treatment was far too low to justify the conviction.

In Switzerland, public health law effectively made it a crime simply for people with HIV to have any  unprotected sex. However this court has now changed this. It accepted expert testimony from Professor Bernard Hirschel – one of the authors of the Swiss Federal Commission for HIV/AIDS consensus statement on the effect of treatment on transmission – that the risk of sexual HIV transmission during unprotected sex on successful treatment is 1 in 100,000. It ruled that this level of risk was far too low to keep unprotected sex a public health crime.

The case began in Lausanne in 2007, when a court sentenced the HIV-positive man, originally from the Democratic Republic of the Congo, to a suspended 28-month sentence for having unprotected sex, without telling his woman partner his HIV status.

Swiss HIV Law

Under the public health parts of the Swiss criminal law, Article 231 allows prosecutions against HIV-positive individuals for having unprotected sex, with or without disclosure. The UK doesn’t have a public health criminal law about disease exposure. Prosecuting and criminalising public health was dropped in the UK because it goes against the principle of encouraging people to come for testing and treatment. Criminalising public health drives people with health needs underground and protecting public health becomes far more difficult.

People with HIV in Switzerland can also be prosecuted under Article 122, for an attempt to engender grievous bodily harm. This makes it an attempted grievous bodily harm to have unprotected sex, even if there is no HIV transmission. People with HIV in Switzerland are jailed simply for having unprotected sex. This can't happen under English law. Here HIV transmission has to take place before the charge of "grievous bodily harm" can be made. There is no English crime of attempted grievous bodily harm.

Deborah Glejser of Swiss community HIV organisation, Groupe SIDA Genève, explains that although this public health law could be used even more harshly, to prosecute unprotected sex even when HIV status has been disclosed, in practice, the Swiss only prosecute HIV exposure without disclosure. Suspended sentences are normal so this man’s imprisonment was unusual.

Trial judge refused to consider Swiss statement

A second complaint last year led to the man standing trial again in Geneva in November 2008. According to a report in The Geneva Tribune, an expert medical witness had testified that although treatment greatly reduces the risk of transmission, there remained a residual risk. Although the man's lawyer had put forward the statement by the Swiss Federal Commission for HIV/AIDS as evidence, and Geneva's deputy public prosecutor wanted to suspend the hearing to consult with the Swiss HIV Commission, the lower Geneva court refused to allow this. This made it his second conviction so he was sent to jail for 18 months, in December 2008.

This clearly annoyed the deputy Public Prosecutor who felt justice was not being done or being seen to be done. The court refused to consider the evidence even the prosecutor thought was relevant. We are left with the suspicion that a white Swiss native would have not been jailed for 18 months like this black African migrant. The British pattern of a disproportionate numbers of migrants being jailed for HIV crimes is found across much of the globe

It's Super-Public-Prosecutor to the rescue

Late in February the deputy public prosecutor came to the rescue and told the Geneva Court of Justice that he was convinced by the Swiss Federal Commission for HIV/AIDS that the risk of transmission for an HIV-positive individual on successful treatment was less than 1 in 100,000. Under the circumstances he wanted to appeal so as to withdraw the charge and for the court to cancel the conviction.

On Monday, the Geneva Court of Justice acquitted the man, who was freed  after almost three months in prison. Geneva’s deputy public prosecutor, Yves Bertossa, called for the appeal, told the newspaper Le Temps that although there is still some debate regarding the slight risks of transmission in people on successful treatment this should not be used unfairly: "One shouldn't convict people for hypothetical risks,” he said.

Swiss statement did what it set out to do

Professor Hirschel said that he was very pleased with the outcome. It was, he said, the main reason that he and his colleagues issued their January 2008 statement of advise for courts and prosecutors.

The Swiss panel has had enormous global attention and a great deal of criticism for openly talking about and applying the lessons of modern HIV treatment to the lives of people living with HIV. Swiss HIV clinicians wanted to put a stop to much of the jailing of people with HIV - simply for having unprotected sex without any HIV transmission.

Deborah Glejser of Groupe SIDA Genève added that Monday’s ruling means that, in Switzerland, HIV-positive people on treatment which is working properly should no longer be prosecuted for having unprotected sex. She hopes that this ruling will help people in other countries that prosecute HIV exposure – and she’s been contacted by many already.

Hopes for fall in global prosecutions

Last May, a five member US Court of Appeals for the Armed Forces panel rejected, but only by a narrow majority, an appeal by an HIV-positive soldier who had previously pleaded guilty to HIV exposure, following unprotected sex with two women without disclosing his HIV status. And last July, a Canadian court considered and rejected the Swiss statement in the case of a man charged with having unprotected sex with six women.

Following Monday's ruling, however, Geneva’s deputy public prosecutor, Yves Bertossa, believes it is only a matter of time before other jurisdictions realise that prosecutions for HIV exposure should not take place when the accused is on successful antiretroviral therapy. He told Radio Lac: “There are some medical advances which can change the law. I think that in other [parts of Switzerland] or in other countries, the same conclusions should apply to their laws."

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Undetectable But Infectious?

posted: 10/02/2009

One of the hottest topics over the last twelve months has been the infectiousness (or otherwise) of people taking HIV treatment who have an undetectable viral load in their blood.
 

The debate was kick-started a year ago by what’s come to be known as the “Swiss Statement”. This said that individuals taking HIV treatment who had an undetectable viral load and no sexually transmitted infections were essentially non-infectious to their partner in a monogamous heterosexual relationship.
 

The authors of the Swiss Statement noted that effective HIV treatment suppressed viral load to undetectable levels in both blood and semen.
However, two studies presented to the CROI Conference in Montreal, Canada, have confirmed that HIV can be undetectable in blood, but still detectable in semen in a minority of men, even without any STIs.
 

1 in 7 "undetectable" men have detectable and infectious semen

A Canadian study involving 25 men found that undetectable viral load in the blood, was found with detectable virus in about 1 in 7 semen samples. The virus in semen was potentially infectious.
 

Semen virus sometimes blips and becomes detectable

The study also showed that viral load in semen occasionally “blipped” to detectable levels.
About a third of men who’d been taking long-term HIV treatment that suppressed viral load to undetectable levels in the blood occasionally had detectable HIV in their semen.

A larger French study looked at paired blood and semen samples from 145 men taking HIV treatment. Viral load was undetectable in 85% of these paired samples. But in 3% of samples, HIV was undetectable in blood and detectable in semen – viral load in these samples ranged between 250 and 1200 copies/ml.
Most of these detectable samples were “blips”, and the French researchers found good levels of anti-HIV drugs in the patients’ semen.
 

There was discussion about the implications of these findings, in particular if the levels of HIV found in semen involved a significant risk of HIV transmission. There was only one case of HIV transmission in the French study, but this involved a patient who wasn’t taking his treatment properly.
 

Swiss should not claim undetectable people can never transmit

However, both sets of researchers concluded that an undetectable viral load in blood doesn’t always mean that viral load is undetectable in semen, and that successful HIV treatment doesn’t entirely eliminate the risk of HIV transmission. So the Swiss statement was a bit too dogmatic - transmission is possible but seems really unlikely.

You can sign up for NAM's CROI conference dailiy update here