HIV treatment and infectiousness
One of the hottest topics in HIV at the moment is the impact of HIV treatment on infectiousness.
Two new pieces of research have been published which will further inform debate on this very controversial area.
Infections have modest impact on cervical viral load
HIV treatment reduces viral load in blood and other body fluids, including genital secretions.
However, it’s known that viral load in genital fluids is increased if a person has a sexually transmitted infection.
But a small Kenyan study suggests that in many cases these increases are modest.
The study involved 147 women who were taking HIV treatment. A total of 30 women had a recent cervical infection such as gonorrhoea or chlamydia.
When they had these infections, the women had an average cervical viral load of 115 copies/ml – just above the limit of detection. The highest cervical viral load was 820 copies/ml.
But the study’s authors warn that even low viral loads could be infectious.
Real world impact of treatment on infectiousness?
The evidence about the impact of treatment on the risk of HIV transmission largely comes from big cohort studies.
People enrolled in trials should receive a lot of support and good medical care. Often this is at a higher level than is available from routine medical services.
“Real world” evidence from the US and Canada has suggested that treatment may be able to help prevent new infections.
Chinese researchers also looked at this question. Their research involved 1927 couples where one partner was HIV-positive and the other HIV-negative.
These couples were monitored for approximately three years.
The transmission rate in couples where the HIV-positive partner was taking treatment was 5%, compared to a transmission rate of 3% in the other couples. The researchers did not provide any information on the viral load of the individuals who transmitted HIV to their partners, or about measures to support adherence.
In an editorial that accompanied the study, a senior US HIV doctor said the results of this study should cause those who support the wider use of HIV treatment as a way of controlling the spread of the virus to “pause.”
Treatment, undetectable viral load and HIV transmission risk in gay couples
Most of the evidence on the impact of treatment on infectiousness comes from heterosexuals.
Using condoms all the time provided the most protection against HIV. The researchers calculated that there was a 1% risk of transmission in these circumstances.
Having unprotected sex within six months of the most recent undetectable viral load, but using condoms at all other times was associated with a 3% risk of transmission.
Never using condoms was associated with a 22% risk of transmission.
The researchers say the key message is that consistent condom use is the best way of protecting one's partner. They also say that the most crucial time to use condoms is when more than three months have gone by since the last undetectable viral load result.
HIV and heart disease
Low CD4 cell count increases risk of heart attack
There’s now a lot of evidence showing that people with HIV have an increased risk of cardiovascular diseases such as heart attack and stroke.
The reasons for this are debated. Traditional risk factors such as smoking are important, and some anti-HIV drugs can cause increases in blood fats that can increase the long-term risk of cardiovascular diseases.
But there’s evidence that infection with HIV may also be important.
Their study involved over 6000 patients who received HIV care between 1998 and 2008.
Approximately 4% of these individuals had a heart attack.
Even after the researchers took into account traditional risk factors, they found that having a CD4 cell count below 200 substantially increased the risk of heart attack.
The researchers also found some evidence that having a viral load above 100,000 copies/ml also increased the risk of heart attack.
Current UK HIV treatment guidelines recommend that patients should start taking HIV treatment when their CD4 cell count is around 350. Those with a high risk of cardiovascular disease are especially encouraged to start treatment at this time.
Abacavir and the risk of heart attack
At first sight, the statistics were alarming, showing that those taking the drug were 90% more likely to have a heart attack than people in the general population.
Therefore, treatment with abacavir is not recommended for those with a risk of cardiovascular disease.
A team of researchers have attempted to clarify the heart attack risk associated with abacavir treatment, taking into account individual risk factors.
They estimated that a 40-year-old man with no other risk factors for heart disease had a very low risk of a heart attack if they were taking the drug.
But the more traditional risk factors a patient had, the higher the risk of heart attack when taking the drug.
The researchers have developed an online tool for doctors and patients to calculate the impact of abacavir use according to individual risk factors.