HIV Weekly - 27th November 2013

A round-up of the latest HIV news, for people living with HIV in the UK and beyond.

Drug-resistant HIV

People with HIV who aren’t taking treatment are a major source of transmitted drug-resistant HIV, a new study shows. Researchers in Switzerland examined transmitted resistance in gay men and found that the majority of cases of transmitted resistance could be traced back to possible sources who weren’t taking HIV treatment.

HIV can become resistant to antiretroviral drugs. Resistance can develop if someone is taking HIV treatment that does not fully suppress the virus. The most important thing you can do to reduce your risk of developing drug resistance is to take your HIV treatment as prescribed, to give it the best chance of working.

A drug-resistant strain of the virus can also be passed on between people. The presence of transmitted resistance can limit treatment choices, even before someone has taken a single anti-HIV drug.

Often the source of transmitted resistance is unknown. But a technique called phylogenetic analysis can be used to see if infections are linked or clustered.

Swiss investigators looked at the genetic profiles of HIV in approximately 1700 gay men newly diagnosed with HIV between 1996 and 2009. A little over two-thirds (67%) belonged to a transmission cluster.

Overall, 8% of the men had acquired drug-resistant HIV. Over half – 58% – of people with transmitted resistance belonged to a transmission cluster where it was possible to identify at least one genetically linked infection.

The vast majority – 86% – of study participants with transmitted resistance had at least one possible source who had never taken HIV treatment.

Long transmission chains involving up to eleven people with genetically linked drug-resistant virus were identified by the researchers.

The researchers think their findings have important implications for HIV prevention and antiretroviral treatment strategies. They conclude their findings “indicate a high potential for HIV drug resistance to circulate among treatment-naive patients [people who have not taken HIV treatment]. This highlights the importance of limiting the acquisition of drug resistance before it becomes established in untreated patients, and of early test-and-treat strategies to prevent resistance transmission from untreated patients.”

For more information on taking HIV treatment and understanding HIV drug resistance, you may find our Adherence & resistance booklet helpful. It’s available in UK clinics and HIV organisations, and you can view it online at www.aidsmap.com/booklets

The UK HIV epidemic

Newly released UK figures show that 3250 gay men were diagnosed with HIV in 2012 – more than in any previous year.

Researchers think there are a number of possible explanations for this record number of diagnoses, including increased rates of testing, and ongoing risky sexual behaviour.

Just over a third (34%) of gay men were diagnosed late (defined as having a CD4 cell count below 350), down from 38% in 2010.

The continuing HIV epidemic among UK gay men is part of a much wider global trend, and a senior public health figure recently expressed concern about a “resurgence” of HIV among gay men around the world.

There was a fall in the number of new diagnoses involving heterosexual people. Around half of these new diagnoses involved people of black African ethnicity. Among heterosexual people who were born abroad, 48% of new diagnoses involved HIV infections probably acquired in the UK.

The newly released figures also showed that about a fifth of HIV infections in the UK are undiagnosed.

But 97% of people with diagnosed HIV are linked to specialist care, 95% remain in care and 89% of people with a CD4 cell count below 350 are taking HIV treatment. 

Sexual transmission of hepatitis C

Gay men need better information about sexual transmission of hepatitis C virus (HCV), according to research conducted in France.

Investigators interviewed 31 gay men with HIV about their experiences of living with hepatitis C co-infection.

Hepatitis C is a blood-borne virus. Sex that involves contact with blood can involve a risk of transmission. Fisting, unprotected anal sex, sharing sex toys and lubricant have all been identified as risk factors, as have injecting and snorting drugs.

While some of the respondents had been aware of the possibility of sexual transmission of hepatitis C before their own diagnosis (often because someone they knew had had it), clear information about transmission routes hadn’t been available.

Most participants only disclosed their hepatitis C status to a few individuals and others said it was difficult to discuss hepatitis.

The researcher found that there was a brief period after their hepatitis C diagnosis during which some men were open to reconsidering their sexual choices – healthcare providers should discuss prevention at this time.

We’ve recently published four illustrated leaflets giving basic information about hepatitis C, including one written for gay men, called How hepatitis C is passed on during sex.

Drug interactions

Ritonavir (Norvir) is the cause of the drug-drug interaction between the hepatitis C protease inhibitor telaprevir (Incivo or Incivek) and ritonavir-boosted atazanavir, new research shows.

Telaprevir and boceprevir (Victrelis) are HCV protease inhibitors. The standard of care for people with genotype-1 hepatitis C now includes treatment with one of these drugs in combination with pegylated interferon and ribavirin.

Telaprevir is processed by the body via the liver in the same way as some anti-HIV protease inhibitors. This means there’s a potential for drug-drug interactions.

Atazanavir, boosted with ritonavir, is the only HIV protease inhibitor currently recommended for use with telaprevir.

The latest research involved 14 people with HIV and hepatitis C, who were taking HIV and hepatitis C treatment. Blood levels of the drugs were measured while they were taking telaprevir and atazanir with ritonavir, and then without ritonavir. The study found that taking ritonavir reduced blood levels of both atazanavir and telaprevir, although the half-life of atazanavir was reduced when ritonavir was stopped.

This finding could be of clinical significance. For instance, outcomes among people taking telaprevir-based hepatitis C therapy have been associated with blood concentrations of telaprevir.