New York, Jul 24 (IANS): People living with HIV who maintain low -- but still detectable -- levels of the virus and adhere to their antiretroviral regimen have almost zero risk of transmitting it to their sexual partners, according to a systematic review published in The Lancet.

Findings indicate the risk of sexual transmission of HIV is almost zero at viral loads of less than 1,000 copies of the virus per millilitre of blood -- also commonly referred to as having a suppressed viral load.

“These findings are important as they indicate that it is extremely rare for people who maintain low levels of HIV to transmit it to their sexual partners. Crucially, this conclusion can promote the expansion of alternative viral load testing modalities that are more feasible in resource-limited settings,” said lead author Laura Broyles, from the Global Health Impact Group in Atlanta, US.

“Improving access to routine viral load testing could ultimately help people with HIV live healthier lives and reduce transmission of the virus,” she added.

Taking daily medicine to treat HIV -- antiretroviral therapy, or ART -- lowers the amount of the virus in the body which preserves immune function and reduces morbidity and mortality associated with the virus and helps reduce HIV progression.

Without ART, people living with HIV can have a viral load of 30,000 to more than 500,000 copies/mL, depending on the stage of infection.

Researchers conducted a systematic review of eight studies, providing data on 7,762 serodiscordant couples -- in which one partner was living with HIV -- across 25 countries.

Of the 323 sexual transmissions of HIV detected across all eight studies, only two involved a partner with a viral load of less than 1000 copies/mL.

In both cases, the viral load test was performed at least 50 days before transmission, suggesting individuals’ viral load may have risen in the period following the test.

In studies that provided the full range of viral loads in partners with HIV, at least 80 per cent of transmissions involved viral loads greater than 10,000 copies/mL.

“The ultimate goal of antiretroviral therapy for people living with HIV is to maintain undetectable viral loads, which will improve their own health and prevent transmission to their sexual partners and children,” said co-author Lara Vojnov, from the World Health Organization.

“But these new findings are also significant as they indicate that the risk of sexual transmission of HIV at low viral loads is almost zero. This provides a powerful opportunity to help destigmatise HIV, promote the benefits of adhering to antiretroviral therapy, and support people living with HIV,” she added.

The authors also acknowledge some limitations to their study such as some of the data analysed were imprecise.