Diagnostic tools for HIV
It can take anywhere from weeks to months to diagnose an infant infected with HIV. Amazingly, two new diagnostic tools for HIV have shortened that to an hour.

Many diagnostic tools for HIV are serological, meaning they test for HIV antibodies in blood or other bodily fluids. In infants, though, maternal HIV antibodies are passed to the baby passively during pregnancy and continue to do so as the mother breastfeeds.

When infected babies produce antibodies of their own, the test has difficulty differentiating between the mother’s and the baby’s antibodies. It also takes some time for HIV antibodies to develop with which the serological assay can react. The test won’t be positive until there are antibodies to react with, which means the baby also has to wait longer to be diagnosed with HIV.

In 2007, the World Health Organization noted that there was a higher risk of death among HIV-infected children under two years old. It recommended that national programs establish the capacity to provided early virological training.

Virological tests look for evidence of the virus in the blood rather than the virus’s antibodies. Usually, these tests require laboratories with substantial amounts of equipment and infrastructure, but now due to two recent developments, these tests need substantially less time and supplies.

Alere q HIV-1/2 Detect and Xpert HIV-1 Qual Assay take as little as an hour to deliver a diagnosis. In 2015, WHO estimates that more than 1.2 million infants were born HIV positive globally, but just over half had access to an infant diagnostic test. WHO also reports that only half of the children infected with HIV receive the care they need.

Both tests use a disposable cartridge preloaded with the necessary materials to identify HIV in a blood sample. The WHO Pre-Qualification Programme, which works to assure quality for international procurement agencies distributed in low-income countries, prequalified both tests. This is meant to provide U.N. agencies and countries with quality assurance and give these agencies and countries confidence to buy and use the products.

The Xpert test uses the same technology as TB diagnoses, making it cost-effective and usable for multiple types of diagnoses. It requires very little training to use it and can test whole blood or dried blood spots. The test has a 90-minute run time, but it can also run multiple tests at a time. Its one drawback is that it requires a continuous power supply to work.

Alere runs on an eight-hour battery, making it more sustainable for work in remote rural areas. Like Xpert, it is a point-of-care diagnostic tool for HIV, so laboratories in urban areas are no longer necessary. Alere, however, only has a 52-minute run time.

Pre-qualification was an 18-month process. Groups involved included WHO, South Africa’s National Health Laboratory Service and the U.S. Centers for Disease Control and Prevention. Mercedes Perez Gonzalez, a technical officer in the Department of Essential Medicines and Health Products that coordinated the performance evaluations, reported in a press release that the team conducting the performance evaluations also needed 150 HIV positive “infant specimens.”

Now that Alere and Xpert have prequalified, they’re being used and studied in countries with high levels of HIV to know their maximum utilization. New diagnostic tools for HIV like Alere and Xpert are changing the world for the better, one scan at a time.

Anastazia Vanisko

Photo: Pixabay