Ten: that's the age of the youngest person with HIV that Sesenieli Naitala has ever met.

When she first started Fiji's Survivor Advocacy Network in 2013, that young boy was yet to be born. Now he is one of thousands of Fijians to have contracted the bloodborne virus in recent years – many of them aged 19 or younger, and many of them through intravenous drug use.

More young people are using drugs, Ms Naitala, whose organisation provides support to sex workers and drug users in the Fijian capital Suva, tells the BBC. He (the boy) was one of those young people that were sharing needles on the street during Covid.

Over the past five years, Fiji – a tiny South Pacific nation with a population of less than a million – has become the locus of one of the world's fastest-growing HIV epidemics.

In 2014, the country had fewer than 500 people living with HIV. By 2024 that number had soared to approximately 5,900 – an elevenfold leap. That same year, Fiji recorded 1,583 new cases – a thirteenfold increase on its usual five-year average. Of those, 41 were aged 15 or younger, compared to just 11 in 2023.

Such figures prompted the country's minister for health and medical services to declare an HIV outbreak in January. Last week, assistant health minister Penioni Ravunawa warned Fiji may record more than 3,000 new HIV cases by the end of 2025.

This is a national crisis, he said. And it is not slowing down.

The BBC spoke to multiple experts, advocates, and frontline workers about the reasons for such a meteoric rise in case numbers. Several pointed out that as awareness around HIV spreads and stigma diminishes, more people have been coming forward and getting tested.

At the same time though, they also noted that countless more remain invisible to the official figures – and that the true scale of the issue is likely much bigger than even the record-breaking numbers suggest.

Underpinning Fiji's HIV epidemic is a spiraling trend of drug use, unsafe sex, needle sharing, and bluetoothing. Otherwise known as hotspotting, this latter term describes a practice where an intravenous drug user withdraws their blood after a hit and injects it into a second person – who may then do the same for a third, and so on.

Kalesi Volatabu, executive director for the NGO Drug Free Fiji, has seen it happen firsthand. Last May, she was on one of her regular early morning walks through the Fijian capital of Suva when she turned a corner and saw a group huddled together. I saw the needle with the blood – it was right there in front of me, she recalls.

This alarming practice is linked to not only the increasing number of drug users but also economic conditions and a lack of resources for harm reduction initiatives. As a result, health authorities express concern about an impending avalanche of cases driven by existing infections that may not yet be reported.

José Sousa-Santos, head of the Pacific Regional Security Hub at New Zealand's University of Canterbury, emphasizes the urgent need for improved health resources to address this spiraling crisis. Without it, both public health and social support systems in Fiji may be unable to cope with the devastating impacts of such a widespread epidemic.