After being diagnosed, it was revealed that the woman had a high viral load and a low white blood cell count, indicating that she was in an advanced stage of the disease. After discussing past events, it was discovered that the woman shared manicure equipment, including cuticle scissors, with an HIV positive cousin when she was 12 years old. Although the relative, who was a manicurist, knew she was infected as she was diagnosed 17 years ago, she did not share her status with her cousin.
With no other leads, the researchers decided to pursue this possibility and sequenced the viral genomes of both women. This revealed that the viruses were highly similar, indicating that they shared a common origin. Furthermore, when they traced the viral sequences back in time, they found that the estimated common ancestor date corresponded with the same year that they shared the tools.