The Kerala Police will examine the blood of at least 12 donors in order to find out how a nine-year-old patient contracted HIV during treatment at a cancer hospital in Thiruvananthapuram, The Hindu reported on Monday.

The state had on Friday formed a team of medical experts to investigate the case after the girl tested positive for HIV reportedly after a blood transfusion. However, the police said it is also possible that the girl contracted HIV at other clinics before she was admitted to the Regional Cancer Centre.

The child’s guardians had produced 12 people to donate blood to her during her chemotherapy. Efforts are under way to trace the donors and test them for HIV at a unit of the Kerala AIDS Control Society, investigators said.

The girl had gone to the Regional Cancer Centre about six months ago for treatment for leukaemia. Recently, after noticing swelling in her eyes, doctors at the institute had carried out many tests, including a blood test, which showed that she was HIV-positive. She had received at least 49 units of blood at the cancer centre.

She had reportedly tested negative for HIV when she was first treated.