Aniva confessed to having unprotected sex with 104 women and girls – with some being as young as just 12.
And he told the BBChe kept quiet about his HIV-positive status after being hired by the families of the children to perform the sexual initiation.
So-called “sexual cleansing” is common practice in southern Malawi, and women are required to participate at various points in their life – including if their husband dies or if they have an abortion.
Young girls are sent to “initiation camps” by their families before puberty, where they are taught how to have sex.
They are forced into the act over three days after their first period “to avoid infection with their parents or the rest of the community”.
“Hyenas” are trusted to be disease-free due to their “good morals” – and condoms are prohibited in Malawi tradition.
But in spite of local traditions, President Peter Mutharika intervened in the case, ordering cops to investigate and charge Aniva over his apparent confessions on camera.
Presidential spokesman Mgeme Kalilani said: “While we must promote positive cultural values and positive socialisation of our children, the president says harmful cultural and traditional practices cannot be accepted in this country.”
The president slammed the tradition, saying: “These horrific practices, although done by a few, also tarnish the image of the whole nation of Malawi internationally and bring shame to us all.”
However, despite the presidential intervention, no girls came forward to testify against the “hyena”.
So Aniva was instead charged with engaging in a “harmful cultural practice” under Malawi’s Gender Equality Act, in relation to accusations that he had sex with newly bereaved widows.
Two women came forward to testify against him in this regard – although one said she escaped before he was able to abuse her, while the other claimed her ordeal happened before the practice was outlawed.
The final verdict in the trial is expected to be delivered some time this week.
If convicted, Aniva faces a possible five-year jail term.
But the case has caused outrage in Malawi, with many calling for Aniva to face a harsher sentence.
Speaking outside a hospital that treats HIV sufferers in the city of Blantyre, Pastor Paul Mzimu told the BBC: “How can someone with this status do what he did?
“I think this man is the devil – greedy and selfish. If I could judge him, I would give him a murder sentence and life imprisonment.
And young mum Memory Lakson said: “He was HIV-positive and he has now given HIV to innocent women. He should die in jail.”