A number of criminal cases in the UK in which somebody has accused a sexual partner of infecting him/her with HIV has resulted in numerous convictions. However, according to a report in the British Medical Journal (BMJ) virological evidence cannot prove HIV transmission in such cases.

Viral phylogenetics is a method of assessing the relations between viruses from different individuals. We can make an estimate about whether a virus from two different people probably had a recent common origin. However, this technique has its limits, write Professor Deenan Pillay and colleagues.

Health professionals and community groups are alarmed that such (criminal) cases may have a negative effect on disclosure of HIV infection and voluntary HIV testing. There have been cases where virological evidence has been presented as if it were as reliable as DNA fingerprinting.

The analogy is very misleading, say the writers. Virological evidence must be used with caution when trying to prove that transmission happened between two specific people, they write. The evidence cannot stand alone; it must be backed up with clinical and epidemiological evidence.

By establishing a link between two people points the finger at those two people, and nothing else. It does not say who infected whom – which person passed it on. Another complication is finding every sexual partner one person had and testing them. Co-infection with genetically diverse strains further complicates the reliability of ‘evidence’, they say – plus the similarities in two virus genomes that evolved in parallel.

The writers urge people to be cautious when interpreting such data – it is in no way as indisputable as DNA evidence is in a criminal court.

Phylogenetic evidence cannot prove transmission – however, along with clinical and epidemiological evidence regarding an infection’s duration, sexual history and other related factors can provide support for linkage between cases.

On the other hand, phylogenetics can be extremely helpful in some investigations, write the authors. As was the case recently regarding the timing of HIV-1 infections among Libyan children in a Libyan hospital – it showed that the children became infected before the accused medical professionals ever set foot in the country. (Five Bulgarian Nurses and one Palestinian doctor were accused of deliberately infecting 400 children in Libya with HIV. Evidence pointed to poor hygiene as the reason for their infections. The accused spent several years in prison, and at one point were nearly executed. They are now free)

They conclude that sufficient checks and balances must be put in place to allow full use of HIV surveillance data for the benefit of public health. Rather than having to worry that the underlying purpose might be to aid criminal proceedings.

Editorial: HIV phylogenetics
BMJ Volume 335 pp 460-61
Deenan Pillay, Andrew Rambaut, Anna Maria Geretti, Andrew J Leigh Brown
Click here to see first 150 words of the full text online

Written by: Christian Nordqvist