Evidence from HIV sequencing for blood-borne transmission in Africa

The consensus view that heterosexual transmission dominates human immunodeficiency viruses (HIV) epidemics in sub-Saharan Africa survives side-by-side with surveys and studies reporting infections in children with HIV-negative mothers, in virgins, and in adolescents and adults who claim no possible sexual exposure to HIV.

In this scoping review, we aim to show what phylogenetic analyses of HIV sequences say about the possible contribution of blood-borne transmission to HIV epidemics.

The focus was on sub-Saharan Africa.

The authors conducted a search on PubMed and other platforms for studies reporting phylogenetic analyses of HIV in blood samples collected from at least 100 infected adults through community-based surveys in sub-Saharan Africa. They focussed on identifying information pertinent to assessing blood-borne transmission.

Sixteen reports met the search criteria and provided information to assess blood-borne transmission. In five studies, similar HIV sequences from (reported or assumed) household couples identified a likely heterosexual source for 0.3% - 7.5% of community adults with sequenced HIV. In 10 studies, a median of 43% of sequence pairs linked two people of the same sex. Two studies report clusters of recent infections too large to be easily explained by sexual transmission.

Evidence from sequencing agrees with much other evidence that blood-borne HIV transmission is not rare in sub-Saharan Africa. Evidence also allows that blood-borne transmission could be making a major contribution to Africa's HIV epidemics.

Evidence of harm is sufficient to stimulate discussions about what more could be done to address this continuing problem.