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A genetic analysis of a large UK database of people living with HIV shows that 18% of men with HIV who claim to be exclusively heterosexual belong in fact to groups of infections linked to infections in men.
This provides a minimum value for the proportion of men with HIV in the UK who are what the researchers call "found only among men who have sex with men (MSM)." It is a minimum value because other men who have contracted HIV through sex with other men may be immersed in other groups of different affective sexual expressions.
The data were presented by Ragonnet-Cronin and colleagues from Manon at the University of Edinburgh at the Conference on Retroviruses and Opportunistic Infections last week.
In a second analysis of the same data were found that MSM were more likely to be the linking partners between an MSM and a woman than the woman in being the link between a man and a bisexual declared than a heterosexual man .
Phylogenetic analysis analyzed the 50,025 genetic sequences of HIV subtypes A1, B and C from the UK's HIV Resistance to Medicines database, which contains sequences of 60% of all people with HIV in the UK (other 10.000 sequences belonging to other HIV subtypes were not included).
People were counted as belonging to a "grouping" if HIV RNA shares descend from a common ancestor to another person with HIV in the last five years, so for the purposes of the present analysis a "grouping" had to include at least , three people.
There were 223 totally "male" groups containing 1204 men (mean, 5.4 per cluster). The total number of self-reported heterosexual men who belonged in a cluster, male-only or mixed, was 1341.
However 249 of these heterosexual men supposedly effectively belonged to all male groups, which means that 18% of heterosexual men were in fact probably undisclosed MSM (ndHSH).
these ndHSH * Na (not disclosed) were considerably more likely to be of the black African ethnicity than any other ethnic group. They were also much less likely to have had a recent HIV infection: only 12,5% had a recent infection versus 75% of declared MSM. This could mean two things, both of which could be true: HSHS are much more likely to be late presenters and may also be older than declared MSM.
The ndHSH were much more susceptible to being peripheral rather than central groups. They were twice as likely as MSM to be declared on edge of groups, ie only linked to her through a partner. This implies that they have fewer partners and may be less likely to transmit HIV.
However they were also highly "amplexo collected in the field," meaning that they were much more likely to be linked to another ndHSH than if the mix was random, and if they were connected to more than one partner, it was much more likely that at least one of them was another ndHSH.
This analysis places only the measures supposedly of heterosexual men who only had male contacts. However there was concern since the beginning of the epidemic that bisexual men, who could have link between the gay population and the general population. This has proven not to be a major problem in countries with concentrated epidemics but may become a factor in countries with a more widespread epidemic.
The researchers thus did an analysis of the few groups of three or more people on the network where "bridges" between declared MSM and heterosexual men or women did not happen.
They counted two types of articulation. In one, the woman was a link between an openly bisexual MSM and a heterosexual man, meaning she seemed susceptible to having received her infection from one and passed her to the other. In the second, a man who said he was a link between heterosexuals from a declared MSM and a woman and probably caught from one HIV passed to another. Note that none of these settings can show who infected that: establishing the sense of infection in phylogenetic analysis is much more difficult than demonstrating the joint.
The configuration with which the man was in the middle and therefore most likely an undisclosed MSM was 2,24 times more likely than the one where the woman was in the middle. Of the 1341 heterosexual men in groups, 54 (4%) associated with MSM women In contrast only 32 out of 1711 Women in groups (1,9%) were the link between a person declared MSM and a heterosexual man.
This study provides a considerably higher estimate of the proportion of "heterosexual men with HIV in the UK who are indeed in a previous study in the year of 2014. MSM booked. This estimate of the proportion of 6%, although estimates that the proportion of ndHSH among black Africans was raised to 21%. However in this study only observed subtype B HIV infections, and would therefore be prone to lose more infections in non-whites, which are susceptible to have other subtypes.
It would be interesting to see an analysis of all subtypes, which would include subtype D (also common in parts of East Africa, and increasingly in the Middle East) and subtype AE (which is the predominant type in both heterosexuals and MSM in Southeast Asia ).
Translated by Claudio Souza's original One in five 'heterosexual' men in the UK Their caught HIV from another man No. Aidsmap
Reviewed by Penny Lane