Papers explored in earlier STI blogs have traced the distribution through the world of the different HIV subtypes (http://blogs.bmj.com/sti/2013/01/04/reading-the-history-of-the-progress-of-the-hiv-epidemic-through-the-evidence-of-hiv-subtype-distribution/?q=w_sti_blog_sidetab; http://sti.bmj.com/content/87/2/101.full?sid=2b7658a8-4f84-4d8a-b2bc-d5104c523180), and have used this information to track the origins of HIV-AIDS in central/western Africa probably at the beginning of the last century (http://journals.lww.com/aidsonline/pages/results.aspx?k=Tatem%20AND%20Salemi&Scope=AllIssues&txtKeywords=Tatem%20AND%20Salemi).  Now a research article published in Evolutionary Biology – Zhao, Roca et al. – has attempted to take back the story a further stage to the crossing of the species barrier and before (http://www.biomedcentral.com/1471-2148/12/237/abstract). Certainty in these matters is impossible; but Zhao, Roca et al. develop an interesting hypothesis based on genetic evidence – which is as follows.

Their point of departure is that transmission of the virus from the common chimpanzee to humans must have taken place at least four times, since the four principal HIV-1 strains present in humans (M, N, O, P) are closer in genetic sequence to strains of SIV, the chimpanzee form of HIV, than they are to the various HIV-1 sub-groups (A,B,C etc.) that derive from  strain M. On this basis, the authors hypothesize that, given the existence of SIV strains for 20,000 years, if the virus crossed the species barrier four times (between 1884 and 1924), in all probability it crossed it repeatedly over the centuries, but failed to generate persistent outbreaks in humans before the appearance of large cities.  If this hypothesis is correct, then genomic “signatures” in the chromosomes of the descendants of the affected populations ought to reflect the generation of selection pressure in these populations for resistance to SIV/HIV.

Among the diverse populations intensively genotyped as part of the human genome diversity panel are the Biaka Western Pygmies of the Central African Republic who have always resided within range of the SIV infected common chimpanzee.  The researchers seek genetic evidence for selection among the Biaka, by running pairwise genomic comparisons between the Biaka and four other central African peoples (including the Mbuti Eastern Pygmies, who are genetically close to the Biaka, but have always lived out of range of SIV infected chimpanzees).  They look for regions of the genome that: 1. signal strong selection pressure, and 2. have been associated with HIV-1 by various kinds of studies.

What they find is that of the ten possible pairwise comparisons between the five peoples, five comparisons detect regions with strong selection associated with HIV.  These involved CUL5, TRIM5, PARD3B and TSG101 which are detected as under strong selection eight times across the pairwise comparisons.  Seven out of the eight involve the Biaka.  The probability that randomly drawn genes would overlap seven or more signals of selection in a single population is reckoned by the authors at 0.05.  For the purposes of this analysis the researchers exclude from consideration host-genes associated with HIV that are below a genome-wise significance p<5×10⁸.  Where this restriction is lifted a total of eight genomic regions are specified as showing protective variants.

On the basis of this evidence the authors consider their hypothesis that SIV/HIV has shaped the genomes of some west central African populations as worthy of further investigation.

The impact of human mobility on the spread of HIV is often recognized in the medical literature (http://sti.bmj.com/content/78/suppl_1/i91.abstract?sid=2b7658a8-4f84-4d8a-b2bc-d5104c523180). Does it follow that the existence and development of transport infrastructure may have had its part in the history of the epidemic?  Can we go further, and read the whole history of an epidemic like HIV in terms of “spatial accessibility”?

Tatem & Salemi (AIDS journal) adopt a geographically-based approach, setting out to demonstrate that “the HIV/AIDS pandemic worldwide is a travel story whose episodes can be traced by molecular tools and epidemiology” (http://journals.lww.com/aidsonline/Fulltext/2012/11280/Spatial_accessibility_and_the_spread_of_HIV_1.10.aspx).  The evidence on the basis of which this story is reconstructed – the medium in which we find it written – consists in the data of HIV-1 subtypes and recombinants.  “The distribution of HIV-1 subtypes in a population”, state Mumtaz & Raddad in a study of the HIV pandemic in the Middle East, “tracks the spread and evolution of the epidemic” (http://sti.bmj.com/content/87/2/101.full?sid=2b7658a8-4f84-4d8a-b2bc-d5104c523180). Tatem & Salemi go a step further than this, interpreting the story of HIV-1 subtype distribution, as represented by 72 locations across sub-Saharan Africa (SSA), in reference to a sophisticated measure of spatial accessibility (“surface friction”) that takes into account surface cover, transport network, gradient etc., in order to reflect the ease of human travel across a landscape.

The results are presented graphically in the map on p.2353.  The 72 locations clearly fall, by and large, into four or so regions (broadly: west Africa, N. Ethiopia, east African, southern Africa), each of which is characterized by a relative homogeneity in the distribution of subtypes within it, and by a relative heterogeneity in relation to the distribution of subtypes characteristic of other regions.  These “regions” also show up on the map as continuous areas of high connectivity separated from each other by areas of low, or lower, accessibility.  Interestingly, there are four or five locations in central Africa (characterized by relatively low accessibility) which fail to show the pattern of strong dominance by one or two subtypes that we find in each of the regions of high accessibility.

There appears, therefore, to be a pattern of subtype dominance within continuous areas of high accessibility.  How does this accord with what we know about the epidemiology of HIV/AIDS?  The relative subtype homogeneity across accessible regions seems to reflect the swift diffusion of the infection across those regions.  Conversely, the greater diversity of subtypes attested in low-accessibility areas is evidence of slow spread.  The story, therefore, has two phases.  The first, during the earlier part of the twentieth century, takes place in central African subsequent to the infection crossing the species barrier.  During this period there is little diffusion, owing to poor connectivity, and the diversification of HIV-1 into its many subtypes.  The second phase, during the latter part of the century, sees the seeding of particular subtypes in different religions of high accessibility and their explosive growth thanks to good connectivity within those regions.  Subtypes A and D arrive in eastern Africa in the 1950s and 1960s respectively, whereas it is subtype C which starts the epidemic in southern Africa around 1970s, and travels to Ethiopia around 1982.

Apparently, recent analyses of the distribution of Malaria resistance markers show a similar spatial pattern to the one we see here.  The authors conclude that a comprehensive understanding of accessibility, travel and mobility in resource-poor settings could provide a valuable resource for the strategic planning of disease control.  Certainly, their study demonstrates the value of a multi-disciplinary approach to public health issues.

Epidemiological research has sometimes addressed the impact on men who have sex with men (MSM) sexual behaviour of being “non-gay identifying” (NGI) (Yun, Wang et al. (http://sti.bmj.com/content/87/7/563.full?sid=a367a77d-f830-46ee-b761-eec8d9e22da2 ); Mercer & Cassell (http://ijsa.rsmjournals.com/content/20/2/87.full) or of belonging to a culture in which openness about sexuality by MSM is sometimes difficult and personally costly (Lane, Kegeles et al. (http://sti.bmj.com/content/84/6/430.full?sid=ab090fad-0769-479b-a7d5-e6ba10da5609).

The position of MSM in the US military under the recently abolished “Don’t Ask, Don’t Tell” (DADT) policy was an extreme case – possibly a limit-case – of this situation:  up until September 2011, an admission of sexual orientation by MSM, or evidence such as hand-holding, could result in ejection from the military.

How does this kind of situation influence patterns of HIV transmission among MSM, and what is the impact on the sexual behaviour of those MSM who engage in relationships with men regardless?  Would we expect the repressive effects of DADT to result in a relatively lower proportion of total HIV infection due to MSM sexual contact than in the general population – or the reverse?

Results of a recent online survey of the sexual behaviour prior to forced HIV testing of  US Navy and Marine Corps personnel who sero-converted under DADT intriguingly lifts the lid on this formerly closed epidemiological world – and perhaps, to some degree, on other similarly closed worlds.  Of course, the survey itself has major limitations: most importantly its restriction to a minority (64 (524): 26%), and an apparently not very representative minority, who responded to the survey; also the often considerable lapse of time since the behaviours reported.  Despite all these limitations the forced imposition of an HIV test on the whole group allows the survey to capture HIV prevalence at a moment in time.

Among the men who became HIV-infected  84% had had sex with men in the 3-year period prior to diagnosis: 55% reporting sex with just men, and 30% reporting sex with both men and women.  DADT would not then appear to have had much impact on reducing the burden of MSM infection as a proportion of total burden.  This higher figure relative to earlier surveys of the US military (84% as opposed to 59% reporting sex with men) probably reflects the liberalizing effects of DADT repeal.  The frequency of inconsistent condom use with anal sex was 65%, and more than three quarters expressed surprise at their HIV diagnosis.

The story these figures tell mirrors other “repressive” settings such as those with which we began our blog.  On the whole, a culture of repression drives the unwelcome sexual behaviour underground rather than eliminating it, while, at the same time, discouraging responsible behaviour and the adoption of risk-reduction strategies.  As the authors note,  “Several opportunities for primary prevention messaging now possible after DADT repeal are evident”.

With the roll-out of the Bill and Melinda Gates initiated Avahan interventions in India over the last decade, a growing body of evidence has accumulated on the contribution of commercial sex-work to the spread of the HIV epidemic, and the effectiveness of behavioural interventions focussed on this sector.  With the international effort concentrating elsewhere primarily on the deployment of ART, the epidemiological and preventative emphasis of Avahan has broken new ground: attention has been increasingly focussed on influencing the behaviour of key populations (http://sti.bmj.com/content/86/Suppl_1/i6.full?sid=8303ee2c-d0ce-4be1-92a5-f867afdc04d5 ).  Commercial male and female sex workers (FSW/MSW) seem to be an important one of these in the Indian context, due to the importance of male sex activity outside marriage as a factor in Indian HIV epidemiology (http://sti.bmj.com/content/87/6/516.abstract?sid=8133c62b-75db-4498-950e-e277d5687aed).  One neglected aspect of this behaviour has apparently been the disclosure of HIV status.  This is a gap in the research that Saggurti, Samat et al. seek to fill a recent paper (https://springerlink3.metapress.com/content/h26722575803101p/resource-secured/?target=fulltext.html&sid=d0ncj2mkanq0gcji3muoiwrc&sh=www.springerlink.com).

Their headline finding is that 58% of the 211 women (FSM) surveyed by the study, and 41% of the 205 men (clients) had not disclosed their sero-status to any sexual partner.  This would seem to have implications that are more interesting for the relationships of FSM to their non-commercial partners than to their commercial ones.  After all, non-disclosure between FSM and clients is surely what we would expect.  However, non-disclosure in the context of non-commercial and married partners, where consistent condom use may not be the norm (http://sti.bmj.com/content/87/Suppl_1/A67.1.abstract?sid=a9751fe7-af53-4e56-ac3c-352cb5079122) indicates the potential vulnerability of “bridging populations”.  Here Saggurti et al. give further data on the 18 married women and 76 married men included in the study:  39% of the women and 1% of the men had not disclosed HIV status to their married partner; while 78% of the women and 36% of the men claimed not to know the sero-status of the partner.  These findings suggest a marked imbalance – though an imbalance that might reflect behavioural differences between sex-workers and sex-workers’ clients, rather than gender differences per se.

Literature on the epidemiology of HIV transmission stresses the importance of “bridging populations” – which in the case of FSM presumably includes the wives of male clients, on the one hand, and the non-commercial partners of the FSM themselves, on the other.  As regards the former group, a recent study of FSW in Karnataka (Shaw, Deering, Blanchard et al., 2011) indicates that clients of FSW with NCP are less likely (OR 1.8) than those without NCP to use a condom, and more likely (OR 1.5) to be infected with HSV-2.  (http://sti.bmj.com/content/87/Suppl_1/A67.1.abstract?sid=a9751fe7-af53-4e56-ac3c-352cb5079122). But with this group the findings of Saggurti et al. suggest high levels of disclosure.  The case is different with the NCP of FSW, who represent the other bridging group (though here the bridge could well be from NCP to FSW rather than from FSW to NCP).  One of the few studies of the latter group, also from Karnataka (Deering, Bhattacharjee, Alary et al., 2011) finds that levels of consistent condom use (CCU) of FSW with husbands and cohabiting partners is low (22.6% and 40.3% respectively) (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3287549/).  Thus, here, low disclosure would appear to go with low CCU.  An interesting recent study of FSW and their NCP in Vietnam that would seem to bear out this general picture, Hoffman & Niccolai 2011, examines the relationship between intra-couple “communication divergence” and low CCU, and discovers a relatively strong correlation of OR 0.54 (http://www.springerlink.com.libproxy.ucl.ac.uk/content/r562533h71367j06/fulltext.html).

At the 19^th International AIDS Conference meeting in Washington DC recently, researchers presented important data from the HIV Prevention Trials Network (HPTN) 061 study (due to publish November 2012) on incidence and social correlates of HIV in black men who have sex with men (MSM).  With a view to investigating the acceptability and feasibility of running a randomized control trial of an prevention package (maybe involving PrEP (pre-exposure prophylaxis)), this study recruited 1,553 black MSM across six US HIV “hotspots” who, over three visits arranged over the year of their participation, were questioned, tested and offered counselling and care (http://www.aidsmap.com/page/2448636/).

The headline datum of the report was the figure of 6% for yearly incidence of HIV in young (18-30) black MSM – which places this particular US population in the same league as the populations of the worst-affected sub-Saharan countries.

Analyses of data from US population-based behavioural surveys and surveillance registries have indicated enormously increased HIV risk among MSM, with particularly high incidence among non-Hispanic blacks in places like New York (http://sti.bmj.com/content/87/Suppl_1/A351.2.full.pdf+html?sid=2d473bd2-195f-4979-8c68-81f97d953cdf).  Such indications are confirmed by the findings of HPTN 061, which set itself the not inconsiderable challenge of recruiting and retaining large numbers of participants for a longitudinal study of this socially disadvantaged group.  Not the least significant finding of the study is the existence within this population of a readiness to engage with health care services in projects of this nature (http://www.hptn.org/web%20documents/HPTN061/061FactSheet12Sep11.pdf).

At 12.4% levels of undiagnosed HIV (at the outset of the study) in US black MSM are much higher than in non-black MSM.  This situation seems, incidentally, to be replicated in the UK (15.8% vv. <6%) (http://sti.bmj.com/content/81/4/345.full.pdf+html?sid=c5b94909-c971-4a86-b320-1610763b5be8). Interestingly, 45% of the HPTN 061 participants had female as well as male partners.

Particularly salient in the report was the association (with multi-variate analysis) of undiagnosed HIV with unemployment (OR 2.4) and low income (OR 3.6 for income <$10,000, and OR 3.3 for income >$10,000 but  <$50,000).  Indeed, the researchers’ focus on behaviour and biological factors was questioned by some audience members, on account of the evident structural and socio-economic factors behind the elevated black MSM risk.

A meta-analysis in The Lancet Infectious Diseases offers a global picture of the heightened risks of HIV borne by female sex workers in low- and middle-income countries.  The analysis includes 112  papers and national reports, extracted from 19,180 relevant studies, and covers 50 low- and middle-income nations.  A table gives, for each of the 50 countries, an estimate of the relative burden of HIV disease in the female population that is borne by sex workers, expressed as an odds ratio, and the percentage of HIV infections that occur among female sex workers.  In addition, pooled figures are given for regions, where sufficient data is available: i.e. for Asia, Latin America and sub-Saharan Africa (though not for Eastern Europe or the Middle East, for which sufficient data was lacking).

Globally, the odds ratio for a female sex worker being infected as against any female is 13.5, and the overall HIV prevalence for female sex workers is 11.8%. Discussion is devoted largely to the differences between regions (i.e. Asia etc.) and the possible impact of recent and ongoing programs.

Asia is distinguished by a relatively large pooled odds ratio: 29.2 as opposed to 12 and 12.4 for Latin America and sub-Saharan Africa respectively, indicating a remarkably heavy burden of female HIV borne by sex-workers Asia.  The cases of Latin America and sub-Saharan Africa differ from each other in respect to the general prevalence of HIV in the population, though female sex-workers appear to bear a similar proportion of it (OR 12 and OR 12.4 respectively).  Thus, the prevalence of 5.2% for sex workers in Latin American has to be set against relatively low background prevalence in the female population as a whole, while the figure of 36.9% for sub-Saharan Africa reflects vastly higher levels of general prevalence.

There is some rather piecemeal discussion of recent interventions affecting female sex-workers in these regions.  The authors point out the effects of such interventions could take time to show up in the data.  Nevertheless the overall impression is given of a problem that has in all the regions so far proved extremely refractory in the face of a number of serious and large-scale interventions.  For example, following the scale-up of the Avahan and Sonagachi HIV prevention programs across India, female sex workers still carry more than a 50-times increased odds of HIV infection.

Needless to say, the authors recommend a scale-up of access to quality HIV-prevention programming and services among female sex workers on account of their heightened burden of disease, and the likelihood of onward transmission through high numbers of sexual partners.

Stefan Baral, Deanna Kerrigan et al., “Burden of HIV among female sex workers in low-income and middle-income countries: a systematic review and meta-analysis”, The Lancet: Infectious Diseases, published online 15^th March, 2012

http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(12)70066-X/abstract

Papers on related issues published in STI journal:

Michele R. Decker, Stefan D. Baral, Chris Beyrer et al., “Injection drug use, sexual risk, violence and STI/HIV among Moscow female sex workers”, published Online First: 27^th January 2012

[Abstract][Full text][PDF]

C. T. Bautista, J. K. Carr et al., “Seroprevalence of and risk factors for HIV-1 infection among female commercial sexworkers in South America”, 2006:82:311-316

[Abstract][Full text]

N. Makyao, S. Kamazima et al., Oral Sessions epidemiology: oral session 8: STIs and HIV in female sex workers: 01-S08.01: High HIV prevalence within a generalised epidemic; condom use, violence, and sexually transmitted infections among female sex workers in Dar es Salaam, Tanzania, 2011:87:A40-A41 

[Abstract][PDF]

 Nurholis Majid, Robert Magnani et al., “Syphilis among female sex workers in Indonesia: need and opportunity for intervention”, published online first: 3^rd June 2012

[Abstract][Full text][PDF]

Can we put a figure on the infectivity of HIV infection per coital act, and on the relative importance of the various determinants of transmission?

Estimates are needed in order to plan effective interventions.  A recent paper, published in the Journal of Infectious Diseases (Hughes, Celum et al.), discussed by an editorial (Gray & Wawer) of the same issue, represents the latest attempt at estimating infectivity and its determinants for sub-Saharan Africa.  The study was conducted on the back of a large randomized trial of HSV-2 suppression for prevention of HIV transmission between sero-discordant couples, and involved 3,293 couples at 14 sites in S and E Africa over a period of 24 months.

First the figures.  Transmission per coital act was estimated at 0.0019 for male-to-female, and 0.001 for female-to-male.  The major driver of transmission was HIV load in the infected partner: each log₁₀ increment in viral load produced a 2.9 fold adjusted risk of transmission.  Condom use reduced risk by 82%.

On the whole, these findings provide reassuring corroboration of the findings of earlier, smaller studies.  The figure for overall infectivity is similar to that reported during the latent stage of HIV infection in low-income countries.  Such a figure does not explain the rapid spread of the infection in many sub-Saharan settings – because, as Gray and Wawer point out, a study of this kind, involving stable sero-discordant couples, is unable to factor in the vastly higher levels of infectivity associated with early and late stage disease.

The figure of 2.9 for the multiplication of risk with log₁₀ viral load increment is higher than prior estimates, and may reflect more precise estimates enabled in this study by quarterly viral load measurements (Lingappa, Hughes, Wang et al.).

Numerous earlier attempts to establish HIV infectivity and its determinants are surveyed in a recent meta-analysis (Boily, Baggaley and Wang et al.).  Two things distinguish the present paper.  The first is sheer scale:  at 3,293 couples, the number of recruits exceeds considerably that of the next largest study (Fideli, Aldrovandi et al.), and far exceeds participation in previous studies (generally placed at  <200 participant couples).  The size of a study like this is an important factor because it enhances its ability to reliably estimate co-factors of transmission.  The second distinguishing feature is the seriousness of the effort to estimate the number of sexual events:  participant couples were interviewed about their sexual activity every month – a frequency that greatly exceeds the frequency of interviews in comparable studies.  These factors, along with frequency of quarterly viral load measurements, seem to mark a considerable gain in reliability, as against earlier attempts to place a figure on latent HIV infectivity.

James P. Hughes, Connie Celum et al., “Determinants of Per-Coital-Act HIV-1 Infectivity Among African HIV-1- Serodiscordant Couples”, Journal of Infectious Diseases 205:3, January 2012

http://jid.oxfordjournals.org/content/205/3/358.full

Ronald H. Gray and Maria J. Wawer, “Probability of Heterosexual HIV-1 Transmission per Coital Act in Sub-Saharan Africa” (Editorial), Journal of infectious Diseases 205:3, January 2012

http://jid.oxfordjournals.org/content/205/3/351.full

J. R. Lingappa, J.P. Hughes, R.S. Wang et al., “Estimating the impact of plasma HIV-1 RNA reductions on herosexual HIV-1 transmission risk”, PLoS One 2010,10.1371/journal.pone.0012598

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0012598

M. C. Boily, R.F. Baggaley, L. Wang et al. “Heterosexual risk of HIV-1 infection per sexual act: systematic review and meta-analysis of observational studies, Lancet Infectious Diseases 2009; vol. 9, no.2, Feb. 2009

http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(09)70021-0/fulltext

U. S. Fideli, S. A. Allen, R. Musonda et al., “Virologic and immunologic determinants of heterosexual transmission of human immunodeficiency virus type 1 in Africa”, AIDS Res Hum Retroviruses 2001; 17 (10): 901-10

http://www.ncbi.nlm.nih.gov/pubmed/11461676?dopt=Abstract

A large, recently published French study, based in metropolitan Paris, places a question mark over the value of non-targeted HIV screening as a strategy to lower the number of undiagnosed infections and improve early detection.

Late diagnosis of HIV remains a common problem both in France – where, despite accessible testing, one-third of diagnoses are in conjunction with CD4 counts less than 200/μL – and in other countries.  National health authorities have therefore promoted untargeted testing in the US, the UK and France.    However, the strategy remains controversial.  The authors of this study claim that it is the first large-scale study to have assessed its effectiveness.

The testing was conducted in 29 Paris Emergency Departments (ED) – an ideal setting for assessing the impact of untargeted testing, given that 25% of French population visit an ED at least once a year, including low-income, uninsured and other subgroups that might not be reached in other health care settings.  Of the 20,962 eligible patients who visited the EDs during the periods when screening was operative (i.e. during the 6-week period randomly assigned to each participant ED), a total of 12,754, or 63% of those eligible, consented to the test.

The number of HIV cases newly diagnosed (18 or 0.14%) as a result of the study, though small, fell within the authors’ expectations.  The significant finding relates to the characteristics of those newly diagnosed.  With one exception, they all belonged to high risk groups – sub-Saharan African or men having sex with men (MSM).  8 were being seen for HIV related symptoms, 7 of them with advanced-stage disease.  Of the 18 newly diagnosed, 6 did not return for a follow-up visit despite repeated calls, 4 were hospitalized immediately, 8 returned for the follow-up.  Among the 12 patients successfully linked to care, only 4 had CD4 counts greater than 350μ/L.

Certainly, this intervention does not appear to have reached infected persons not belonging to high-risk groups.  The authors point out that an ED-based screening strategy limited to men aged 18-45 and African-born persons would have identified all new HIV infections for 50% fewer HIV tests!   Questionnaires administered to consenting patients demonstrate characteristics that seem broadly representative of the Paris population, and findings of a complementary study of covariates of HIV refusal in 7 EDs suggest that refusal-associated factors did not unduly bias the results of the study.  The authors conclude that their observations do not support the implementation of non-targeted screening in the ED setting.  Given this study group appears highly representative of the general population, the authors are also very sceptical of the likely value of untargeted screening in other healthcare settings – at least in France.

The applicability of these findings to other countries cannot be assumed.  But the study certainly highlights the need for additional country-specific studies of the effectiveness of the strategy of untargeted HIV testing.

Kayigan Wilson d’Almeida, Anne-Claude Crémieux et al., “Modest Public Health Impact of Nontargeted Human Immunodeficiency Virus Screening in 29 Emergency Departments”, Archives of Internal Medicine, published online 24^th October 2011

http://archinte.ama-assn.org/cgi/content/full/archinternmed.2011.535

For national strategies supportive of untargeted HIV testing, see the following:

In the US:  http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5514a1.htm;  in the UK http://www.hpa.org.uk/Publications/InfectiousDiseases/HIVAndSTIs/1011TimetotestHIVtesting/; in France http://www.sante.gouv.fr/plan-national-de-lutte-contre-le-vih-sida-et-les-ist-2010-2014.html.

What evidence is there of HIV epidemiology among MSM populations in the Muslim countries of the Middle East and North Africa (MENA)?  More than one might suppose, according to the authors of a recent systematic review, which draws on a comprehensive re-examination of all literature containing data points relating to HIV, as well as of specific data on MSM, in order to offer the fullest possible picture of a population that has, for reasons of stigma, remained largely hidden.  The recent scientific literature, they contend, contains some “well-designed” studies.

At roughly 2-3%, levels of MSM engaging in anal sex in MENA is consistent with reported global levels, though a fluidity of gender distinctions seems to be a characteristic of the region, with a large fraction of MSM not identifying as sharing any sexual orientation (i.e. “gay”, or “bisexual”).  Yet, up to 2003 or so, incidence of HIV was low.  Even today HIV prevalence among MSM in MENA is lower than in other global settings where MSM HIV transmission plays a key role in epidemiology.  Now, however, evidence points to a disquieting emergence of HIV epidemics in the region.  This evidence includes: 1. considerable MSM HIV prevalence documented in recent well-designed studies after limited or no earlier prevalence (e.g. rates of 14.8% and 9.3% in Iran and Sudan respectively); 2. increasing prevalence suggested by some recent and well designed studies (e.g. three rounds of surveillance surveys in Pakistan, indicating rates among hijra (transgender) sex workers of 0.8%, 1.8% and 6.4% in 2005, 2006, and 2008 respectively); 3. rising contribution of MSM transmission in case notification reports (e.g. 19.7% in Egypt, as in the most recent quarterly report, as opposed to 13.2% cumulatively prior to that report); 4. phylogenetic evidence in certain settings (e.g. Iran and Pakistan) linking MSM transmission to recent IDU epidemics.

In addition, much of this systematic review is taken up with characterizing aspects of MSM sexual practice and behaviour in MENA that could be seen as rendering MSM populations in this area particularly vulnerable as and when HIV epidemics emerge – such as the prevalence of male sex work in MENA; the engagement of MSM in heterosexual sex with non-commercial female partners; the overlapping of steady, casual and commercial relationships;  the overlap of MSM risk behaviours with IDU risk behaviour; low condom use and inadequate HIV knowledge.  Given the likelihood that HIV epidemics may still be at a relatively early stage, this paper offers a disquieting picture of immanent but probably still unrealized possibilities for further HIV expansion in MENA, as and when the disease reaches its epidemic potential.  The authors therefore urge prevention of MSM HIV as a “top priority” for HIV/AIDS strategies.  Given a moral, social and legal climate in MENA countries that seems unconducive to outreach for these vulnerable populations, the authors point to the past fruitfulness of programmes involving partnership of MENA governments with NGOs as a possible solution.

Ghina Mumtaz, Laith J. Abu-Raddad et al., “Are HIV Epidemics among Men Who Have Sex with Men Emerging in the Middle East and North Africa?: A Systematic Review and Data Synthesis”, Public Library of Science (PLoS) – Medicine, 2^nd August 2009Top of Form

Bottom of Form

http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000444

Estimations of HIV incidence in the US from 2006 to 2009, based on data from 16 states extrapolated to the country as a whole, show stability over the period in respect to rates overall yearly incident cases (2006: 48,000; 2009: 48,100) and stability in respect to its ethnic distribution (incidence for Blacks and Hispanics respectively 7.4 and 2.8 times incidence for Whites in 2006, and 7.7 and 2.9 times in 2009).  However, this stability in overall incidence conceals a significant shift in age distribution over the four years 2006-2009 – notably a 21% increase for the 13-29 age group, with a concomitant fall in other groups.  The authors show this increase in the youngest age group to be driven by a 48% increase of incidence for young Black MSM, with no other ethnic sub-groups of the 13-29 age group showing a significant increase.

All this would suggest that, in US as elsewhere, the HIV problem is increasingly located in specific populations.  Prevention and treatment will need to attend to the needs of these populations – as indicated in the UNAIDS strategy and 2011 report.

Estimating yearly HIV incidence is not straightforward due to the long latency between infection and symptom development.  These estimates, originating from the HIV Incidence Surveillance Group, set up by the US Centers for Disease Control and Prevention (CDC), rely on systems funded in selected localities by the CDC to submit remnant HIV-positive blood specimens to serological testing and collect supplementary data on HIV testing and antiretroviral use required for the estimation.  They also rely – given the less than universal coverage of these systems, and the logistical challenges of securing blood specimens even in selected areas – on development of extrapolation methods.  The research paper, containing the estimates, provides a full account of the extrapolation method employed.

Since 2008 HIV incidence surveillance areas have included 25 health departments, including 18 state and 7 city/county health departments.  Only localities meeting certain criteria (including 15% completion of the serological test) were included in the analysis – amounting in all to 16 states and 2 cities.  It would be interesting to learn whether and how far the US experience of developing systems of HIV incidence surveillance replicates that of other countries.

Joseph Prejean, H. Irene Hall et al., for the HIV Incidence Surveillance Group, “Estimated HIV Incidence in the United States, 2006–2009”, Public Library of Science (PLoS) – one, 3^rd August 2011

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017502