Influencia social y uso del preservativo en la prevención de la transmisión heterosexual del VIH = Social influence and condom use for VIH heterosexual transmission prevention

Se revisan diferentes formas en que la influencia social puede incidir sobre los comportamientosheterosexuales de prevención de la transmisión del VIH de los jóvenes y se presentanlos resultados de algunos trabajos de las autoras, así como de otros investigadores, en que seanalizan dichas relaciones. Se concluye resaltando: 1) la utilidad clínica de la evaluación de lasexpectativas de autoeficacia para poder intervenir específicamente en aquellas áreas en que losjóvenes se perciban con menores capacidades para ser preventivos, 2) la relación observadaentre el uso de preservativo autoinformado y la creencia en su aceptación por parte de los referentessociales más cercanos y 3) la conveniencia de que los jóvenes posean suficientes habilidadesde comunicación que les permitan negociar con éxito el uso del preservativo y les ayudena compensar posibles influencias sociales en contra de su empleo

Influencia social y uso del preservativo en la prevención de la transmisión heterosexual del VIH = Social influence and condom use for VIH heterosexual transmission prevention

Se revisan diferentes formas en que la influencia social puede incidir sobre los comportamientos heterosexuales de prevención de la transmisión del VIH de los jóvenes y se presentan los resultados de algunos trabajos de las autoras, así como de otros investigadores, en que se analizan dichas relaciones. Se concluye resaltando: 1) la utilidad clínica de la evaluación de las expectativas de autoeficacia para poder intervenir específicamente en aquellas áreas en que los jóvenes se perciban con menores capacidades para ser preventivos, 2) la relación observada entre el uso de preservativo autoinformado y la creencia en su aceptación por parte de los referentes sociales más cercanos y 3) la conveniencia de que los jóvenes posean suficientes habilidades de comunicación que les permitan negociar con éxito el uso del preservativo y les ayuden a compensar posibles influencias sociales en contra de su empleo

Genotypic Resistance Tests Sequences Reveal the Role of Marginalized Populations in HIV-1 Transmission in Switzerland.

Targeting hard-to-reach/marginalized populations is essential for preventing HIV-transmission. A unique opportunity to identify such populations in Switzerland is provided by a database of all genotypic-resistance-tests from Switzerland, including both sequences from the Swiss HIV Cohort Study (SHCS) and non-cohort sequences. A phylogenetic tree was built using 11,127 SHCS and 2,875 Swiss non-SHCS sequences. Demographics were imputed for non-SHCS patients using a phylogenetic proximity approach. Factors associated with non-cohort outbreaks were determined using logistic regression. Non-B subtype (univariable odds-ratio (OR): 1.9; 95% confidence interval (CI): 1.8-2.1), female gender (OR: 1.6; 95% CI: 1.4-1.7), black ethnicity (OR: 1.9; 95% CI: 1.7-2.1) and heterosexual transmission group (OR:1.8; 95% CI: 1.6-2.0), were all associated with underrepresentation in the SHCS. We found 344 purely non-SHCS transmission clusters, however, these outbreaks were small (median 2, maximum 7 patients) with a strong overlap with the SHCS'. 65% of non-SHCS sequences were part of clusters composed of >= 50% SHCS sequences. Our data suggests that marginalized-populations are underrepresented in the SHCS. However, the limited size of outbreaks among non-SHCS patients in-care implies that no major HIV outbreak in Switzerland was missed by the SHCS surveillance. This study demonstrates the potential of sequence data to assess and extend the scope of infectious-disease surveillance.

AIDS along Brazil`s borders, 1990-2003

Objective. To study the AIDS epidemic in Brazil`s border areas, from the spatial and temporal perspective. Methods. This was an ecological study in which the cases of AIDS reported to the Ministry of Health of Brazil from 1990-2003 were grouped according to ""hunger areas"" as defined by Josue de Castro in the 1940s and according to 19 cultural subregions. Spatial assessment was based on incidence rates for border municipalities; temporal assessment considered the absolute number of cases occurring quarterly from 1990-2003 in each of the hunger areas studied (Extreme South, Midwest, and Amazon). Results. During the study period, 7 973 cases of AIDS were reported from the Brazilian border areas: 648 in the Amazon area, 1 579 in the Midwest, and 5 746 in the Extreme South (populations of 668 098, 895 489, and 2 769 361, respectively). The subregions with the highest AIDS incidence rates in each of the three border areas were those near triple-borders, between more than two Latin American countries. Sexual transmission was predominant, with heterosexual transmission being the most frequent, followed by transmission by male homosexuality. These two categories accounted for 87.2% of the cases reported. The estimates of the trend parameter in the temporal analysis were 0.53 (P < 0.0001), 0.83 (P < 0.0001), and 3.47 (P < 0.0001), respectively, for the Amazon, Midwest, and Extreme South areas. Conclusion. The improvement of health care services along Brazil`s borders may be a strategy for territorial integration and for dealing with the AIDS epidemic, as long as social, economic, and cultural differences are taken into account.

AIDS in Latin America: assessing the current status of the epidemic and the ongoing response

Background This article provides a summary of the current status of the HIV/AIDS epidemic in Latin America, as well as an outline of the diverse responses to it. Methods A search of international databases (Pubmed and ISI-Web of Science), regional databases (Scielo and Lilacs), regional and national documents and UNAIDS reports. Data are presented according to subregion. Results In Mexico HIV remains concentrated among urban men who have sex with men (MSM), and has been growing among injecting drug users (IDU) and in rural areas in relation to migration. An increasing proportion of women among those affected is observed in all countries in Central America, the most affected region, as well as increasing the impact on other vulnerable groups, such as indigenous populations. The Andean Countries have urban epidemics concentrated among MSM. In Peru, non-traditional vulnerable populations were identified. In the Southern Cone heterosexual transmission became more relevant, probably in connection with IDU epidemics and is increasingly affecting lower income groups. Incidence rates have been declining since 2002 in Brazil, the first country to guarantee free, universal access to antiretrovirals, where one-third of drug-nave patients are still initiating treatment at an advanced stage. Generally, access to treatment has improved as a result of support from the Global Fund and other initiatives, but there are concerns regarding coverage, equity and sustainability. Conclusions HIV is still concentrated among MSM in Latin America. Non-traditional vulnerable groups such as migrants and lower income populations, usually considered part of the general population, deserve attention. Programmes confronting sexual exclusion are still needed. Access to treatment has improved over time, but inequalities persist.

Nonhuman primate models and the failure of the Merck HIV-1 vaccine in humans

The adenovirus type 5 (Ad5)-based vaccine developed by Merck failed to either prevent HIV-1 infection or suppress viral load in subsequently infected subjects in the STEP human Phase 2b efficacy trial. Analogous vaccines had previously also failed in the simian immunodeficiency virus (SIV) challenge-rhesus macaque model. In contrast, vaccine protection studies that used challenge with a chimeric simian-human immunodeficiency virus (SHIV89.6P) in macaques did not predict the human trial results. Ad5 vector -based vaccines did not protect macaques from infection after SHIV89.6P challenge but did cause a substantial reduction in viral load and a preservation of CD4(+) T cell counts after infection, findings that were not reproduced in the human trials. Although the SIV challenge model is incompletely validated, we propose that its expanded use can help facilitate the prioritization of candidate HIV-1 vaccines, ensuring that resources are focused on the most promising candidates. Vaccine designers must now develop T cell vaccine strategies that reduce viral load after heterologous challenge.

Étude des facteurs influençant la susceptibilité à l'infection au VIH chez des femmes africaines

Chez la femme, la majorité des cas d’infection au VIH sont acquis lors de relations hétérosexuelles. Cependant, très peu d’informations sont disponibles concernant l’immunité locale naturelle du tractus génital féminin, les facteurs influençant la susceptibilité à l’infection au VIH dans ce compartiment, ainsi que la réponse immunitaire de la muqueuse enclenchée après l’infection. Le but de notre projet est donc d’étudier certains facteurs pouvant être impliqués dans la susceptibilité à l’infection au VIH, afin de mieux comprendre l’immunité du tractus génital féminin. Nous avons, dans un premier temps, analysé le rôle du polymorphisme des gènes HLA-G et HLA-E sur la susceptibilité au VIH dans une population de femmes zimbabwéennes. La présence de l’allèle HLA-G*0105N, en combinaison avec le génotype HLA-EG/HLA-EG, était associée avec une diminution du risque d’infection. Puis, dans une étude cas-contrôle de travailleuses du sexe (TS) du Bénin, nous avons mesuré l’expression de HLA-G soluble au niveau du plasma. Nous avons observé une différence significative dans l’expression de HLA-G soluble, celle-ci étant plus faible dans le groupe des TS VIH positives comparé aux groupes de TS VIH négatives et de femmes VIH négatives de la population générale. Nous avons aussi analysé l’expression de cytokines et chimiokines dans le sérum et le tractus génital des participantes de l’étude du Bénin. Nous avons constaté que chez les TS VIH positives il y avait une expression plus élevée des chimiokines MPC-3, IP-10 et MIG dans le tractus génital et le sérum comparativement aux deux autres groupes. Les patrons d’expression des cytokines variaient selon les compartiments : le niveau de TNF-α et IFN-γ était plus élevé dans le tractus génital des TS VIH positives, alors que le niveau d’IL-2, d’IL-10 et de TNF-α était plus faible dans le sang des TS VIH positives, comparativement aux deux autres groupes. Ainsi, au niveau du tractus génital des femmes VIH positives, il semble y avoir une activation chronique du système immunitaire dans le but de favoriser la dissémination/perpétuation du virus. Les patrons d’expression différents entre le milieu systémique et génital nous montrent que l’immunité présente dans un compartiment n’est pas nécessairement le reflet de l’autre. Nous avons aussi observé une augmentation significative des niveaux d’IL-4, de MIP-1α, de MIP-1β et de MCP-1 dans le sérum des TS VIH négatives. Ces personnes, hautement exposées mais non infectées, semblent démontrer une plus grande capacité à enclencher une réponse immunitaire précoce pour empêcher la dissémination du virus. Notre étude a donc permis d’acquérir de nouvelles connaissances sur l’immunité du tractus génital féminin en relation avec l’infection au VIH.

A distinctive clade B HIV type 1 is heterosexually transmitted in Trinidad and Tobago

HIV-1 transmission worldwide is predominantly associated with heterosexual activity, and non-clade B viruses account for the most spread. The HIV-1 epidemic in Trinidad/Tobago and the Caribbean shares many features with such heterosexual epidemics, including a prominent role for coincident sexually transmitted diseases. This study evaluates the molecular epidemiology of HIV-1 in Trinidad/Tobago during a period when abrupt transition from homosexual to heterosexual transmission occurred in the absence of injecting drug use, concomitant with a rapid rise in HIV-1 prevalence in the heterosexual population. Of 31 viral isolates studied during 1987–1995, all cluster with subtype B reference strains. In the analysis of full env genes from 22 early seroconverters, the Trinidad isolates constitute a significant subcluster within the B subtype. The Trinidad V3 consensus sequence differs by a single amino acid from the prototype B V3 consensus and demonstrates stability over the decade of this study. In the majority of isolates, the V3 loop of env contains a signature threonine deletion that marks the lineage of the Trinidad HIV-1 clade B epidemic from pre-1984. No phenotypic features, including syncitium induction, neutralization profiles, and chemokine receptor usage, distinguish this virus population from other subtype B viruses. Thus, although the subtype B HIV-1 viruses being transmitted in Trinidad are genetically distinguishable from other subtype B viruses, this is probably the result of a strong founder effect in a geographically circumscribed population rather than genetic selection for heterosexual transmission. These results demonstrate that canonical clade B HIV-1 can generate a typical heterosexual epidemic.

Predictors of safer sex behaviors of midlife and older women

Heterosexual transmission of the human immunodeficiency virus (HIV) in midlife and older women is increasing, yet little is known about the safer sex practices of these women. Identification of HIV risk and protective factors necessitates understanding of the influences of individual, interpersonal, and socio-environmental factors on the sexual behaviors of this understudied, at-risk population. The purpose of this study was to determine the influence of self esteem, sensation seeking, self silencing, sexual assertiveness, and HIV-stigma on the safer sex behaviors of women aged 50 and older. ^ This study was guided by the ecological perspective which emphasizes the multilevel factors affecting health behaviors within individual, interpersonal, and socio-environmental contexts. A community-based, ethnically diverse sample of 572 women aged 50 to 93 (M = 63.6 years, SD = 10.5) completed a 128-item anonymous questionnaire. This study used a cross-sectional, correlational research design. The data were analyzed using Pearson correlation coefficients and multiple regression analysis. ^ Results from the regression analysis with the predictors (i.e., ethnicity, education, self esteem, sensation seeking, self silencing, sexual assertiveness, and HIV stigma) indicated the model significantly predicted safer sex behaviors (p < .001). Self silencing (β = -.115, p < .05) was a significant predictor. The lower the self silencing scores, the higher the safer sex behavior scores. Further exploration of the data revealed that the greater the age of the woman, the more likely she is to engage in safer sex behaviors (β = .173, p < .001). While the data showed this model was statistically significant, its practical significance may be limited due to the low proportion of variance explained by age and self silencing. HIV/AIDS prevention interventions that are socially anchored, age-appropriate, and gender-specific are discussed and recommendations for socially meaningful strategies to reduce the number of new cases of HIV/AIDS in midlife and older women are presented. ^

Hepatitis C: sexual or intrafamilial transmission? Epidemiological and phylogenetic analysis of hepatitis C virus in 24 infected couples

The role of sexual or intrafamilial transmission of hepatitis C is controversial. A phylogenetic analysis was performed on the non-structural region 5B of the hepatitis C virus (NS5B-HCV). High percentages of homology (mean of 98.3%) were shown between the couples. Twenty (83.3%) of the 24 men but only two of the women (8.3%) reported having had sexually transmitted diseases during their lives. The risk factors for HCV acquisition were blood transfusion (10 couples), use of illegal injected drugs (17), use of inhalants (15), acupuncture (5) and tattoos (5). The shared use of personal hygiene items included toothbrushes between six couples (25%), razor blades between 16 (66.7%), nail clippers between 21 (87.5%) and manicure pliers between 14 (58.3%). The high degree of similarity of the hepatitis C virus genome supports the hypothesis of hepatitis C virus transmission between these couples. The shared use of personal hygiene items suggests the possibility of intrafamilial transmission of infection.

Autochthonous horizontal transmission of a CRF02_AG strain revealed by a human immunodeficiency virus type 1 diversity survey in a small city in inner state of Rio de Janeiro, Southeast Brazil

As part of an ongoing study on the features of AIDS spread towards small cities and rural areas, we present a molecular survey of human immunodeficiency virus type 1 (HIV-1) polymerase sequences recovered between 2004 and 2006 from 71 patients receiving care in the city of Saquarema, inner state of Rio de Janeiro. Phylogenetic reconstructions found the two prevalent lineages in the state (subtypes B [59 strains, 83.1%], F1 [6 strains; 8.4%], and BF1 recombinants [four strains; 5.6%]), as well as two (2.8%) CRF02_AG strains, which seems to be an emerging lineage in the capital. These CRF02_AG sequences were recovered from a married heterosexual couple who never traveled abroad, thus providing the first molecular evidence of autochthonous horizontal transmission of this lineage of major global importance. Also, three phylogenetic clusters of strains recovered from a total of 18.3% of the cohort were uncovered. Their close genetic relatedness suggests they were recovered from patients who probably took part in the same chain of viral spread. In conjunction with our previous surveys from inner Rio de Janeiro, these results suggest that although small cities harbor unique molecular features of HIV-1 infection, they also clearly reflect and may rapidly absorb the diversity recorded in large urban centers.

Molecular epidemiology reveals long-term changes in HIV type 1 subtype B transmission in Switzerland.

BACKGROUND: Sequence data from resistance testing offer unique opportunities to characterize the structure of human immunodeficiency virus (HIV) infection epidemics. METHODS: We analyzed a representative set of HIV type 1 (HIV-1) subtype B pol sequences from 5700 patients enrolled in the Swiss HIV Cohort Study. We pooled these sequences with the same number of sequences from foreign epidemics, inferred a phylogeny, and identified Swiss transmission clusters as clades having a minimal size of 10 and containing >or=80% Swiss sequences. RESULTS: More than one-half of Swiss patients were included within 60 transmission clusters. Most transmission clusters were significantly dominated by specific transmission routes, which were used to identify the following patient groups: men having sex with men (MSM) (38 transmission clusters; average cluster size, 29 patients) or patients acquiring HIV through heterosexual contact (HETs) and injection drug users (IDUs) (12 transmission clusters; average cluster size, 144 patients). Interestingly, there were no transmission clusters dominated by sequences from HETs only. Although 44% of all HETs who were infected between 1983 and 1986 clustered with injection drug users, this percentage decreased to 18% for 2003-2006 (P<.001), indicating a diminishing role of injection drug users in transmission among HETs over time. CONCLUSIONS: Our analysis suggests (1) the absence of a self-sustaining epidemic of HIV-1 subtype B in HETs in Switzerland and (2) a temporally decreasing clustering of HIV infections in HETs and IDUs.

Social meets molecular: Combining phylogenetic and latent class analyses to understand HIV-1 transmission in Switzerland.

Switzerland has a complex human immunodeficiency virus (HIV) epidemic involving several populations. We examined transmission of HIV type 1 (HIV-1) in a national cohort study. Latent class analysis was used to identify socioeconomic and behavioral groups among 6,027 patients enrolled in the Swiss HIV Cohort Study between 2000 and 2011. Phylogenetic analysis of sequence data, available for 4,013 patients, was used to identify transmission clusters. Concordance between sociobehavioral groups and transmission clusters was assessed in correlation and multiple correspondence analyses. A total of 2,696 patients were infected with subtype B, 203 with subtype C, 196 with subtype A, and 733 with recombinant subtypes (mainly CRF02_AG and CRF01_AE). Latent class analysis identified 8 patient groups. Most transmission clusters of subtype B were shared between groups of gay men (groups 1-3) or between the heterosexual groups "heterosexual people of lower socioeconomic position" (group 4) and "injection drug users" (group 8). Clusters linking homosexual and heterosexual groups were associated with "older heterosexual and gay people on welfare" (group 5). "Migrant women in heterosexual partnerships" (group 6) and "heterosexual migrants on welfare" (group 7) shared non-B clusters with groups 4 and 5. Combining approaches from social and molecular epidemiology can provide insights into HIV-1 transmission and inform the design of prevention strategies.

The role of migration and domestic transmission in the spread of HIV-1 non-B subtypes in Switzerland.

BACKGROUND: By analyzing human immunodeficiency virus type 1 (HIV-1) pol sequences from the Swiss HIV Cohort Study (SHCS), we explored whether the prevalence of non-B subtypes reflects domestic transmission or migration patterns. METHODS: Swiss non-B sequences and sequences collected abroad were pooled to construct maximum likelihood trees, which were analyzed for Swiss-specific subepidemics, (subtrees including ≥80% Swiss sequences, bootstrap >70%; macroscale analysis) or evidence for domestic transmission (sequence pairs with genetic distance <1.5%, bootstrap ≥98%; microscale analysis). RESULTS: Of 8287 SHCS participants, 1732 (21%) were infected with non-B subtypes, of which A (n = 328), C (n = 272), CRF01_AE (n = 258), and CRF02_AG (n = 285) were studied further. The macroscale analysis revealed that 21% (A), 16% (C), 24% (CRF01_AE), and 28% (CRF02_AG) belonged to Swiss-specific subepidemics. The microscale analysis identified 26 possible transmission pairs: 3 (12%) including only homosexual Swiss men of white ethnicity; 3 (12%) including homosexual white men from Switzerland and partners from foreign countries; and 10 (38%) involving heterosexual white Swiss men and females of different nationality and predominantly nonwhite ethnicity. CONCLUSIONS: Of all non-B infections diagnosed in Switzerland, <25% could be prevented by domestic interventions. Awareness should be raised among immigrants and Swiss individuals with partners from high prevalence countries to contain the spread of non-B subtypes.

Transmission of HIV-1 drug resistance in Switzerland: a 10-year molecular epidemiology survey.

OBJECTIVES: Representative prevalence data of transmitted drug-resistant HIV-1 are essential to establish accurate guidelines addressing resistance testing and first-line treatments. METHODS: Systematic resistance testing was carried out in individuals in Switzerland with documented HIV-1 seroconversion during 1996-2005 and available samples with RNA > 1000 copies/ml obtained within 1 year of estimated seroconversion. Resistance interpretation used the Stanford list of mutations for surveillance of transmitted drug resistance and the French National Agency for AIDS Research algorithm. RESULTS: Viral sequences from 822 individuals were available. Risk groups were men having sex with men (42%), heterosexual contacts (32%) and intravenous drug users (20%); 30% were infected with non-B subtype viruses. Overall, prevalence of transmitted resistance was 7.7% [95% confidence interval (CI), 5.9-9.5] for any drug, 5.5% (95% CI, 3.9-7.1) for nucleoside reverse transcriptase inhibitors, 1.9% (95% CI, 1.0-2.8) for non-nucleoside reverse transcriptase inhibitors and 2.7% (95% CI, 1.6-3.8) for protease inhibitors. Dual- or triple-class resistance was observed in 2% (95% CI, 0.8-2.5). No significant trend in prevalence of transmitted resistance was observed over years. There were no differences according to ethnicity, risk groups or gender, but prevalence of transmitted resistance was highest among individuals infected with subtype B virus. CONCLUSIONS: The transmission rate of drug-resistant HIV-1 has been stable since 1996, with very rare transmission of dual- or triple-class resistance. These data suggest that transmission of drug resistance in the setting of easy access to antiretroviral treatment can remain stable and be kept at a low level.