Infectiousness of HIV between male homosexual partners
ABSTRACT To estimate the risk of transmission of HIV per receptive anal sexual contact, 329 homosexually-active men, representing 155 sexual partnerships, were enrolled into a study. Information on HIV infection status and sexual behavior within and outside the primary relationship was collected. Of these 329 men, 24 had AIDS and 31 had ARC. Of the 155 couples, 35 consisted of partners that were both HIV +; 62 of partners that were both HIV-; and 58 were discordant. A binomial model was fit to data obtained in the first visit to estimate per contact risk of HIV transmission. Assuming a constant risk of transmission per sexual contact between infected and uninfected partners, the estimated risk is about 5 to 30 per 1000 receptive anal exposures to ejaculate. Although the average risk of HIV transmission per sexual contact appears to be low, there appears to be great variability in infectivity. To model this variability over time and across individuals, more complex models must be fit to longitudinal studies of sexual partners.
- SourceAvailable from: Allanise Cloete
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- "In terms of HIV, sex between men is highly infectious because it can involve anal sex which when unprotected carries a very high risk of HIV transmission (De Gruttola et al., 1989). On the other hand, the vulnerability to HIV infection of WSW is not the result of specific sexual practices, but the result of a myriad of societal factors. "
ABSTRACT: South Africa is home to the largest population of people living with HIV/AIDS (PLWHA). Of this population gender non-conforming women like women who have sex with women (WSW) remain undocumented. This study is an attempt to fill this information gap as it describes the demographic, health and sexual behaviours of 72 HIV positive WSW. The data indicate that WSW are not protected from HIV because of their same sex desires. These findings suggest the need to include WSW as a most at risk group for both HIV prevention and treatment programmes. Key words: Women who have sex with women (WSW), lesbians, HIV positive, corrective rape, female-to-female transmission of HIV, South Africa.
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- "Researchers in sexually transmitted diseases have developed Bernoulli process models to explore and compare the impact on risk of various HIV/AIDS interventions *including increased condom use, reductions in the number of sexual partners and the careful selection of partners (Fineberg, 1988; Hearst & Hulley, 1988; Pinkerton & Abramson, 1998; Wiley & Herschkorn, 1988) *as well as to derive estimates of the per-contact probability of HIV transmission for unprotected sexual intercourse (DeGruttola et al., 1989). In this type of model, each act of sexual intercourse is treated as an independent Bernoulli trial and the probability of a 'success' (i.e. "
ABSTRACT: Understanding sexual behavior and assessing transmission risk among people living with HIV-1 is crucial for effective HIV-1 prevention. We describe sexual behavior among HIV-positive persons initiating highly active antiretroviral therapy (HAART) in Beira, Mozambique. We present a Bernoulli process model (tool available online) to estimate the number of sexual partners who would acquire HIV-1 as a consequence of sexual contact with study participants within the prior three months. Baseline data were collected on 350 HAART-naive individuals 18-70 years of age from October 2004 to February 2005. In the three months prior to initiating HAART, 45% (n = 157) of participants had sexual relationships with 191 partners. Unprotected sex occurred in 70% of partnerships, with evidence suggesting unprotected sex was less likely with partners believed to be HIV-negative. Only 26% of the participants disclosed their serostatus to partners with a negative or unknown serostatus. Women were less likely to report concurrent relationships than were men (21 versus 66%; OR 0.13; 95%CI: 0.06, 0.26). Given baseline behaviors, the model estimated 23.2 infections/1,000 HIV-positive persons per year. The model demonstrated HAART along with syphilis and herpes simplex virus type 2 (HSV-2) treatment combined could reduce HIV-1 transmission by 87%; increasing condom use could reduce HIV-1 transmission by 67%.AIDS Care 06/2007; 19(5):594-604. DOI:10.1080/09540120701203337 · 1.60 Impact Factor
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- "It is generally believed that a successful HIV-1 infection, on a per exposure basis, is a lowprobability event (Gray et al., 2001), but increases in persons who have a history of multiple exposures or other sexually transmitted diseases(DeGruttola et al., 1989;Galvin and Cohen, 2004;Jewell and Shiboski, 1990). Furthermore, a correlation between plasma viral load and transmission probability has been reported(Garcia et al., 1999;Gray et al., 2001;Quinn et al., 2000), with recent studies showing that the risk of HIV-1 transmission is increased in the setting of primary infection when viral burden is highest(Pilcher et al., 2004;Wawer et al., 2005). "
ABSTRACT: We examined the effect of inoculum dose on SHIV transmission and infection. We found that repeated low-dose intravaginal exposure with either R5-SHIV(SF162P3) or X4-SHIV(SF33A) results in infections that are blunted and rapidly controlled. Interestingly, although the transmission rate after all repeated exposures is comparable for the two viruses, the probability of low-dose vaginal transmission is greater for the X4 than R5 virus. Furthermore, X4-SHIV(SF33A) replication predominates in low-dose dually-exposed macaques, suggesting that it is better at establishing a systemic infection following transmission. However, X4-SHIV(SF33A) advantage in transmission and infection is not observed in macaques inoculated intravenously with low-dose mixed inoculum. The finding that although matched in tissue culture infectious dose, the X4 inoculum is more complex leads us to hypothesize that the greater genetic heterogeneity of the X4 virus population may have rendered it less susceptible to the severe bottleneck effects imposed by IVAG inoculation with small doses, allowing for greater probability of transmission and establishment of a generalized infection. These data have implications for HIV-1 transmission and infection in humans.Virology 06/2007; 362(1):207-16. DOI:10.1016/j.virol.2006.12.024 · 3.28 Impact Factor