Virologic and Immunologic Determinants of Heterosexual Transmission of Human Immunodeficiency Virus Type 1 in Africa

Fideli, U.; Allen, Susan; Musonda, Rosemary; Trask, Stan; Hahn, Beatrice H.; Weiss, Helen A.; Mulenga, Joseph; Kasolo, Francis; Vermund, Sten H.; Aldrovandi, Grace M.

doi:10.1089/088922201750290023

Cited by 331 publications

(305 citation statements)

References 52 publications

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“…In four other studies of HIV transmission in serodiscordant African couples (with most individuals not aware of their HIV status and/or with continuing unprotected sex), the unweighted average HIVincidence for men (women) was 7.6 (10.0) per 100 person years (PYs) 27± 30 , comparable to an incidence of 4.8± 7.2 per 100 PYs in European men and/or women with HIV-positive partners who continued unprotected sex 25,31,32 . Moreover, these data may overstate heterosexual transmission in African couples; a Zambian study that sequenced viruses to determine epidemiological linkage reported at least 13% of sequences in newly infected persons were not related to their partner's HIV 33 .…”

Section: Unexplained High Implicit Rates Of Heterosexual Transmissionmentioning

confidence: 99%

HIV infections in sub-Saharan Africa not explained by sexual or vertical transmission

et al. 2002

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An expanding body of evidence challenges the conventional hypothesis that sexual transmission is responsible for more than 90% of adult HIV infections in Africa. Differences in epidemic trajectories across Africa do not correspond to differences in sexual behaviour. Studies among African couples find low rates of heterosexual transmission, as in developed countries. Many studies report HIV infections in African adults with no sexual exposure to HIV and in children with HIV-negative mothers. Unexplained high rates of HIV incidence have been observed in African women during antenatal and postpartum periods. Many studies show 20%–40% of HIV infections in African adults associated with injections (though direction of causation is unknown). These and other findings that challenge the conventional hypothesis point to the possibility that HIV transmission through unsafe medical care may be an important factor in Africa's HIV epidemic. More research is warranted to clarify risks for HIV transmission through health care.

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Section: Unexplained High Implicit Rates Of Heterosexual Transmissionmentioning

confidence: 99%

HIV infections in sub-Saharan Africa not explained by sexual or vertical transmission

et al. 2002

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“…Viral load is the single greatest risk factor for all modes of transmission. 35,36 Sexual transmission of HIV has been closely linked to viral load in the blood of the infected host, [37][38][39][40][41] which probably serves as a surrogate, albeit imperfect, for HIV concentration in the genital tract. 42,43 In addition to lowering plasma viral load to nearly undetectable levels, ART can decrease viral load in genital secretions, 44,45 although patients having a detectable semen HIV load may have no detectable virus in their blood plasma, highlighting the residual risk of HIV-1 transmission during unprotected intercourse.…”

Section: Introductionmentioning

confidence: 99%

AIDS Vaccines and Preexposure Prophylaxis: Is Synergy Possible?

Excler

Rida²,

Priddy

et al. 2011

AIDS Research and Human Retroviruses

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While the long-term goal is to develop highly effective AIDS vaccines, first generation vaccines may be only partially effective. Other HIV prevention modalities such as preexposure prophylaxis with antiretrovirals (PrEP) may have limited efficacy as well. The combined administration of vaccine and PrEP (VAXPREP), however, may have a synergistic effect leading to an overall benefit that is greater than the sum of the individual effects. We propose two test-of-concept trial designs for an AIDS vaccine plus oral or topical ARV. In one design, evidence that PrEP reduces the risk of HIV acquisition is assumed to justify offering it to all participants. A two-arm study comparing PrEP alone to VAXPREP is proposed in which 30 to 60 incident infections are observed to assess the additional benefit of vaccination on risk of infection and setpoint viral load. The demonstrated superiority of VAXPREP does not imply vaccine alone is efficacious. Similarly, the lack of superiority does not imply vaccine alone is ineffective, as antagonism could exist between vaccine and PrEP. In the other design, PrEP is assumed not to be in general use. A 2Â2 factorial design is proposed in which high-risk individuals are randomized to one of four arms: placebo vaccine given with placebo PrEP, placebo vaccine given with PrEP, vaccine given with placebo PrEP, or VAXPREP. Between 60 and 210 infections are required to detect a benefit of vaccination with or without PrEP on risk of HIV acquisition or setpoint viral load, with fewer infections needed when synergy is present.

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“…8 Among adults, gender differences in heterosexual HIV infection rates have been attributed to various biological (immunologic, genetic, viral, and hormonal), social, and behavioral factors. [9][10][11][12][13][14][15] Among children, gender-specific differences could indicate inherent physiologic factors that influence not only differential progression of the disease but also acquisition of the virus as early as in utero. Few studies have observed more HIV infection among girls than boys.…”

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confidence: 99%

Gender Differences in Perinatal HIV Acquisition Among African Infants

et al. 2005

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ABSTRACT. Objective. We investigated gender-specific risks of mother-to-child transmission (MTCT) at birth and at 6 to 8 weeks among infants born to HIVinfected African women.Design. Follow-up study of infants enrolled in 2 randomized, phase III, clinical trials to prevent MTCT, conducted in Blantyre, Malawi, in southeast Africa.Methods. Infants were enrolled at birth and monitored postnatally, and their HIV status was assessed at birth and at 6 to 8 weeks (assessment beyond 6 -8 weeks is ongoing). Statistical analyses were stratified according to gender, and comparisons were made with descriptive, univariate, and multivariate statistical tests. MTCT was estimated at birth and at 6 to 8 weeks among infants who were not infected at birth.Results. Overall, 966 boys and 998 girls were enrolled. The rate of HIV transmission at birth was 9.5% (187 of 1964 infants). However, at birth significantly more girls (12.6%) than boys (6.3%) were infected with HIV. This association remained significant after controlling for maternal viral load and other factors. Among infants who were uninfected at birth, 8.7% (135 of 1554 infants) acquired HIV by 6 to 8 weeks; of these infants, more girls acquired HIV (10.0%), compared with boys (7.4%).Conclusions. Female infants may be more susceptible to HIV infection before birth and continuing after birth. Alternatively, in utero mortality rates of HIV-infected male infants may be disproportionately higher and thus more HIV-infected female infants are born. In areas of sub-Saharan Africa, where HIV infection rates are high among women of reproductive age, the magnitude of the gender transmission differences observed in this study could have clinical, preventive, and demographic implications. Pediatrics 2005;115:e167-e172. URL: www. pediatrics.org/cgi/doi/10.1542/peds.2004-1590; acquisition, Africa, gender, HIV, mother-to-child transmission, susceptibility.ABBREVIATIONS. MTCT, mother-to-child transmission; CI, confidence interval; NVP, nevirapine; ZDV, zidovudine. I n developing countries, the risk of mother-tochild transmission (MTCT) of HIV is ϳ15 to 40% 1 but varies with antiretroviral treatment and breastfeeding. MTCT of HIV can occur in utero (20 -25%), intrapartum (65-70%), or postnatally (10 -15%). 2 As with other infectious diseases, the probability of HIV transmission is dependent on the infectiousness of the index case, the mode of spread, and the susceptibility of exposed individuals. 3,4 For MTCT of HIV, infectiousness is determined by maternal viral load, a risk factor strongly associated with perinatal infection 5-7 and the potential for HIV transmission through the in utero, intrapartum, and postpartum routes. Susceptibility, however, may be determined by genetic factors and/or acquired resistance. 8 Among adults, gender differences in heterosexual HIV infection rates have been attributed to various biological (immunologic, genetic, viral, and hormonal), social, and behavioral factors. 9-15 Among children, gender-specific differences could indicate inherent physiologic facto...

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Virologic and Immunologic Determinants of Heterosexual Transmission of Human Immunodeficiency Virus Type 1 in Africa

Cited by 331 publications

References 52 publications

HIV infections in sub-Saharan Africa not explained by sexual or vertical transmission

HIV infections in sub-Saharan Africa not explained by sexual or vertical transmission

AIDS Vaccines and Preexposure Prophylaxis: Is Synergy Possible?

Gender Differences in Perinatal HIV Acquisition Among African Infants

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