Objectives: To review the scientific data on the role of sexually transmitted diseases (STDs) in sexual transmission of HIV infection and discuss the implications of these findings for HIV and STD prevention policy and practice Methods: Articles were selected from a review of Medline, accessed with the OVID search engine The search covered articles from January 1987 to September 1998 and yielded 2101 arti- cles Methods used to uncover articles which might have been missed included searching for related articles by author, and combing literature reviews In addition, all abstracts under the cat- egory "sexually transmitted diseases" from the XI and XII International Conferences on AIDS (Vancouver 1996 and Geneva 1998) and other relevant scientific meetings were reviewed Efforts were made to locate journal articles which resulted from the research reported in the identified abstracts All original journal articles and abstracts which met one of the following criteria were included: (1) studies of the biological plausibility or mechanism of facilitation of HIV infectious- ness or susceptibility by STDs, (2) prospective cohort studies (longitudinal or nested case-control) which estimate the risk of HIV infection associated with specific STDs or STD syndromes, or (3) intervention studies which quantitate the eVect which STD treatment can have on HIV incidence Results: Strong evidence indicates that both ulcerative and non-ulcerative STDs promote HIV transmission by augmenting HIV infectiousness and HIV susceptibility via a variety of biological mechanisms These eVects are reflected in the risk estimates found in numerous prospective studies from four continents which range from 20 to 235, with most clustering between 2 and 5 The relative importance of ulcerative and non-ulcerative STDs appears to be complex Owing to the greater frequency of non-ulcerative STDs in many populations, these infections may be responsible for more HIV transmission than genital ulcers However, the limited reciprocal impact of HIV infection on non-ulcerative STDs and the evidence that non-ulcerative STDs may increase risk primarily for the receptive partner (rather than bidirectionally) may modulate the impact of these diseases The results of two community level randomised, controlled intervention trials conducted in Africa suggest that timely provision of STD services can substantially reduce HIV incidence, but raise additional questions about the optimal way to target and implement these services to achieve the greatest eVect on HIV transmission Conclusions: Available data leave little doubt that other STDs facilitate HIV transmission through direct, biological mechanisms and that early STD treatment should be part of a high quality, comprehensive HIV prevention strategy Policy makers, HIV prevention programme managers, and providers should focus initial implementation eVorts on three key areas: (i) improving access to and quality of STD clinical services; (ii) promoting early and eVective STD related healthcare behaviours; and (iii) establishing surveillance systems to monitor STD and HIV trends and their interrelations (Sex Transm Inf 1999;75:3-17)

https://sti.bmj.com/content/sextrans/75/1/3.full.pdf

From epidemiological synergy to public health policy and practice: the contribution of other sexually transmitted diseases to sexual transmission of HIV infection.

Impact of improved treatment of sexually transmitted diseases on HIV infection in rural Tanzania: randomised controlled trial

Transmission through sexual contact accounts for 75 to 85 percent of the nearly 28 million infections with the human immunodeficiency virus (HIV) that have occurred so far1 The probability of infection through sexual contact, although it varies greatly, appears to be lower than that of infection through other routes of exposure (Figure 1) The variability observed among and within routes of HIV exposure depends partly on the viral dose and also on whether the virus is transmitted directly into the blood or onto a mucous membrane In addition, these differences are influenced by a variety of host factors, including both   

https://www.nejm.org/doi/pdf/10.1056/NEJM199704103361507?articleTools=true

Sexual transmission of HIV

Objective: To examine how concurrent partnerships amplify the rate of HIV spread, using methods that can be supported by feasible data collection. 

Methods: A fully stochastic simulation is used to represent a population of individuals, the sexual partnerships that they form and dissolve over time, and the spread of an infectious disease. Sequential monogamy is compared with various levels of concurrency, holding all other features of the infection process constant. Effective summary measures of concurrency are developed that can be estimated on the basis of simple local network data. 

Results: Concurrent partnerships exponentially increase the number of infected individuals and the growth rate of the epidemic during its initial phase. For example, when one-half of the partnerships in a population are concurrent, the size of the epidemic after 5 years is 10 times as large as under sequential monogamy. The primary cause of this amplification is the growth in the number of people connected in the network at any point in time: the size of the largest "component'. Concurrency increases the size of this component, and the result is that the infectious agent is no longer trapped in a monogamous partnership after transmission occurs, but can spread immediately beyond this partnership to infect others. The summary measure of concurrency developed here does a good job in predicting the size of the amplification effect, and may therefore be a useful and practical tool for evaluation and intervention at the beginning of an epidemic. 

Conclusion: Concurrent partnerships may be as important as multiple partners or cofactor infections in amplifying the spread of HIV. The public health implications are that data must be collected properly to measure the levels of concurrency in a population, and that messages promoting one partner at a time are as important as messages promoting fewer partners.

/pdf/concurrent-partnerships-and-the-spread-of-hiv-3e8bhlnlgo.pdf

Concurrent partnerships and the spread of HIV.

http://www.columbia.edu/itc/hs/pubhealth/p8473/misc/wawer_lec_9.pdf

Control of sexually transmitted diseases for AIDS prevention in Uganda: a randomised community trial

There is only a small probability that HIV-1 will be transmitted via any single sexual contact. The risk of transmission however during such an act may be greatly increased by the presence of ulcerative genital sexually transmitted disease (STD). Little evidence is published on whether infection with non-ulcerative STD facilitates the transmission of HIV-1. The authors therefore investigated whether treatable STD enhanced the sexual transmission of HIV-1 in a cohort of female prostitutes in Kinshasa Zaire. 431 initially HIV-1-seronegative women were followed prospectively in this nested case-control study for a mean duration of two years in monthly STD check-ups and three-monthly HIV-1 serology. The 68 women who seroconverted were compared against the 126 women who remained HIV-1-seronegative for the incidence of STD and sexual exposure during the presumed period of HIV-1 acquisition. There was a 9.8% annual incidence of HIV-1 in this cohort of subjects. Seroconverters were of mean age 24.6 years compared to 26.8 years for the HIV-seronegative women. During the period of HIV-1 acquisition cases had a much higher incidence of gonorrhea chlamydial infection and trichomoniasis and engaged in unprotected sex with clients and partners more frequently than controls. After controlling for sexual exposure by multivariate analysis adjusted odds ratio for seroconversion were 4.8 for gonorrhea 3.6 for chlamydial infection and 1.9 for trichomoniasis. Genital ulcers were more frequent in cases than controls but much less common than other STD. These findings therefore suggest that non-ulcerative STDs were risk factors for the sexual transmission of HIV-1 in these women. Such STD may be a considerable population-attributable risk in the transmission of HIV-1 worldwide given the high prevalence of non-ulcerative STDs in some populations.

Batter

Papers

Non-ulcerative sexually transmitted diseases as risk factors for HIV-1 transmission in women: results from a cohort study.