Increased HIV testing will modestly reduce HIV incidence among gay men in NSW and would be acceptable if HIV testing becomes convenient.

Objective: Determine the acceptability and epidemiological impact of increases in HIV testing in gay men in New South Wales (NSW), Australia- particularly pertinent when considering treatment as prevention and the need to reduce undiagnosed infections.

Methods: We conducted an online survey and focus groups to assess whether increases in HIV testing would be acceptable to gay men in NSW. In parallel, we assessed the potential impact of increases in testing coverage and/or frequency using an individual-based model of HIV transmission.

Increasing gay men's testing rates and enhancing partner notification can reduce the incidence of syphilis.

Background: We sought to determine whether gay men would be willing to increase syphilis testing and partner notification, and assessed the possible epidemiological impact these changes might have in the Australian population.

Methods: We conducted an online survey (n=2306) and focus groups to determine whether interventions to increase testing for syphilis and enhanced partner notification are likely to be acceptable to gay men in Australia. An individual-based mathematical model was developed to estimate the potential population-level impact of changes in these factors.

Could implementation of Australia's national gay men's syphilis action plan have an indirect effect on the HIV epidemic?

Objectives: The number of incident infections of syphilis and HIV have increased over the past decade across Australia, particularly among gay men. In other industrialised settings, syphilis epidemics have also resurged coincidentally with increases in HIV diagnoses. Sexually transmissible infections (STI) are a biologically plausible cofactor for increasing HIV transmission.

Will changes in gay men's sexual behavior reduce syphilis rates?

Background: Reducing rates of partner change and increasing condom usage among gay men are obvious targets for potentially reducing syphilis transmission among gay men.

Methods: We developed an agent-based stochastic model to examine syphilis transmission among a population of gay men, representative of gay men in Australia. This model was used to explore the potential impact of changes in sexual behavior over 1 month, 3 month, and indefinite time frames on syphilis epidemics.

Would gay men change their sexual behavior to reduce syphilis rates?

Background: The community at which public health strategies for reducing syphilis epidemics are potentially targeted may have different considerations with regards to their sexual and health priorities. We aimed to elicit information on the acceptability of behavior change interventions among gay men for reducing syphilis transmission.

Methods: We conducted an online survey (n = 2306 participants) and focus groups to determine whether further sexual behavior change to reduce syphilis is likely to be acceptable to gay men in Australia.

Expected epidemiological impacts of introducing an HIV vaccine in Thailand: a model-based analysis.

Background: The RV144 trial conducted in Thailand was the first to demonstrate modest protective efficacy of an HIV vaccine. Its estimated initial efficacy was ∼74%, but this waned considerably over time.

Methods: We developed a mathematical model to reflect historical and current HIV trends across different at-risk populations in Thailand.

Expected epidemiological impact of the introduction of a partially effective HIV vaccine among men who have sex with men in Australia.

A trial of the ALVAC-AIDSVAX HIV vaccine was recently found to be partially effective in preventing HIV transmission among study participants in Thailand. The success of this trial means that vaccination may become a viable intervention for the prevention of HIV infection in the medium-term future. Assuming that the vaccine has similar relative protective effectiveness per exposure event for reducing transmission among men who have sex with men (MSM) in high-income settings we investigated the potential population-level impact of rolling out such a vaccine among MSM in New South Wales, Australia.

Chemoprophylaxis is likely to be acceptable and could mitigate syphilis epidemics among populations of gay men.

Background: Over the last decade, syphilis epidemics have resurged around the world, particularly among gay men. An innovative public health response could be the use of chemoprophylaxis. We sought out to determine the acceptability of syphilis chemoprophylaxis and its likely population effectiveness if it were adopted.

Hidden drug resistant HIV to emerge in the era of universal treatment access in Southeast Asia.

Background: Universal access to first-line antiretroviral therapy (ART) for HIV infection is becoming more of a reality in most low and middle income countries in Asia. However, second-line therapies are relatively scarce.

Methods And Findings: We developed a mathematical model of an HIV epidemic in a Southeast Asian setting and used it to forecast the impact of treatment plans, without second-line options, on the potential degree of acquisition and transmission of drug resistant HIV strains.

Frequent testing of highly sexually active gay men is required to control syphilis.

Background: The incidence of syphilis infections has been substantially increasing in gay men in the developed world.

Methods: We developed an individual-based mathematical model describing syphilis transmission within a gay male population: we used the model to simulate the expected relative impact of numerous screening and treatment interventions, targeting different at-risk groups with various coverage and frequency rates and follow-up schedules.

Results: The model predicts that increasing the proportion of gay men tested each year would have a relatively modest impact on syphilis incidence.

What impact might the economic crisis have on HIV epidemics in Southeast Asia?

Objective: To evaluate the potential impact of the current global economic crisis (GEC) on the spread of HIV.

Design: To evaluate the impact of the economic downturn we studied two distinct HIV epidemics in Southeast Asia: the generalized epidemic in Cambodia where incidence is declining and the epidemic in Papua New Guinea (PNG) which is in an expansion phase.

Methods: Major HIV-related risk factors that may change due to the GEC were identified and a dynamic mathematical transmission model was developed and used to forecast HIV prevalence, diagnoses, and incidence in Cambodia and PNG over the next 3 years.

Importance of promoting HIV testing for preventing secondary transmissions: modelling the Australian HIV epidemic among men who have sex with men.

Background: We address the research questions: (i) what proportion of new HIV infections is transmitted from people who are (a) undiagnosed, (b) in primary HIV infection (PHI), (c) on antiretroviral therapy?; and (ii) what is the expected epidemiological impact of (a) increasing the proportion of newly acquired HIV infections receiving early treatment, and (b) increasing HIV testing rates?

Methods: We used a mathematical model to simulate HIV transmission in the population of men who have sex with men (MSM) in Australia. We calibrated the model using established biological and clinical data and a wide range of Australian MSM epidemiological and behavioural data sources.

Results: We estimate that ~19% of all new HIV infections are transmitted from the ~3% of Australian HIV-infected MSM who are in PHI; ~31% of new HIV infections are estimated to be transmitted from the ~9% of MSM with undiagnosed HIV.

Using mathematical modelling to help explain the differential increase in HIV incidence in New South Wales, Victoria and Queensland: importance of other sexually transmissible infections.

Background: Since 1999 there has been an increase in the number of HIV diagnoses in Australia, predominantly among men who have sex with men (MSM), but the magnitude of increase differs between states: approximately 7% rise in New South Wales, approximately 96% rise in Victoria, and approximately 68% rise in Queensland.

Methods: Epidemiological, clinical, behavioural and biological data were collated into a mechanistic mathematical model to explore possible reasons for this increase in HIV notifications in MSM. The model was then used to make projections to 2015 under various scenarios.

Sampling and sensitivity analyses tools (SaSAT) for computational modelling.

SaSAT (Sampling and Sensitivity Analysis Tools) is a user-friendly software package for applying uncertainty and sensitivity analyses to mathematical and computational models of arbitrary complexity and context. The toolbox is built in Matlab, a numerical mathematical software package, and utilises algorithms contained in the Matlab Statistics Toolbox. However, Matlab is not required to use SaSAT as the software package is provided as an executable file with all the necessary supplementary files.

Spatial constraints within the chlamydial host cell inclusion predict interrupted development and persistence.

Background: The chlamydial developmental cycle involves the alternation between the metabolically inert elementary body (EB) and the replicating reticulate body (RB). The triggers that mediate the interchange between these particle types are unknown and yet this is crucial for understanding basic Chlamydia biology.

Presentation Of The Hypothesis: We have proposed a hypothesis to explain key chlamydial developmental events whereby RBs are replicating strictly whilst in contact with the host cell membrane-derived inclusion via type three secretion (T3S) injectisomes.