A mathematical model of HIV transmission in NSW prisons

Dynamic Models of Infectious Disease Transmission in Prisons and the General Population

Incarcerated populations experience elevated burdens of infectious diseases, which are exacerbated by limited access to prevention measures. Dynamic models are used to assess the spread and control of diseases within correctional facilities and repercussions on the general population. Our systematic review of dynamic models of infectious diseases within correctional settings identified 34 studies published between 1996 and 2017. Of these, 23 focused on disease dynamics and intervention in prison without accounting for subsequent spread to the community. The main diseases modeled in these studies were human immunodeficiency virus (HIV; n = 14, 41%), tuberculosis (TB; n = 10, 29%), and hepatitis C virus (HCV; n = 7, 21%). Models were fitted to epidemiologic data in 14 studies; uncertainty and sensitivity analyses were conducted in 8, and validation of model projection against empirical data was done in 1 study. According to the models, prison-based screening and treatment may be highly effective strategies for reducing the burden of HIV, TB, HCV, and other sexually transmissible infections among prisoners and the general community. Decreasing incarceration rates were projected to reduce HIV and HCV infections among people who inject drugs and TB infections among all prisoners. Limitations of the modeling studies and opportunities for using dynamic models to develop quantitative evidence for informing prison infection control measures are discussed.

HIV/AIDS and other infectious diseases among correctional inmates: transmission, burden, and an appropriate response

Correctional inmates engage in drug-related and sexual risk behaviors, and the transmission of HIV, hepatitis, and sexually transmitted diseases occurs in correctional facilities. However, there is uncertainty about the extent of transmission, and hyperbolic descriptions of its extent may further stigmatize inmates and elicit punitive responses. Whether infection was acquired within or outside correctional facilities, the prevalence of HIV and other infectious diseases is much higher among inmates than among those in the general community, and the burden of disease among inmates and releasees is disproportionately heavy. A comprehensive response is needed, including voluntary counseling and testing on request that is linked to high-quality treatment, disease prevention education, substance abuse treatment, and discharge planning and transitional programs for releasees.

Do needle syringe programs reduce HIV infection among injecting drug users: a comprehensive review of the international evidence

This first international review of the evidence that needle syringe programs reduce HIV infection among injecting drug users found that conservative interpretation of the published data fulfills six of the nine Bradford Hill criteria (strength of association, replication of findings, temporal sequence, biological plausibility, coherence of evidence, and reasoning by analogy) and all six additional criteria (cost-effectiveness, absence of negative consequences, feasibility of implementation, expansion and coverage, unanticipated benefits, and application to special populations). The Bradford Hill criteria are often used to evaluate public health interventions. The principal finding of this review was that there is compelling evidence of effectiveness, safety, and cost-effectiveness, consistent with seven previous reviews conducted by or on behalf of U.S. government agencies. Authorities in countries affected or threatened by HIV infection among injecting drug users should carefully consider this convincing evidence now available for needle syringe programs with a view to establishing or expanding needle syringe programs to scale.

Health and Economic Impacts of an HIV Intervention in Out of Treatment Substance Abusers: Evidence from a Dynamic Model

INTRODUCTION

A community-based intervention program found that the high-risk target population interacts with its surrounding community as a source of drugs and prostitution, creating a measure of co-dependence in the health status of each group.

METHODOLOGY

The intervention collected extensive data on sexual and drug use practices in the target population. A dynamic compartment model estimates the epidemiological impact of the intervention, which serves as the basis for the economic assessment comparing intervention costs and lifetime HIV treatment costs.

RESULTS

Approximately 2/3 of the new infections arise in the surrounding community. Intervention spillover benefits in the surrounding community are sufficient to make the intervention cost-saving in the first year--a savings of approximately 534,000 dollars.

CONCLUSIONS

Conducting the intervention results in health benefits and cost-savings not only for the risk group, but for the entire community in which it resides. Quantifying the spillovers is vital to policymakers attempting to allocate scarce public health resources.

Doing the possible: harm reduction, injecting drug use and blood borne viral infections in Australia

Most surveys show that, other than among men who inject drugs and have a history of homosexual contact, the prevalence of HIV infection among injecting drug users (IDUs) in Australia is about 2%. Rates of needle sharing have also declined greatly in the last decade, although the high prevalence and incidence of hepatitis C infection suggest that existing strategies have not yet brought this epidemic under control. Harm reduction has been the major Australian approach to the reduction of blood borne viral infections (BBVIs) in IDUs. Harm reduction strategies include needle distribution schemes, drug substitution therapies and education about safe administration practices. Importantly, with IDUs as with gay men, the infected and affected communities have been brought into partnership with health educators, researchers and policy makers. This paper will review Australia's approach to the prevention of BBVI in IDUs and the effectiveness of current strategies. I will argue that while HIV/AIDS among heterosexual IDUs appears to have been successfully prevented, international experiences of rapidly emerging epidemics demonstrate there is little room for complacency. Moreover, reducing the incidence of hepatitis C and hepatitis B among IDUs remains a major challenge.

HIV transmission in a prison system in an Australian State

OBJECTIVE

To investigate possible HIV transmission among prison inmates.

SETTING

A prison system in an Australian State.

PARTICIPANTS

13 ex-prisoners and their prison contacts.

METHODS

Ex-prisoners who claimed to have been infected with HIV in prison and their prison contacts were interviewed about HIV risk behaviour. Entries in prison and community medical records were used by a three-member expert panel to establish the likelihood of primary HIV infection and its possible timing and location.

MAIN OUTCOME MEASURES

Determination of whether HIV infection probably occurred in prison.

RESULTS

There was a very high probability that at least four of 13 ex-prisoners investigated acquired HIV in prison from shared injection equipment. Another two ex-prisoners most probably acquired HIV infection outside prison. The location of infection for the remaining seven could not be determined.

CONCLUSIONS

HIV transmission in prison has substantial public health implications as most drug-using prisoners soon return to the community. HIV prevention strategies known to be effective in community settings, such as methadone maintenance treatment and syringe exchange schemes, should be considered for prisoners.

A bleach program for inmates in NSW: an HIV prevention strategy

Syringe cleaning guidelines for injecting drug users (IDUs) were revised in 1993. This paper examines efforts by IDUs in NSW prisons to adopt the revised guidelines in 1994. Consecutive inmates (229) nearing release were visited and asked to call a toll free number for an interview once released. Respondents (102) did not differ from non-respondents (127). Many respondents (64%) reported ever injecting and many of these reported injecting (58%), sharing (48%) and syringe cleaning (46%) when last in prison. Some (23%) respondents reported adopting the revised syringe cleaning guidelines. Tattooing (38%) was reported more often than sexual activity in prison (4%). A new methodology for prison research was found to be feasible in this study. The potential for HIV to spread in prison still poses major public health challenges.