OBJECTIVES: This study characterized the AIDS epidemic among urban men who have sex with men (MSM). METHODS: A probability sample of MSM was obtained in 1997 (n = 2881; 18 years and older) from New York, Los Angeles, Chicago, and San Francisco, and HIV status was determined through self-report and biological measures. RESULTS: HIV prevalence was 17% (95% confidence interval = 15%, 19%) overall, with extremely high levels in African Americans (29%), MSM who used injection drugs (40%), "ultraheavy" noninjection drug users (32%), and less educated men (< high school, 37%). City-level HIV differences were non-significant once these other factors were controlled for. In comparing the present findings with historical data based on public records and modeling, HIV prevalence appears to have declined as a result of high mortality (69%) and stable, but high, incidence rates (1%-2%). CONCLUSIONS: Although the findings suggest that HIV prevalence has declined significantly from the mid-1980s, current levels among urban MSM in the United States approximate those of sub-Saharan countries (e.g., 14%-25%) and are extremely high in many population subsegments. Despite years of progress, the AIDS epidemic continues unabated among subsegments of the MSM community.

The continuing HIV epidemic among men who have sex with men

Summary Background Routine national incidence testing with enzyme immunoassay for recent HIV-1 infections (EIA-RI) has been done in France since January, 2003. From the reported number of HIV infections diagnosed as recent, and accounting for testing patterns and under-reporting, we aimed to estimate the incidence of HIV infection in France in 2003–08. Methods We analysed reports from the French National Institute for Public Health Surveillance for patients who were newly diagnosed with HIV between January, 2003, and December, 2008. Missing data were imputed with multiple imputation. Patients were classified with non-recent or recent infection on the basis of an EIA-RI test, which was calibrated with serial measurements from HIV seroconverters from the French ANRS-PRIMO cohort. We used an adapted stratified extrapolation approach to calculate the number of new HIV infections in men who have sex with men (MSM), injecting drug users (IDUs), and heterosexual men and women by nationality. Population sizes were obtained from the national census and national behavioural studies. Findings After accounting for under-reporting, there were 6480 (95% CI 6190–6780) new diagnoses of HIV infection in France in 2008. We estimate that there were 6940 (6200–7690) new HIV infections in 2008, suggesting an HIV incidence of 17 per 100 000 person-years. In 2008, there were 3550 (3040–4050) new infections in heterosexuals (incidence of 9 per 100 000 person-years), 3320 (2830–3810) in MSM (incidence of 1006 per 100 000 person-years), and 70 (0–190) in IDUs (incidence of 86 per 100 000 person-years). Overall HIV incidence decreased between 2003 and 2008 (p Interpretation In France, HIV transmission disproportionately affects certain risk groups and seems to be out of control in the MSM population. Incidence should be tracked to monitor transmission dynamics in the various population risk groups and to help to target and assess prevention strategies. Funding French National Institute for Public Health Surveillance (InVS) and French National Agency for Research on AIDS and Viral Hepatitis (ANRS).

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Population-based HIV-1 incidence in France, 2003–08: a modelling analysis

UNAIDS and WHO produce biannual country-specific estimates of HIV/AIDS and its impact These estimates are based on methods and assumptions that reflect the best understanding of HIV epidemiology and demography at the time Where significant advances are made in epidemiological and demographic research, the methods and assumptions must evolve to match these advances UNAIDS established an Epidemiology Reference Group in 1999 to advise them and other organisations on HIV epidemiology and methods for making estimates and projections of HIV/AIDS During the meeting of the reference group in 2001, four priority areas were identified where methods and assumptions should be reviewed and perhaps modified: a) models of the HIV epidemic, b) survival of adults with HIV-1 in low and middle income countries, c) survival of children with HIV-1 in low and middle income countries, and d) methods to estimate numbers of AIDS orphans Research and literature reviews were carried out by Reference Group members and invited specialists, prior to meetings held during 2001-2 Recommendations reflecting the consensus of the meeting participants on the four priority areas were determined at each meeting These recommendations were followed in UNAIDS and WHO development of country-specific estimates of HIV/AIDS and its impact for end of 2001

Improved methods and assumptions for estimation of the HIV/AIDS epidemic and its impact: Recommendations of the UNAIDS Reference Group on Estimates, Modelling and Projections.

RNA viruses display high mutation rates and their populations replicate as dynamic and complex mutant distributions, termed viral quasispecies. Repeated genetic bottlenecks, which experimentally are carried out through serial plaque-to-plaque transfers of the virus, lead to fitness decrease (measured here as diminished capacity to produce infectious progeny). Here we report an analysis of fitness evolution of several low fitness foot-and-mouth disease virus clones subjected to 50 plaque-to-plaque transfers. Unexpectedly, fitness decrease, rather than being continuous and monotonic, displayed a fluctuating pattern, which was influenced by both the virus and the state of the host cell as shown by effects of recent cell passage history. The amplitude of the fluctuations increased as fitness decreased, resulting in a remarkable resistance of virus to extinction. Whereas the frequency distribution of fitness in control (independent) experiments follows a log-normal distribution, the probability of fitness values in the evolving bottlenecked populations fitted a Weibull distribution. We suggest that multiple functions of viral genomic RNA and its encoded proteins, subjected to high mutational pressure, interact with cellular components to produce this nontrivial, fluctuating pattern.

Resistance of virus to extinction on bottleneck passages: Study of a decaying and fluctuating pattern of fitness loss

Aquaculture production is an important industry in many countries and there has been a growth in the use of medicines to ensure the health and cost effectiveness of the industry. This study focused on the inputs of sea lice medication to the marine environment. Diflubenzuron, teflubenzuron, emamectin benzoate, cypermethrin, and deltamethrin were measured in water, sediment, and biota samples in the vicinity of five aquaculture locations along the Norwegian coast. Deltamethrin and cypermethrin were not detected above the limits of detection in any samples. Diflubenzuron, teflubenzuron, and emamectin benzoate were detected, and the data was compared the UK Environmental Quality Standards. The concentrations of emamectin benzoate detected in sediments exceed the environmental quality standard (EQS) on 5 occasions in this study. The EQS for teflubenzuron in sediment was exceeded in 67% of the samples and exceeded for diflubenzuron in 40% of the water samples collected. A crude assessment of the concentrations detected in the shrimp collected from one location and the levels at which chronic effects are seen in shrimp would suggest that there is a potential risk to shrimp. It would also be reasonable to extrapolate this to any species that undergoes moulting during its life cycle.

Do Antiparasitic Medicines Used in Aquaculture Pose a Risk to the Norwegian Aquatic Environment

The effects of repetitive 24-hr weekly exposures to diflubenzuron (Dimilin®) on juvenile fiddler crabs (Uca pugilator) were studied in static seawater systems for 10 weeks. Crabs surviving the 10-week exposure period were maintained in clean seawater until death. Survival, molting, and behavior were monitored daily. The no-effect concentration (NOEC) for molting (time to the first molt), survival (time until death), and behavior (ability to escape from the test container) were 20, 2, and 0.2 μg/L DFB, respectively. The behavioral effect induced by diflubenzuron (DFB) exposures (>2 μg/L) was the most sensitive indicator of DFB activity and potentially may influence the ability of juvenile crabs to avoid predation, construct burrows, or feed adequately to survive in nature.

Effects of diflubenzuron (Dimilin) on survival, molting, and behavior of juvenile fiddler crabs, Uca pugilator.

Information from 12 studies is combined to estimate the AIDS incubation distribution with greater precision than is possible from a single study. The analysis uses a hierarchy of parametric models based on a four-parameter generalized F distribution. This general model contains four standard two-parameter distributions as special cases. The cases are the Weibull, gamma, log-logistic, lognormal distributions. These four special cases subsume three distinct asymptotic hazard behaviors. As time increases beyond the median of approximately 10 years, the hazard can increase to infinity (Weibull), can plateau at some constant level (gamma), or can decrease to zero (log-logistic and lognormal). The Weibull, gamma and 'log-logistic distributions' which represent the three distinct asymptotic hazard behaviors, all fit the data as well as the generalized F distribution at the 25 percent significance level. Hence, we conclude that incubation data is still too limited to ascertain the specific hazard assumption that should be utilized in studies of the AIDS epidemic. Accordingly, efforts to model the AIDS epidemic (e.g., back-calculation approaches) should allow the incubation distribution to take several forms to adequately represent HIV estimation uncertainty. It is recommended that, at a minimum, the specific Weibull, gamma and log-logistic distributions estimated in this meta-analysis should all be used in modeling the AIDS epidemic, to reflect this uncertainty.

Lawrence E. Myers

Papers

Effects of diflubenzuron (Dimilin) on survival, molting, and behavior of juvenile fiddler crabs, Uca pugilator.

A meta-analysis of estimates of the AIDS incubation distribution