Future issues in HIV/AIDS surveillance.

Public health surveillance for human immunodeficiency virus (HIV) seeks to define and quantity the spectrum of HIV risk, infection, and disease at the local, state, and national levels. Reporting of cases of acquired immunodeficiency syndrome (AIDS) or HIV and seroepidemiologic surveys are the primary methods. In selected areas, this infrastructure supports supplemental systems that address issues of risk or infection beyond the scope of routine surveillance. Future concerns include maintaining the basic HIV/AIDS surveillance infrastructure, maintaining flexibility to meet emerging needs, improving surveillance for incident infections and risk behaviors, and enhancing the capacity of community-based groups to use surveillance data in setting priorities for prevention and care.     

Diagnosis and reporting of HIV and AIDS in states with HIV/AIDS surveillance--United States, 1994-2000

Before advances in therapy, public health surveillance of acquired immunodeficiency syndrome (AIDS) provided reliable population-based information that represented trends in the incidence of human immunodeficiency virus (HIV) infection. However, since 1996, highly active antiretroviral therapy (HAART) has prolonged substantially the interval between the diagnosis of HIV infection and the development of AIDS, which has diminished the capacity of AIDS surveillance alone to monitor the underlying patterns of HIV transmission. As a result, CDC recommends that states conduct HIV-infection reporting in addition to AIDS surveillance. This report describes trends in newly diagnosed cases of HIV infection in 25 states that conducted name-based HIV/AIDS surveillance during 1994-2000. The findings indicate that the number of diagnosed HIV infections declined in these states during 1994-1997 and remained constant during 1998-2000. HIV/AIDS surveillance should be conducted by all states to fully characterize persons infected with HIV who need treatment and prevention services.     

广西某县HIV现场监测与定点监测的流行病学特征研究

目的 探讨现场监测与定点监测发现人类免疫缺陷病毒（human immunodeficiency virus, HIV）阳性人群的流行病学特征,为有效发现HIV阳性病例提供防治依据。方法 在广西艾滋病高发区选择某县,获取2013年1月1日～2014年3月31日发现报告的HIV阳性数据（定点监测）,同期对当地常住人口进行现场HIV抗体检测同时收集相关信息（现场监测）。运用对应分析法分析两种疾病监测方式下发现的HIV阳性人群流行病学特征间的关联性。结果 现场监测214 586人,发现阳性1 195例,发现率0.56%（1 195/214 586）;定点监测151 365人,发现阳性584例,发现率0.39%（584/151 365）,现场监测发现率高于定点监测（χ2=53.69,P<0.001）;对应分析显示,现场监测更容易发现“年龄在55～岁、文盲/小学文化、农村、异性传播、HIV感染者和CD4细胞计数≥200（个/mm3）”的特征人群;定点监测更容易发现“30～岁、初中高中及以上文化、城镇、艾滋病、其他传播途径和CD4细胞计数<200（个/mm3）”的特征人群。结论 实施现场监测有利于发现非病症感染者,老年人群、低文化程度和农村人群是HIV感染的重点高危人群。     

Investigating interactions between HIV infection and tropical diseases

The health of developing country populations in Africa where there is a high incidence of human immunodeficiency virus (HIV) infection is already seriously compromised by malnutrition and endemic diseases such as tuberculosis. Not only may HIV infection compromise currently used methods for the treatment of tropical diseases, but there may be a synergistic relationship between HIV and other diseases. Epidemiologic studies are thus needed to identify and quantify and such interactions. At present, evidence of such interactions may be limited by the fact that tropical diseases are most prevalent in rural areas while HIV cases have so far been concentrated in urban areas. However, any unexplained rise in the incidence or severity of a specific disease in areas where HIV is prevalent should be investigated as a possible interaction effect. Likewise, if the progression from HIV infection to acquired immunodeficiency syndrome (AIDS) seems to be occurring particularly rapidly in an area, AIDS patients should be examined for the presence of other diseases that may be triggering AIDS. Possible interactions between HIV infection and tropical diseases can be set forth in a schematic form in which both are divided into 3 infection states--uninfected, infected without clinical symptoms, and infected and diseases--and arrows are used to represent the transitions between states and possible interactions.     

A Bayesian hierarchical model with novel prior specifications for estimating HIV testing rates

Human immunodeficiency virus (HIV) infection is a severe infectious disease actively spreading globally, and acquired immunodeficiency syndrome (AIDS) is an advanced stage of HIV infection. The HIV testing rate, that is, the probability that an AIDS‐free HIV infected person seeks a test for HIV during a particular time interval, given no previous positive test has been obtained prior to the start of the time, is an important parameter for public health. In this paper, we propose a Bayesian hierarchical model with two levels of hierarchy to estimate the HIV testing rate using annual AIDS and AIDS‐free HIV diagnoses data. At level one, we model the latent number of HIV infections for each year using a Poisson distribution with the intensity parameter representing the HIV incidence rate. At level two, the annual numbers of AIDS and AIDS‐free HIV diagnosed cases and all undiagnosed cases stratified by the HIV infections at different years are modeled using a multinomial distribution with parameters including the HIV testing rate. We propose a new class of priors for the HIV incidence rate and HIV testing rate taking into account the temporal dependence of these parameters to improve the estimation accuracy. We develop an efficient posterior computation algorithm based on the adaptive rejection metropolis sampling technique. We demonstrate our model using simulation studies and the analysis of the national HIV surveillance data in the USA. Copyright © 2015 John Wiley & Sons, Ltd.     

Increases in HIV diagnoses--29 States, 1999-2002

Since the advent of highly active antiretroviral therapy (HAART) in 1996, progression from receiving diagnosis of human immunodeficiency virus (HIV) infection to having acquired immunodeficiency syndrome (AIDS) has slowed substantially, making HIV-transmission patterns less predictable through AIDS surveillance alone. Consequently, CDC has recommended that states report diagnoses of HIV infections in addition to cases of AIDS. Recent estimates of HIV diagnoses suggested a leveling of the downward trend in HIV infections nationally and increases in HIV infections among certain populations. Reports of syphilis outbreaks and increased unprotected sex raised concerns regarding increases in HIV transmission among men who have sex with men (MSM). In response to these developments, CDC analyzed trends in HIV diagnoses in 29 states that conducted name-based HIV/AIDS surveillance during 1999-2002. This report summarizes the results of that study, which indicated that HIV diagnoses increased among men, particularly MSM, and also among non-Hispanic whites and Hispanics. The findings emphasize the need for new prevention strategies to reverse potential increases in HIV transmission among these populations.     

Projections of HIV infections and AIDS cases to the year 2000

After the recognition of AIDS (acquired immunodeficiency syndrome) in the early 1980s, uncertainty about the present and future dimensions of HIV (human immunodeficiency virus) infection led to the development of many models to estimate current and future numbers of HIV infections and AIDS cases. The Global Programme on AIDS (GPA) of the World Health Organization (WHO) has developed an AIDS projection model which relies on available HIV seroprevalence data and on the annual rate of progression from HIV infection to AIDS for use in areas where reporting of AIDS cases is incomplete, and where scant data are available to quantify biological and human behavioural variables. Virtually all models, including the WHO model, have projected large increases in the number of AIDS cases by the early 1990s. Such short-term projections are considered relatively reliable since most of the new AIDS cases will develop in persons already infected with HIV. Longer-term prediction (10 years or longer) is less reliable because HIV prevalence and future trends are determined by many variables, most of which are still not well understood. WHO has now applied the Delphi method to project HIV prevalence from the year 1988 to mid-2000. This method attempts to improve the quality of the judgements and estimates for relatively uncertain issues by the systematic use of knowledgeable "experts". The mean value of the Delphi projections for HIV prevalence in the year 2000 is between 3 and 4 times the 1988 base estimate of 5.1 million; these projections have been used to obtain annual estimates of adult AIDS cases up to the year 2000. Coordinated HIV/AIDS prevention and control programmes are considered by the Delphi participants to be potentially capable of preventing almost half of the new HIV infections that would otherwise occur between 1988 and the year 2000. However, more than half of the approximately 5 million AIDS cases which are projected for the next decade will occur despite the most rigorous and effective HIV/AIDS prevention efforts since these AIDS cases will develop in persons whose HIV infection was acquired prior to 1989. The Delphi projections of HIV infection and AIDS cases derived from the WHO projection model need to be periodically reviewed and modified as additional data become available. These projections should be viewed as the first of many attempts to develop estimates for planning strategies to combat the HIV/AIDS pandemic in the 1990s.     

Trends in HIV/AIDS diagnoses--33 states, 2001-2004

In 2003, more than 1 million persons in the United States were estimated to be living with human immunodeficiency virus (HIV) infection. As a result of advances in treatment with highly active antiretroviral therapy (HAART) since 1996, persons infected with HIV are living longer than before and progression to acquired immunodeficiency syndrome (AIDS) has decreased. Consequently, AIDS surveillance no longer provides accurate population-based monitoring of the current HIV epidemic. Therefore, CDC recommends that all states and territories adopt confidential, name-based surveillance systems to report HIV infection. This report describes the characteristics of persons for whom HIV infection was diagnosed during 2001-2004 and reported to 33 state and local health departments with name-based HIV reporting. The findings indicate that the rate of HIV diagnosis in these states decreased among non-Hispanic blacks from 2001 to 2004; however, the rate of HIV diagnosis among blacks remained disproportionately high. In 2004, the rate among blacks was 8.4 times higher than among whites. Improved knowledge of HIV status and access to care and prevention services is important to decrease the number of new HIV infections among those populations most affected.     

The Global HIV/AIDS pandemic, 2006

Since the first cases of acquired immunodeficiency syndrome (AIDS) were reported in 1981, infection with human immunodeficiency virus (HIV) has grown to pandemic proportions, resulting in an estimated 65 million infections and 25 million deaths. During 2005 alone, an estimated 2.8 million persons died from AIDS, 4.1 million were newly infected with HIV, and 38.6 million were living with HIV. HIV continues to disproportionately affect certain geographic regions (e.g., sub-Saharan Africa and the Caribbean) and subpopulations (e.g., women in sub-Saharan Africa, men who have sex with men [MSM], injection-drug users [IDUs], and sex workers). Effective prevention and treatment of HIV infection with antiretroviral therapy (ART) are now available, even in countries with limited resources. Nonetheless, comprehensive programs are needed to reach all persons who require treatment and to prevent transmission of new infections.     

Impact of the human immunodeficiency virus epidemic on mortality trends in young men, United States.

Following a long-term decline, death rates in men 25-44 years of age increased from 212 deaths/100,000 in 1983 to 236 deaths/100,000 in 1987. To assess the impact of human immunodeficiency virus (HIV) infections on this trend and to identify causes that are increasing in association with the HIV epidemic, we analyzed national mortality statistics and compared death rates in states with high and low incidence of acquired immunodeficiency syndrome (AIDS). In 1987, there were 10,248 deaths with HIV infection, AIDS, or conditions in the AIDS surveillance definition assigned as the underlying cause, representing 11 percent of deaths for men in this age group compared to less than 1 percent in 1980. In addition, deaths with other underlying causes, such as other infections, drug abuse, and unknown/unspecified causes, had diverging and higher rates in states with high versus low AIDS incidence. In the absence of deaths due to HIV/AIDS and excess deaths due to these associated conditions, we estimate that death rates for men 25-44 years of age would have been 201-209/100,000 in 1987. For 1987, approximately 70-90 percent of HIV-related deaths were reported through national AIDS surveillance. The HIV epidemic has led to a reversal in mortality trends and to increases in various causes of death for young men.     

A short term projection of HIV infection and AIDS cases in Cameroon.

By September 1991 Cameroon had reported 650 cases of the acquired immune deficiency syndrome (AIDS). The results from the sentinnel surveillance system showed a seroprevalence of human immunodeficiency virus (HIV)1 of 1.3% among pregnant women, 2.5% in people attending sexually transmitted disease clinics and 3.5% in tuberculosis patients in 1990. The estimated number of persons infected with HIV varies between 10,000 and 30,000. The World Health Organization projection model was used to make a short-term projection of HIV infection and AIDS cases; it indicated that the number of persons infected with HIV will double by the year 1995, with an estimated 8500 AIDS cases. Even in a low prevalence country such as Cameroon, the impact of the HIV epidemic is important and will result in a burden for the health care system.     

HIV-2 Infection Surveillance--United States, 1987-2009

Human immunodeficiency virus (HIV) is categorized into two types, HIV-1 and HIV-2. Worldwide, most HIV infections are HIV-1, whereas HIV-2 largely has been confined to persons in or from West Africa. HIV-1 and HIV-2 have the same routes of transmission, and both can cause acquired immunodeficiency syndrome (AIDS); however, HIV-2 infections should be differentiated from HIV-1 infections because they are less likely to cause AIDS and their clinical management differs. CDC's current surveillance case definition for HIV infection applies to both variants of HIV but lacks criteria for differentiating between HIV-1 and HIV-2. To enumerate and describe HIV-2 cases reported in the United States, a working case definition was developed. During 1988--June 2010, a total of 242 HIV-2 cases were reported to CDC. Of these, 166 met the working definition. These HIV-2 cases were concentrated in the Northeast (66%, including 46% in New York City) and occurred primarily among persons born in West Africa (81%). Ninety-seven of the HIV-2 cases also had a positive HIV-1 immunoblot antibody test result (e.g., Western blot). Immunoblot antibody tests currently used to confirm HIV reactive screening tests do not contain reagents specific to HIV-2 and thus are not reliable for identification of HIV-2 infections. Additional testing specific to HIV-2 should be considered if HIV-1 test results are atypical or inconsistent with clinical findings, especially for persons from West Africa. If an HIV case is reported to the health department but subsequently identified as HIV-2, health-care providers should update the case report to reflect the correct type.     

Epidemiology of reported cases of AIDS in lesbians, United States 1980-89.

National surveillance data for reported cases of acquired immunodeficiency syndrome (AIDS) were used to assess demographic characteristics and behavioral risk factors in lesbians. From June 1, 1980 through September 30, 1989, 79 women with AIDS reported sex relations only with a female partner; most of these women (95 percent) were intravenous drug users. Prevention of human immunodeficiency virus (HIV) infection in the lesbian community will require efforts to prevent and reduce intravenous drug use.     

Estimating HIV incidence in the United States from HIV/AIDS surveillance data and biomarker HIV test results

The development of an human immunodeficiency virus (HIV) test that detects recent infection has enabled the U.S. Centers for Disease Control and Prevention (CDC) to estimate annual HIV incidence (number of new infections per year, not per person at risk) in the United States from data on new HIV and acquired immunodeficiency syndrome (AIDS) diagnoses reported to HIV/AIDS surveillance. We developed statistical procedures to estimate the probability that an infected person will be detected as recently infected, accounting for individuals choosing whether and how frequently to seek HIV testing, variation of testing frequency, the reporting of test results only for infected persons, and infected persons who never had an HIV-negative test. The incidence estimate is the number of persons detected as recently infected divided by the estimated probability of detection. We used simulation to show that, under the assumptions we make, our procedures have acceptable bias and correct confidence interval coverage. Because data on the biomarker for recent infection or on testing history were missing for many persons, we used multiple imputation to apply our models to surveillance data. CDC has used these procedures to estimate HIV incidence in the United States.     

Numbers of people with HIV/AIDS reported and not reported to surveillance in Japan

BACKGROUND: Trends in the numbers of Japanese patients with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) reported to the HIV/AIDS surveillance system in Japan were examined. We attempted to estimate the cumulative number of Japanese with HIV, including people with HIV not reported to the surveillance. METHODS: Data from the HIV/AIDS surveillance in Japan up to the end of 2002 were available. The number of unreported HIV cases was estimated using the back-calculation method. To evaluate this method, the number of reported HIV cases up to 1996 (before highly active antiretroviral treatments were widely available in Japan) was compared with the number estimated by the same method. RESULTS: The number of AIDS cases who were initially reported as having AIDS without having been reported as HIV-infected markedly increased as did the number of reported HIV cases. The number of AIDS cases who had been initially reported as HIV-infected and who were then reported as AIDS progression increased up to 1996 but decreased in the period of 1997-2002. The cumulative number of people with HIV at the end of 2002 was estimated as 14,000, which was 4.2 times higher than the number of reported HIV cases. The cumulative number of HIV cases reported up to 1996 was nearly equal to the number estimated by the above-mentioned method. CONCLUSIONS: HIV infection would appear to be spreading widely among Japanese population. The number of HIV cases actually reported to surveillance might still be low.     

Second-generation HIV surveillance: better data for decision-making

This paper seeks to outline the key elements of the expanded surveillance efforts recommended by the second-generation HIV surveillance approach. Second-generation systems focus on improving and expanding existing surveillance methods and combine them in ways that have the greatest explanatory power. The main elements of this approach include: considering biological surveillance - HIV, AIDS, sexually transmitted infections (STIs) - and behavioural surveillance as integral components, targeting surveillance efforts at segments of the population where most new infections are concentrated - which might differ depending on the stage and type of the epidemic - and providing the rationale for the optimal use of data generated for monitoring the HIV epidemic and evaluating national AIDS control programmes. The paper emphasizes improvements in existing surveillance methodologies and discusses in detail crucial issues such as the validity of HIV prevalence data measured in pregnant women and linking HIV surveillance and behavioural data collection. In addition, a strategic partnership between second-generation surveillance and AIDS programme evaluation is proposed that stresses the complementary roles of these data collection activities in determining the effectiveness of prevention and care programmes and explaining the epidemiological trend data collected by sentinel serosurveillance systems. In conclusion, second-generation HIV surveillance systems provide a comprehensive, cost-effective and appropriate response to the information needs of AIDS control programmes. The implementation of such systems, including a better use of the data generated by the system, will ensure that national programmes are in the best possible position to respond to the challenges of the epidemic.     

Routine surveillance data on AIDS and HIV infections in the UK: a description of the data available and their use for short-term planning

In the UK surveillance of AIDS and HIV infection is based on routine reporting systems. Whilst attempts are made to ensure that AIDS data are as complete as possible, numbers of reports fluctuate from month to month for reasons which are described. In 1986 there was an increase in death certificates naming AIDS as a cause of death in patients who were not identifiable in the surveillance data. More active surveillance is now undertaken in order to minimize this and other possible discrepancies. It is probable that most cases of AIDS are reported and therefore these data can be used to describe trends in the epidemic by 'risk group'. Laboratory reports of HIV antibody-positive tests could give an earlier indication of trends because of the long incubation period of AIDS. But these laboratory data are difficult to interpret because they represent an incomplete and biased sample of all positive persons. AIDS cases are still being reported at a rate which is increasing approximately exponentially. Short-term predictions are presented showing a growth in the epidemic which is consistent with previously published predictions. Most cases are in the homosexual risk group. New asymptomatic homosexual patients with HIV antibody are still being identified. The epidemic of AIDS in haemophilia patients should be of finite size although new cases of AIDS are likely to continue to be diagnosed for several years. AIDS due to blood transfusion given in the UK before donor screening appears to be a much smaller epidemic. The epidemic in drug abusers is increasing. Heterosexually acquired AIDS and HIV infections are being reported in small but increasing numbers.     

Identifying newly acquired cases of hepatitis C using surveillance: a literature review

SUMMARY Surveillance of newly acquired hepatitis C virus (HCV) infection is crucial for understanding the epidemiology of HCV and informing public health practice. However, monitoring such infections via surveillance systems is challenging because they are commonly asymptomatic. A literature review was conducted to identify methodologies used by HCV surveillance systems to identify newly acquired infections; relevant surveillance systems in 15 countries were identified. Surveillance systems used three main strategies to identify newly acquired infections: (1) asking physicians to classify cases; (2) identifying symptomatic cases or cases with elevated alanine aminotransferases; and (3) identifying cases with documented evidence of anti-HCV antibody seroconversion within a specific time-frame. Case-ascertainment methods varied with greater completeness of data in enhanced compared to passive surveillance systems. Automated systems that extract and link testing data from multiple laboratory and clinic databases may provide an opportunity for collecting testing histories for individuals that is less resource intensive than enhanced surveillance.     

An age- and sex-structured HIV epidemiological model: features and applications.

An important challenge in modelling the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) epidemic is to use the increasing quantity of disease surveillance data to validate estimates and forecasts. Presented is a novel model for forecasting HIV incidence by age and sex and among sentinel groups for which data are available. This approach permits a closer relationship between forecasting and surveillance activities, and more accurate estimates validated to data. As inputs the model uses an estimate of the HIV prevalence, country demographic data, and a profile of the sexual risk of HIV infection by age, to project HIV incidence, prevalence, number of AIDS cases and population. The following examples of the use of the model are given: forecasting HIV incidence in East Africa, by age, sex, and among pregnant women; 3-5-year forecasts of HIV incidence; modelling mixed risk behaviour HIV epidemics in South-east Asia; demographic indicators; and targeting a preventive vaccine by age group.     

Occupationally acquired human immunodeficiency virus (HIV) infection: national case surveillance data during 20 years of the HIV epidemic in the United States.

OBJECTIVE: To characterize occupationally acquired human immunodeficiency virus (HIV) infection detected through case surveillance efforts in the United States. DESIGN: National surveillance systems, based on voluntary case reporting. SETTING: Healthcare or laboratory (clinical or research) settings. PATIENTS: Healthcare workers, defined as individuals employed in healthcare or laboratory settings (including students and trainees), who are infected with HIV. METHODS: Review of data reported through December 2001 in the HIV/AIDS Reporting System and the National Surveillance for Occupationally Acquired HIV Infection. RESULTS: Of 57 healthcare workers with documented occupationally acquired HIV infection, most (86%) were exposed to blood, and most (88%) had percutaneous injuries. The circumstances varied among 51 percutaneous injuries, with the largest proportion (41%) occurring after a procedure, 35% occurring during a procedure, and 20% occurring during disposal of sharp objects. Unexpected circumstances difficult to anticipate during or after procedures accounted for 20% of all injuries. Of 55 known source patients, most (69%) had acquired immunodeficiency syndrome (AIDS) at the time of occupational exposure, but some (11%) had asymptomatic HIV infection. Eight (14%) of the healthcare workers were infected despite receiving postexposure prophylaxis (PEP). CONCLUSIONS: Prevention strategies for occupationally acquired HIV infection should continue to emphasize avoiding blood exposures. Healthcare workers should be educated about both the benefits and the limitations of PEP, which does not always prevent HIV infection following an exposure. Technologic advances (eg, safety-engineered devices) may further enhance safety in the healthcare workplace.