Molecular epidemiology of hepatitis B virus infections in Denmark.

BACKGROUND: Denmark has a low incidence of acute hepatitis B (HBV) infections but the impact of an increasing number of immigrants with chronic HBV infection on HBV transmission is unknown. OBJECTIVES: To characterise individuals with chronic and acute HBV infection in a defined region and to examine the importance of different risk groups for the current HBV transmission. METHODS: During 2000-2001 all consecutive HBV infected individuals routinely diagnosed through the regional HBV serology laboratory in the County of Funen were classified according to ethnicity, presumed route of transmission and stage of infection based on clinical data mainly supplied by the requesting physician. HBV DNA was sequenced and subjected to phylogenetic analysis. RESULTS: Of 309 identified cases, 91 (29%) were classified as acute infection. HBV DNA sequencing was possible in 54 (59%) of these cases. Phylogenetic analysis showed that HBV isolated from injecting drug users (IDUs) was identical or closely related. Among acute cases acquired in Denmark 89% (74/83) were seen in IDUs (65) or in individuals presumably exposed to IDUs (nine) and phylogenetic analysis corroborated the assumption of IDU related transmission in every case with available sequence data. Among 83 ethnic Danes who acquired their HBV infection in Denmark, no new cases of transmission from immigrants were detected. CONCLUSION: Injecting drug use was the single most important factor for hepatitis B transmission in Denmark. The current Danish vaccination strategy is unable to protect IDUs from HBV infection and IDUs pose a greater risk of HBV transmission to the general population than immigrants.     

Molecular epidemiology of acute hepatitis B in the Netherlands in 2004: nationwide survey

To gain insight into hepatitis B virus (HBV) transmission in the Netherlands, epidemiological data and sera were collected from reported cases of acute HBV infections in the Netherlands in 2004. Cases were classified according to mode of transmission. A fragment of the S-gene of HBV (648 bp) was amplified, sequenced, and subjected to phylogenetic analysis. Of the 291 acute HBV cases reported in 2004, 158 (54%) were available for genotyping. Phylogenetic analysis identified 6 genotypes: A (64%), B (3%), C (3%), D (21%), E (5%) and F (5%). Of HBV infected men having sex with men, 86% were infected with genotype A, accounting for 43% of all patients infected with this genotype. There were only three reported cases of injecting drug use of which one was available for sequencing (genotype A). Unlike the genotype A cluster, sequences within the genotype B-E clusters were heterogenic. Within genotype F, several isolates had identical sequences, but patients could not be epidemiologically linked. Sexual transmission, particularly by men having sex with men was the most important transmission route for HBV. Injecting drug use plays a minor role. Genotype A is predominant in the Netherlands, especially among men having sex with men. In addition to imported strains, there seems to be a pool of related but non-identical strains circulating among chronic carriers in the migrant population, from which occasionally new patients are infected, primarily by heterosexual transmission.     

Molecular epidemiology of a large community-based outbreak of hepatitis B in Bristol, UK

Background

A large outbreak of hepatitis B virus (HBV) infection in the UK occurred between 2001 and 2005 in Bristol, UK.

Objectives

To identify HBV strains circulating amongst risk groups in the HBV outbreak cohort.

Study design

Cross-sectional study of acute HBV outbreak cases in Bristol.

Results

HBV sequences from sera of 95 of the 237 cases (40%) were characterised. The majority of cases (77%) were found to carry an HBV variant belonging to genotype D, designated HBV^BV. Eighty-eight percent (36/41) of sequences from injection drug users were HBV^BV as were 70% (19/27) from those with heterosexual intercourse as the primary identified risk factor. Of 15 sequences characterised from cases of pre-outbreak acute or chronic hepatitis B residing in Bristol, 40% also carried HBV^BV; the earliest was from a case identified in 1994.

Conclusion

The findings from this study link the spread of HBV^BV from injecting drug users to the general population through heterosexual intercourse during the outbreak. The molecular sequencing of specimens from this outbreak reports the emergence of HBV^BV, a HBV strain circulating in Bristol and South West England, as the cause of one of the largest outbreaks of acute hepatitis B in the UK.     

Two decades of hepatitis B infections among drug users in Amsterdam: Are they still a high‐risk group?

In general, little is known about the incidence of hepatitis B virus (HBV) among drug users, especially among non‐injecting drug users. Therefore, changes in incidence, risk factors, and circulating genotypes over time were determined among drug users in Amsterdam over an 18‐year period (1985–2002). Sera of 1,268 drug users, both injecting and non‐injecting, were screened for anti‐HBc. HBV genotypes of the anti‐HBc seroconverters were determined. Poisson regression was used to test for temporal trends in incidence and to identify risk factors for seroconversion. Of the 598 participants who were anti‐HBc negative at entry, 83 seroconverted for anti‐HBc. The incidence of HBV declined from 5.9/100 Person Years up to 1993 to 0/100 Person Years in 2002. Of the drug users infected acutely, both injecting and non‐injecting, 88% were infected with the same genotype D, serotype ayw3 strain. Multivariate analyses revealed current injecting, age, and calendar year of visit as independent risk factors. The decline in the incidence of HBV among drug users in Amsterdam is probably caused by a decline in injecting behavior. Injecting and non‐injecting drug users were infected with the same strain, indicating that drug users infect one another, regardless of their risk behavior. After 2000, no injecting drug users with an acute HBV infection were reported to the Public Health Service Amsterdam and the specific genotype D strain had disappeared. These findings suggest that drug users may no longer be a high‐risk group for HBV infection in Amsterdam. However, trends in drug use need to be monitored. J. Med. Virol. 81:1163–1169, 2009. © 2009 Wiley‐Liss, Inc.     

Transmission of hepatitis B in Hamburg,Germany, 1998–2002: a prospective,population-based study

To study the pattern of transmission of HBV in a large urban community, an in-depth prospective study was performed in Hamburg between 1 January 1998 and 31 December 2002. In total, 524 patients were classified as hepatitis B cases according to the case definition of the Robert Koch Institute, comprising 197 foreign-born and 327 German-born persons. The principal risk factor was parenteral drug use, with 17.7% (n=93/524) of all documented cases of hepatitis B, followed by immigration as refugees (13.9%; n=73). Of all 524 cases, 72 (13.7%) were associated with heterosexual (n=41) or homosexual (n=31) transmission. Household contacts of HBV carriers or of patients with acute infectious disease contributed to 9.0% of the cases (n=47). Medical procedures were most probably the source in 7.4% (n=39), although only 3.2% (n=17) of all patients were health-care workers. In multivariate analysis of household contacts, male–male sexual activity was found to be the greatest risk factor for acquiring an acute HBV infection, followed by asylum-seeking status and the number of contacts. The incidence was 3.5-fold higher among foreign-born persons (16.1 per 100,000) than among German-born individuals (4.5 per 100,000) suggesting that a targeted intervention in this population group is a public-health need. The current national policy of vaccination in defined age groups should be extended to the immunization of all children of foreign-born parents as well as the screening and immunisation of susceptible foreign-born adults.     

Hepatitis B virus infection in a group of heterosexuals with multiple partners in Amsterdam,The Netherlands: Implications for vaccination?

The aim of the study was to assess prevalence and incidence of hepatitis B virus (HBV) infection among heterosexual men and women with multiple partners attending a sexually transmitted disease (STD) clinic and to establish risk factors of HBV infection in order to consider immunisation for those subjects. A prospective study of heterosexual men and women selected on having multiple partners and presenting to an STD clinic as new patients was carried out from October 1987 through December 1989. Follow-up continued until December 1990 at the STD clinic of the Municipal Health Service of Amsterdam. Five hundred ninety-eight men and women entered the study. More than 70% of both women and men had had commercial sexual partners in the last 5 years. Three hundred eighty-one participants were born in HBV low endemic countries, 205 came from HBV intermediate endemicity regions. The prevalence of HBV markers in both men and women from low endemic regions was 10%, and for men and women from middle endemic regions 42% and 19%, respectively. Logistic regression analysis showed that number of years involved in commercial sex was an independent risk factor in male participants from HBV low endemic regions (odds ratio [OR] 1.10 per year) and for women sexual contact with men at high risk of HBV infection (OR 2.59). In people from middle endemic regions more men than women had HBV markers, HBV-positive men were older than HBV-negatives (OR 1.05 per year), and for HBV-positive women the number of years involved in commercial sex was an independent predictor (OR 1.23 per year). No new cases of HBV infection were found in both groups (upper 95% limit of confidence 7.1 per 1,000 and 35.8 per 1,000 for the participants from low and middle endemic countries, respectively). The duration of follow-up was 419.9 person-years at risk for the group from low endemic regions and 83.7 person-years for the people from middle endemic regions. The participants must be considered to have been at continuous high risk of heterosexual transmission. The incidence of HBV was so tow that we decided for the moment not to offer hepatitis B vaccination to all heterosexual men and women attending our STD clinic. © 1994 Wiley-Liss, Inc.     

Hepatitis C infection among intravenous drug users attending therapy programs in Cyprus

The most high‐risk population for HCV transmission worldwide today are intravenous drug users. HCV genotypes in the general population in Cyprus demonstrate a polyphyletic infection and include subtypes associated with intravenous drug users. The prevalence of HCV, HBV, and HIV infection, HCV genotypes and risk factors among intravenous drug users in Cyprus were investigated here for the first time. Blood samples and interviews were obtained from 40 consenting users in treatment centers, and were tested for HCV, HBV, and HIV antibodies. On the HCV‐positive samples, viral RNA extraction, RT‐PCR and sequencing were performed. Phylogenetic analysis determined subtype and any relationships with database sequences and statistical analysis determined any correlation of risk factors with HCV infection. The prevalence of HCV infection was 50%, but no HBV or HIV infections were found. Of the PCR‐positive samples, eight (57%) were genotype 3a, and six (43%) were 1b. No other subtypes, recombinant strains or mixed infections were observed. The phylogenetic analysis of the injecting drug users' strains against database sequences observed no clustering, which does not allow determination of transmission route, possibly due to a limitation of sequences in the database. However, three clusters were discovered among the drug users' sequences, revealing small groups who possibly share injecting equipment. Statistical analysis showed the risk factor associated with HCV infection is drug use duration. Overall, the polyphyletic nature of HCV infection in Cyprus is confirmed, but the transmission route remains unknown. These findings highlight the need for harm‐reduction strategies to reduce HCV transmission. J. Med. Virol. 82:263–270, 2010. © 2009 Wiley‐Liss, Inc.     

柳州市2008年新报告HIV/AIDS流行病学分析

目的 了解柳州市2008年新发现HIV阳性者流行病学特征,为今后制定艾防政策提供依据。方法 对全国艾滋病综合防治管理系统中2008年柳州市报告的553例HIV阳性者,其＂艾滋病个案流行病学调查表＂进行整理分析。结果 2008年新报告553例HIV阳性者,其中64.6%是感染者,柳州市本地人占28.8%,大部分是其他县区人（61.7%）;年龄最小4岁,最大77岁,50岁以上达22.2%;553例中有5个儿童,2人在幼托,3人散居;31.5%为家政、家务及待业者,8%是离退休人员;58.6%已婚有配偶;经异性传播56.4%,经注射毒品血液传播17.4%。结论 柳州市艾滋病疫情形势严峻,三种传播途径并存,异性传播已经超过吸毒传播而成为主要传播途径;已婚有配偶者居多,出现多例老年病例,疫情有向一般人群扩散的趋势。     

Outbreaks of hepatitis A in England and Wales associated with two co-circulating hepatitis A virus strains

During 2002, an upsurge in frequency of hepatitis A outbreaks among injecting drug users was observed in England and Wales. As lack of risk factor information and the high mobility of the cases made linkage of outbreaks difficult, the relationship of nucleotide sequences in the VP1/2PA junction of the hepatitis A virus (HAV) genome amplified from serum of case-patients was investigated. A total of 204 HAV RNA positive sera obtained from a network of 23 laboratories were studied. Comparison of the sequences identified two principal strains: ES1 (n=95) belonging to type IB, and ES2 (n=72) to type IIIA. Of the remaining samples, 15 were type IA, 11 were type IB and 11 were type IIIA. ES1 predominated in Doncaster and other towns in Trent and northern England, and ES2 in the Midlands and southern England; the difference in geographical distribution between these two strains was significant (P<0.0001). In comparison to the sporadic cases, cases infected by either ES1 or ES2 tended to be younger, injecting drug users, people in contact with injecting drug users, or those with a history of incarceration in prisons or homelessness (P<0.0001). Cases infected by ES1 tended to be younger than those by ES2 (P<0.0001). The association of the outbreaks to two geographically restricted strains implicates two principal transmission pathways associated with injecting behavior. Identifying these routes may be conducive to preventing further outbreaks.     

Molecular epidemiology of hepatitis B virus in Amsterdam 1992-1997.

To gain insight into the spread of hepatitis B among various risk groups in Amsterdam a 6-year (1992-1997) retrospective DNA sequencing study was carried out on isolates from stored sera from reported primary cases of acute hepatitis B infection. Cases were classified according to risk behavior, as determined in interviews. Of the available serum, a selected region of hepatitis B-virus-DNA was amplified and sequenced. The nucleotide alignments were subjected to phylogenetic tree analysis. When nucleotide alignments were subjected to phylogenetic analysis, the strains of 54 isolates, 26% of the 204 reported primary cases, clustered in five genotypes: A, C, D, E, and F. In genotype A, a cluster related to men having sex with men was identified. In genotype D, two subclusters could be identified: one was related to injecting drug use and another was related to the Moroccan population in Amsterdam. The remaining strains showed a high genetic variability within three different genotypes: F, E, and C. Of the 14 identical isolates in the "homosexual men cluster," one was isolated from a female heterosexual. Of the 14 identical strains in the "drug users strain," six were from non-drug using heterosexual active individuals. In the cluster of twelve isolates related to hepatitis B-endemic areas, probable modes of transmission were varied. Sequence analysis provides important insight into the spread of hepatitis B among various high-risk groups. The analysis indicates that the prevention strategy in The Netherlands fails to stop transmission of hepatitis B from persistently infected individuals originating from hepatitis B endemic countries.     

Clinical features of acute retroviral syndrome differ by route of infection but not by gender and age

The rate of HIV disease progression is associated with the severity of the acute retroviral syndrome (ARS). We explored the clinical features of ARS by gender, age and route of infection among 378 individuals with documented ARS enrolled in 5 prospective cohort studies with similar enrollment criteria. No major differences were detected by gender or by age. Several symptoms were reported less frequently in the injecting drug users as compared with infection acquired through sexual contacts (either heterosexual or homosexual). This was observed in particular for fever (50% vs. 77%, p=.001), skin rash (21% vs. 51%, p=.001), pharyngitis (18% vs. 43%, p=.004), and myalgia (29% vs. 52%, p=.01). Genital ulcerations were present only in cases of sexual exposure to HIV. Injecting drug users had or reported symptoms associated with the ARS less frequently than persons acquiring HIV via sexual transmission.     

Prevalence and associated clinical characteristics of hepatitis B,C, and HIV infections among injecting drug users in Korea

Injecting drug use is associated with an increased risk of blood‐borne viral infections, such as hepatitis B and C viruses (HBV and HCV, respectively) and human immunodeficiency virus (HIV). However, their prevalence, virological characteristics, and associated factors are not clear among the injecting drug users in Korea. The aim of this study was to determine the prevalence of HBV, HCV, and HIV infection, as well as their virological and clinical characteristics of injecting drug users in South Korea. Between 2007 and 2010, 318 injecting drug users (89.3% male; mean ± age 41.9 ± 8.15 years) were participated. While HIV infection was not found, the seroprevalence of anti‐HCV and HBV surface antigen (HBsAg) was 48.4% (n = 154) and 6.6% (n = 21), respectively. HBV/HCV co‐infection was found in 4.1% (n = 13). Occult HBV infection was suggested in 5.0% (n = 16). Among the HCV genotypes, 1b (37.7%) and 2a/2c (35.7%) were mostly often detected. HCV RNA was detected in 98.1% (n = 151/154) and high‐level viremia (HCV RNA level, ≥400,000 IU/ml) were observed in 59.6% (n = 90/151). In multiple logistic regression analysis, old age (OR 1.18 per year, 95% CI = 1.09–1.27) and ever‐sharing injecting equipment (OR 4.17, 95% CI = 1.39–12.45) independently predicted HCV mono‐infection. The prevalence of HBV and HCV infection were high but largely undiagnosed in the present sample of Korean injecting drug users. Strategic prevention, screening, and treatment are needed to reduce further transmission and morbidity. J. Med. Virol. 85:575–582, 2013. © 2013 Wiley Periodicals, Inc.     

Epidemiology of hepatitis B and C in Croatia

The incidence of HBV and HCV infection is hard to determine because of the high number of asymptomatic infections. According to data of the Croatian Institute of Public Health, there are 200 newly infected persons with hepatitis B and approximately the same number of newly identified HBsAg carriers occur each year. Accordingly, Croatia is among the countries with less than 2% of HBsAg carriers in the general population. In these circumstances, HBV infection is most often spread among adolescents and younger adults. The route of transmission is most often sexual (semen) or through the skin in high-risk groups. An increased risk of infection is found in newborns of HBsAg positive mothers, i.v. addicts, promiscuous individuals, male homosexuals, person in close contact with acutely ill or chronic HBsAg carriers, persons that come in contact with blood and other potentially contaminated body fluids, dialysis patients, patients with multiple blood transfusions, patients with transplanted organ or tissue, patients treated for hematologic malignancies and hemophilia, and persons who undergo acupuncture, tattooing or piercing, or travel to areas with a high prevalence of HBV infection. The estimated prevalence of HCV infection marker (anti-HCV) in the Croatian general population is more than 1% and the number of yearly infected with hepatitis C reported to the Croatian Institute of Public Health is around 200 cases. The highest incidence is found in the 20-40 age groups at a high risk of infection by the use of drug injection. At risk are persons who received transfusion of blood or blood products prior to the availability of blood screening of voluntary blood donors.     

上海市男性同性恋HIV感染者中乙型肝炎、丙型肝炎病毒的合并感染情况横断面研究

目的 探讨男性同性恋HIV感染者中乙型肝炎病毒（HBV）、丙型肝炎病毒（HCV）的合并感染情况。方法 选择2016年1月~2018年1月在本区域内进行治疗的男性同性恋HIV感染者157例,以横断面调查的方法进行研究,收集所有入组患者的性别、年龄、文化程度、感染途径等资料。对所有患者HBV抗体、HCV抗体进行检测。结果 不同感染途径人群合并感染发生率对比,差异具有统计学意义（P＜0.05）:同性性行为患者单纯HIV感染发生率最高,吸毒患者HIV+HBV感染率最高,输血患者HIV+HCV感染率最高,HIV+HBV+HCV感染率最高者为吸毒患者。不同学历合并感染发生率对比,差异具有统计学意义（P＜0.05）:大专及以上的患者以HIV单纯感染为主,高中及中专患者以HIV和HIV+HBV为主,初中及以下的患者则以合并感染为主。不同职业合并感染发生率对比,差异具有统计学意义（P＜0.05）:单纯HIV感染患者以自由职业及职员为主,职员在HIV+HBV感染发病率高于自由职业者及农民,农民在HIV+HCV及HIV+HBV+HCV的发病率均高于其他职业患者。结论 男性同性恋HIV感染者中乙型肝炎病毒、丙型肝炎病毒合并感染发生率均较高,患者感染途径、文化程度及职业的不同,合并感染情况均有显著差异。     

An outbreak of serious illness and death among injecting drug users in England during 2000

An outbreak of serious illness and death occurred in injecting drug users during 2000 in Scotland, Ireland and England. National and international collaboration was necessary for the investigation and management of this outbreak. In England and Wales active case-finding was initiated, coupled with standardised data collection and microbiological investigation of cases. Twenty-six definite or probable cases were identified in England between 1 April and 31 Aug. 2000; 17 of these occurred in the North. The overall case fatality was 50% (13/26). The principal apparent risk factor was a history of intramuscular or subcutaneous injection of heroin and the limited duration of the outbreak suggested that the problem might have been related to a particular supply of heroin. Clostridium novyi was isolated from two English cases. Taken in conjunction with contemporaneous microbiological and epidemiological results from Scottish and Irish cases, the probable aetiology for this outbreak was infection with C. novyi associated with both a particular supply of heroin and the method of preparation and injection used. A 'toolkit' was distributed in Sept. 2000 to all Consultants for Communicable Disease Control in England and Wales to assist them with the ongoing surveillance, investigation and management of this condition. Lessons learned have been used to produce guidance for the investigation and management of outbreaks of unexplained serious illness of possible infective aetiology.     

Epidemiology of Varicella-Zoster Virus in England and Wales

Many countries are studying currently the possibility of mass vaccination against varicella. The objective of this study was to provide a complete picture of the pre-vaccine epidemiology of the Varicella-Zoster Virus in England and Wales to aid in the design of immunisation programs. Population-based data including general practitioner sentinel surveillance, hospitalisation data, and death certificates from England and Wales were analysed. The average incidence rates for varicella and zoster between 1991 and 2000 were 1,291 and 373 per 100,000 years, respectively. Overall hospitalisation rates were equal for varicella and zoster (4.5 vs. 4.4 hospitalisation per 100,000 population) with 5 and 8%, respectively, having underlying immunosuppressive conditions. The age-specific proportion of cases hospitalised and length of stay were similar between the two diseases. However, the overall burden of disease is considerably higher for zoster. The number of inpatient days and case-fatality due to zoster are roughly 4 to 6 times greater than for varicella (11 vs. 3 days and 25 vs. 4 deaths per 100,000 case). These results provide base-line estimates should mass varicella vaccination be introduced in England and Wales.     

Characterization of HBV2-like infections in Spain

Hepatitis B viral serum markers suggestive of infection by hepatitis B virus type 2 were found in 354 patients tested in the laboratory during a 2.5 year period of study. Confirmation of the HBsAg reactivity by neutralization and subtyping analysis and determination of serum HBV-DNA by molecular hybridization were carried out on selected samples from these patients. Clinical and epidemiological data were obtained from 234 patients and serological follow-up was done in 70 cases. The results obtained from the confirmatory tests and DNA assays indicated that HBsAg reactivities were specific, being frequently associated to low levels of HBV-DNA. The incidence rates obtained for HBV2 serological patterns among patients at different level of risk for HBV infection, as well as the finding of a high rate of coinfection with hepatitis A virus among those showing acute hepatitis, suggested that the HBV2 agent could be transmitted by the oral route. An hypothesis considering the so called HBV2 infections as resulting from infections by an HBV variant strain which has an improved ability for non-sexual, non-parenteral transmission is suggested. Specific recommendations for detection and confirmation of such cases in blood banks are also outlined.     

Antibodies to hepatitis delta virus in intravenous drug addicts and male homosexuals in Spain

In a study to determine the incidence of infection with hepatitis delta virus (HDV) in high-risk groups in Spain, tests to detect serological markers of infection with hepatitis B virus (HBV) and total antibodies against HDV (anti-HDV) were performed in serum samples from 451 unselected intravenous drug addicts and 168 homosexual or bisexual men. Most samples were obtained from primary health care units in Madrid. In drug addicts 87.4% of samples were positive for HBV markers and 15.1% were positive for anti-HDV. However, the incidence of anti-HD was much higher in HBsAg carriers (70.7%) than in individuals positive for anti-HBs (10.4%). Ninety-two samples (54.8%) from homosexual men were positive for HBV markers, but all were negative for anti-HD. Thus, parenteral transmission seems to play a major role in the spread of HDV in Spain, the sexual route being of minor relevance.     

Incarceration and risk for HIV infection among injection drug users in Bangkok.

OBJECTIVE: To assess potential multiple relationships between incarceration and HIV infection among injecting drug users (IDUs) in Bangkok. Previous cross-sectional studies have shown strong relationships between incarceration and HIV infection but have not been able to assess potential causal pathways. METHODS: Injection drug users seen at methadone treatment programs in Bangkok were screened during 1995 to 1996 for enrollment into the study. With informed consent, 1,209 seronegative IDUs were enrolled in a cohort study to determine HIV incidence and identify factors associated with incident infections. Follow-up visits were conducted every 4 months, with HIV testing and assessment of risk behaviors. RESULTS: Overall incidence rate was 5.8 per 100 person-years (95% confidence interval [CI], 4.8-6.8) of follow-up. A four-step "injection risk" scale was constructed that included less frequent than daily injection, daily injection, daily injection with reported sharing of injection equipment, and injection while incarcerated. This scale was strongly related to HIV incidence, with incidence approximately doubling for each step in the scale. Incidence rate for follow-up periods that contained drug injection while incarcerated was 35/100 person-years at risk. In multivariate analyses, incarceration was related to incident HIV infection in multiple ways: previous incarceration and recent incarceration without drug injection, and the injection risk scale were all independently predictors of incident HIV infection. CONCLUSIONS: Incarceration is related to incident HIV infection through multiple pathways. Previous incarcerations are likely to serve as markers for unmeasured high-risk behaviors, and it is also highly likely that HIV is transmitted during periods of incarceration. Programs to reduce HIV transmission in jails and prisons, including drug abuse treatment of inmates and programs to reduce the likelihood of incarceration of IDUs, are needed urgently. Given the current diffusion of injecting drug use, of HIV infection among drug injectors, and of the common policy of incarcerating drug users, it is very likely that the problem of HIV transmission in jails and prisons is increasing in many countries throughout the world.