Instruct: Given a scientific claim, retrieve documents that support or refute the claim.
Query: Urbanization is an important risk factor related to the transmission of dengue fever.
BACKGROUND Transmission of dengue viruses (DENV), the leading cause of arboviral disease worldwide, is known to vary through time and space, likely owing to a combination of factors related to the human host, virus, mosquito vector, and environment. An improved understanding of variation in transmission patterns is fundamental to conducting surveillance and implementing disease prevention strategies. To test the hypothesis that DENV transmission is spatially and temporally focal, we compared geographic and temporal characteristics within Thai villages where DENV are and are not being actively transmitted. METHODS AND FINDINGS Cluster investigations were conducted within 100 m of homes where febrile index children with (positive clusters) and without (negative clusters) acute dengue lived during two seasons of peak DENV transmission. Data on human infection and mosquito infection/density were examined to precisely (1) define the spatial and temporal dimensions of DENV transmission, (2) correlate these factors with variation in DENV transmission, and (3) determine the burden of inapparent and symptomatic infections. Among 556 village children enrolled as neighbors of 12 dengue-positive and 22 dengue-negative index cases, all 27 DENV infections (4.9% of enrollees) occurred in positive clusters (p < 0.01; attributable risk [AR] = 10.4 per 100; 95% confidence interval 1-19.8 per 100]. In positive clusters, 12.4% of enrollees became infected in a 15-d period and DENV infections were aggregated centrally near homes of index cases. As only 1 of 217 pairs of serologic specimens tested in positive clusters revealed a recent DENV infection that occurred prior to cluster initiation, we attribute the observed DENV transmission subsequent to cluster investigation to recent DENV transmission activity. Of the 1,022 female adult Ae. aegypti collected, all eight (0.8%) dengue-infected mosquitoes came from houses in positive clusters; none from control clusters or schools. Distinguishing features between positive and negative clusters were greater availability of piped water in negative clusters (p < 0.01) and greater number of Ae. aegypti pupae per person in positive clusters (p = 0.04). During primarily DENV-4 transmission seasons, the ratio of inapparent to symptomatic infections was nearly 1:1 among child enrollees. Study limitations included inability to sample all children and mosquitoes within each cluster and our reliance on serologic rather than virologic evidence of interval infections in enrollees given restrictions on the frequency of blood collections in children. CONCLUSIONS Our data reveal the remarkably focal nature of DENV transmission within a hyperendemic rural area of Thailand. These data suggest that active school-based dengue case detection prompting local spraying could contain recent virus introductions and reduce the longitudinal risk of virus spread within rural areas. Our results should prompt future cluster studies to explore how host immune and behavioral aspects may impact DENV transmission and prevention strategies. Cluster methodology could serve as a useful research tool for investigation of other temporally and spatially clustered infectious diseases.
Abstract Overcrowding has increased in the U.S. after decades of decline—dramatically so in some locales and for some ethnic groups. The nature of the problem and its very definition for policy purposes are also changing. We examine the special characteristics of the overcrowded, where they are located, why the incidence of crowding has resurged, and why it is confined to specific locales. Ethnicity, age, immigration, and poverty play important roles, but housing market conditions appear much less important. We also show that the planning standard used to judge overcrowding is a relative one that has varied over time, and that the social norms vary among ethnic groups. The issue of overcrowding may exemplify the current perplexities about imposing uniform standards in an evolving multiethnic society. Worst-case housing needs would be better targeted in highly impacted locales by allowing more “place diversity” in the setting of standards.
Understanding local variability in malaria transmission risk is critically important when designing intervention or vaccine trials. Using a combination of field data, satellite image analysis, and GIS modeling, we developed a high-resolution map of malaria entomological inoculation rates (EIR) in The Gambia, West Africa. The analyses are based on the variation in exposure to malaria parasites experienced in 48 villages in 1996 and 21 villages in 1997. The entomological inoculation rate (EIR) varied from 0 to 166 infective bites per person per rainy season. Detailed field surveys identified the major Anopheles gambiae s.l. breeding habitats. These habitats were mapped by classification of a LANDSAT TM satellite image with an overall accuracy of 85%. Village EIRs decreased as a power function based on the breeding areas size and proximity. We use this relationship and the breeding habitats to map the variation in EIR over the entire 2500-km(2) study area.
BACKGROUND High genetic diversity at both inter- and intra-host level are hallmarks of RNA viruses due to the error-prone nature of their genome replication. Several groups have evaluated the extent of viral variability using different RNA virus deep sequencing methods. Although much of this effort has been dedicated to pathogens that cause chronic infections in humans, few studies investigated arthropod-borne, acute viral infections. METHODS AND PRINCIPAL FINDINGS We deep sequenced the complete genome of ten DENV2 isolates from representative classical and severe cases sampled in a large outbreak in Brazil using two different approaches. Analysis of the consensus genomes confirmed the larger extent of the 2010 epidemic in comparison to a previous epidemic caused by the same viruses in another city two years before (genetic distance = 0.002 and 0.0008 respectively). Analysis of viral populations within the host revealed a high level of conservation. After excluding homopolymer regions of 454/Roche generated sequences, we found 10 to 44 variable sites per genome population at a frequency of >1%, resulting in very low intra-host genetic diversity. While up to 60% of all variable sites at intra-host level were non-synonymous changes, only 10% of inter-host variability resulted from non-synonymous mutations, indicative of purifying selection at the population level. CONCLUSIONS AND SIGNIFICANCE Despite the error-prone nature of RNA-dependent RNA-polymerase, dengue viruses maintain low levels of intra-host variability.
The fly Musca sorbens Wiedemann (Diptera: Muscidae) apparently transmits Chlamydia trachomatis, causing human trachoma. The literature indicates that M. sorbens breeds predominantly in isolated human faeces on the soil surface, but not in covered pit latrines. We sought to identify breeding media of M. sorbens in a rural Gambian village endemic for trachoma. Test breeding media were presented for oviposition on soil-filled buckets and monitored for adult emergence. Musca sorbens emerged from human (6/9 trials), calf (3/9), cow (3/9), dog (2/9) and goat (1/9) faeces, but not from horse faeces, composting kitchen scraps or a soil control (0/9 of each). After adjusting for mass of medium, the greatest number of flies emerged from human faeces (1426 flies/kg). Median time for emergence was 9 (inter quartile range = 8-9.75) days post-oviposition. Of all flies emerging from faeces 81% were M. sorbens. Male and female flies emerging from human faeces were significantly larger than those from other media, suggesting that they would be more fecund and live longer than smaller flies from other sources. Female flies caught from children's eyes were of a similar size to those from human faeces, but significantly larger than those from other media. We consider that human faeces are the best larval medium for M. sorbens, although some breeding also occurs in animal faeces. Removal of human faeces from the environment, through the provision of basic sanitation, is likely to greatly reduce fly density, eye contact and hence trachoma transmission, but if faeces of other animals are present M. sorbens will persist.
West Nile virus (WNV) is a major cause of mosquito-borne illness in the United States. Human disease ranges from mild febrile illness to severe fatal neurologic infection. Adults aged >60 years are more susceptible to neuroinvasive disease accompanied by a high mortality rate or long-lasting neurologic sequelae. A chimeric live attenuated West Nile virus vaccine, rWN/DEN4&Dgr;30, was shown to be safe and immunogenic in healthy adults aged 18–50 years. This study evaluated rWN/DEN4&Dgr;30 in flavivirus-naive adults aged 50–65 years and found it to be safe and immunogenic. Outbreaks of WNV infection tend to be unpredictable, and a safe and effective vaccine will be an important public health tool.
Vitamin D insufficiency affects almost 50% of the population worldwide. An estimated 1 billion people worldwide, across all ethnicities and age groups, have a vitamin D deficiency (VDD). This pandemic of hypovitaminosis D can mainly be attributed to lifestyle (for example, reduced outdoor activities) and environmental (for example, air pollution) factors that reduce exposure to sunlight, which is required for ultraviolet-B (UVB)-induced vitamin D production in the skin. High prevalence of vitamin D insufficiency is a particularly important public health issue because hypovitaminosis D is an independent risk factor for total mortality in the general population. Current studies suggest that we may need more vitamin D than presently recommended to prevent chronic disease. As the number of people with VDD continues to increase, the importance of this hormone in overall health and the prevention of chronic diseases are at the forefront of research. VDD is very common in all age groups. As few foods contain vitamin D, guidelines recommended supplementation at suggested daily intake and tolerable upper limit levels. It is also suggested to measure the serum 25-hydroxyvitamin D level as the initial diagnostic test in patients at risk for deficiency. Treatment with either vitamin D2 or vitamin D3 is recommended for deficient patients. A meta-analysis published in 2007 showed that vitamin D supplementation was associated with significantly reduced mortality. In this review, we will summarize the mechanisms that are presumed to underlie the relationship between vitamin D and understand its biology and clinical implications.
Experience gained from the Global Malaria Eradication Program (1955-72) identified a set of shared technical and operational factors that enabled some countries to successfully eliminate malaria. Spatial data for these factors were assembled for all malaria-endemic countries and combined to provide an objective, relative ranking of countries by technical, operational, and combined elimination feasibility. The analysis was done separately for Plasmodium falciparum and Plasmodium vivax, and the limitations of the approach were discussed. The relative rankings suggested that malaria elimination would be most feasible in countries in the Americas and Asia, and least feasible in countries in central and west Africa. The results differed when feasibility was measured by technical or operational factors, highlighting the different types of challenge faced by each country. The results are not intended to be prescriptive, predictive, or to provide absolute assessments of feasibility, but they do show that spatial information is available to facilitate evidence-based assessments of the relative feasibility of malaria elimination by country that can be rapidly updated.
An observational prospective cohort study assessed malaria risk perception, knowledge and prophylaxis practices among individuals of African ethnicity living in Paris and travelling to their country of origin to visit friends or relatives (VFR). The study compared two groups of VFR who had visited a travel clinic (TC; n=122) or a travel agency (TA; n=69) before departure. Of the 47% of VFR citing malaria as a health concern, 75% knew that malaria is mosquito-borne and that bed nets are an effective preventive measure. Perception of high malaria risk was greater in the TA group (33%) than in the TC group (7%). The availability of a malaria vaccine was mentioned by 35% of VFR, with frequent confusion between yellow fever vaccine and malaria prevention. Twenty-nine percent took adequate chemoprophylaxis with complete adherence, which was higher among the TC group (41%) than the TA group (12%). Effective antivector protection measures used were bed nets (16%), wearing long clothes at night (14%) and air conditioning (8%), with no differences between the study groups except in the use of impregnated bed nets (11% of the TC group and none of the TA group). Media coverage, malaria chemoprophylaxis repayment and cultural adaptation of preventive messages should be improved to reduce the high rate of inadequate malaria prophylaxis in VFR.
By the year 2000 there will be six million pregnant women and five to ten million children infected with HIV-1. Intervention strategies have been planned and in some instances already started. A timely and cost-effective strategy needs to take into account that most HIV-1 infected individuals reside in developing countries. Further studies are needed on immunological and virological factors affecting HIV-1 transmission from mother to child, on differential disease progression in affected children, and on transient infection.
This paper seeks to establish the strength of association between contemporary tuberculosis (TB) in England and Wales and several potential aetiological factors. It presents an ecological analysis of standardised annual TB mortality rates for the 403 local authority districts between 1982 and 1992, disaggregated by age and sex. Social, demographic and ethnicity measures from the 1981 and 1991 censuses and standardised annual AIDS-related mortality rates for young men are used to calculate Poisson regression models. A strong association was found between all TB mortality groups and overcrowding at the household level. For women, no other measures improved the explanatory power of the models. In multiple regressions, both poverty and AIDS-related mortality explained additional variation in the model for younger men. The link between ethnicity and tuberculosis notifications was not reflected in this analysis of mortality. For all groups no evidence of a positive relationship with ethnicity was found, once overcrowding had been accounted for. The significance of household as opposed to district level crowding suggests that prolonged contact is required for disease transmission. Regression analysis indicates that it is the overcrowding and poverty among ethnic populations that is significant for their tuberculosis mortality. The fact that the relationship between AIDS and TB is confined to the group most typical of AIDS patients provides evidence that AIDS has little influence on the level of tuberculosis mortality in the wider population. Explanations for the observed relationship include preferential certification, migration for treatment and shortcomings in health care provision.
Paratransgenesis, the genetic manipulation of insect symbiotic microorganisms, is being considered as a potential method to control vector-borne diseases such as malaria. The feasibility of paratransgenic malaria control has been hampered by the lack of candidate symbiotic microorganisms for the major vector Anopheles gambiae. In other systems, densonucleosis viruses (DNVs) are attractive agents for viral paratransgenesis because they infect important vector insects, can be genetically manipulated and are transmitted to subsequent generations. However, An. gambiae has been shown to be refractory to DNV dissemination. We discovered, cloned and characterized the first known DNV (AgDNV) capable of infection and dissemination in An. gambiae. We developed a flexible AgDNV-based expression vector to express any gene of interest in An. gambiae using a two-plasmid helper-transducer system. To demonstrate proof-of-concept of the viral paratransgenesis strategy, we used this system to transduce expression of an exogenous gene (enhanced green fluorescent protein; EGFP) in An. gambiae mosquitoes. Wild-type and EGFP-transducing AgDNV virions were highly infectious to An. gambiae larvae, disseminated to and expressed EGFP in epidemiologically relevant adult tissues such as midgut, fat body and ovaries and were transmitted to subsequent mosquito generations. These proof-of-principle data suggest that AgDNV could be used as part of a paratransgenic malaria control strategy by transduction of anti-Plasmodium peptides or insect-specific toxins in Anopheles mosquitoes. AgDNV will also be extremely valuable as an effective and easy-to-use laboratory tool for transient gene expression or RNAi in An. gambiae.
Homeless youth suffer from high rates of health problems, yet little is known about their perceptions of or context for their own health issues. In this study, a combination of qualitative techniques from participatory rural appraisal and rapid assessment procedures was used to investigate the perceptions of health needs of shelter-based youth in Baltimore, MD in the U.S.A. The most common youth-identified health problems included STDs, HIV/AIDS, pregnancy, depression, drug use and injuries. These correlate well with more objective health status data for the same youth. The youth spoke of environmental safety threats of violence and victimization by adults, as well as racism and sexism in their lives. Youth reported that trusted adult figures such as grandmothers are important sources of health advice. Many homeless youth from less than ideal family situations remain in contact with and continue to seek advice from parents and other family members. Health interventions with urban street youth need to acknowledge the primacy of the social context for these youth, as well as the reality of violence as a daily health threat.
Hepatitis C virus (HCV) is a leading cause of liver cancer and cirrhosis, and Egypt has possibly the highest HCV prevalence worldwide. In this article we use a newly developed Bayesian inference framework to estimate the transmission dynamics of HCV in Egypt from sampled viral gene sequences, and to predict the public health impact of the virus. Our results indicate that the effective number of HCV infections in Egypt underwent rapid exponential growth between 1930 and 1955. The timing and speed of this spread provides quantitative genetic evidence that the Egyptian HCV epidemic was initiated and propagated by extensive antischistosomiasis injection campaigns. Although our results show that HCV transmission has since decreased, we conclude that HCV is likely to remain prevalent in Egypt for several decades. Our combined population genetic and epidemiological analysis provides detailed estimates of historical changes in Egyptian HCV prevalence. Because our results are consistent with a demographic scenario specified a priori, they also provide an objective test of inference methods based on the coalescent process.
Despite its key role in determining the stability and intensity of malaria transmission, the infectiousness of human populations to mosquitoes has rarely been estimated. Field-based analyses of malaria transmission have frequently relied on the prevalence of asexual parasites or gametocytes as proxies for infectiousness. We now summarize empirical data on human infectiousness from Africa and Papua New Guinea. Over a wide range of transmission intensities there is little relationship between the infectiousness of human populations to vector mosquitoes and mosquito-to-human transmission intensity. We compare these data with the predictions of a stochastic simulation model of Plasmodium falciparum epidemiology. This model predicted little variation in the infectiousness of the human population for entomologic inoculation rates (EIRs) greater than approximately 10 infectious bites per year, demonstrating that the lack of relationship between the EIR and the infectious reservoir can be explained without invoking any effects of acquired transmission-blocking immunity. The near absence of field data from areas with an EIR < 10 per year precluded validation of the model predictions for low EIR values. These results suggest that interventions reducing mosquito-to-human transmission will have little or no effect on human infectiousness at the levels of transmission found in most rural areas of sub-Saharan Africa. Unless very large reductions in transmission can be achieved, measures to prevent mosquito-to-human transmission need to be complemented with interventions that reduce the density or infectiousness of blood stage parasites.
BACKGROUND Prior to emergence in human populations, zoonoses such as SARS cause occasional infections in human populations exposed to reservoir species. The risk of widespread epidemics in humans can be assessed by monitoring the reproduction number R (average number of persons infected by a human case). However, until now, estimating R required detailed outbreak investigations of human clusters, for which resources and expertise are not always available. Additionally, existing methods do not correct for important selection and under-ascertainment biases. Here, we present simple estimation methods that overcome many of these limitations. METHODS AND FINDINGS Our approach is based on a parsimonious mathematical model of disease transmission and only requires data collected through routine surveillance and standard case investigations. We apply it to assess the transmissibility of swine-origin influenza A H3N2v-M virus in the US, Nipah virus in Malaysia and Bangladesh, and also present a non-zoonotic example (cholera in the Dominican Republic). Estimation is based on two simple summary statistics, the proportion infected by the natural reservoir among detected cases (G) and among the subset of the first detected cases in each cluster (F). If detection of a case does not affect detection of other cases from the same cluster, we find that R can be estimated by 1-G; otherwise R can be estimated by 1-F when the case detection rate is low. In more general cases, bounds on R can still be derived. CONCLUSIONS We have developed a simple approach with limited data requirements that enables robust assessment of the risks posed by emerging zoonoses. We illustrate this by deriving transmissibility estimates for the H3N2v-M virus, an important step in evaluating the possible pandemic threat posed by this virus. Please see later in the article for the Editors' Summary.
Many viruses go through a maturation step in the final stages of assembly before being transmitted to another host. The maturation process of flaviviruses is directed by the proteolytic cleavage of the precursor membrane protein (prM), turning inert virus into infectious particles. We have determined the 2.2 angstrom resolution crystal structure of a recombinant protein in which the dengue virus prM is linked to the envelope glycoprotein E. The structure represents the prM-E heterodimer and fits well into the cryo-electron microscopy density of immature virus at neutral pH. The pr peptide beta-barrel structure covers the fusion loop in E, preventing fusion with host cell membranes. The structure provides a basis for identifying the stages of its pH-directed conformational metamorphosis during maturation, ending with release of pr when budding from the host.
BACKGROUND Falciparum malaria or malaria tropica is one of the leading causes of childhood mortality worldwide. Malaria-related deaths occur mainly in sub-Saharan Africa, where an estimated 365 million clinical cases of Plasmodium falciparum malaria occur each year. In Europe, imported malaria cases occur due to returning travellers or immigration mostly from African countries. Children are more at risk than adults. The objective of this study was to identify high risk groups for imported childhood malaria in Europe in order to guide development of strategies for prevention, early recognition and management. METHODS In the period May 2003-January 2005 we reviewed all cases of paediatric malaria in the Netherlands notified by the Dutch Paediatric Surveillance System (Nederland Signalerings Centrum Kindergeneeskunde, NSCK) and the literature on imported malaria in children in Europe published between 1996 and 2006. RESULTS Malaria occurred mainly in children of long-term (n = 15, 47%) and new (n = 8, 25%) immigrants and was mostly acquired in sub-Saharan Africa. The dominant species was P. falciparum. Only one quarter of children had used adequate malaria chemoprophylaxis. Complicated disease occurred in 10 (31%) of cases. We also reviewed the literature and found 6082 reported cases of imported malaria among children in Europe; among these, four died and only one was reported to develop neurological sequelae. CONCLUSION Imported malaria in children remains an important problem and is unlikely to decrease unless the reasons for inadequate prophylaxis are addressed.
Until the 1990s, Amblyomma americanum was regarded primarily as a nuisance species, but a tick of minor importance as a vector of zoonotic pathogens affecting humans. With the recent discoveries of Ehrlichia chaffeensis, Ehrlichia ewingii, and "Borrelia lonestari," the public health relevance of lone star ticks is no longer in question. During the next 25 years, the number of cases of human disease caused by A. americanum-associated pathogens will probably increase. Based on current trajectories and historic precedents, the increase will be primarily driven by biological and environmental factors that alter the geographic distribution and intensity of transmission of zoonotic pathogens. Sociologic and demographic changes that influence the likelihood of highly susceptible humans coming into contact with infected lone star ticks, in addition to advances in diagnostic capabilities and national surveillance efforts, will also contribute to the anticipated increase in the number of recognized cases of disease.
Information on global human movement patterns is central to spatial epidemiological models used to predict the behavior of influenza and other infectious diseases. Yet it remains difficult to test which modes of dispersal drive pathogen spread at various geographic scales using standard epidemiological data alone. Evolutionary analyses of pathogen genome sequences increasingly provide insights into the spatial dynamics of influenza viruses, but to date they have largely neglected the wealth of information on human mobility, mainly because no statistical framework exists within which viral gene sequences and empirical data on host movement can be combined. Here, we address this problem by applying a phylogeographic approach to elucidate the global spread of human influenza subtype H3N2 and assess its ability to predict the spatial spread of human influenza A viruses worldwide. Using a framework that estimates the migration history of human influenza while simultaneously testing and quantifying a range of potential predictive variables of spatial spread, we show that the global dynamics of influenza H3N2 are driven by air passenger flows, whereas at more local scales spread is also determined by processes that correlate with geographic distance. Our analyses further confirm a central role for mainland China and Southeast Asia in maintaining a source population for global influenza diversity. By comparing model output with the known pandemic expansion of H1N1 during 2009, we demonstrate that predictions of influenza spatial spread are most accurate when data on human mobility and viral evolution are integrated. In conclusion, the global dynamics of influenza viruses are best explained by combining human mobility data with the spatial information inherent in sampled viral genomes. The integrated approach introduced here offers great potential for epidemiological surveillance through phylogeographic reconstructions and for improving predictive models of disease control.
Obesity is now so common within the world's population that it is beginning to replace undernutrition and infectious diseases as the most significant contributor to ill health. In particular, obesity is associated with diabetes mellitus, coronary heart disease, certain forms of cancer, and sleep-breathing disorders. Obesity is defined by a body-mass index (weight divided by square of the height) of 30 kg m(-2) or greater, but this does not take into account the morbidity and mortality associated with more modest degrees of overweight, nor the detrimental effect of intra-abdominal fat. The global epidemic of obesity results from a combination of genetic susceptibility, increased availability of high-energy foods and decreased requirement for physical activity in modern society. Obesity should no longer be regarded simply as a cosmetic problem affecting certain individuals, but an epidemic that threatens global well being.
Homelessness affects tens of thousands of canadians and has important health implications. Homeless people are at increased risk of dying prematurely and suffer from a wide range of health problems, including seizures, chronic obstructive pulmonary disease, musculoskeletal disorders, tuberculosis, and skin and foot problems. Homeless people also face significant barriers that impair their access to health care. More research is needed to identify better ways to deliver care to this population.
Transformation and conjugation permit the passage of DNA through the bacterial membranes and represent dominant modes for the transfer of genetic information between bacterial cells or between bacterial and eukaryotic cells. As such, they are responsible for the spread of fitness-enhancing traits, including antibiotic resistance. Both processes usually involve the recognition of double-stranded DNA, followed by the transfer of single strands. Elaborate molecular machines are responsible for negotiating the passage of macromolecular DNA through the layers of the cell surface. All or nearly all the machine components involved in transformation and conjugation have been identified, and here we present models for their roles in DNA transport.
As time passes, the AIDS pandemic continues to spike, affecting an estimated 38.6 million people worldwide. In response, a satellite health clinic is being d esigned by two Cal Poly students to serve the Maasai people living in the Kajiado district in Southern Kenya. The Maasai have traditionally lived as pastoralists, surviving off of their cattle with which they share their water, increasing the risk for contamination. However, as the population of Kenya increases, the land the Maasai have traditionally used for grazing is shrink­ ing. For this reason, some have turned to farming to maintain their liveli­ hood. These factors have contributed to the desertification and deforestation of their region. As the lifestyle of the Maasai evolves, they rely more on maize than meat and dairy products for their nutrients. All of these changes have contributed to the evolution of the Maasai culture. We will address these changes in order to better understand the Maasai, as well as highlight pos­ sible further aid needed to support their survival.
Injection drug users (IDUs) are at increased risk for HIV, viral hepatitis, and tuberculosis, and making up more than a quarter of the incarcerated population in the United States. Methadone maintenance treatment of opiate addiction is highly effective at reducing drug use, drug-related criminal activity, and risk of HIV transmission. Recently released inmates are at particularly high risk for overdose and disease transmission. Linkage to methadone treatment immediately upon release from incarceration is a promising opportunity to combat disease transmission, facilitate reentry into the community, and reduce recidivism.