A socio-ecological autopsy of the E. coli O157:H7 outbreak in Walkerton, Ontario, Canada

Extreme rainfall disproportionately impacts E. coli concentrations in Texas recreational waterbodies

Waterborne pathogen contamination poses a significant threat to water resources globally and the exposure to waterborne pathogen contamination is widely recognized as unevenly distributed. Extreme weather events could exacerbate inequalities in waterborne disease as climate variability continues to escalate. However, there is a limited understanding of how extreme rainfall affects E. coli levels and whether disadvantaged communities experience disproportionate impacts from extreme rainfall on E. coli contamination. Leveraging 21 years of E. coli data along with climate data and watershed characteristics, this study employed Multiscale Geographically Weighted Regression (MGWR) models to quantify the seasonal and spatial impacts of extreme rainfall on E. coli concentrations in Texas. Our results indicate that during dry seasons, regions in northern and eastern Texas exhibit significantly higher impacts of extreme rainfall on E. coli concentrations, which is associated with high proportions of pastures, wetlands, and silt. However, during wet seasons, western and southern regions experience slightly higher extreme rainfall induced E. coli contamination risks likely due to significantly increased runoff from the rainfall together with higher slopes and clay-rich soil. In addition, we found census tracts with higher proportions of Black and Latino populations experience greater extreme rainfall impacts on E. coli levels in different months. Furthermore, an analysis of historical trends in extreme rainfall intensity indicates that climate variability could further amplify the existing inequalities in exposure to E. coli contamination. Our findings highlight the disproportionate impacts of extreme rainfall induced E. coli contamination on disadvantaged communities and emphasize the critical need for targeted intervention strategies to mitigate these risks effectively and equitably in Texas.

Aptamers and Aptamer-Coupled Biosensors to Detect Water-Borne Pathogens

Aptamers can serve as efficient bioreceptors for the development of biosensing detection platforms. Aptamers are short DNA or RNA oligonucleotides that fold into specific structures, which enable them to selectively bind to target analytes. The method used to identify aptamers is Systematic Evolution of Ligands through Exponential Enrichment (SELEX). Target properties can have an impact on aptamer efficiencies. Therefore, characteristics of water-borne microbial targets must be carefully considered during SELEX for optimal aptamer development. Several aptamers have been described for key water-borne pathogens. Here, we provide an exhaustive overview of these aptamers and discuss important microbial aspects to consider when developing such aptamers.

Extended urbanisation and the spatialities of infectious disease: Demographic change, infrastructure and governance

This paper argues that contemporary processes of extended urbanisation, which include suburbanisation, post-suburbanisation and peri-urbanisation, may result in increased vulnerability to infectious disease spread. Through a review of existing literature at the nexus of urbanisation and infectious disease, we consider how this (potential) increased vulnerability to infectious diseases in peri- or suburban areas is in fact dialectically related to socio-material transformations on the metropolitan edge. In particular, we highlight three key factors influencing the spread of infectious disease that have been identified in the literature: demographic change, infrastructure and governance. These have been chosen given both the prominence of these themes and their role in shaping the spread of disease on the urban edge. Further, we suggest how a landscape political ecology framework can be useful for examining the role of socio-ecological transformations in generating increased risk of infectious disease in peri- and suburban areas. To illustrate our arguments we will draw upon examples from various re-emerging infectious disease events and outbreaks around the world to reveal how extended urbanisation in the broadest sense has amplified the conditions necessary for the spread of infectious diseases. We thus call for future research on the spatialities of health and disease to pay attention to how variegated patterns of extended urbanisation may influence possible outbreaks and the mechanisms through which such risks can be alleviated.

What caused the 2012 dengue outbreak in Pucallpa, Peru? A socio-ecological autopsy

Dengue is highly endemic in Peru, with increases in transmission particularly since vector re-infestation of the country in the 1980s. Pucallpa, the second largest city in the Peruvian Amazon, experienced a large outbreak in 2012 that caused more than 10,000 cases and 13 deaths. To date, there has been limited research on dengue in the Peruvian Amazon outside of Iquitos, and no published review or critical analysis of the 2012 Pucallpa dengue outbreak. This study describes the incidence, surveillance, and control of dengue in Ucayali to understand the factors that contributed to the 2012 Pucallpa outbreak. We employed a socio-ecological autopsy approach to consider distal and proximal contributing factors, drawing on existing literature and interviews with key personnel involved in dengue control, surveillance and treatment in Ucayali. Spatio-temporal analysis showed that relative risk of dengue was higher in the northern districts of Calleria (RR = 2.18), Manantay (RR = 1.49) and Yarinacocha (RR = 1.25) compared to all other districts between 2004 and 2014. The seasonal occurrence of the 2012 outbreak is consistent with typical seasonal patterns for dengue incidence in the region. Our assessment suggests that the outbreak was proximally triggered by the introduction of a new virus serotype (DENV-2 Asian/America) to the region. Increased travel, rapid urbanization, and inadequate water management facilitated the potential for virus spread and transmission, both within Pucallpa and regionally. These triggers occurred within the context of failures in surveillance and control programming, including underfunded and ad hoc vector control. These findings have implications for future prevention and control of dengue in Ucayali as new diseases such as chikungunya and Zika threaten the region.

Postinfectious Hemolytic Uremic Syndrome

Post-infectious hemolytic uremic syndrome (HUS) is caused by specific pathogens in patients with no identifiable HUS-associated genetic mutation or autoantibody. The majority of episodes is due to infections by Shiga toxin (Stx) producing Escherichia coli (STEC). This chapter reviews the epidemiology and pathogenesis of STEC-HUS, including bacterial-derived factors and host responses. STEC disease is characterized by hematological (microangiopathic hemolytic anemia), renal (acute kidney injury) and extrarenal organ involvement. Clinicians should always strive for an etiological diagnosis through the microbiological or molecular identification of Stx-producing bacteria and Stx or, if negative, serological assays. Treatment of STEC-HUS is supportive; more investigations are needed to evaluate the efficacy of putative preventive and therapeutic measures, such as non-phage-inducing antibiotics, volume expansion and anti-complement agents. The outcome of STEC-HUS is generally favorable, but chronic kidney disease, permanent extrarenal, mainly cerebral complication and death (in less than 5 %) occur and long-term follow-up is recommended. The remainder of this chapter highlights rarer forms of (post-infectious) HUS due to S. dysenteriae, S. pneumoniae, influenza A and HIV and discusses potential interactions between these pathogens and the complement system.

Sociocultural and economic dimensions of Rift Valley fever

Health researchers have advocated for a cross-disciplinary approach to the study and prevention of infectious zoonotic diseases, such as Rift Valley Fever. It is believed that this approach can help bring out the social determinants and effects of the zoonotic diseases for the design of appropriate interventions and public health policy. A comprehensive literature review using a systematic search strategy was undertaken to explore the sociocultural and economic factors that influence the transmission and spread of Rift Valley Fever. Although the findings reveal a paucity of social research on Rift Valley Fever, they suggest that livestock sacrificial rituals, food preparation and consumption practices, gender roles, and inadequate resource base for public institutions are the key factors that influence the transmission. It is concluded that there is need for cross-disciplinary studies to increase the understanding of Rift Valley Fever and facilitate appropriate and timely response and mitigation measures.

Watershed management and public health: an exploration of the intersection of two fields as reported in the literature from 2000 to 2010

Watersheds are settings for health and well-being that have a great deal to offer the public health community due to the correspondence between the spatial form of the watershed unit and the importance to health and well-being of water. However, managing watersheds for human health and well-being requires the ability to move beyond typical reductionist approaches toward more holistic methods. Health and well-being are emergent properties of inter-related social and biophysical processes. This paper characterizes points of connection and integration between watershed management and public health and tests a new conceptual model, the Watershed Governance Prism, to determine the prevalence in peer-reviewed literature of different perspectives relating to watersheds and public health. We conducted an initial search of academic databases for papers that addressed the interface between watershed management (or governance) and public health themes. We then generated a sample of these papers and undertook a collaborative analysis informed by the Watershed Governance Prism. Our analysis found that although these manuscripts dealt with a range of biophysical and social determinants of health, there was a tendency for social factors and health outcomes to be framed as context only for these studies, rather than form the core of the relationships being investigated. At least one cluster of papers emerged from this analysis that represented a cohesive perspective on watershed governance and health; "Perspective B" on the Watershed Governance Prism, "water governance for ecosystems and well-being," was dominant. Overall, the integration of watershed management/governance and public health is in its infancy.

Barriers and bridges to infection prevention and control: results of a qualitative case study of a Netherlands' surgical unit

OBJECTIVES

The objectives of the study are to observe the overall work environment including infection prevention and control (IP&C) practices on the target surgical unit; to analyse the policies and procedures in the hospital and unit environments; to analyse the barriers and bridges to IP&C that practitioners identify in visual narratives of their unit environment and to collect monthly specific IP&C-related anonymised data.

DESIGN

In this qualitative case study analysis, a socio-ecological approach on health systems informed the research design and provided a framework to better understand the complexity of implementing effective IP&C.

SETTING

The study was conducted on a surgical unit at a Netherlands' hospital that reported successful reductions in the prevalence of targeted multidrug-resistant organisms.

METHODS

Research methods included unit observations (n=3), review of relevant policies and procedures, five practitioner-led photo walkabouts of the unit (n=7), three photo elicitation focus groups with practitioners (n=13) and the review of related IP&C data.

RESULTS

The findings indicate some conditions and processes present that may influence the low prevalence of multidrug-resistant organisms, including the 'search and destroy' active surveillance strategy, low occupancy rates, a centralised bed cleaning system and the presence of an active grass roots Hygiene in Practice group, which engages practitioners in several ongoing activities to promote IP&C on the units.

CONCLUSIONS

Further research on the benefits of practitioner-led community of practices on IP&C practices such as the Hygiene in Practice group is also recommended. Additional case studies to compare theses practices with other acute care hospital around the world would be a valuable way to better understand what IP&C programmes are most effective in which contexts and for what reasons. Further data are available by contacting the primary author directly.

Social ecological analysis of an outbreak of pufferfish egg poisoning in a coastal area of Bangladesh

Recurrent outbreaks of marine pufferfish poisoning in Bangladesh highlight the need to understand the context in which the outbreaks occurred. In a recent outbreak investigation, a multidisciplinary team conducted a mixed-method study to identify the demography and clinical manifestation of the victims and to explore different uses of pufferfish, and local buying, selling, and processing practices. The outbreak primarily affected a low income household where an elderly woman collected and cooked pufferfish egg curry. Nine persons consumed the curry, and symptoms developed in 6 (67%) of these persons. Symptoms included vomiting, diarrhea, paresis, and tingling sensation; 2 (22%) persons died. The unstable income of the affected family, food crisis, and the public disposal of unsafe pufferfish byproducts all contributed to the outbreak. A multi-level intervention should be developed and disseminated with the participation of target communities to discourage unsafe discarding of pufferfish scraps and to improve the community knowledge about the risk of consuming pufferfish.

An integrative review of infection prevention and control programs for multidrug-resistant organisms in acute care hospitals: a socio-ecological perspective

BACKGROUND

The infection rates of multidrug-resistant organisms (MDRO) are increasing in Canada and the United States. The prevention and control of MDRO infections remain an important issue in acute care hospitals. Although comprehensive infection prevention and control programs have been recommended, there is little evidence to date of their effectiveness or of what aspects are most important.

OBJECTIVES

Our objectives were to review and critique the literature on the relationship between an MDRO infection and control program and MDRO rates in acute care hospitals.

METHODS

Studies including original research published between January 1, 1998, and May 14, 2009, were identified through MEDLINE, CINAHL, EMBASE, PUBMED, The Cochrane Library, and expert consultation. A comprehensive search strategy was developed with a librarian to find studies that covered the main subject areas of this integrative review.

RESULTS

Of the 1,382 papers retrieved, 47 were reviewed, and 32 studies met the inclusion criteria. The interventions in the included studies were assessed using the tier 1/tier 2 framework. A total of 18 (56.25%) studies had an administrative measure as an intervention; 20 (62.5%) studies had education and training of health care personnel; 8 (25.0%) studies had judicious use of antimicrobial agents; 17 (53.1%) studies used surveillance; 24 (75.0%) studies had infection control precautions to prevent transmission; 7 studies (21.9%) introduced environmental measures; and 9 (28.1%) studies used patient decolonization. Although all the 32 studies were quasiexperimental studies, only 2 (5.9%) studies provided sample size calculations, and only 5 studies reported confounding factors. Whereas 27 used an interrupted time series design and 2 were controlled pre- and post-intervention designs, 3 were pre- and post-intervention without control groups.

CONCLUSION

This integrative review demonstrated that the evidence of the relationship between MDRO infection prevention and control programs and the rates of MDRO is weak. Although major methodologic weaknesses exist in the published literature making it not possible to exclude other plausible explanations for the reduction of the acquisition of MDRO, the overall evidence does support the use of multiple interventions to reduce the rates of MDRO in acute care hospitals. Whereas it is unclear which bundles of interventions are effective, there is a clear suggestion that multiple simultaneous interventions can be effective in reducing MDRO infections. In addition, despite the limitations of interrupted time series, multiple studies employing active surveillance cultures were associated with reduced MDRO infections. Future individual reports of outbreaks and intervention studies should be written in a standardized manner using the recommended Outbreak Reports and Intervention Studies of Nosocomial Infection (ORION) guidelines. Further research is needed on the proposed tier 1/tier 2 framework clearly indicating all the interventions implemented.

Escherichia coliO157: comparing awareness of rural residents and visitors in livestock farming areas

This research compared public opinions aboutEscherichia coliO157 (an increasing environmental hazard associated with livestock) in two farming areas with contrasting incidence ofE. coliO157 disease. A questionnaire was administered in rural Grampian (10·8 cases/100 000 population per year) and North Wales (2·5 cases/100 000 population per year). Awareness was highest among farmers in Grampian (91%) and lowest among visitors to both areas (28%). Respondents were more likely to indicate vomiting (76%) than bloody diarrhoea (48%) as a common symptom. Undercooked meat and contact with farm animal faeces were identified by 60% of all respondents as risk factors who described ‘basic hygiene’ for risk reduction indoors. Visitors viewE. coliO157 as a food hazard, not an environmental hazard that produces vomiting not dysentery. Efforts to reduce human infections in livestock farming areas could be improved with proximate reminders for visitors of the environmental pathway ofE. coliO157 infection.

The impact of biofilm growth on transport of Escherichia coli O157:H7 in sand

Understanding the transport behavior, survival, and persistence of pathogens such as Escherichia coli O157:H7 in the subsurface is essential to protection of public health. In this study, the transport of E. coli O157:H7 in a two-dimensional bench-scale sand aquifer system, hereafter referred to as the sandbox, was investigated, with a focus on the impact of biofilm development on E. coli retention and survival. Biofilm growth was initiated through flushing with unsterilized groundwater and addition of glucose, nitrate, and phosphate. Retention of E. coli from an injection test in clean sand, prior to promotion of biofilm growth, was approximately 9%. Subsequent to biofilm growth, 47% of injected E. coli cells were retained under similar flow conditions. After 10 d of no flow, sterile water was flushed through the biofouled sandbox and substantial concentrations (up to 1.5 × 10(5) cells/mL) of E. coli were measured in the effluent indicating that E. coli had survived the starvation period. Confocal laser scanning microscopy revealed that E. coli were located not only on the surface but also within the biofilm. Imposition of starvation conditions resulted in biofilm sloughing and possible mobilization of biofilm-associated E. coli.

Reconciling the new demands for food protection with environmental needs in the management of livestock wastes

Government policy in many countries has been to promote manure management methods to reduce the negative impacts related to water and air pollution. The central strategy of encouraging manure as a fertiliser rather than treating it as a waste, is under threat from new concerns on public health and especially food quality. Restrictions on manure applications to certain food crops and the stipulation of treatment to 70 degrees C for 1h (in the case of manure products) represent barriers to the use of such material as a useful organic product in the farming and horticultural industries. However, the sensible development of spreading plans in which high and low risk land is identified can enable appropriate and effective treatment for each situation and minimise overall cost. In the high risk situations, processes based on heat treatment remain the most reliable but there still remains the need to ensure a minimum temperature to ensure a satisfactory treatment. Direct application of heat available from biogas coupled with heat recovery may make thermal treatment of effluents a viable option where no effective environmental friendly alternatives exist.

Research priorities for coordinating management of food safety and water quality

Efforts to exclude disease organisms from farms growing irrigated lettuce and leafy vegetables on California's central coast are conflicting with traditionally accepted strategies to protect surface water quality. To begin resolving this dilemma, over 100 officials, researchers, and industry representatives gathered in April 2007 to set research priorities that could lead to effective co-management of both food safety and water quality. Following the meeting, research priorities were refined and ordered by way of a Delphi process completed by 35 meeting participants. Although water quality and food safety experts conceptualized the issues differently, there were no deep disagreements with respect to research needs. Top priority was given to investigating the fate of pathogens potentially present on farms. Intermediate priorities included characterizing the influence of specific farm management practices on food safety and improving our understanding of vector processes. A scientific subdiscipline focusing on competing risks is needed to characterize and resolve conflicts between human and environmental health.

Measurement of OH radical CT for inactivating Cryptosporidium parvum using photo/ferrioxalate and photo/TiO2 systems

AIM

This study investigates the inactivation of Cryptosporidium parvum using the OH radical and reports the OH radical CT (OH radical concentration x contact time) values for C. parvum inactivation.

METHODS AND RESULTS

Although a wealth of information has demonstrated the efficacy of the microbial inactivation activity of the OH radical, no studies have performed a quantitative estimation of the OH radical for C. parvum inactivation. The CT value of the OH radical required for 2 log C. parvum inactivation was measured with two OH radical-generating systems, photo/ferrioxalate and photo/TiO2. The OH radical was approx. 10(4)-10(7)-fold more effective for microbial inactivation than other popular chemical disinfectants such as ozone, chlorine dioxide and free chlorine.

CONCLUSIONS

The OH radical appears to be suitable for microbial inactivation with a calculated CT value required for 2 log C. parvum inactivation of 9.3 x 10(-5) mg min l(-1).

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is the first report of an investigation on the role of the OH radical in the photo/ferrioxalate and photo/TiO2 systems and on the OH radical CT required for C. parvum inactivation.

Analysis of social epidemiology research on infectious diseases: historical patterns and future opportunities

BACKGROUND

Despite the many triumphs of biomedical research over infectious diseases, human pathogens continue to impact profoundly populations deprived of social resources. Correspondingly, health researchers have advocated a social determinants approach to the study and prevention of infectious diseases. However, it is unknown whether this call has resulted in an increase in the number of studies examining social determinants of infectious outcomes.

METHODS

Research on social determinants of infectious diseases was systematically quantified by assessing temporal trends in the published literature using MEDLINE, PsycINFO and ISI Web of Science.

RESULTS

Results of the literature review spanning 1966-2005 show that socially related citations increased an annual average of 180.3 for neuropsychiatric conditions, 81.9 for chronic conditions, 44.7 for sexually transmitted diseases and 18.9 for non-sexually transmitted infectious diseases (p<0.0001). Of the 279 publications found to employ the term "social epidemiology", 15 (5.4%) investigated infectious outcomes.

CONCLUSIONS

The results of the literature review suggest a paucity of social research on infectious diseases. There is a need for increased dialogue and collaboration between infectious disease epidemiologists and social epidemiologists.

The political ecology of lead poisoning in eastern North Carolina

In the United States, childhood blood lead levels have dropped substantially since 1991, when the Centers for Disease Control and Prevention (CDC) implemented new screening guidelines. Many states, including North Carolina, have established successful screening and intervention programs. Still, pockets of higher lead poisoning rates continue to be a problem in some geographic areas. One of these areas consists of several counties in eastern North Carolina. This cluster of higher rates cannot be explained by poverty and housing characteristics alone. Instead, the explanation requires an understanding of place that encompasses a range of historical, social, political, and economic processes. This paper utilizes a political ecology approach to provide a deeper understanding of how these processes can contribute to ill health.

Disaster incubation, cumulative impacts and the urban/ex-urban/rural dynamic

This article explores environmental impacts and risks that can accumulate in rural and ex-urban areas and regions and their relation to urban and global development forces. Two Southern Ontario cases are examined: an area level water disaster and cumulative change at the regional level. The role of disaster incubation analysis and advanced environmental assessment tools are discussed in terms of their potential to contribute to more enlightened and effective assessment and planning processes. It is concluded that conventional approaches to EA and planning are characteristically deficient in addressing the full range of impacts and risks, and particularly those originating from pathogens, dispersed and insidious sources. Rigorous application of disaster incubation analysis and more advanced forms of EA has considerable potential to influence a different pattern of planning and decision making.

Policy windows, policy change, and organizational learning: watersheds in the evolution of watershed management

Employing in-depth, elite interviews, this empirical research contributes to understanding the dynamics among policy windows, policy change, and organizational learning. First, although much of the research on agenda setting-how issues attract enough attention that action is taken to address them-has been conducted at the national scale, this work explores the subnational, regional scale. With decentralization, regional-scale environmental decision-making has become increasingly important. Second, this research highlights the role of policy windows and instances of related organizational learning identified by natural resources managers. Having practitioners identify focusing events contrasts with the more typical approach of the researcher identifying a particular focusing event or events to investigate. A focusing event is a sudden, exceptional experience that, because of how it leads to harm or exposes the prospect for great devastation, is perceived as the impetus for policy change.

Rapid health-risk assessment of effluent irrigation on an Australian university campus

Rapid health-risk assessment of chlorinated sewage-effluent irrigation of lawns, fields and crops adjacent to populated areas at the University of Western Sydney was carried out in response to warnings from the supplying authority of deteriorating bacteriological quality of the water. Irrigation with low-quality effluent offered potential for the contamination of a range of foodstuffs and the exposure of staff, students and visitors. The need for early investigation was emphasised by eutrophication presenting as sudden algal bloom in one of the campus dams and an odour suggestive of anaerobic proteolysis on irrigation. No baseline data existed regarding improvement or deterioration in water quality with passage through the dams, or relating to potential for direct or indirect exposure. The assessment design incorporated three methodologies to generate biophysical, environmental and social data. Environmental and social data were used to augment short-term data for biophysical indicators in the estimation of risk. Where required qualitative information was converted to quantitative data using categorical ranking tables, and risk evaluation was carried out using ranked risk and uncertainty values. Results for biophysical indicators showed a steady improvement in water quality with passage through campus dams, emphasising a need to regard the impoundments as part of a treatment chain, rather than as passive storage units. Effluent quality at most irrigation sites marginally exceeded regional action thresholds for relevant crop types, suggesting a need for risk management through revised irrigation practice, system design, distribution management and risk communication. Problems requiring urgent intervention included the concentration of contaminants of bovine faecal origin in one dam as the result of a closed loop within the reticulation. Also of concern was the exposure of certain most susceptible individuals including crèche children who visited pasture land and orchards where irrigated oranges were collected, and potentially immunocompromised or mentally challenged adults in a work-opportunity gardening scheme. Despite its limitations, rapid risk assessment enabled identification and proactive management of major risk factors, promoted risk communication and awareness, and laid the foundation for ongoing risk surveillance.

Detection of Shiga toxin genes stx1, stx2, and the +93 uidA mutation of E. coli O157:H7/H-using SYBR® Green I in a real-time multiplex PCR

Enterohemorrhagic Escherichia coli (EHEC) is a major foodborne pathogen capable of causing diarrhea and vomiting, but more serious complications such as hemorrhagic colitis and hemolytic-uremic syndrome (HUS) can result. A real-time PCR method to detect the presence of Shiga toxin producing E. coli (STEC) and E. coli O157:H7 was investigated using SYBR Green I (SG). Primers were designed to target the Shiga toxin genes (stx1 and stx2) and a highly conserved base substitution at +93 of the beta-glucuronidase gene (uidA) unique to E. coli O157:H7. An initial test panel of five E. coli and non-E. coli isolates was tested with individual primer sets (simplex assay) and all primer sets including stx1, stx2, and uidA (multiplex assay). All strains were correctly identified in both assays. Average melt temperatures (Tm's, degrees C) for PCR products were 85.42--stx1, 81.93--stx2, and 88.25--uidA in simplex assays and 85.20--stx1, 81.20--stx2, and 88.16--uidA when multiplexed. Each of the three gene targets in one multiplex reaction could be distinguished by melt curve data with significantly different Tm's. The assay was expanded to a panel of 138 isolates consisting of STEC, E. coli O157:H7, non-toxigenic E. coli, and non-E. coli isolates with melt peaks consistent with those stated above.

All Hands on Deck: Transdisciplinary Approaches to Emerging Infectious Disease

The increasing burden of emerging infectious diseases worldwide confronts us with numerous challenges, including the imperative to design research and responses that are commensurate to understanding the complex social and ecological contexts in which infectious diseases occur. A diverse group of scientists met in Hawaii in March 2005 to discuss the linked social and ecological contexts in which infectious diseases emerge. A subset of the meeting was a group that focused on “transdisciplinary approaches” to integrating knowledge across and beyond academic disciplines in order to improve prevention and control of emerging infections. This article is based on the discussions of that group. Here, we outline the epidemiological legacy that has dominated infectious disease research and control up until now, and introduce the role of new, transdisciplinary and systems-based approaches to emerging infectious diseases. We describe four cases of transboundary health issues and use them to discuss the potential benefits, as well as the inherent difficulties, in understanding the social–ecological contexts in which infectious diseases occur and of using transdisciplinary approaches to deal with them.