EcoHealth

Antipodean pioneers of transdisciplinary (TD) thinking at the University of Newcastle, Glenn Albrecht and Nick Higginbotham have applied this perspective to contexts of human health globally and to the development of health social science as an emerging TD field. Nick Higginbotham has successfully championed the cause of TD thinking in international networks such as The International Clinical Epidemiology Network (INCLEN) and the International Forum for Social Sciences (IFSSEH). Glenn Albrecht has connected the Newcastle variety of TD thinking to its independently created doppelganger in the form of TD Ecosystem Health as pioneered by David Rapport in Canada. The convergence of TD thinking and Ecosystem Health at Newcastle has promoted a new curriculum in both undergraduate and postgraduate health and environmental sciences courses. Furthermore, TD research teams have been created and pursue investigations of both health and environmental problems. A successful national conference on transdisciplinary approaches to ecosystem health in Australia was held at Newcastle in April 2003. This article details the history of the evolution and synthesis of transdisciplinarity, ecosystem health, and ecohealth at the University of Newcastle, Australia, over a period from 1988 to the present.

The pathogenic chytrid fungus, Batrachochytrium dendrobatidis, has been implicated as the main driver of many enigmatic amphibian declines in neotropical sites at high elevation. Batrachochytrium dendrobatidis is thought to be a waterborne pathogen limited by temperature, and the extent to which it persists and causes disease in amphibians at lower elevations in the neotropics is not known. It also is unclear by what mechanism(s) B. dendrobatidis has emerged as a pathogenic organism. To test whether B. dendrobatidis is limited by elevation in Panamá, we sought to determine the prevalence and intensity of B. dendrobatidis in relation to anuran abundance and diversity using quantitative PCR (qPCR) analyses. Sites were situated at varying elevations, from 45 to 1215 m, and were at varying stages of epizootic amphibian decline, including pre-epizootic, mid-epizootic, 2 years post-epizootic, and 10 years post-epizootic. Batrachochytrium dendrobatidis was found in all sites regardless of elevation or stage of epizootic decline. Levels of prevalence and infection intensity were comparable across all sites except at the mid-epizootic site, where both prevalence and intensity were significantly higher than at other sites. Symptoms of chytridiomycosis and corresponding declines in amphibian populations were variably seen at all elevations along a post-epizootic gradient. Because it is inherently difficult to prove a negative proposition, it can neither be proven that B. dendrobatidis is truly not present where it is not detected nor proven that it is only recently arrived where it is detected. Thus, there will always be doubts about whether B. dendrobatidis is enzootic or invasive. In any case, our results, coupled with current knowledge, suggest most clearly that the disease, chytridiomycosis, may be novel and invasive, and that the pathogen, B. dendrobatidis either is, or is becoming, globally ubiquitous.

Many livestock diseases rely on wildlife for the transmission or maintenance of the pathogen, and the wildlife–livestock interface represents a potential site of disease emergence for novel pathogens in livestock. Predicting which pathogen species are most likely to emerge in the future is an important challenge for infectious disease surveillance and intelligence. We used a machine learning approach to conduct a data-driven horizon scan of bacterial associations at the wildlife–livestock interface for cows, sheep, and pigs. Our model identified and ranked from 76 to 189 potential novel bacterial species that might associate with each livestock species. Wildlife reservoirs of known and novel bacteria were shared among all three species, suggesting that targeting surveillance and/or control efforts towards these reservoirs could contribute disproportionately to reducing spillover risk to livestock. By predicting pathogen-host associations at the wildlife–livestock interface, we demonstrate one way to plan for and prevent disease emergence in livestock.

Leptospirosis is a zoonotic infectious disease of global significance. Political, economic, demographic, ecologic, and other anthropogenically driven environmental changes have fueled the reemergence of this disease in industrialized and developing countries, and in both urban and rural settings. We argue that conventional disciplinary, even interdisciplinary, research methods are not sufficient to elucidate the complex mechanisms and causal relationships among the myriad factors responsible for infectious disease emergence. To address the significant gaps in the field of leptospirosis, an integrated research agenda is needed to guide successful public health remediation of the disease. Based on both working group analysis of literature and newly obtained information, we describe cross-disciplinary collaborative approaches that allow a novel approach to understand leptospirosis emergence with regard to mountain-to-sea ecosystems in Hawai‘i and other region-specific ecosystems. Leptospirosis research is a model for how complementary disciplines in the social, cultural, ecological, and biomedical sciences can optimally interact towards a higher understanding of emerging infectious diseases.

Rodent-borne hantaviruses are a group of zoonotic agents that cause hemorrhagic fever in humans. The transmission of hantaviruses among rodent hosts may be higher with the increase of reservoir host abundance in a given area (density-dependent transmission) and with the decrease of small mammal diversity (dilution effect phenomenon). These population and community parameters may be modified by habitat fragmentation; however, studies that focus on fragmentation and its effect on hantavirus infection risk are scarce. To further understanding of this issue, we assessed some population and community responses of rodents that may increase the risk for hantavirus transmission among wildlife hosts in the Americas. We conducted a meta-analysis of published studies to assess the responses of small mammals to fragmentation of native habitats, relative to patch size. Our analyses included five countries and 14 case studies for abundance of reservoir hosts (8 species) and 15 case studies for species richness. We found that a reduction of patch area due to habitat fragmentation is associated with increased reservoir host abundances and decreased small mammal richness, which is mainly due to the loss of non-host small mammals. According to these results, habitat fragmentation in the Americas should be considered as an epidemiological risk factor for hantavirus transmission to humans. These findings are important to assess potential risk of infection when fragmentation of native habitats occurs.