Disease ecology Research Papers - Academia.edu (original) (raw)

MicroRNAs (miRNAs) are small, highly conserved, non-coding RNAs that regulate gene expression of target mRNAs through cleavage or translational inhibition. miRNAs are most often identified through computational prediction from genome... more

MicroRNAs (miRNAs) are small, highly conserved, non-coding RNAs that regulate gene expression of target mRNAs through cleavage or translational inhibition. miRNAs are most often identified through computational prediction from genome sequences. The rainbow trout genome sequence is not available yet, which does not allow miRNA prediction for this species which is of great economic interest for aquaculture and sport fisheries, and is a model research organism for studies related to carcinogenesis, toxicology, comparative immunology, disease ecology, physiology and nutrition. To identify miRNAs from rainbow trout, we constructed a miRNA library from a pool of nine somatic tissues. Analysis of the library identified 210 unique sequences representing 54 distinct miRNAs; 50 with conserved sequences matching previously identified miRNAs and four novel miRNAs. In addition, 13 miRNAs were computationally predicted from the rainbow trout transcriptome. Real-time PCR was used to measure miRNA expression patterns in adult somatic tissues and unfertilized eggs. The majority of the miRNAs showed characteristic tissue-specific expression patterns suggesting potential roles in maintaining tissue identity. Potential miRNA-target interactions were computationally predicted and single nucleotide polymorphisms (SNPs) were identified in the miRNAs and their target sites in the rainbow trout transcripts. The rainbow trout miRNAs identified and characterized in this study provide a new tool for functional genome research in salmonids. Tissue-specific miRNAs may serve as molecular markers, predictive of specific functional and diagnostic implications. The data on genetic polymorphisms in miRNA-target interactions is particularly useful for rainbow trout breeding programs.

Cercarial dermatitis or swimmer's itch has been a problem at Devil's Lake (Sauk County,Wisconsin) for decades. We investigated swimmer's itch in Devil's Lake during, the summer of 1999. The project focused on identifying the species of... more

Cercarial dermatitis or swimmer's itch has been a problem at Devil's Lake (Sauk County,Wisconsin) for decades. We investigated swimmer's itch in Devil's Lake during, the summer of 1999. The project focused on identifying the species of schistosome cercariae and their snail intermediate hosts causing the swimmer's itch problem in the lake. We determined the aquatic habitats associated with intermediate host snail species and their densities to elucidate ecologically safe management options to reduce the incidence of swimmer's itch to the users of Devil's Lake. Swimmer's itch was not a significant problem at Devil’s Lake this summer. Visitors reported 5 swimmer's itch cases to park officials, while 50-100 cases a summer have been reported in past years. No cercariae causing swimmer's itch were found in our samples. However, 3 of the 17 snail species found in the lake were documented in the scientific literature to be intermediate hosts of swimmer's itch parasites. All three host species - Physa skinneri, Gyraulus parvus and Fossaria obrussa (Say) group (exigua strain) - were most dense along the entire north and south shorelines of the lake. At least one of the three species was found at all 10 sampling sites around the perimeter of the lake. We suggest that broad ecological control measures that reduce snail densities are needed to control the swimmer's itch problem in the lake. These include reducing lake phosphorus concentrations through various management options, which in turn would lead to a reduction in periphyton growth, the major food source of snails. Periphyton growth is currently high in the lake. Alternatively, sustained fish manipulations that lead to greater predation rates on snails also may be effective. Both control measures are directed at decreasing the probability of snail infection by the short-lived miracidia released from parasite-infected waterfowl, which seasonally frequent the lake in large numbers. Finally, we recommend that public surveys of the swimmer's itch problem on not only Devil's Lake but lakes throughout Wisconsin be conducted each year to help direct future state-wide research efforts.

Honey bees are important pollinators of agricultural crops and the dramatic losses of honey bee colonies have risen to a level of international concern. Potential contributors to such losses include pesticide exposure, lack of floral... more

Honey bees are important pollinators of agricultural crops and the dramatic losses of honey bee colonies have risen to a level of international concern. Potential contributors to such losses include pesticide exposure, lack of floral resources and parasites and pathogens. The damaging effects of all of these may be exacerbated by apicultural practices. To meet the pollination demand of US crops, bees are transported to areas of high pollination demand throughout the year. Compared to stationary colonies, risk of parasitism and infectious disease may be greater for migratory bees than those that remain in a single location, although this has not been experimentally established. Here, we conducted a manipulative experiment to test whether viral pathogen and parasite loads increase as a result of colonies being transported for pollination of a major US crop, California almonds. We also tested if they subsequently transmit those diseases to stationary colonies upon return to their home apiaries. Colonies started with equivalent numbers of bees, however migratory colonies returned with fewer bees compared to stationary colonies and this difference remained one month later. Migratory colonies returned with higher black queen cell virus loads than stationary colonies, but loads were similar between groups one month later. Colonies exposed to migratory bees experienced a greater increase of deformed wing virus prevalence and load compared to the isolated group. The three groups had similar infestations of Varroa mites upon return of the migratory colonies. However, one month later, mite loads in migratory colonies were significantly lower compared to the other groups, possibly because of lower number of host bees. Our study demonstrates that migratory pollination practices has varying health effects for honey bee colonies. Further research is necessary to clarify how migratory pollination practices influence the disease dynamics of honey bee diseases we describe here. How to cite this article Alger et al. (2018), Home sick: impacts of migratory beekeeping on honey bee (Apis mellifera) pests, pathogens, and colony size. PeerJ 6:e5812; DOI 10.7717/peerj.5812

Medieval York was one of the largest and most important cities in England. The close confines of the city, the household and industrial waste, alongside the air and water pollution made this a city known for its pervasive smells, which at... more

Medieval York was one of the largest and most important cities in England. The close confines of the city, the household and industrial waste, alongside the air and water pollution made this a city known for its pervasive smells, which at the time were considered to be a leading cause of disease. This paper aims to present the environmental context for disease combined with the human osteological record to reconstruct the pathoecology of medieval York. Combining archaeological and historical data, we gain insight into the interplay between medieval culture, disease, health, and the urban environment. It is clear that local authorities were concerned about urban pollution, and historical evidence demonstrates that legal measures were taken to remove or regulate some of the perceived causes of pollution. There is a demonstrable trend towards improving environmental conditions in York between the 11th and mid-16th century. However, it is likely that the extant socio-environmental conditions continued to contribute to morbidity, as evidenced by the prevalence of infection.

In teasing out the diverse origins of our “modern, ecological understanding of epidemic disease” (Mendelsohn, in: Lawrence and Weisz (eds) Greater than the parts: holism in biomedicine, 1920–1950, Oxford University Press, Oxford, 1998),... more

In teasing out the diverse origins of our “modern, ecological understanding
of epidemic disease” (Mendelsohn, in: Lawrence and Weisz (eds) Greater than the parts: holism in biomedicine, 1920–1950, Oxford University Press, Oxford, 1998), historians have downplayed the importance of parasitology in the development of a natural history perspective on disease. The present article reassesses the significance of parasitology for the “invention” of medical ecology in post-war France. Focussing on the works of microbiologist Charles Nicolle (1866–1936) and on that of physician and zoologist Hervé Harant (1901–1986), I argue that French “medical ecology” was not professionally (or cognitively) insulated from some major trends in parasitology, especially in Tunis where disciplinary borders in the medical sciences collapsed. This argument supports the claim that ecological perspectives of disease developed in colonial context (Anderson in Osiris 19: 39–61, 2004) but I show that parasitologists such as Harant built on the works of medical geographers who had called attention to the dynamic and complex biological relations between health and environment in fashioning the field of medical ecology in the mid-1950s. As the network of scientists who contributed to the global emergence of “disease ecology” is widening, both medical geography and parasitology stand out as relevant sites of inquiries for a broader historical understanding of the multiple “ecological visions” in twentieth-century biomedical sciences.

There is an urgent need to develop the underlying theory and principles of “sustainability science,” based on an understanding of the fundamental interactions between nature and humans. This requires a new research and education paradigm... more

There is an urgent need to develop the underlying theory and principles of “sustainability science,” based on an understanding of the fundamental interactions between nature and humans. This requires a new research and education paradigm that embraces biocomplexity, integrates the physical, biological, and social sciences, and uses a coupled, human–natural systems approach. An initiative aligned with this paradigm and approach, and centered on the Hawaiian Island’s unique mountain-to-sea ecosystems, is developing at the University of Hawai‘i. These ecosystems, extending from upland tropical forests to the fringing coral reefs, correspond to the roughly wedge-shaped catchments, traditionally called ahupua‘a in the Hawaiian language. Despite the collapse of the ahupua‘a system and, tragically, the Native Hawaiian population, its legacy of ecological and cultural stewardship remains. This legacy, and the potential of these ecosystems as microcosms for addressing the core questions of sustainability science, has provided the impetus for a growing number of projects employing a social–ecological systems perspective. An overview of three projects that employ a “learning community” approach and cultural stewardship perspective inspired by the ahupua‘a system is provided. These include the Ecosystems Thrust Area of Hawai‘i EPSCoR, a U.S. National Science Foundation research infrastructure program, focused on ecosystem research and monitoring activities; a sustainability curriculum program, Mālama I Ka ‘Āina, of the College of Education; and a project that builds on programs of the Division of Ecology and Health and its affiliated Asia-Pacific Center for Infectious Disease Ecology, linking ecosystem resilience and infectious diseases.

Traditionally, the termination of parasite epidemics has been attributed to ecological causes: namely, the depletion of susceptible hosts as a result of mortality or acquired immunity. Here, we suggest that epidemics can also end because... more

Traditionally, the termination of parasite epidemics has been attributed to ecological causes: namely, the depletion of susceptible hosts as a result of mortality or acquired immunity. Here, we suggest that epidemics can also end because of rapid host evolution. Focusing on a particular host–parasite system, Daphnia dentifera and its parasite Metschnikowia bicuspidata, we show that Daphnia from lakes with recent epidemics were more resistant to infection and had less variance in susceptibility than Daphnia from lakes without recent epidemics. However, our studies revealed little evidence for genetic variation in infectivity or virulence in Metschnikowia. Incorporating the observed genetic variation in host susceptibility into an epidemiological model parameterized for this system reveals that rapid evolution can explain the termination of epidemics on time scales matching what occurs in lake populations. Thus, not only does our study provide rare evidence for parasite-mediated selection in natural populations, it also suggests that rapid evolution has important effects on short-term host–parasite dynamics.

"Background The American bison (Bison bison) reflects the resiliency of a species that was brought to the brink of extinction at the turn of the 19th century due to widespread market hunting and the accumulated years of systematic... more

Exposure of bobcats (Lynx rufus) and gray foxes (Urocyon cinereoargenteus )t o a range of common canine and feline pathogens was assessed in urban and rural zones of Golden Gate National Recreation Area, a National Park in the San... more

Exposure of bobcats (Lynx rufus) and gray foxes (Urocyon cinereoargenteus )t o a range of common canine and feline pathogens was assessed in urban and rural zones of Golden Gate National Recreation Area, a National Park in the San Francisco Bay Area, (California, USA) from 1992 to 1995. Testing included serology for canine distemper virus, canine parvovirus (CPV), canine adenovirus,

Despite the number of virulent pathogens that are projected to benefit from global change and to spread in the next century, we suggest that a combination of coextinction risk and climate sensitivity could make parasites at least as... more

Despite the number of virulent pathogens that are projected to benefit from global change and to spread in the next century, we suggest that a combination of coextinction risk and climate sensitivity could make parasites at least as extinction prone as any other trophic group. However, the existing interdisciplinary toolbox for identifying species threatened by climate change is inadequate or inappropriate when considering parasites as conservation targets. A functional trait approach can be used to connect parasites' ecological role to their risk of disappearance, but this is complicated by the taxonomic and functional diversity of many parasite clades. Here, we propose biological traits that may render parasite species particularly vulnerable to extinction (including high host specificity, complex life cycles and narrow climatic tolerance), and identify critical gaps in our knowledge of parasite biology and ecology. By doing so, we provide criteria to identify vulnerable parasite species and triage parasite conservation efforts.

Large mammals have drastically declined in the past few decades yet we know little about their ecology. Giraffe numbers for instance, have dropped by more than 40% in the last 15 years and recently, a skin disease, has been observed in... more

Large mammals have drastically declined in the past few decades yet we know little about their ecology. Giraffe numbers for instance, have dropped by more than 40% in the last 15 years and recently, a skin disease, has been observed in numerous giraffe populations across Africa. The disease(s), commonly referred to as giraffe skin disease (GSD), manifests as lesions, wrinkled skin, and encrustations that can affect the limbs, shoulder or neck of giraffes. Here, we review GSD cases from literature reports and surveying efforts of individuals working with giraffes in the wild and in captivity. The aim of this review was to describe spatial variation in the anatomical location of lesions, prevalence, and severity of GSD. In total, we retrieved 16 published sources that referenced GSD and we received 63 respondents to our survey. We found that GSD has been observed in 13 protected areas across 7 countries in Africa and in 11 out of 48 zoos distributed across 6 countries. The prevalence of GSD in wild populations ranged from 2% to 80% of observed giraffes. Although little research to date has focused on GSD, our review reveals that the disease is more prevalent than initially thought and more severe in some areas than previously assumed. With vast areas of Sub-Saharan Africa still without information on GSD, researching the prevalence and conservation impacts of this disease should be a priority. We propose broader and longer-term studies to further describe and comprehend the effects of GSD on giraffe vital rates among populations in the wild and in captivity.

The decline of many bumblebee species (Bombus spp.) has been linked to an increased prevalence of pathogens caused by spillover from managed bees. Although poorly understood , RNA viruses are suspected of moving from managed honeybees... more

The decline of many bumblebee species (Bombus spp.) has been linked to an increased prevalence of pathogens caused by spillover from managed bees. Although poorly understood , RNA viruses are suspected of moving from managed honeybees (Apis mellifera) into wild bumblebees through shared floral resources. We examined if RNA viruses spillover from managed honeybees, the extent to which viruses are replicating within bumblebees, and the role of flowers in transmission. Prevalence and active infections of deformed wing virus (DWV) were higher in bumblebees collected near apiaries and when neighboring hon-eybees had high infection levels. We found no DWV in bumblebees where honeybee forag-ers and honeybee apiaries were absent. The prevalence of black queen cell virus (BQCV) was also higher in bumblebees collected near apiaries. Furthermore, we detected viruses on 19% of flowers, all of which were collected within apiaries. Our results corroborate the hypothesis that viruses are spilling over from managed honeybees to wild bumblebees and that flowers may be an important route for transmission.

Dung beetles are detrivorous insects that feed and reproduce with the fecal material of vertebrates. This dependency on vertebrate feces implies frequent contact between dung beetles and parasitic helminths with a fecal component to their... more

Dung beetles are detrivorous insects that feed and reproduce with the fecal material of vertebrates. This dependency on vertebrate feces implies frequent contact between dung beetles and parasitic helminths with a fecal component to their life-cycle. Interactions between dung beetles and helminths carry both positive and negative consequences for successful parasite transmission, however to date there has been no systematic review of dung beetle-helminth interactions, their epidemiological importance, or their underlying mechanisms. Here we review the observational evidence of beetle biodiversity-helminth transmission relationships, propose five mechanisms by which dung beetles influence helminth survival and transmission, and highlight areas for future research. Efforts to understand how anthropogenic impacts on biodiversity may influence parasite transmission must include the development of detailed, mechanistic understanding of the multiple interactions between free-living and parasitic species within ecological communities. The dung beetle-helminth system may be a promising future model system with which to understand these complex relationships.

The helminth community of a population of Rattus norvegicus from an urban Brazilian slum and the threat of zoonotic diseases. Parasitology 145, 797-806. Abstract Urban slums provide suitable conditions for infestation by rats, which... more

The helminth community of a population of Rattus norvegicus from an urban Brazilian slum and the threat of zoonotic diseases. Parasitology 145, 797-806. Abstract Urban slums provide suitable conditions for infestation by rats, which harbour and shed a wide diversity of zoonotic pathogens including helminths. We aimed to identify risk factors associated with the probability and intensity of infection of helminths of the digestive tract in an urban slum population of Rattus norvegicus. Among 299 rats, eleven species/groups of helminths were identified, of which Strongyloides sp., Nippostrongylus brasiliensis and, the human pathogen, Angiostrongylus cantonensis were the most frequent (97, 41 and 39%, respectively). Sex interactions highlighted behavioural differences between males and females, as eg males were more likely to be infected with N. brasiliensis where rat signs were present, and males presented more intense infections of Strongyloides sp. Moreover, rats in poor body condition had higher intensities of N. brasiliensis. We describe a high global richness of parasites in R. norvegicus, including five species known to cause disease in humans. Among these, A. cantonensis was found in high prevalence and it was ubiquitous in the study area-knowledge which is of public health importance. A variety of environmental, demographic and body condition variables were associated with helminth species infection of rats, suggesting a comparable variety of risk factors for humans.

The continual emergence of new pathogens and the increased spread of antibiotic resistance in bacterial populations remind us that microbes are living entities that evolve at rates that impact public health interventions. Following the... more

The continual emergence of new pathogens and the increased spread of antibiotic resistance in bacterial populations remind us that microbes are living entities that evolve at rates that impact public health interventions. Following the historical thread of the works of Pasteur and Darwin shows how reconciling clinical microbiology, ecology, and evolution can be instrumental to understanding pathology, developing new therapies, and prolonging the efficiency of existing ones.

The Swiss-born medical researcher Karl Friedrich Meyer (1884–1974) is best known as a ‘microbe hunter’ who pioneered investigations into diseases at the intersection of animal and human health in California in the 1920s and 1930s. In... more

The Swiss-born medical researcher Karl Friedrich Meyer (1884–1974) is best known as a ‘microbe hunter’ who pioneered investigations into diseases at the intersection of animal and human health in California in the 1920s and 1930s. In particular, historians have singled out Meyer’s 1931 Ludwig Hektoen Lecture in which he described the animal kingdom as a ‘reservoir of disease’ as a forerunner of ‘one medicine’ approaches to emerging zoonoses. In so doing, however, historians risk overlooking Meyer’s other intellectual contributions. Developed in a series of papers from the mid-1930s onwards, these were ordered around the concept of latent infections and sought to link microbial behavior to broader bio-ecological, environmental, and social factors that impact host-pathogen interactions. In this respect Meyer—like the comparative pathologist Theobald Smith and the immunologist Frank Macfarlane Burnet—can be seen as a pioneer of modern ideas of disease ecology. However, while Burnet’s and Smith’s contributions to this scientific field have been widely acknowledged, Meyer’s have been largely ignored. Drawing on Meyer’s published writings and private correspondence, this paper aims to correct that lacuna while contributing to a reorientation of the historiography of bacteriological epidemiology. In particular I trace Meyer’s intellectual exchanges with Smith, Burnet and the animal ecologist Charles Elton, over brucellosis, psittacosis and plague—exchanges that not only showed how environmental and ecological conditions could ‘tip the balance’ in favor of parasites but which transformed Meyer thinking about resistance to infection and disease.

Pathogen prevalence within blacklegged ticks (Ixodes scapularis Say, 1821) tends to vary across sites and geographic regions, but the underlying causes of this variation are not well understood. Efforts to understand the ecology of Lyme... more

Pathogen prevalence within blacklegged ticks (Ixodes scapularis Say, 1821) tends to vary across sites and geographic regions, but the underlying causes of this variation are not well understood. Efforts to understand the ecology of Lyme disease have led to the proposition that sites with higher host diversity will result in lower disease risk due to an increase in the abundance of inefficient reservoir species relative to the abundance of species that are highly competent reservoirs. Although the Lyme disease transmission cycle is often cited as a model for this “dilution effect hypothesis”, little empirical evidence exists to support that claim. Here we tested the dilution effect hypothesis for two pathogens transmitted by the blacklegged tick along an urban-to-rural gradient in the northeastern United States using landscape fragmentation as a proxy for host biodiversity. Percent impervious surface and habitat fragment size around each site were determined to assess the effect of landscape fragmentation on nymphal blacklegged tick infection with Borrelia burgdorferi and Anaplasma phagocytophilum. Our results do not support the dilution effect hypothesis for either pathogen and are in agreement with the few studies to date that have tested this idea using either a landscape proxy or direct measures of host biodiversity.

In contrast to the traditional genre of eco-apocalyptic fiction, Sarah Moss’ debut novel, Cold Earth (2009), does not culminate in a collective catastrophe. It instead employs archaeology, environmental apocalypse, viruses and ghosts to... more

In contrast to the traditional genre of eco-apocalyptic fiction, Sarah Moss’ debut novel, Cold Earth (2009), does not culminate in a collective catastrophe. It instead employs archaeology, environmental apocalypse, viruses and ghosts to disclose the transformative power of the archive. This article surveys the ways through which the archaeological motif, environmental apocalypse, elegiac tones and disarrayed temporality can function as archiving vehicles, preserving past memory and opening up to the future. And yet, in doing this, both landscape and writing melancholically internalize losses, so as to become themselves archives, while eventually edging towards post-melancholic attachments.

We compared the success of different techniques of relocations as a means of mitigating the impacts of the construction of a major highway on Box Turtles (Terrapene carolina) in Maryland. We compared the movement patterns, home range... more

We compared the success of different techniques of relocations as a means of mitigating the impacts of the construction of a major highway on Box Turtles (Terrapene carolina) in Maryland. We compared the movement patterns, home range size, and survival of turtles from three treatment groups between 2008-2011; turtles native to the study site and not moved during the study (native turtles), turtles native to the site, but which were moved from the limit of disturbance (LOD) of the highway (on-site relocations), and turtles not native to the site, which were relocated onto the site (off-site relocations). Turtles in the off-site relocation group had larger home ranges and moved longer distances than either on-site or native turtles. However, unlike other studies, off-site relocated turtles did not make directional movements off of the study area nor did they have difficulty finding suitable sites for overwintering. We found no statistically-significant differences in survival between our three treatment groups. However, overall survival rates were <65% over the three years of our study, considerably lower than rates seen in other Box Turtle populations, perhaps due to an emerging pathogen (Ranavirus), which caused numerous deaths of Box Turtles. Our recommendations for “Best Practices” centered on the need for more effective wildlife exclusion fences to be built and maintained earlier in the construction timeline. Failure to create and maintain such a barrier in our study lead to numerous “trespass” events, where turtles moved onto the LOD and would likely have been killed without our intervention