scholarly journals Host and pathogen ecology drive the seasonal dynamics of a fungal disease, white-nose syndrome

2015 ◽  
Vol 282 (1799) ◽  
pp. 20142335 ◽  
Author(s):  
Kate E. Langwig ◽  
Winifred F. Frick ◽  
Rick Reynolds ◽  
Katy L. Parise ◽  
Kevin P. Drees ◽  
...  
Keyword(s):  
Infection Intensity ◽  
Pathogen Transmission ◽  
Late Winter ◽  
Infection Prevalence ◽  
Pseudogymnoascus Destructans ◽  
Spatial Spread ◽  
Seasonal Transmission ◽  
White Nose Syndrome ◽  
Contact Rates ◽  
The Impact

Seasonal patterns in pathogen transmission can influence the impact of disease on populations and the speed of spatial spread. Increases in host contact rates or births drive seasonal epidemics in some systems, but other factors may occasionally override these influences. White-nose syndrome, caused by the emerging fungal pathogen Pseudogymnoascus destructans , is spreading across North America and threatens several bat species with extinction. We examined patterns and drivers of seasonal transmission of P. destructans by measuring infection prevalence and pathogen loads in six bat species at 30 sites across the eastern United States. Bats became transiently infected in autumn, and transmission spiked in early winter when bats began hibernating. Nearly all bats in six species became infected by late winter when infection intensity peaked. In summer, despite high contact rates and a birth pulse, most bats cleared infections and prevalence dropped to zero. These data suggest the dominant driver of seasonal transmission dynamics was a change in host physiology, specifically hibernation. Our study is the first, to the best of our knowledge, to describe the seasonality of transmission in this emerging wildlife disease. The timing of infection and fungal growth resulted in maximal population impacts, but only moderate rates of spatial spread.

scholarly journals Destructin-1 is a collagen-degrading endopeptidase secreted by Pseudogymnoascus destructans, the causative agent of white-nose syndrome

2015 ◽  
Vol 112 (24) ◽  
pp. 7478-7483 ◽  
Author(s):  
Anthony J. O’Donoghue ◽  
Giselle M. Knudsen ◽  
Chapman Beekman ◽  
Jenna A. Perry ◽  
Alexander D. Johnson ◽  
...  
Keyword(s):  
Causative Agent ◽  
Genetic Manipulation ◽  
Hydrolytic Enzymes ◽  
Collagen Degradation ◽  
Mammalian Host ◽  
Peptidase Activity ◽  
Pseudogymnoascus Destructans ◽  
White Nose Syndrome ◽  
Proteolytic Activities ◽  
The Impact

Pseudogymnoascus destructans is the causative agent of white-nose syndrome, a disease that has caused the deaths of millions of bats in North America. This psychrophilic fungus proliferates at low temperatures and targets hibernating bats, resulting in their premature arousal from stupor with catastrophic consequences. Despite the impact of white-nose syndrome, little is known about the fungus itself or how it infects its mammalian host. P. destructans is not amenable to genetic manipulation, and therefore understanding the proteins involved in infection requires alternative approaches. Here, we identify hydrolytic enzymes secreted by P. destructans, and use a novel and unbiased substrate profiling technique to define active peptidases. These experiments revealed that endopeptidases are the major proteolytic activities secreted by P. destructans, and that collagen, the major structural protein in mammals, is actively degraded by the secretome. A serine endopeptidase, hereby-named Destructin-1, was subsequently identified, and a recombinant form overexpressed and purified. Biochemical analysis of Destructin-1 showed that it mediated collagen degradation, and a potent inhibitor of peptidase activity was identified. Treatment of P. destructans-conditioned media with this antagonist blocked collagen degradation and facilitated the detection of additional secreted proteolytic activities, including aminopeptidases and carboxypeptidases. These results provide molecular insights into the secretome of P. destructans, and identify serine endopeptidases that have the clear potential to facilitate tissue invasion and pathogenesis in the mammalian host.

scholarly journals A comparison of fertility control and lethal control of bovine tuberculosis in badgers: the impact of perturbation induced transmission

1997 ◽  
Vol 352 (1353) ◽  
pp. 619-631 ◽  
Author(s):  
J. Swinton ◽  
F. Tuyttens ◽  
D. Macdonald ◽  
D. J. Nokes ◽  
C. L. Cheeseman ◽  
...  
Keyword(s):  
Bovine Tuberculosis ◽  
Fertility Control ◽  
Transmission Model ◽  
Infection Prevalence ◽  
Lethal Control ◽  
Advantages And Disadvantages ◽  
Contact Rates ◽  
Age Cohort ◽  
The Impact

In this paper we use mathematical modelling to consider the broad advantages and disadvantages of fertility control over lethal control for bovine tuberculosis in badger populations. We use a deliberately simple model, attempting to capture only the key transmission processes. The model is parametrized with reference to the long–term Woodchester Park study. Estimates of mortality rate from this study suggest no significant extra mortality risk for animals with evidence of infection as indicated by the presence of anti- Mycobacterium bovis antibodies or M. bovis isolation. We find that large reductions in prevalence are sometimes the consequence of only moderate reductions in population numbers. If we assume that the act of control does not in itself affect transmission rates, then as far as eradication is concerned, both fertility control and mortality control operate through the same epidemiological mechanism, the removal of susceptibles: if one is in principle capable of keeping a population low enough to be infection free then so is the other. It is necessary to continue either form of control at regular intervals to maintain a constant level of infection in the long term. If control were to be stopped, return to precontrol levels of badger population and infection prevalence would be expected within a few years. Fertility control is less effective in reducing population density than lethal control since it can only act, at maximum, to remove one age cohort per year. It is also less effective in reducing transmission as it can only ever remove susceptibles, while lethal control also removes infectious badgers. However, if the social disturbance caused by lethal control does in fact increase contact rates for the remaining infectious badgers, the relative efficacies of the two strategies become a great deal less clear. While we have no quantitative data on the extent to which social perturbation does act to promote transmission, model simulations show that it is possible to develop plausible scenarios in which the lethal control may actually act to increase the absolute numbers of animals infected, while reducing the number of uninfected animals to very low numbers.

scholarly journals Field trial of a probiotic bacteria and a chemical, chitosan, to protect bats from white-nose syndrome

2019 ◽  
Author(s):  
Joseph R. Hoyt ◽  
Kate E. Langwig ◽  
J. Paul White ◽  
Heather M. Kaarakka ◽  
Jennifer A. Redell ◽  
...  
Keyword(s):  
Field Trial ◽  
Infection Intensity ◽  
Probiotic Bacterium ◽  
Myotis Lucifugus ◽  
Probiotic Bacteria ◽  
Control Group ◽  
Pseudogymnoascus Destructans ◽  
Overwinter Survival ◽  
Cage Experiment ◽  
White Nose Syndrome

AbstractTools for reducing wildlife disease impacts are needed to conserve biodiversity. White-nose syndrome (WNS), caused by the fungusPseudogymnoascus destructans, has caused widespread declines in North American bat populations and threatens several species with extinction. Few tools exist for managers to reduce WNS impacts. We tested the efficacy of two treatments, a probiotic bacterium,Pseudomonas fluorescens, and a chemical, chitosan, to reduce impacts of WNS in two simultaneous experiments conducted with caged and free-flyingMyotis lucifugusbats at a mine in Wisconsin, USA. In the free-flying experiment, treatment withP. fluorescensincreased apparent overwinter survival five-fold compared to the control group (from 8.4% to 46.2%) by delaying emergence of bats from the site by 30 days. Apparent overwinter survival for free-flying chitosan-treated bats was 18.0%, which did not differ significantly from control bats. In the cage experiment, chitosan-treated bats had significantly higher survival until release on March 8 (53%) than control andP. fluorescens-treated bats (both 27%). However, these differences were likely due to within-cage disturbance and not reduced WNS impacts, because chitosan-treated bats actually had significantly higher UV-fluorescence (a measure of disease severity), and body mass, not infection intensity, predicted mortality. Further, few of the bats released from the cage experiment were detected emerging from the mine, indicating that the survival estimates at the time of release did not carryover to overwinter survival. These results suggest that treatment of bats may reduce WNS mortality, but additional measures are needed to prevent declines.

scholarly journals Sex and hibernaculum temperature predict survivorship in white-nose syndrome affected little brown myotis ( Myotis lucifugus )

2015 ◽  
Vol 2 (2) ◽  
pp. 140470 ◽  
Author(s):  
Laura E. Grieneisen ◽  
Sarah A. Brownlee-Bouboulis ◽  
Joseph S. Johnson ◽  
DeeAnn M. Reeder
Keyword(s):  
Infectious Disease ◽  
Myotis Lucifugus ◽  
Eastern North America ◽  
The Novel ◽  
Pseudogymnoascus Destructans ◽  
Term Survival ◽  
White Nose Syndrome ◽  
Myotis Myotis ◽  
The Impact

White-nose syndrome (WNS), an emerging infectious disease caused by the novel fungus Pseudogymnoascus destructans , has devastated North American bat populations since its discovery in 2006. The little brown myotis, Myotis lucifugus , has been especially affected. The goal of this 2-year captive study was to determine the impact of hibernacula temperature and sex on WNS survivorship in little brown myotis that displayed visible fungal infection when collected from affected hibernacula. In study 1, we found that WNS-affected male bats had increased survival over females and that bats housed at a colder temperature survived longer than those housed at warmer temperatures. In study 2, we found that WNS-affected bats housed at a colder temperature fared worse than unaffected bats. Our results demonstrate that WNS mortality varies among individuals, and that colder hibernacula are more favourable for survival. They also suggest that female bats may be more negatively affected by WNS than male bats, which has important implications for the long-term survival of the little brown myotis in eastern North America.

scholarly journals Seasonality and pathogen transmission in pastoral cattle contact networks

2017 ◽  
Vol 4 (12) ◽  
pp. 170808 ◽  
Author(s):  
Kimberly VanderWaal ◽  
Marie Gilbertson ◽  
Sharon Okanga ◽  
Brian F. Allan ◽  
Meggan E. Craft
Keyword(s):  
Water Resources ◽  
Disease Outbreaks ◽  
Dry Season ◽  
Pathogen Transmission ◽  
Contact Network ◽  
Wet Season ◽  
Contact Networks ◽  
Contact Rates ◽  
Animal Populations ◽  
The Impact

Capturing heterogeneity in contact patterns in animal populations is essential for understanding the spread of infectious diseases. In contrast to other regions of the world in which livestock movement networks are integral to pathogen prevention and control policies, contact networks are understudied in pastoral regions of Africa due to the challenge of measuring contact among mobile herds of cattle whose movements are driven by access to resources. Furthermore, the extent to which seasonal changes in the distribution of water and resources impacts the structure of contact networks in cattle is uncertain. Contact networks may be more conducive to pathogen spread in the dry season due to congregation at limited water sources. Alternatively, less abundant forage may result in decreased pathogen transmission due to competitive avoidance among herds, as measured by reduced contact rates. Here, we use GPS technology to concurrently track 49 free-roaming cattle herds within a semi-arid region of Kenya, and use these data to characterize seasonal contact networks and model the spread of a highly infectious pathogen. This work provides the first empirical data on the local contact network structure of mobile herds based on quantifiable contact events. The contact network demonstrated high levels of interconnectivity. An increase in contacts near to water resources in the dry season resulted in networks with both higher contact rates and higher potential for pathogen spread than in the wet season. Simulated disease outbreaks were also larger in the dry season. Results support the hypothesis that limited water resources enhance connectivity and transmission within contact networks, as opposed to reducing connectivity as a result of competitive avoidance. These results cast light on the impact of seasonal heterogeneity in resource availability on predicting pathogen transmission dynamics, which has implications for other free-ranging wild and domestic populations.

scholarly journals Five-Year Follow-Up on the Prevalence and Intensity of Infections of Schistosoma mansoni in a Hard-to-Reach District of Madagascar

2021 ◽  
Author(s):  
Stephen A. Spencer ◽  
Cortland Linder ◽  
James M. St. J. Penney ◽  
Hannah J. Russell ◽  
Kate Hyde ◽  
...  
Keyword(s):  
Public Health ◽  
Health Education ◽  
Schistosoma Mansoni ◽  
Infection Intensity ◽  
Public Health Problem ◽  
Infection Prevalence ◽  
Major Public Health Problem ◽  
Intermediate Hosts ◽  
Biomphalaria Pfeifferi ◽  
The Impact

Schistosomiasis is a major public health problem in Madagascar. The WHO recommends preventive chemotherapy by mass drug administration (MDA) with praziquantel as the primary approach to control Schistosoma mansoni–related morbidity in endemic populations, alongside complementary interventions such as health education. The impact of annual MDA and health education programs was assessed in the hard-to-reach Marolambo district of eastern Madagascar, an area endemic for S. mansoni. Repeated cross-sectional studies undertaken 2015–2019 examined between 300 and 381 school-aged children (aged 5–14 years) annually. The prevalence and infection intensity of S. mansoni were assessed by urine-circulating cathodic antigen (CCA) dipsticks and coproscopy using Kato–Katz (KK) methodologies. After four rounds of annual MDA, a reduction in S. mansoni prevalence was seen in CCA (93.9% in year 1–87.7% in year 5; P = 0.007) and KK (73.9% in year 1–59.4% in year 5; P < 0.0001). The prevalence of heavy-intensity infections roughly halved from 23.7% to 10.1% (P < 0.0001), and the mean intensity of infection fell by 55.0% (480.2–216.3 eggs per gram of feces). A malacological survey found Biomphalaria pfeifferi snail intermediate hosts in multiple water contact sites including rice paddies, streams, and Nosivolo River. Despite reductions in infection prevalence and intensity, schistosomiasis still poses a significant public health challenge in Marolambo district. Twice yearly MDA cycles and/or community-wide MDA are suggested to better reduce infections. Expanding health education; improving standards of water, sanitation, and hygiene; and attention on snail-related control will also be important, especially in rice paddy irrigated areas.

scholarly journals Environmental reservoir dynamics predict global infection patterns and population impacts for the fungal disease white-nose syndrome

2020 ◽  
Vol 117 (13) ◽  
pp. 7255-7262 ◽  
Author(s):  
Joseph R. Hoyt ◽  
Kate E. Langwig ◽  
Keping Sun ◽  
Katy L. Parise ◽  
Aoqiang Li ◽  
...  
Keyword(s):  
Disease Outbreaks ◽  
Population Declines ◽  
Pseudogymnoascus Destructans ◽  
White Nose Syndrome ◽  
Infection Dynamics ◽  
Environmental Reservoir ◽  
Severe Infections ◽  
Seasonal Epidemics ◽  
Host Infection ◽  
The Impact

Disease outbreaks and pathogen introductions can have significant effects on host populations, and the ability of pathogens to persist in the environment can exacerbate disease impacts by fueling sustained transmission, seasonal epidemics, and repeated spillover events. While theory suggests that the presence of an environmental reservoir increases the risk of host declines and threat of extinction, the influence of reservoir dynamics on transmission and population impacts remains poorly described. Here we show that the extent of the environmental reservoir explains broad patterns of host infection and the severity of disease impacts of a virulent pathogen. We examined reservoir and host infection dynamics and the resulting impacts of Pseudogymnoascus destructans, the fungal pathogen that causes white-nose syndrome, in 39 species of bats at 101 sites across the globe. Lower levels of pathogen in the environment consistently corresponded to delayed infection of hosts, fewer and less severe infections, and reduced population impacts. In contrast, an extensive and persistent environmental reservoir led to early and widespread infections and severe population declines. These results suggest that continental differences in the persistence or decay of P. destructans in the environment altered infection patterns in bats and influenced whether host populations were stable or experienced severe declines from this disease. Quantifying the impact of the environmental reservoir on disease dynamics can provide specific targets for reducing pathogen levels in the environment to prevent or control future epidemics.

scholarly journals Assessing early child development and its association with stunting and schistosome infections in rural Zimbabwean children using the Griffiths Scales of Child Development

2021 ◽  
Vol 15 (8) ◽  
pp. e0009660
Author(s):  
Francisca Mutapi ◽  
Lorraine Pfavayi ◽  
Derick Osakunor ◽  
Rivka Lim ◽  
Maritha Kasambala ◽  
...  
Keyword(s):  
Early Childhood ◽  
Child Development ◽  
Infection Intensity ◽  
Cognitive Stimulation ◽  
Childhood Development ◽  
Curative Treatment ◽  
Average Score ◽  
Infection Prevalence ◽  
General Development ◽  
The Impact

There is a paucity of reference early childhood development (ECD) data at community level in rural Africa. Our objective was to conduct a comprehensive assessment of ECD in rural Zimbabwe and determine the impact of stunting and schistosome infections on ECD. Using the Griffiths Scales of Child Development, we conducted a cross sectional assessment of Eye and Hand Coordination (EHC), Personal-Social-Emotional (PSE), Language and Communication (LC), Foundations of Learning (FL) and Gross Motor (GM) domains and the summary General Development (GD) in 166 children aged 6–72 months. The effects of stunting, malnutrition and Schistosoma haematobium infection on ECD was determined. The impact of praziquantel curative treatment of schistosome infection on the developmental scores was determined through a longitudinal follow up at 6 and 12 months. From an initial 166 children, 11 were found to have developmental deficits warranting further investigation. Of the remaining 155, 58.7% recorded a good (≥ average) score for the overall General Development (GD). Proportions of children scoring above the cut-off (≥ average) for each domain were GM (84.5%), PSE (80.6%), EHC (61.9%), FL (43.9%) and LC (44.5%). The prevalence of stunting was 26.8% (95% CI = 20.1%–34.8%) Scores for stunted children were significantly lower for EHC (p = 0.0042), GM (p = 0.0099), and GD (p = 0.0014) with the fraction of lower scores attributable to stunting being GM = 63.4%, GD = 46.6%, EHC = 45%, and LC = 21%. S. haematobium infection prevalence was 39.7% and mean infection intensity was 5.4 eggs/10 ml urine. Infected children had poorer cognitive performance scores for the FL (p = 0.0005) with 30.8% of poor FL attributable to the infection. Performance in all domains improved to the expected normal or above reference levels at 6 and 12 months post curative treatment of schistosome infections. Our study documented reference values for ECD in rural Zimbabwean children. The study detected deficiencies in the FL domain, which were more pronounced in children, infected with schistosomes, highlighting the need for provision of cognitive stimulation tools and access to early childhood foundation education. There is also need for improved child nutrition and treatment of schistosome infections to improve child development outcomes.

scholarly journals Resistance in persisting bat populations after white-nose syndrome invasion

2017 ◽  
Vol 372 (1712) ◽  
pp. 20160044 ◽  
Author(s):  
Kate E. Langwig ◽  
Joseph R. Hoyt ◽  
Katy L. Parise ◽  
Winifred F. Frick ◽  
Jeffrey T. Foster ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fungal Pathogen ◽  
Infection Intensity ◽  
Myotis Lucifugus ◽  
Pseudogymnoascus Destructans ◽  
White Nose Syndrome ◽  
The Face ◽  
Declining Populations ◽  
Little Brown Bat ◽  
Declining Species

Increases in anthropogenic movement have led to a rise in pathogen introductions and the emergence of infectious diseases in naive host communities worldwide. We combined empirical data and mathematical models to examine changes in disease dynamics in little brown bat ( Myotis lucifugus ) populations following the introduction of the emerging fungal pathogen Pseudogymnoascus destructans , which causes the disease white-nose syndrome. We found that infection intensity was much lower in persisting populations than in declining populations where the fungus has recently invaded. Fitted models indicate that this is most consistent with a reduction in the growth rate of the pathogen when fungal loads become high. The data are inconsistent with the evolution of tolerance or an overall reduced pathogen growth rate that might be caused by environmental factors. The existence of resistance in some persisting populations of little brown bats offers a glimmer of hope that a precipitously declining species will persist in the face of this deadly pathogen. This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.

scholarly journals Host persistence or extinction from emerging infectious disease: insights from white-nose syndrome in endemic and invading regions

2016 ◽  
Vol 283 (1826) ◽  
pp. 20152861 ◽  
Author(s):  
Joseph R. Hoyt ◽  
Kate E. Langwig ◽  
Keping Sun ◽  
Guanjun Lu ◽  
Katy L. Parise ◽  
...  
Keyword(s):  
North America ◽  
Infection Prevalence ◽  
Disease Dynamics ◽  
Pseudogymnoascus Destructans ◽  
Endemic Region ◽  
White Nose Syndrome ◽  
Resistant Species ◽  
Host Pathogen ◽  
Lower Transmission ◽  
Host Infection

Predicting species' fates following the introduction of a novel pathogen is a significant and growing problem in conservation. Comparing disease dynamics between introduced and endemic regions can offer insight into which naive hosts will persist or go extinct, with disease acting as a filter on host communities. We examined four hypothesized mechanisms for host–pathogen persistence by comparing host infection patterns and environmental reservoirs for Pseudogymnoascus destructans (the causative agent of white-nose syndrome) in Asia, an endemic region, and North America, where the pathogen has recently invaded. Although colony sizes of bats and hibernacula temperatures were very similar, both infection prevalence and fungal loads were much lower on bats and in the environment in Asia than North America. These results indicate that transmission intensity and pathogen growth are lower in Asia, likely due to higher host resistance to pathogen growth in this endemic region, and not due to host tolerance, lower transmission due to smaller populations, or lower environmentally driven pathogen growth rate. Disease filtering also appears to be favouring initially resistant species in North America. More broadly, determining the mechanisms allowing species persistence in endemic regions can help identify species at greater risk of extinction in introduced regions, and determine the consequences for disease dynamics and host–pathogen coevolution.

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