scholarly journals A series of terribly unfortunate events: How environment and infection synergized to cause the Kihansi spray toad extinction

2021 ◽  
Author(s):  
Thomas R Sewell ◽  
Lucy van Dorp ◽  
Pria Ghosh ◽  
Claudia Wierzbicki ◽  
Cristian Caroe ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Batrachochytrium Dendrobatidis ◽  
Abiotic Factors ◽  
Emerging Infectious Diseases ◽  
Molecular Dating ◽  
Habitat Modification ◽  
Mountainous Region ◽  
Extinction Event ◽  
Negative Impacts ◽  
Kihansi Spray Toad

Outbreaks of emerging infectious diseases are trained by local biotic and abiotic factors, with host declines occurring when conditions favour the pathogen. Extinction of the Tanzanian Kihansi spray toad (Nectophrynoides asperginis) in 2004 was contemporaneous with the construction of a dam, implicating habitat modification in the loss of this species. However, high burdens of a globally emerging infection, Batrachochytrium dendrobatidis (Bd) were synchronously observed implicating infectious disease in this toads extinction. Here, by shotgun sequencing skin DNA from archived toad mortalities and assembling chytrid mitogenomes, we prove this outbreak was caused by the BdCAPE lineage and not the panzootic lineage BdGPL that is widely associated with global amphibian extinctions. Molecular dating showed an invasion of BdCAPE across Southern Africa overlapping with the timing of the extinction event. However, post-outbreak surveillance of conspecific species inhabiting this mountainous region showed widespread infection by BdCAPE yet no signs of amphibian ill-health or species decline. Our findings show that despite efforts to mitigate the environmental impact caused by dams construction, invasion of the pathogen ultimately led to the loss of the Kihansi spray toad; a synergism between emerging infectious disease and environmental change that likely heralds wider negative impacts on biodiversity in the Anthropocene.

scholarly journals Disease driven extinction in the wild of the Kihansi spray toad (Nectophrynoides asperginis)

2019 ◽  
Author(s):  
C. Weldon ◽  
A. Channing ◽  
G. Misinzo ◽  
A.A. Cunningham
Keyword(s):  
Captive Breeding ◽  
Batrachochytrium Dendrobatidis ◽  
Population Decline ◽  
Population Monitoring ◽  
Habitat Modification ◽  
Epidemic Disease ◽  
Amphibian Species ◽  
Extinction Event ◽  
In The Wild ◽  
Kihansi Spray Toad

AbstractThe Kihansi spray toad, Nectophrynoides asperginis, became extinct in the wild despite population monitoring and conservation management of its habitat in the Kihansi gorge, Tanzania. Anecdotal evidence has indicated human induced habitat modification, predators, pesticides and disease as possible causes of a rapid population decline and the species extirpation. Here, we systematically investigate the role of disease in the extinction event of the wild toad population. The amphibian chytrid fungus, Batrachochytrium dendrobatidis, was detected in spray toads that died during the extinction event and subsequently in other amphibian species in Kihansi Gorge and the adjacent Udagaji Gorge, but not in any toads collected prior to this. Following the population decline, the remnant spray toad population gradually disappeared over a nine-month period. We demonstrate how demographic and behavioral attributes predisposed the spray toads to chytridiomycosis, due to B. dendrobatidis infection, and how epidemic disease could have been exacerbated by altered environmental conditions in the spray wetlands. Our results show that chytridiomycosis was the proximate cause of extinction in the wild of N. asperginis. This represents the first known case of extinction by disease of an amphibian species in Africa. A captive breeding program in the US and Tanzania ensures the survival of the species and a reintroduction program is underway. However, we caution that chytridiomycosis remains an existing threat that requires a comprehensive mitigation strategy before the desired conservation outcome of an established population of repatriated toads can be achieved.

scholarly journals Is overwintering mortality driving enigmatic declines? Evaluating the impacts of trematodes and the amphibian chytrid fungus on an anuran from hatching through overwintering

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262561
Author(s):  
Olivia Wetsch ◽  
Miranda Strasburg ◽  
Jessica McQuigg ◽  
Michelle D. Boone
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Species Conservation ◽  
Emerging Infectious Diseases ◽  
The Novel ◽  
Chytrid Fungus ◽  
Growth And Survival ◽  
Critical Life Events ◽  
Overwintering Mortality ◽  
Amphibian Chytrid Fungus

Emerging infectious diseases are increasing globally and are an additional challenge to species dealing with native parasites and pathogens. Therefore, understanding the combined effects of infectious agents on hosts is important for species’ conservation and population management. Amphibians are hosts to many parasites and pathogens, including endemic trematode flatworms (e.g., Echinostoma spp.) and the novel pathogenic amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Our study examined how exposure to trematodes during larval development influenced the consequences of Bd pathogen exposure through critical life events. We found that prior exposure to trematode parasites negatively impacted metamorphosis but did not influence the effect of Bd infection on terrestrial growth and survival. Bd infection alone, however, resulted in significant mortality during overwintering—an annual occurrence for most temperate amphibians. The results of our study indicated overwintering mortality from Bd could provide an explanation for enigmatic declines and highlights the importance of examining the long-term consequences of novel parasite exposure.

scholarly journals Human factors in emerging infectious diseases

2021 ◽  
Vol 2 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Scott B. Halstead
Keyword(s):  
Infectious Disease ◽  
Infectious Diseases ◽  
Human Factors ◽  
Emerging Infectious Diseases ◽  
Emerging Infectious Disease ◽  
Emerging Disease ◽  
Human Behaviour ◽  
Microbial World ◽  
Underlying Causes ◽  
Methods Of Control

When the underlying causes and mechanisms of emerging infectious disease problems are studied carefully, human behaviour is often involved. Even more often, the only methods of control or prevention available are to change human behaviour. Several major recent emerging disease problems can be cited. It is sometimes emphasized that it is human carelessness, human excesses, human ignorance or human habits of conquest or leisure which contribute directly to the biological niches that microorganisms are all too capable of exploiting. We must look at ourselves as the engines of microbial opportunism. It is not likely that we will ever conquer the microbial world;we must look instead to control the human factors that contribute to emergence.

scholarly journals Habitat fragmentation in the Brazilian Atlantic Forest is associated with erosion of frog immunogenetic diversity and increased fungal infections

2021 ◽  
Author(s):  
Anat Belasen ◽  
Kevin Amses ◽  
Rebecca Clemons ◽  
Guilherme Becker ◽  
Felipe Toledo ◽  
...  
Keyword(s):  
Habitat Fragmentation ◽  
Atlantic Forest ◽  
Batrachochytrium Dendrobatidis ◽  
Fungal Infections ◽  
Emerging Infectious Diseases ◽  
Genetic Erosion ◽  
Population Level ◽  
Brazilian Atlantic Forest ◽  
Frog Species ◽  
Mhc Iib

Habitat fragmentation and infectious disease threaten amphibians globally, but little is known about how these two threats interact. In this study, we examined the effects of Brazilian Atlantic Forest habitat fragmentation on frog genetic diversity at an immune locus known to affect disease susceptibility in amphibians, the MHC IIB locus. We used a custom high-throughput assay to sequence the MHC IIB locus across six focal frog species in two regions of the Atlantic Forest. We also used a molecular assay to quantify infections by the fungal pathogen Batrachochytrium dendrobatidis (Bd). We found that habitat fragmentation is associated with genetic erosion at the MHC IIB locus, and that this erosion is most severe in frog species restricted to intact forests. Significant Bd infections were recovered only in one Atlantic Forest region, potentially due to the relatively higher elevation. In this region, forest specialists showed an increase in both Bd prevalence and loads in fragmented habitats. We also found that reduced population-level MHC IIB diversity was associated with increased Bd infection risk. On the individual-level, MHC IIB heterozygotes (by allelic genotype as well as supertype) exhibited a reduced risk of Bd infection. Our results suggest that habitat fragmentation increases infection susceptibility in amphibians, mediated at least in part through loss of immunogenetic diversity. Our findings have implications for the conservation of fragmented populations in the face of emerging infectious diseases.

Biodegradable Waste a Nutrient Asset for Upholding Soil Health and Crop Production

2020 ◽  
pp. 36-51
Author(s):  
Ifra Ashraf ◽  
Shazia Ramzan ◽  
Nowsheeba Rashid ◽  
Ikhlaq A. Mir ◽  
Asima Jillani
Keyword(s):  
Waste Disposal ◽  
Crop Production ◽  
Abiotic Factors ◽  
Soil Health ◽  
Solid Wastes ◽  
Human Beings ◽  
Management Technology ◽  
Negative Impacts ◽  
Environmentally Sound

Management of solid wastes is a grave concern because of its associated significant negative impacts on quality of the environs. Accretion and putrefaction of solid wastes have potent hazardous effects on biotic and abiotic factors of the environment including human beings. Unmanaged solid wastes especially organic in nature add efficient quantity of greenhouse gases in the atmosphere. For dealing with wastes purely organic in nature, there is a need of an adequate waste management technology to reduce the quantity of organic waste being disposed of traditionally. Composting is an environmentally sound and sustainable approach to manage biodegradable fractions of solid waste. It has received considerable attention in the last few decades because of its potential of redressing the environmental pollution concerns associated with other waste disposal methods. This chapter is aimed to review supremacy of composting over other waste disposal methods.

scholarly journals Epidemic and endemic pathogen dynamics correspond to distinct host population microbiomes at a landscape scale

2017 ◽  
Vol 284 (1857) ◽  
pp. 20170944 ◽  
Author(s):  
Andrea J. Jani ◽  
Roland A. Knapp ◽  
Cheryl J. Briggs
Keyword(s):  
Infectious Disease ◽  
Fungal Pathogen ◽  
Batrachochytrium Dendrobatidis ◽  
Infection Intensity ◽  
Host Population ◽  
Symbiotic Bacteria ◽  
Skin Microbiome ◽  
Pathogen Infection ◽  
Microbiome Composition ◽  
Pathogen Invasion

Infectious diseases have serious impacts on human and wildlife populations, but the effects of a disease can vary, even among individuals or populations of the same host species. Identifying the reasons for this variation is key to understanding disease dynamics and mitigating infectious disease impacts, but disentangling cause and correlation during natural outbreaks is extremely challenging. This study aims to understand associations between symbiotic bacterial communities and an infectious disease, and examines multiple host populations before or after pathogen invasion to infer likely causal links. The results show that symbiotic bacteria are linked to fundamentally different outcomes of pathogen infection: host–pathogen coexistence (endemic infection) or host population extirpation (epidemic infection). Diversity and composition of skin-associated bacteria differed between populations of the frog, Rana sierrae , that coexist with or were extirpated by the fungal pathogen, Batrachochytrium dendrobatidis (Bd). Data from multiple populations sampled before or after pathogen invasion were used to infer cause and effect in the relationship between the fungal pathogen and symbiotic bacteria. Among host populations, variation in the composition of the skin microbiome was most strongly predicted by pathogen infection severity, even in analyses where the outcome of infection did not vary. This result suggests that pathogen infection shapes variation in the skin microbiome across host populations that coexist with or are driven to extirpation by the pathogen. By contrast, microbiome richness was largely unaffected by pathogen infection intensity, but was strongly predicted by geographical region of the host population, indicating the importance of environmental or host genetic factors in shaping microbiome richness. Thus, while both richness and composition of the microbiome differed between endemic and epidemic host populations, the underlying causes are most likely different: pathogen infection appears to shape microbiome composition, while microbiome richness was less sensitive to pathogen-induced disturbance. Because higher richness was correlated with host persistence in the presence of Bd, and richness appeared relatively stable to Bd infection, microbiome richness may contribute to disease resistance, although the latter remains to be directly tested.

scholarly journals Invasive vegetation affects amphibian skin microbiota and body condition

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8549 ◽  
Author(s):  
Obed Hernández-Gómez ◽  
Allison Q. Byrne ◽  
Alex R. Gunderson ◽  
Thomas S. Jenkinson ◽  
Clay F. Noss ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Body Condition ◽  
Invasive Plant ◽  
Batrachochytrium Dendrobatidis ◽  
Community Diversity ◽  
Habitat Modification ◽  
Sequence Variant ◽  
Soil Arthropods ◽  
Amphibian Skin ◽  
Skin Microbiota

Invasive plants are major drivers of habitat modification and the scale of their impact is increasing globally as anthropogenic activities facilitate their spread. In California, an invasive plant genus of great concern is Eucalyptus. Eucalyptus leaves can alter soil chemistry and negatively affect underground macro- and microbial communities. Amphibians serve as excellent models to evaluate the effect of Eucalyptus invasion on ground-dwelling species as they predate on soil arthropods and incorporate soil microbes into their microbiotas. The skin microbiota is particularly important to amphibian health, suggesting that invasive plant species could ultimately affect amphibian populations. To investigate the potential for invasive vegetation to induce changes in microbial communities, we sampled microbial communities in the soil and on the skin of local amphibians. Specifically, we compared Batrachoseps attenuatus skin microbiomes in both Eucalyptus globulus (Myrtaceae) and native Quercusagrifolia (Fagaceae) dominated forests in the San Francisco Bay Area. We determined whether changes in microbial diversity and composition in both soil and Batrachoseps attenuatus skin were associated with dominant vegetation type. To evaluate animal health across vegetation types, we compared Batrachoseps attenuatus body condition and the presence/absence of the amphibian skin pathogen Batrachochytrium dendrobatidis. We found that Eucalyptus invasion had no measurable effect on soil microbial community diversity and a relatively small effect (compared to the effect of site identity) on community structure in the microhabitats sampled. In contrast, our results show that Batrachoseps attenuatus skin microbiota diversity was greater in Quercus dominated habitats. One amplicon sequence variant identified in the family Chlamydiaceae was observed in higher relative abundance among salamanders sampled in Eucalyptus dominated habitats. We also observed that Batrachoseps attenuatus body condition was higher in Quercus dominated habitats. Incidence of Batrachochytrium dendrobatidis across all individuals was very low (only one Batrachochytrium dendrobatidis positive individual). The effect on body condition demonstrates that although Eucalyptus may not always decrease amphibian abundance or diversity, it can potentially have cryptic negative effects. Our findings prompt further work to determine the mechanisms that lead to changes in the health and microbiome of native species post-plant invasion.

scholarly journals HIV, Homosexuality and Depression – Challenges at Primary Care: A Case Report

2020 ◽  
Vol 4 (2) ◽  
pp. 145
Author(s):  
Fadzilah Mohamad ◽  
Lee Ping Yein ◽  
Maliza Mawardi
Keyword(s):  
Quality Of Life ◽  
Infectious Disease ◽  
Primary Care ◽  
Case Report ◽  
Health Sciences ◽  
Major Depressive ◽  
Immunodeficiency Virus ◽  
Negative Impacts ◽  
Sex With Men

Human Immunodeficiency Virus (HIV) is a chronic lifelong infectious disease that greatly impairs the quality of life. HIV and men who have sex with men (MSM) are seen to be synonyms to each other and both were shown to be the risks for depression. This case report is about a homosexual man who contracted HIV via the MSM activity. Being both homosexual and HIV-infected had given him a lot of negative impacts, stigma and discrimination, which drove him into having major depressive disorder. Having depression with underlying HIV and homosexuality has made this case complicated and challenging, especially when it has to be managed at the primary care level.International Journal of Human and Health Sciences Vol. 04 No. 02 April’20 Page : 145-147

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