scholarly journals Reservoir hosts experiencing food stress alter transmission dynamics for a zoonotic pathogen

2021 ◽  
Vol 288 (1956) ◽  
pp. 20210881
Author(s):  
J. C. Owen ◽  
H. R. Landwerlen ◽  
A. P. Dupuis ◽  
A. V. Belsare ◽  
D. B. Sharma ◽  
...  
Keyword(s):  
Host Resistance ◽  
Food Limitation ◽  
Disease Outbreaks ◽  
Host Population ◽  
Transmission Dynamics ◽  
Avian Host ◽  
Mosquito Vector ◽  
Key Factor ◽  
In The Wild ◽  
Reservoir Hosts

Food limitation is a universal stressor for wildlife populations and is increasingly exacerbated by human activities. Anthropogenic environmental change can significantly alter the availability and quality of food resources for reservoir hosts and impact host–pathogen interactions in the wild. The state of the host's nutritional reserves at the time of infection is a key factor influencing infection outcomes by altering host resistance. Combining experimental and model-based approaches, we investigate how an environmental stressor affects host resistance to West Nile virus (WNV). Using American robins ( Turdus migratorius ), a species considered a superspreader of WNV, we tested the effect of acute food deprivation immediately prior to infection on host viraemia. Here, we show that robins food deprived for 48 h prior to infection, developed higher virus titres and were infectious longer than robins fed normally. To gain an understanding about the epidemiological significance of food-stressed hosts, we developed an agent-based model that simulates transmission dynamics of WNV between an avian host and the mosquito vector. When simulating a nutritionally stressed host population, the mosquito infection rate rose significantly, reaching levels that represent an epidemiological risk. An understanding of the infection disease dynamics in wild populations is critical to predict and mitigate zoonotic disease outbreaks.

scholarly journals Dynamics of host populations affected by the emerging fungal pathogen Batrachochytrium salamandrivorans

2017 ◽  
Vol 4 (3) ◽  
pp. 160801 ◽  
Author(s):  
Benedikt R. Schmidt ◽  
Claudio Bozzuto ◽  
Stefan Lötters ◽  
Sebastian Steinfartz
Keyword(s):  
Emerging Infectious Diseases ◽  
Disease Outbreaks ◽  
Host Population ◽  
Mitigation Measures ◽  
Disease Emergence ◽  
Batrachochytrium Salamandrivorans ◽  
In The Wild ◽  
Successful Control ◽  
Using Data ◽  
Local Extirpation

Emerging infectious diseases cause extirpation of wildlife populations. We use an epidemiological model to explore the effects of a recently emerged disease caused by the salamander-killing chytrid fungus Batrachochytrium salamandrivorans ( Bsal ) on host populations, and to evaluate which mitigation measures are most likely to succeed. As individuals do not recover from Bsal , we used a model with the states susceptible, latent and infectious, and parametrized the model using data on host and pathogen taken from the literature and expert opinion. The model suggested that disease outbreaks can occur at very low host densities (one female per hectare). This density is far lower than host densities in the wild. Therefore, all naturally occurring populations are at risk. Bsal can lead to the local extirpation of the host population within a few months. Disease outbreaks are likely to fade out quickly. A spatial variant of the model showed that the pathogen could potentially spread rapidly. As disease mitigation during outbreaks is unlikely to be successful, control efforts should focus on preventing disease emergence and transmission between populations. Thus, this emerging wildlife disease is best controlled through prevention rather than subsequent actions.

scholarly journals The environmental and ecological determinants of elevated Ross River Virus exposure in koalas residing in urban coastal landscapes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Brian J. Johnson ◽  
Amy Robbins ◽  
Narayan Gyawali ◽  
Oselyne Ong ◽  
Joanne Loader ◽  
...  
Keyword(s):  
Animal Movement ◽  
Ross River Virus ◽  
Mosquito Vector ◽  
Large Numbers ◽  
Culex Annulirostris ◽  
Coastal Landscapes ◽  
In The Wild ◽  
Virus Exposure ◽  
Elevated Exposure ◽  
The Impact

AbstractKoala populations in many areas of Australia have declined sharply in response to habitat loss, disease and the effects of climate change. Koalas may face further morbidity from endemic mosquito-borne viruses, but the impact of such viruses is currently unknown. Few seroprevalence studies in the wild exist and little is known of the determinants of exposure. Here, we exploited a large, spatially and temporally explicit koala survey to define the intensity of Ross River Virus (RRV) exposure in koalas residing in urban coastal environments in southeast Queensland, Australia. We demonstrate that RRV exposure in koalas is much higher (> 80%) than reported in other sero-surveys and that exposure is uniform across the urban coastal landscape. Uniformity in exposure is related to the presence of the major RRV mosquito vector, Culex annulirostris, and similarities in animal movement, tree use, and age-dependent increases in exposure risk. Elevated exposure ultimately appears to result from the confinement of remaining coastal koala habitat to the edges of permanent wetlands unsuitable for urban development and which produce large numbers of competent mosquito vectors. The results further illustrate that koalas and other RRV-susceptible vertebrates may serve as useful sentinels of human urban exposure in endemic areas.

scholarly journals Sarcoptic mange in wild ruminants in Spain: solving the epidemiological enigma using microsatellite markers

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Barbara Moroni ◽  
Samer Angelone ◽  
Jesús M. Pérez ◽  
Anna Rita Molinar Min ◽  
Mario Pasquetti ◽  
...  
Keyword(s):  
Microsatellite Markers ◽  
Sarcoptes Scabiei ◽  
Host Population ◽  
Sarcoptic Mange ◽  
Wild Ruminant ◽  
Capra Pyrenaica ◽  
Wild Ruminants ◽  
In The Wild ◽  
Genetic Clusters ◽  
Genetic Strains

Abstract Background In Spain, sarcoptic mange was first described in native wildlife in 1987 in Cazorla Natural Park, causing the death of nearly 95% of the local native population of Iberian ibex (Capra pyrenaica). Since then, additional outbreaks have been identified in several populations of ibex and other wild ungulate species throughout the country. Although the first epizootic outbreak in wildlife was attributed to the introduction of an infected herd of domestic goats, the origin and the cause of its persistence remain unclear. The main aims of this study are to understand (i) the number of Sarcoptes scabiei “strains” circulating in wild ruminant populations in Spain, and (ii) the molecular epidemiological relationships between S. scabiei and its hosts. Methods Ten Sarcoptes microsatellite markers were used to characterize the genetic structure of 266 mites obtained from skin scrapings of 121 mangy wild ruminants between 2011 and 2019 from 11 areas in Spain. Results Seventy-three different alleles and 37 private alleles were detected. The results of this study show the existence of three genetic strains of S. scabiei in the wild ruminant populations investigated. While two genetic clusters of S. scabiei were host- and geography-related, one cluster included multi-host mites deriving from geographically distant populations. Conclusions The molecular epidemiological study of S. scabiei in wild ruminants in Spain indicates that the spreading and persistence of the parasite may be conditioned by host species community composition and the permissiveness of each host population/community to the circulation of individual “strains,” among other factors. Wildlife–livestock interactions and the role of human-driven introduction or trade of wild and domestic animals should be better investigated to prevent further spread of sarcoptic mange in as yet unaffected natural areas of the Iberian Peninsula.

scholarly journals Blood parasites in vectors reveal a united blackfly community in the upper canopy

2020 ◽  
Author(s):  
Nayden Chakarov ◽  
Helge Kampen ◽  
Anja Wiegmann ◽  
Doreen Werner ◽  
Staffan Bensch
Keyword(s):  
Forest Canopy ◽  
Habitat Preferences ◽  
Blood Parasites ◽  
Avian Host ◽  
Haemosporidian Parasite ◽  
Host Group ◽  
Haemosporidian Parasites ◽  
Blood Sucking ◽  
In The Wild ◽  
Host Parasite

Abstract Background: The behaviour of blood-sucking arthropods is a crucial determinant of blood protozoan distribution and hence of host-parasite coevolution, but it is very challenging to study in the wild. The molecular identification of parasite lineages in vectors can be a useful key to understand the behaviour and transmission patterns realised by these vectors. Methods: In this study, we collected blackflies around nests of three raptor species in the upper forest canopy in central Europe and examined the presence of vertebrate DNA and haemosporidian parasites in them. We molecularly analysed 156 blackfly individuals, their vertebrate blood meals, and the haemosporidian parasite lineages they carried. Results: We identified nine species of Simulium blackflies, largely belonging to the subgenera Nevermannia and Eusimulium. Only 1% of the collected specimens was visibly engorged, and only 4% contained remains of host DNA. However, in 29% of the blackflies Leucocytozoon lineages were identified, which is evidence of a previous blood meal on an avian host. Based on the known vertebrate hosts of the recorded Leucocytozoon lineages, we can infer that large and/or abundant birds, such as thrushes, crows, pigeons, birds of prey, owls and tits are the main targets of ornithophilic blackflies in the canopy. Blackfly species contained similar proportions of host group-specific parasite lineages and thus do not appear to be associated with particular host groups. Conclusions: The Leucocytozoon clade infecting thrushes, crows, and pigeons present in most represented blackfly species suggests a lack of association between hosts and blackflies, which can increase the probability of host switches of blood parasites. However, the composition of the simuliid species differed between nests of common buzzards, goshawks and red kites. This segregation can be explained by coinciding habitat preferences between host and vector, and may lead to the fast speciation of Leucocytozoon parasites. Thus, subtle ecological preferences and lack of host preference of vectors in the canopy may enable both parasite diversification and host switches, and enforce a habitat-dependent evolution of avian malaria parasites and related haemosporidia.

scholarly journals Experimental Evaluation of the Role of Ecologically-Relevant Hosts and Vectors in Japanese Encephalitis Virus Genotype Displacement

Viruses ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 32 ◽  
Author(s):  
Ajit K. Karna ◽  
Richard A. Bowen
Keyword(s):  
Japanese Encephalitis Virus ◽  
Japanese Encephalitis ◽  
Experimental Evaluation ◽  
Encephalitis Virus ◽  
Viral Fitness ◽  
Avian Host ◽  
Mosquito Vector ◽  
Virus Genotype ◽  
Southern Asia

Japanese encephalitis virus (JEV) is a flavivirus that is maintained via transmission between Culex spp. mosquitoes and water birds across a large swath of southern Asia and northern Australia. Currently JEV is the leading cause of vaccine-preventable encephalitis in humans in Asia. Five genotypes of JEV (G-I–G-V) have been responsible for historical and current outbreaks in endemic regions, and G-I and G-III co-circulate throughout Southern Asia. While G-III has historically been the dominant genotype worldwide, G-I has gradually but steadily displaced G-III. The objective of this study was to better understand the phenomenon of genotype displacement for JEV by evaluating both avian host and mosquito vector susceptibilities to infection with representatives from both G-I and G-III. Since ducks and Culex quinquefasciatus mosquitoes are prevalent avian hosts and vectors perpetuating JEV transmission in JE endemic areas, experimental evaluation of virus replication in these species was considered to approximate the natural conditions necessary for studying the role of host, vectors and viral fitness in the JEV genotype displacement context. We evaluated viremia in ducklings infected with G-I and G-III, and did not detect differences in magnitude or duration of viremia. Testing the same viruses in mosquitoes revealed that the rates of infection, dissemination and transmission were higher in virus strains belonging to G-I than G-III, and that the extrinsic incubation period was shorter for the G-I strains. These data suggest that the characteristics of JEV infection of mosquitoes but not of ducklings, may have play a role in genotype displacement.

scholarly journals Trypanosoma cruzi transmission in the wild and its most important reservoir hosts in Brazil

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana Maria Jansen ◽  
Samanta Cristina das Chagas Xavier ◽  
André Luiz Rodrigues Roque
Keyword(s):  
Trypanosoma Cruzi ◽  
In The Wild ◽  
Reservoir Hosts

scholarly journals Emerging infectious pathogens of wildlife

2001 ◽  
Vol 356 (1411) ◽  
pp. 1001-1012 ◽  
Author(s):  
A. Dobson ◽  
J. Foufopoulos
Keyword(s):  
United States ◽  
Anthropogenic Activities ◽  
Disease Outbreaks ◽  
The United States ◽  
Host Population ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Emerging Pathogens ◽  
Emergent Pathogen ◽  
Insight Into

The first part of this paper surveys emerging pathogens of wildlife recorded on the ProMED Web site for a 2–year period between 1998 and 2000. The majority of pathogens recorded as causing disease outbreaks in wildlife were viral in origin. Anthropogenic activities caused the outbreaks in a significant majority of cases. The second part of the paper develops some matrix models for quantifying the basic reproductive number, R 0 , for a variety of potential types of emergent pathogen that cause outbreaks in wildlife. These analyses emphasize the sensitivity of R 0 to heterogeneities created by either the spatial structure of the host population, or the ability of the pathogens to utilize multiple host species. At each stage we illustrate how the approach provides insight into the initial dynamics of emergent pathogens such as canine parvovirus, Lyme disease, and West Nile virus in the United States.

scholarly journals How to find natural reservoir hosts from endemic prevalence in a multi-host population: A case study of influenza in waterfowl

Epidemics ◽  
2009 ◽  
Vol 1 (2) ◽  
pp. 118-128 ◽  
Author(s):  
Hiroshi Nishiura ◽  
Bethany Hoye ◽  
Marcel Klaassen ◽  
Silke Bauer ◽  
Hans Heesterbeek
Keyword(s):  
Host Population ◽  
Natural Reservoir ◽  
Reservoir Hosts

scholarly journals Asymmetric percolation drives a double transition in sexual contact networks

2017 ◽  
Vol 114 (34) ◽  
pp. 8969-8973 ◽  
Author(s):  
Antoine Allard ◽  
Benjamin M. Althouse ◽  
Samuel V. Scarpino ◽  
Laurent Hébert-Dufresne
Keyword(s):  
Analytical Description ◽  
Sexual Contact ◽  
Transmission Dynamics ◽  
Random Networks ◽  
Mosquito Vector ◽  
Percolation Process ◽  
Contact Networks ◽  
Double Transition ◽  
Sexual Contacts ◽  
Males And Females

Zika virus (ZIKV) exhibits unique transmission dynamics in that it is concurrently spread by a mosquito vector and through sexual contact. Due to the highly asymmetric durations of infectiousness between males and females—it is estimated that males are infectious for periods up to 10 times longer than females—we show that this sexual component of ZIKV transmission behaves akin to an asymmetric percolation process on the network of sexual contacts. We exactly solve the properties of this asymmetric percolation on random sexual contact networks and show that this process exhibits two epidemic transitions corresponding to a core–periphery structure. This structure is not present in the underlying contact networks, which are not distinguishable from random networks, and emerges because of the asymmetric percolation. We provide an exact analytical description of this double transition and discuss the implications of our results in the context of ZIKV epidemics. Most importantly, our study suggests a bias in our current ZIKV surveillance, because the community most at risk is also one of the least likely to get tested.

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