scholarly journals Modelling hantavirus in fluctuating populations of bank voles: the role of indirect transmission on virus persistence

2003 ◽  
Vol 72 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Frank Sauvage ◽  
Michel Langlais ◽  
Nigel G. Yoccoz ◽  
Dominique Pontier
Keyword(s):  
Virus Persistence ◽  
Indirect Transmission ◽  
Bank Voles ◽  
Fluctuating Populations

scholarly journals Testing predator - prey theory by studying fluctuating populations of small mammals.

1995 ◽  
Vol 22 (1) ◽  
pp. 89 ◽  
Author(s):  
S. Boutin
Keyword(s):  
Population Dynamics ◽  
Small Mammals ◽  
Limit Cycles ◽  
Functional Responses ◽  
Predator Satiation ◽  
Linear Type ◽  
Small Component ◽  
Wide Range ◽  
Fluctuating Populations

Fluctuating populations of small mammals provide an excellent opportunity to study the functional and numerical responses of predators because of the wide range in prey density that occurs. I reinterpret data from six studies that have examined the role of predation in the population dynamics of voles in California, southern Sweden and western Finland, of snowshoe hares in northern Canada, and of house mice and rabbits in Australia. Most studies have measured functional responses by relying on changes in diet as reflected by scat or stomach contents. These methods are probably biased toward showing predator satiation. Contrary to previous conclusions I find that there is little evidence for non-linear (Type 111) functional-response curves or predator satiation at high prey densities. Recent studies indicate that the functional and numerical responses of predators can be rapid and strong enough to initiate cyclic declines, dampen fluctuations, or even cause stable numbers. The exception to this appears to be the irruptions of mice and rabbits in Australia. I propose a general explanation for the role of predation whereby the effect of predation is largely dependent on the entire prey community. When potentially cyclic prey are a small component of the overall prey biomass, generalist predators are able to prevent fluctuations by strong functional or numerical responses. As the prey community becomes dominated by a few species that fluctuate, limit cycles predominate. Limit cycles turn into irruptive population dynamics when seasonal prey reproduction is eliminated because of extended periods of vegetation growth (vegetation flushes following drought). In the future we must test assumptions underlying the way we study predation by telemetric monitoring of prey mortality and by experimentally manipulating predation.

scholarly journals Monitoring COVID-19 transmission risks by RT-PCR tracing of droplets in hospital and living environments

2020 ◽  
Author(s):  
Andrea Piana ◽  
Maria Eugenia Colucci ◽  
Federica Valeriani ◽  
Adriano Marcolongo ◽  
Giovanni Sotgiu ◽  
...  
Keyword(s):  
Biological Fluids ◽  
Viral Rna ◽  
Rt Pcr ◽  
The Public ◽  
Indirect Transmission ◽  
Critical Areas ◽  
Massive Sequencing ◽  
Hospital Wards ◽  
Support Evaluation

SARS-CoV-2 environmental contamination occurs through droplets and biological fluids released in the surroundings from patients or asymptomatic carriers. Surfaces and objects contaminated by saliva or nose secretions represent a risk for indirect transmission of COVID-19. We assayed surfaces from hospital and living spaces to identify the presence of viral RNA and the spread of fomites in the environment. Anthropic contamination by droplets and biological fluids was monitored by detecting the microbiota signature using multiplex RT-PCR on selected species and massive sequencing on 16S-amplicons. A total of 92 samples (flocked swab) were collected from critical areas during the pandemic, including indoor (3 hospitals and 3 public buildings) and outdoor surfaces exposed to anthropic contamination (handles and handrails, playgrounds). Traces of biological fluids were frequently detected in spaces open to the public and on objects that are touched with the hands (>80%). However, viral RNA was not detected in hospital wards or other indoor and outdoor surfaces either in the air system of a COVID-hospital, but only in the surroundings of an infected patient, in consistent association with droplets traces and fomites. Handled objects accumulated the highest level of multiple contaminations by saliva, nose secretions and faecal traces, further supporting the priority role of handwashing in prevention. In conclusion, anthropic contamination by droplets and biological fluids is widespread in spaces open to the public and can be traced by RT-PCR. Monitoring fomites can support evaluation of indirect transmission risks for Coronavirus or other flu-like viruses in the environment.

scholarly journals A Non-conventional Approach to Understanding the Geographical Influence on the Transmission of SARS-CoV-2 and IFR

2021 ◽  
Author(s):  
Udaya Ketipearachchi
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Mathematical Modelling ◽  
Outdoor Exposure ◽  
Dew Point ◽  
Effect Of Temperature ◽  
Temperature Dependency ◽  
Indirect Transmission ◽  
Indoor And Outdoor

Abstract Transmission of SARS-CoV-2 is not well understood and different models are needed (i.e. one model cannot answer it all) to understand and fight this disease. Mathematical modelling is a powerful tool for understanding transmission of SARS-CoV-2 and evaluating possible events or scenarios. Here, we present two models based on indirect transmission of SARSCoV-2 that explain the influence of ambient temperature and air pollution on outdoor and indoor behavior of SARS-CoV-2. These models discuss the temperature dependency of the lethality of SARS-CoV-2 and its spread during indoor and outdoor exposure. Furthermore, the temperature effect on the half-life of SARS-CoV-2 is discussed if the SARS-CoV-2 is transmitted via particulate matter or surfaces. It is also important to understand the role of dew point instead of the humidity factor alone as the combined effect of temperature and humidity might play a major role in the transmission of SARS-CoV-2 .

scholarly journals A Non-conventional Approach to Understanding the Geographical Influence on the Transmission of SARS-CoV-2 and IFR

2021 ◽  
Author(s):  
Udaya Ketipearachchi
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Half Life ◽  
Outdoor Exposure ◽  
Dew Point ◽  
Effect Of Temperature ◽  
Temperature Dependency ◽  
Indirect Transmission ◽  
Indoor And Outdoor

Abstract Transmission of SARS-CoV-2 is not well understood and different models are needed (i.e. one model cannot answer it all) to understand and fight this disease. Here, we present two models based on indirect transmission of SARS-CoV-2 that explain the influence of ambient temperature and air pollution on outdoor and indoor behavior of SARS-CoV-2. These models discuss the temperature dependency of the lethality of SARS-CoV-2 and its spread during indoor and outdoor exposure. Furthermore, the temperature effect on the half-life of SARS-CoV-2 is discussed if the SARSCoV-2 is transmitted via particulate matter or surfaces. It is also important to understand the role of dew point instead of the humidity factor alone as the combined effect of temperature and humidity might play a major role in the transmission of SARS-CoV-2 .

scholarly journals Small rodent population synchrony in western Sweden. Effects of landscape structure

Web Ecology ◽  
2008 ◽  
Vol 8 (1) ◽  
pp. 14-21 ◽  
Author(s):  
J. Loman
Keyword(s):  
Landscape Structure ◽  
Agricultural Landscape ◽  
Small Rodent ◽  
Agricultural Region ◽  
Wood Mice ◽  
Bank Voles ◽  
Forest Region ◽  
Continuous Forest ◽  
Made In

Abstract. Small rodents were captured in two regions in western Sweden. One represents an agricultural landscape were captures were made in 19 small habitat islands and in two small forests. The other represents a forest region were captures were made in four sites in a continuous forest. The captures were made for seven years. There were no clear indications of cyclicity. Within both regions, wood mice captures were in synchrony among sites. For bank voles, this was only true in the forest region and for field voles in the agricultural region. Captures of field voles were too few for analysis in the forest region. Among species, captures were not synchronous in the agricultural region but captures of wood mice and bank voles were synchronous in the forest region. These results suggest a role of landscape structure for the population dynamics of these species, rather than differences in predator function.

scholarly journals Porous surfaces: stability and recovery of coronaviruses

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lucy Owen ◽  
Maitreyi Shivkumar ◽  
Richard B. M. Cross ◽  
Katie Laird
Keyword(s):  
Surface Properties ◽  
Close Contact ◽  
Indirect Contact ◽  
Indirect Transmission ◽  
Hydrophobic Materials ◽  
Porous Surfaces ◽  
Potential Risks ◽  
The Stability ◽  
Review Current

The role of indirect contact in the transmission of SARS-CoV-2 is not clear. SARS-CoV-2 persists on dry surfaces for hours to days; published studies have largely focused on hard surfaces with less research being conducted on different porous surfaces, such as textiles. Understanding the potential risks of indirect transmission of COVID-19 is useful for settings where there is close contact with textiles, including healthcare, manufacturing and retail environments. This article aims to review current research on porous surfaces in relation to their potential as fomites of coronaviruses compared to non-porous surfaces. Current methodologies for assessing the stability and recovery of coronaviruses from surfaces are also explored. Coronaviruses are often less stable on porous surfaces than non-porous surfaces, for example, SARS-CoV-2 persists for 0.5 h–5 days on paper and 3–21 days on plastic; however, stability is dependent on the type of surface. In particular, the surface properties of textiles differ widely depending on their construction, leading to variation in the stability of coronaviruses, with longer persistence on more hydrophobic materials such as polyester (1–3 days) compared to highly absorbent cotton (2 h–4 days). These findings should be considered where there is close contact with potentially contaminated textiles.

scholarly journals Role of African swine fever virus (ASFV) proteins EP153R and EP402R in reducing viral persistence in blood and virulence in pigs infected with BeninΔDP148R

2021 ◽  
Author(s):  
Vlad Petrovan ◽  
Anusyah Rathakrishnan ◽  
Muneeb Islam ◽  
Lynnette C. Goatley ◽  
Katy Moffat ◽  
...  
Keyword(s):  
Vaccine Development ◽  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Fever Virus ◽  
Genotype I ◽  
Virus Persistence ◽  
Challenge Virus

The limited knowledge on the role of many of the approximately 170 proteins encoded by African swine fever virus restricts progress towards vaccine development. Previously, the DP148R gene was deleted from the genome of genotype I virulent Benin 97/1 isolate. This virus, BeninΔDP148R, induced transient moderate clinical signs after immunization and high levels of protection against challenge. However, the BeninΔDP148R virus and genome persisted in blood over a prolonged period. In the current study deletion of either EP402R or EP153R genes individually or in combination from BeninΔDP148R genome was shown not to reduce virus replication in macrophages in vitro. However, deletion of EP402R dramatically reduced the period of infectious virus persistence in blood in immunized pigs from 28 to 14 days and virus genome from 59 to 14 days, whilst maintaining high levels of protection against challenge. The additional deletion of EP153R (BeninΔDP148RΔEP153RΔEP402R) further attenuated the virus and no viremia or clinical signs were observed post-immunization. This was associated with decreased protection and detection of moderate levels of challenge virus in blood. Interestingly, the deletion of EP153R alone from BeninΔDP148R did not result in further virus attenuation and did not reduce the period of virus persistence in blood. These results show that EP402R and EP153R have a synergistic role in reducing clinical signs and levels of virus in blood. Importance: African swine fever virus (ASFV) causes a disease of domestic pigs and wild boar which results in death of almost all infected animals. The disease has a high economic impact, and no vaccine is available. We investigated the role of two ASFV proteins, called EP402R and EP153R, in determining the levels and length of time virus persists in blood from infected pigs. EP402R causes ASFV particles and infected cells to bind to red blood cells. Deletion of the EP402R gene dramatically reduced virus persistence in blood but did not reduce the level of virus. Deletion of the EP153R alone did not reduce the period or level of virus persistence in blood. However, deleting both EP153R and EP402R resulted in undetectable levels of virus in blood and no clinical signs showing the proteins act synergistically. Importantly the infected pigs were protected following infection with the wildtype virus that kills pigs.

scholarly journals Experimental Mycobacterium microti Infection in Bank Voles (Myodes glareolus)

2022 ◽  
Vol 10 (1) ◽  
pp. 135
Author(s):  
Enric Vidal ◽  
Judit Burgaya ◽  
Lorraine Michelet ◽  
Claudia Arrieta-Villegas ◽  
Guillermo Cantero ◽  
...  
Keyword(s):  
Horizontal Transmission ◽  
Myodes Glareolus ◽  
Infection Model ◽  
Disease Phenotype ◽  
Bank Voles ◽  
Granulomatous Lesions ◽  
Set Up ◽  
Free Ranging ◽  
Mycobacterium Microti

Voles are maintenance hosts of Mycobacterium microti. In line with the goal to eradicate tuberculosis (TB) in livestock, the role of this mycobacteria needs to be assessed since it might interfere with current M. bovis/M. caprae surveillance strategies. To better understand the pathogenesis of TB in voles, an experimental infection model was set up to reproduce M. microti infection in laboratory Bank voles (Myodes glareolus). Two infection routes (intragastric and intraperitoneal) and doses (105 and 106 CFU/0.1 mL) were assessed. Voles were culled at different post-infection time points. Serology, histopathology, acid-fast bacilli staining, qPCR, and mycobacterial culture from tissues were performed. In addition, qPCR from feces and oral swabs were conducted to assess bacterial shedding. The model allowed us to faithfully reproduce the disease phenotype described in free-ranging voles and characterize the pathogenesis of the infection. Most animals showed multifocal and diffuse granulomatous lesions in the liver and spleen, respectively. Less frequently, granulomas were observed in lungs, lymph nodes, muscles, and salivary gland. Mycobacterial DNA was detected in feces from a few animals but not in oral swabs. However, one contact uninfected vole seroconverted and showed incipient TB compatible lesions, suggesting horizontal transmission between voles.

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