Understanding tick-transmitted pathogens in tick infested areas is crucial for the development of preventive and control measures in response to the increasing cases of tick-borne diseases. A stochastic model for the dynamics of two pathogens, Rickettsia parkeri and Rickettsia amblyommii, in a single tick, Amblyomma americanum, is developed and analysed. The model, a continuous-time Markov chain, is based on a deterministic tick-borne disease model. The extinction threshold for the stochastic model is computed using the multitype branching process and conditions for pathogen extinction or persistence are presented. The probability of pathogen extinction is computed using numerical simulations and is shown to be a good estimate of the probability of extinction calculated from the branching process. A sensitivity analysis is undertaken to illustrate the relationship between co-feeding and transovarial transmission rates and the probability of pathogen extinction. Expected epidemic duration is estimated using sample paths and we show that R. amblyommii is likely to persist slightly longer than R. parkeri. Further, we estimate the duration of possible coexistence of the two pathogens.
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http://dx.doi.org/10.1016/j.tpb.2019.04.004 | DOI Listing |
Virology
December 2024
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Rivadavia 1917, C1083ACA Ciudad Autónoma de Buenos Aires, Argentina; Laboratorio de Virología y Genética Molecular (LVGM), Facultad de Ciencias Naturales y Ciencias de la Salud, Universidad Nacional de la Patagonia San Juan Bosco, Belgrano 160, Trelew, CP, 9100, Argentina. Electronic address:
Intra-host viral variability is related to pathogenicity, persistence, drug resistance, and the emergence of new clades. This work reviews the large amount of data on SARS-CoV-2 intra-host variability accumulated to date, addressing known and potential implications in COVID-19 and the emergence of VOCs and lineage-defining mutations. Topics covered include the distribution of intra-host polymorphisms across the genome, the corresponding mutational signatures, their patterns of emergence and extinction throughout infection, and the processes governing their abundance, frequency, and type (synonymous, nonsynonymous, indels, nonsense).
View Article and Find Full Text PDFMicrobes Environ
December 2024
Institute for Plant Protection, National Agriculture and Food Research Organization (NARO).
White root rot disease caused by Rosellinia necatrix is a growing issue in orchards, and biochar pyrolyzed from the pruned branch residues of fruit trees has potential as a soil amendment agent with a number of benefits, such as long-term carbon sequestration. However, the effects of pruned branch biochar on white root rot disease remain unclear. Therefore, we compared direct antagonism against R.
View Article and Find Full Text PDFG3 (Bethesda)
December 2024
MRC Centre for Medical Mycology, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, United Kingdom, EX4 4QD.
Batrachochytrium dendrobatidis (Bd) is responsible for mass extinctions and extirpations of amphibians, mainly driven by the Global Panzootic Lineage (BdGPL). BdGPL isolate JEL423 is a commonly used reference strain in studies exploring the evolution, epidemiology and pathogenicity of chytrid pathogens. These studies have been hampered by the fragmented, erroneous and incomplete B.
View Article and Find Full Text PDFMar Pollut Bull
December 2024
Biomedical Research Center, Qatar University, P.O. Box 2713, Doha, Qatar. Electronic address:
The Persian Gulf hosts the second-largest population of Dugongs. The International Union for the Conservation of Nature (IUCN) lists them as Vulnerable to Extinction species. Incidental fishing, vessel strikes, environmental pollution, habitat degradation, and infectious diseases currently threaten these sirenians.
View Article and Find Full Text PDFBull Math Biol
December 2024
Department of Mathematics and Statistics, Texas Tech University, Lubbock, TX, 79409, USA.
Avian influenza virus type A causes an infectious disease that circulates among wild bird populations and regularly spills over into domesticated animals, such as poultry and swine. As the virus replicates in these intermediate hosts, mutations occur, increasing the likelihood of emergence of a new variant with greater transmission to humans and a potential threat to public health. Prior models for spread of avian influenza have included some combinations of the following components: multi-host populations, spillover into humans, environmental transmission, seasonality, and migration.
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