scholarly journals Effect of Temperature on Host Preference in Two Lineages of the Brown Dog Tick, Rhipicephalus sanguineus

2021 ◽  
Author(s):  
Laura H. Backus ◽  
Andrés M. López Pérez ◽  
Janet E. Foley
Keyword(s):  
Disease Transmission ◽  
Room Temperature ◽  
Disease Outbreaks ◽  
Rhipicephalus Sanguineus ◽  
Pathogen Transmission ◽  
Effect Of Temperature ◽  
Rickettsia Rickettsii ◽  
Hot Weather ◽  
Dog Tick ◽  
The Impact

Rhipicephalus sanguineus is a species complex of ticks that vector disease worldwide. Feeding primarily on dogs, members of the complex also feed incidentally on humans, potentially transmitting disease agents such as Rickettsia rickettsii, R. conorii, and Ehrlichia species. There are two genetic Rh. sanguineus lineages in North America, designated as the temperate and tropical lineages, which had occurred in discrete locations, although there is now range overlap in parts of California and Arizona. Rh. sanguineus in Europe are reportedly more aggressive toward humans during hot weather, increasing the risk of pathogen transmission to humans. The aim of this study was to assess the impact of hot weather on choice between humans and dog hosts among tropical and temperate lineage Rh. sanguineus individuals. Ticks in a two-choice olfactometer migrated toward a dog or human in trials at room (23.5°C) or high temperature (38°C). At 38°C, 2.5 times more tropical lineage adults chose humans compared with room temperature, whereas temperate lineage adults demonstrated a 66% reduction in preference for dogs and a slight increase in preference for humans. Fewer nymphs chose either host at 38°C than at room temperature in both lineages. These results demonstrate that risk of disease transmission to humans may be increased during periods of hot weather, where either lineage is present, and that hot weather events associated with climatic change may result in more frequent rickettsial disease outbreaks.

scholarly journals Quantity and Quality of Aquaculture Enrichments Influence Disease Epidemics and Provide Ecological Alternatives to Antibiotics

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 335
Author(s):  
Anssi Karvonen ◽  
Ville Räihä ◽  
Ines Klemme ◽  
Roghaieh Ashrafi ◽  
Pekka Hyvärinen ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Bacterial Infections ◽  
Environmental Heterogeneity ◽  
Pathogen Transmission ◽  
Central Component ◽  
Flavobacterium Columnare ◽  
Disease Epidemics ◽  
The Impact ◽  
Environmental Microbes

Environmental heterogeneity is a central component influencing the virulence and epidemiology of infectious diseases. The number and distribution of susceptible hosts determines disease transmission opportunities, shifting the epidemiological threshold between the spread and fadeout of a disease. Similarly, the presence and diversity of other hosts, pathogens and environmental microbes, may inhibit or accelerate an epidemic. This has important applied implications in farming environments, where high numbers of susceptible hosts are maintained in conditions of minimal environmental heterogeneity. We investigated how the quantity and quality of aquaculture enrichments (few vs. many stones; clean stones vs. stones conditioned in lake water) influenced the severity of infection of a pathogenic bacterium, Flavobacterium columnare, in salmonid fishes. We found that the conditioning of the stones significantly increased host survival in rearing tanks with few stones. A similar effect of increased host survival was also observed with a higher number of unconditioned stones. These results suggest that a simple increase in the heterogeneity of aquaculture environment can significantly reduce the impact of diseases, most likely operating through a reduction in pathogen transmission (stone quantity) and the formation of beneficial microbial communities (stone quality). This supports enriched rearing as an ecological and economic way to prevent bacterial infections with the minimal use of antimicrobials.

scholarly journals To die so far from Dixie : modeling epidemic dysentery in a Civil War prison camp

2015 ◽  
Author(s):  
◽  
Rebecca Shattuck Lander
Keyword(s):  
Civil War ◽  
Disease Transmission ◽  
National Level ◽  
Human Movement ◽  
Pathogen Transmission ◽  
Disease Spread ◽  
Computer Simulation Model ◽  
Prison Camp ◽  
The Impact ◽  
The Way

Epidemics have played a role in shaping human experiences of conflict among both soldiers and civilians. Prisoners of war, displaced populations, and confined refugees have experienced, and continue to experience, outbreaks of infectious disease, which are exacerbated by physical, environmental, and psychological stressors. Observations of epidemics at the global, regional, or national level are not always able to provide a complete picture of the unique health challenges of these wartime populations. This research develops and applies a computer simulation model to examine the way human behaviors, and the impact of those behaviors on the environment, can impact the way diarrheal diseases develop and spread in confined high-density living situations. This simulation was tested against the recorded death and sickness patterns for a dysentery outbreak at Camp Douglas, Illinois, a 19th Century Civil War prison camp. The agent-based simulation used in this research is a unique approach, and is based on the feedback relationship between human movement and behavior and the resulting contamination of physical spaces with infectious material, rather than direct person-to-person pathogen transmission. The results of this simulation suggests that modeling disease transmission based on environmental result in distinct epidemic dynamics. The results of this research emphasize the importance of examining the relationship between humans, their environment, and patterns of health and disease. Additionally, it highlights the way that model design can help to increase knowledge of how even limited movement and interaction options available to confined individuals can lead to significant differences in patterns of disease spread and epidemic development, which can help to better design public health interventions targeted at confined populations.

scholarly journals Hot Summers: Effect of Extreme Temperatures on Ozone in Sydney, Australia

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 466 ◽  
Author(s):  
Steven Utembe ◽  
Peter Rayner ◽  
Jeremy Silver ◽  
Elise-Andree Guérette ◽  
Jenny Fisher ◽  
...  
Keyword(s):  
Air Quality ◽  
Elevated Temperatures ◽  
Reaction Rates ◽  
Extreme Heat ◽  
Effect Of Temperature ◽  
Biogenic Emissions ◽  
Hot Weather ◽  
Ozone Episodes ◽  
The Impact ◽  
Averaged Model

Poor air quality is often associated with hot weather, but the quantitative attribution of high temperatures on air quality remains unclear. In this study, the effect of elevated temperatures on air quality is investigated in Greater Sydney using January 2013, a period of extreme heat during which temperatures at times exceeded 40 ∘ C, as a case study. Using observations from 17 measurement sites and the Weather Research and Forecasting Chemistry (WRF-Chem) model, we analyse the effect of elevated temperatures on ozone in Sydney by running a number of sensitivity studies in which: (1) the model is run with biogenic emissions generated by MEGAN and separately run with monthly average Model of Emissions of Gases and Aerosols from Nature ( MEGAN) biogenic emissions (for January 2013); (2) the model results from the standard run are compared with those in which average temperatures (for January 2013) are only applied to the chemistry; (3) the model is run using both averaged biogenic emissions and temperatures; and (4 and 5) the model is run with half and zero biogenic emissions. The results show that the impact on simulated ozone through the effect of temperature on reaction rates is similar to the impact via the effect of temperature on biogenic emissions and the relative impacts are largely additive when compared to the run in which both are averaged. When averaged across 17 sites in Greater Sydney, the differences between ozone simulated under standard and averaged model conditions are as high as 16 ppbv. Removing biogenic emissions in the model has the effect of removing all simulated ozone episodes during extreme heat periods, highlighting the important role of biogenic emissions in Australia, where Eucalypts are a key biogenic source.

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 Assessing the potential impact of vector-borne disease transmission following heavy rainfall events: a mathematical framework

2019 ◽  
Vol 374 (1775) ◽  
pp. 20180272 ◽  
Author(s):  
G. Chowell ◽  
K. Mizumoto ◽  
J. M. Banda ◽  
S. Poccia ◽  
C. Perrings
Keyword(s):  
Disease Transmission ◽  
Disease Outbreaks ◽  
Theme Issue ◽  
Rainfall Events ◽  
Transmission Season ◽  
Vector Borne Disease ◽  
Infectious Disease Outbreaks ◽  
Vector Borne ◽  
The Impact ◽  
Heavy Rainfall Events

Predicting the impact of natural disasters such as hurricanes on the transmission dynamics of infectious diseases poses significant challenges. In this paper, we put forward a simple modelling framework to investigate the impact of heavy rainfall events (HREs) on mosquito-borne disease transmission in temperate areas of the world such as the southern coastal areas of the USA. In particular, we explore the impact of the timing of HREs relative to the transmission season via analyses that test the sensitivity of HRE-induced epidemics to variation in the effects of rainfall on the dynamics of mosquito breeding capacity, and the intensity and temporal profile of human population displacement patterns. The recent Hurricane Harvey in Texas motivates the simulations reported. Overall, we find that the impact of vector-borne disease transmission is likely to be greater the earlier the HREs occur in the transmission season. Simulations based on data for Hurricane Harvey suggest that the limited impact it had on vector-borne disease transmission was in part because of when it occurred (late August) relative to the local transmission season, and in part because of the mitigating effect of the displacement of people. We also highlight key data gaps related to models of vector-borne disease transmission in the context of natural disasters. This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’. This issue is linked with the subsequent theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control’.

Probing Selective Deposition of Aluminum Using in Situ Infrared Spectroscopy

1993 ◽  
Vol 334 ◽  
Author(s):  
Wayne L. Gladfelter ◽  
Michael G. Simmonds ◽  
Larry A. Zazzera ◽  
John F. Evans
Keyword(s):  
Room Temperature ◽  
Silicon Oxide ◽  
Silica Surface ◽  
Effect Of Temperature ◽  
Weakly Bound ◽  
Weak Absorption ◽  
Dimethylethylamine Alane ◽  
The Impact ◽  
In Situ Infrared Spectroscopy

AbstractDimethylethylamine alane (DMEAA) has been used to deposit thin films of aluminum selectively on gold in the presence of silicon oxide. This paper presents studies of the effect of temperature, pressure, and substrate pattern on the selectivity. A specially designed reactor allowed us to probe the structure of the species on the silica surface using infraed spectroscopy. At room temperature two absorptions in the Al-H stretching region were assigned to two species; weakly bound molecules of the intact precursor and a strongly bound dihydride formed from the reaction of DMEAA with surface bound (and H-bonded) hydroxyls (from H2O or silanol groups). At higher temperatures the CH vibrations of the amine disappeared, and the Al-H stretch shifted to higher energy. A weak absorption at 2250 cm−1 attributable to a Si-H also appeared. The impact of these observations on the loss of selectivity is discussed.

scholarly journals Fluid fragmentation shapes rain-induced foliar disease transmission

2015 ◽  
Vol 12 (104) ◽  
pp. 20141092 ◽  
Author(s):  
T. Gilet ◽  
L. Bourouiba
Keyword(s):  
Disease Transmission ◽  
Scaling Laws ◽  
Sessile Drop ◽  
Early Stage ◽  
Leaf Size ◽  
Pathogen Transmission ◽  
Mitigation Strategies ◽  
Plant Diseases ◽  
Foliar Disease ◽  
The Impact

Plant diseases represent a growing threat to the global food supply. The factors contributing to pathogen transmission from plant to plant remain poorly understood. Statistical correlations between rainfalls and plant disease outbreaks were reported; however, the detailed mechanisms linking the two were relegated to a black box. In this combined experimental and theoretical study, we focus on the impact dynamics of raindrops on infected leaves, one drop at a time. We find that the deposition range of most of the pathogen-bearing droplets is constrained by a hydrodynamical condition and we quantify the effect of leaf size and compliance on such constraint. Moreover, we identify and characterize two dominant fluid fragmentation scenarios as responsible for the dispersal of most pathogen-bearing droplets emitted from infected leaves: (i) the crescent-moon ejection is driven by the direct interaction between the impacting raindrop and the contaminated sessile drop and (ii) the inertial detachment is driven by the motion imparted to the leaf by the raindrop, leading to catapult-like droplet ejections. We find that at first, decreasing leaf size or increasing compliance reduces the range of pathogen-bearing droplets and the subsequent epidemic onset efficiency. However, this conclusion only applies for the crescent moon ejection. Above a certain compliance threshold a more effective mechanism of contaminated fluid ejection, the inertial detachment, emerges. This compliance threshold is determined by the ratio between the leaf velocity and the characteristic velocity of fluid fragmentation. The inertial detachment mechanism enhances the range of deposition of the larger contaminated droplets and suggests a change in epidemic onset pattern and a more efficient potential of infection of neighbouring plants. Dimensionless parameters and scaling laws are provided to rationalize our observations. Our results link for the first time the mechanical properties of foliage with the onset dynamics of foliar epidemics through the lens of fluid fragmentation. We discuss how the reported findings can inform the design of mitigation strategies acting at the early stage of a foliar disease outbreak.

scholarly journals Unravelling Transmission in Epidemiological Models and its Role in the Disease-Diversity Relationship

2021 ◽  
Author(s):  
Marjolein E.M. Toorians ◽  
Ailene MacPherson ◽  
T. Jonathan Davies
Keyword(s):  
Disease Transmission ◽  
Disease Outbreaks ◽  
Host Population ◽  
Pathogen Transmission ◽  
Transmission Model ◽  
General Function ◽  
Transmission Method ◽  
Model Framework ◽  
Host Diversity ◽  
Transmission Mechanisms

With the decrease of biodiversity worldwide coinciding with an increase in disease outbreaks, investigating this link is more important then ever before. This review outlines the different modelling methods commonly used for pathogen transmission in animal host systems. There are a multitude of ways a pathogen can invade and spread through a host population. The assumptions of the transmission model used to capture disease propagation determines the outbreak potential, the net reproductive success (R0). This review offers an insight into the assumptions and motivation behind common transmission mechanisms and introduces a general framework with which contact rates, the most important parameter in disease dynamics, determines the transmission method. By using a general function introduced here and this general transmission model framework, we provide a guide for future disease ecologists for how to pick the contact function that best suites their system. Additionally, this manuscript attempts to bridge the gap between mathematical disease modelling and the controversially and heavily debated disease-diversity relationship, by expanding the summarized models to multiple hosts systems and explaining the role of host diversity in disease transmission. By outlining the mechanisms of transmission into a stepwise process, this review will serve as a guide to model pathogens in multi-host systems. We will further describe these models it in the greater context of host diversity and its effect on disease outbreaks, by introducing a novel method to include host species’ evolutionary history into the framework.

scholarly journals Low prevalence of handwashing and importance of signage at California county fair animal exhibits

2021 ◽  
pp. 1-5
Author(s):  
Melissa T. Ibarra ◽  
Cheryl L. Meehan ◽  
Miles Daniels ◽  
Woutrina A. Smith ◽  
Martin H. Smith
Keyword(s):  
Disease Transmission ◽  
Direct Contact ◽  
Disease Outbreaks ◽  
Pathogen Transmission ◽  
Indirect Exposure ◽  
National Public Health ◽  
Geographic Regions ◽  
Zoonotic Disease Transmission ◽  
County Fairs ◽  
Low Prevalence

Disease outbreaks among visitors at venues where animals are exhibited, such as animal shows at county fairs or petting zoos, are national public health concerns. Zoonotic disease transmission at fairs can occur through a variety of pathways, including direct contact with livestock and indirect exposure through contact with animals' immediate surroundings. Handwashing can reduce pathogen transmission. The goal of this observational study was to determine rates of handwashing among county fair visitors and to learn whether signage and/or contact with animals were correlated with handwashing practice. The investigation was conducted at four county fairs located across two geographic regions of California. Observations occurred over the course of one summer. Results from our observations of fair visitors revealed a low overall prevalence (5%) of handwashing behavior. However, fair visitors who made contact with animals were more likely to wash their hands. Additionally, those individuals who walked through barns where handwashing signage was present were significantly more likely to wash their hands than those who visited barns without signage.

scholarly journals Containing the Spread of Infectious Disease on College Campuses

2020 ◽  
Author(s):  
Mirai Shah ◽  
Gabrielle Ferra ◽  
Susan Fitzgerald ◽  
Paul J. Barreira ◽  
Pardis C. Sabeti ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Disease Transmission ◽  
Disease Incidence ◽  
Disease Outbreaks ◽  
Small Population ◽  
College Campuses ◽  
Post Intervention ◽  
Stochastic Variation ◽  
Awareness Campaigns ◽  
The Impact

AbstractCollege campuses are highly vulnerable to infectious disease outbreaks, and there is a pressing need to develop better strategies to mitigate their size and duration, particularly as educational institutions around the world reopen to in-person instruction in the midst of the COVID-19 pandemic. Towards addressing this need, we applied a stochastic compartmental model to quantify the impact of university-level responses to past mumps outbreaks in college campuses and used it to determine which control interventions are most effective. Mumps is a very relevant disease in such settings, given its airborne mode of transmission, high infectivity, and recurrence of outbreaks despite availability of a vaccine. Our model aims to simultaneously overcome three crucial issues: stochastic variation in small populations, missing or unobserved case data, and changes in disease transmission rates post-intervention. We tested the model and assessed various interventions using data from the 2014 and 2016 mumps outbreaks at Ohio State University and Harvard University, respectively. Our results suggest that in order to decrease infectious disease incidence on their campuses, universities should apply diagnostic protocols that address false negatives from molecular tests, stricter quarantine policies, and effective awareness campaigns among their students and staff. Our model can be applied to data from other outbreaks in college campuses and similar small-population settings.

Sign in / Sign up

Export Citation Format

Share Document