Chronic Wasting Disease Transmission Risk Assessment for Farmed Cervids in Minnesota and Wisconsin

CWD (chronic wasting disease) has emerged as one of the most important diseases of cervids and continues to adversely affect farmed and wild cervid populations, despite control and preventive measures. This study aims to use the current scientific understanding of CWD transmission and knowledge of farmed cervid operations to conduct a qualitative risk assessment for CWD transmission to cervid farms and, applying this risk assessment, systematically describe the CWD transmission risks experienced by CWD-positive farmed cervid operations in Minnesota and Wisconsin. A systematic review of literature related to CWD transmission informed our criteria to stratify CWD transmission risks to cervid operations into high-risk low uncertainty, moderate-risk high uncertainty, and negligible-risk low uncertainty categories. Case data from 34 CWD-positive farmed cervid operations in Minnesota and Wisconsin from 2002 to January 2019 were categorized by transmission risks exposure and evaluated for trends. The majority of case farms recorded high transmission risks (56%), which were likely sources of CWD, but many (44%) had only moderate or negligible transmission risks, including most of the herds (62%) detected since 2012. The presence of CWD-positive cervid farms with only moderate or low CWD transmission risks necessitates further investigation of these risks to inform effective control measures.

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Dehydration of Prions on Environmentally Relevant Surfaces Protects Them from Inactivation by Freezing and Thawing

Journal of Virology ◽

10.1128/jvi.02191-17 ◽

2018 ◽

Vol 92 (8) ◽

Cited By ~ 4

Author(s):

Qi Yuan ◽

Glenn Telling ◽

Shannon L. Bartelt-Hunt ◽

Jason C. Bartz

Keyword(s):

Prion Disease ◽

Disease Transmission ◽

Protein Misfolding ◽

Chronic Wasting Disease ◽

Control Strategies ◽

Horizontal Transmission ◽

Freezing And Thawing ◽

Wasting Disease ◽

Live Animal ◽

Weathering Processes

ABSTRACTChronic wasting disease (CWD) is an emerging prion disease in North America. Recent identification of CWD in wild cervids from Norway raises the concern of the spread of CWD in Europe. CWD infectivity can enter the environment through live animal excreta and carcasses where it can bind to soil. Well-characterized hamster prion strains and CWD field isolates in unadsorbed or soil-adsorbed forms that were either hydrated or dehydrated were subjected to repeated rounds of freezing and thawing. We found that 500 cycles of repeated freezing and thawing of hydrated samples significantly decreased the abundance of PrPScand reduced protein misfolding cyclic amplification (PMCA) seeding activity that could be rescued by binding to soil. Importantly, dehydration prior to freezing and thawing treatment largely protected PrPScfrom degradation, and the samples maintained PMCA seeding activity. We hypothesize that redistribution of water molecules during the freezing and thawing process alters the stability of PrPScaggregates. Overall, these results have significant implications for the assessment of prion persistence in the environment.IMPORTANCEPrions excreted into the environment by infected animals, such as elk and deer infected with chronic wasting disease, persist for years and thus facilitate horizontal transmission of the disease. Understanding the fate of prions in the environment is essential to control prion disease transmission. The significance of our study is that it provides information on the possibility of prion degradation and inactivation under natural weathering processes. This information is significant for remediation of prion-contaminated environments and development of prion disease control strategies.

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Modeling Routes of Chronic Wasting Disease Transmission: Environmental Prion Persistence Promotes Deer Population Decline and Extinction

PLoS ONE ◽

10.1371/journal.pone.0019896 ◽

2011 ◽

Vol 6 (5) ◽

pp. e19896 ◽

Cited By ~ 83

Author(s):

Emily S. Almberg ◽

Paul C. Cross ◽

Christopher J. Johnson ◽

Dennis M. Heisey ◽

Bryan J. Richards

Keyword(s):

Disease Transmission ◽

Chronic Wasting Disease ◽

Population Decline ◽

Wasting Disease ◽

Deer Population

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China’s effective control and other countries’ uncharted challenge against COVID-19: an epidemiological and modelling study

10.1101/2020.04.28.20083899 ◽

2020 ◽

Author(s):

Lingling Zheng ◽

Qin Kang ◽

Weiyao Liao ◽

Xiujuan Chen ◽

Shuai Huang ◽

...

Keyword(s):

Disease Transmission ◽

Reproduction Number ◽

Case Reports ◽

Epidemiological Data ◽

Control Measures ◽

Time Dependent ◽

Effective Control ◽

List Type ◽

Global Epidemic ◽

Serial Interval

AbstractBackgroundOn the present trajectory, COVID is inevitably becoming a global epidemic, leading to concerns regarding the pandemic potential in China and other countries.ObjectiveIn this study, we use the time-dependent reproduction number (Rt) to comprise the COVID transmissibility across different countries.MethodsWe used data from Jan 20, 2019, to Feb 29, 2020, on the number of newly confirmed cases, obtained from the reports published by the CDC, to infer the incidence of infectious over time. A two-step procedure was used to estimate the Rt. The first step used data on known index-secondary cases pairs, from publicly available case reports, to estimate the serial interval distribution. The second step estimated the Rt jointly from the incidence data and the information data in the first step. Rt was then used to simulate the epidemics across all major cities in China and typical countries worldwide.ResultsBased on a total of 126 index-secondary cases pairs from 4 international regions, we estimated that the serial interval for SARS-2-CoV was 4.18 (IQR 1.92 – 6.65) days. Domestically, Rt of China, Hubei province, Wuhan had fallen below 1.0 on 9 Feb, 10 Feb and 13 Feb (Rt were 0.99±0.02, 0.99±0.02 and 0.96±0.02), respectively. Internationally, as of 26 Feb, statistically significant periods of COVID spread (Rt >1) were identified for most regions, except for Singapore (Rt was 0.92±0.17).ConclusionsThe epidemic in China has been well controlled, but the worldwide pandemic has not been well controlled. Worldwide preparedness and vulnerability against COVID-19 should be regarded with more care.What is already known on this subject?The basic reproduction number (R0) and the-time-dependent reproduction number (Rt) are two important indicators of infectious disease transmission. In addition, Rt as a derivative of R0 could be used to assess the epidemiological development of the disease and effectiveness of control measures. Most current researches used data from earlier periods in Wuhan and refer to the epidemiological features of SARS, which are possibly biased. Meanwhile, there are fewer studies discussed the Rt of COVID-19. Current clinical and epidemiological data are insufficient to help us understand the full view of the potential transmission of this disease.What this study adds?We use up-to-data observation of the serial interval and cases arising from local transmission to calculate the Rt in different outbreak level area and every province in China as well as five-top sever outbreak countries and other overseas. By comparing the Rt, we discussed the situation of outbreak around the world.

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Chronic Wasting Disease Transmission

Science ◽

10.1126/science.314.5796.13k ◽

2006 ◽

Vol 314 (5796) ◽

pp. 13k-13k

Keyword(s):

Disease Transmission ◽

Chronic Wasting Disease ◽

Wasting Disease

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Elk Use of Wallows and Potential Chronic Wasting Disease Transmission

Journal of Wildlife Diseases ◽

10.7589/0090-3558-43.4.784 ◽

2007 ◽

Vol 43 (4) ◽

pp. 784-788 ◽

Cited By ~ 16

Author(s):

Kurt C. VerCauteren ◽

Patrick W. Burke ◽

Gregory E. Phillips ◽

Justin W. Fischer ◽

Nathan W. Seward ◽

...

Keyword(s):

Disease Transmission ◽

Chronic Wasting Disease ◽

Wasting Disease

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Environmental Sources of Scrapie Prions

Journal of Virology ◽

10.1128/jvi.01133-10 ◽

2010 ◽

Vol 84 (21) ◽

pp. 11560-11562 ◽

Cited By ~ 37

Author(s):

Ben C. Maddison ◽

Claire A. Baker ◽

Linda A. Terry ◽

Susan J. Bellworthy ◽

Leigh Thorne ◽

...

Keyword(s):

Environmental Contamination ◽

Disease Transmission ◽

Protein Misfolding ◽

Chronic Wasting Disease ◽

Horizontal Transmission ◽

Wasting Disease ◽

Prion Infectivity ◽

Protein Misfolding Cyclic Amplification ◽

Sheep Farm

ABSTRACT Ovine scrapie and cervine chronic wasting disease show considerable horizontal transmission. Here we report that a scrapie-affected sheep farm has a widespread environmental contamination with prions. Prions were amplified by protein-misfolding cyclic amplification (sPMCA) from seven of nine environmental swab samples taken, including those from metal, plastic, and wooden surfaces. Sheep had been removed from the areas from which the swabs were taken up to 20 days prior to sampling, indicating that prions persist for at least that long. These data implicate inanimate objects as environmental reservoirs for prion infectivity that are likely to contribute to facile disease transmission.

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Variation In The PRNP Gene Of Pere David’s Deer (Elaphurus Davidianus) May Impact Genetic Vulnerability To Chronic Wasting Disease

10.21203/rs.3.rs-566057/v1 ◽

2021 ◽

Author(s):

Tolulope I.N. Perrin-Stowe ◽

Yasuko Ishida ◽

Emily E. Terrill ◽

Dan Beetem ◽

Oliver A. Ryder ◽

...

Keyword(s):

Captive Breeding ◽

Chronic Wasting Disease ◽

Balancing Selection ◽

Transmissible Spongiform Encephalopathy ◽

Transmission Risk ◽

Spongiform Encephalopathy ◽

Wasting Disease ◽

Père David’S Deer ◽

The Impact ◽

Elaphurus Davidianus

Abstract Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy caused by prions that has spread across cervid species in North America since the 1960s and recently spread to cervids in Eurasia. The Association of Zoos and Aquariums (AZA) considers CWD to be of major concern for cervids in AZA-accredited facilities because of the indirect transmission risk of the disease and the impact of CWD regulatory protocols on captive breeding programs. Vulnerability to CWD is affected by variation in the PRNP gene that encodes the prion protein. We therefore sequenced PRNP in Pere David’s deer (Elaphurus davidianus), a species that was extinct in the wild for more than a century, and descends from ca. 11 founders. In 27 individuals, we detected two PRNP haplotypes, designated Elad1 (51 of 54 chromosomes) and Elad2 (3 of 54 chromosomes). The two haplotypes are separated by four single nucleotide polymorphisms (SNPs), three of which are non-synonymous. Both Elad1 and Elad2 have polymorphisms that in other cervid taxa are associated with reduced vulnerability to CWD. The two haplotypes are more similar in sequence to PRNP in other cervids than to each other. This suggests that PRNP in cervids may have been under long-term balancing selection, as has been shown for PRNP in non-cervid taxa, and which could account for the presence of multiple haplotypes among founders. There may be a fitness benefit in maintaining both PRNP haplotypes in the species because variation in the prion amino acid sequence can limit transmission of CWD.

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Individual-based modeling of COVID-19 transmission in college communities

10.1101/2021.06.03.21258315 ◽

2021 ◽

Author(s):

Qimin Huang ◽

Martial Ndeffo-Mbah ◽

Anirban Mondal ◽

Sara Lee ◽

David Gurarie

Keyword(s):

Risk Reduction ◽

Disease Transmission ◽

Herd Immunity ◽

The United States ◽

Transmission Risk ◽

Effective Control ◽

Social Activities ◽

Modeling Framework ◽

Risk Reduction Measures ◽

And Control

The ongoing COVID-19 pandemic has created major public health and socio-economic challenges across the United States. Among them are challenges to the educational system where college administrators are struggling with the questions of how to reopen in-person activities while prioritizing student safety. To help address this challenge, we developed a flexible computational framework to model the spread and control of COVID-19 on a residential college campus. The modeling framework accounts for heterogeneity in social interactions, activities, disease progression, and control interventions. The relative contribution of classroom, dorm, and social activities to disease transmission were explored. We observed that the dorm has the highest contribution to disease transmission followed by classroom and social activities. Without vaccination, frequent (weekly) random testing coupled with risk reduction measures (e.g. facial mask,) in classroom, dorm, and social activities is the most effective control strategy to mitigate the spread of COVID-19 on college campuses. Moreover, since random screening testing allows for the successful and early detection of both asymptomatic and symptomatic individuals, it successfully reduces the transmission rate such that the maximum quarantine capacity is far lower than expected to further reduce the economic burden caused from quarantine. With vaccination, herd immunity is estimated to be achievable by 50% to 80% immunity coverage. In the absence of herd immunity, simulations indicate that it is optimal to keep some level of transmission risk reduction measures in classroom, dorm, and social activities, while testing at a lower frequency. Though our quantitative results are likely provisional on our model assumptions, extensive sensitivity analysis confirms the robustness of their qualitative nature.

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A Computational Framework for Transmission Risk Assessment of Aerosolized Particles in Classrooms

10.21203/rs.3.rs-902643/v1 ◽

2021 ◽

Author(s):

Kendrick Tan ◽

Boshun Gao ◽

Cheng-Hau Yang ◽

Emily Johnson ◽

Ming-Chen Hsu ◽

...

Keyword(s):

Risk Assessment ◽

Disease Transmission ◽

Ventilation Rate ◽

Mitigation Strategies ◽

Transmission Risk ◽

Computational Framework ◽

Seating Arrangement ◽

K 12 ◽

Education Administrators ◽

Airborne Disease

Abstract The ongoing COVID-19 pandemic has rendered confined spaces as high-risk areas. There is an increasing push to resume in-person activities, for instance, teaching in K-12 and university settings. It becomes important to evaluate the risk of airborne disease transmission while accounting for the physical presence of humans, furniture, and electronic equipment, as well as ventilation. Here, we present a computational framework based on detailed flow physics simulations that allows straightforward evaluation of various seating and operating scenarios to identify risk factors and assess the effectiveness of various mitigation strategies. These scenarios include seating arrangement changes, presence/absence of computer screens, ventilation rate changes, and presence/absence of mask-wearing. This approach democratizes risk assessment by automating a key bottleneck in simulation-based analysis--creating an adequately refined mesh around multiple complex geometries. Not surprisingly, we find that wearing masks (with at least 74% inward protection efficiency) significantly reduced transmission risk against unmasked and infected individuals. The availability of such an analysis approach will allow education administrators, government officials (courthouses, police stations), and hospital administrators to make informed decisions on seating arrangements and operating procedures.

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Methods to infer transmission risk factors in complex outbreak data

Journal of The Royal Society Interface ◽

10.1098/rsif.2011.0379 ◽

2011 ◽

Vol 9 (68) ◽

pp. 456-469 ◽

Cited By ~ 24

Author(s):

Simon Cauchemez ◽

Neil M. Ferguson

Keyword(s):

Risk Factors ◽

Missing Data ◽

Disease Transmission ◽

Control Strategies ◽

Model Fitting ◽

Structured Populations ◽

Transmission Risk ◽

Effective Control ◽

Reconstruction Methods ◽

History Of

Data collected during outbreaks are essential to better understand infectious disease transmission and design effective control strategies. But analysis of such data is challenging owing to the dependency between observations that is typically observed in an outbreak and to missing data. In this paper, we discuss strategies to tackle some of the ongoing challenges in the analysis of outbreak data. We present a relatively generic statistical model for the estimation of transmission risk factors, and discuss algorithms to estimate its parameters for different levels of missing data. We look at the problem of computational times for relatively large datasets and show how they can be reduced by appropriate use of discretization, sufficient statistics and some simple assumptions on the natural history of the disease. We also discuss approaches to integrate parametric model fitting and tree reconstruction methods in coherent statistical analyses. The methods are tested on both real and simulated datasets of large outbreaks in structured populations.

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