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The Hybrid Incidence Susceptible-Transmissible-Removed Model for Pandemics : Scaling Time to Predict an Epidemic's Population Density Dependent Temporal Propagation. Acta Biotheor 2022; 70:10. [PMID: 35092515 PMCID: PMC8800439 DOI: 10.1007/s10441-021-09431-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 11/01/2021] [Indexed: 11/07/2022]
Abstract
The susceptible-transmissible-removed (STR) model is a deterministic compartment model, based on the susceptible-infected-removed (SIR) prototype. The STR replaces 2 SIR assumptions. SIR assumes that the emigration rate (due to death or recovery) is directly proportional to the infected compartment’s size. The STR replaces this assumption with the biologically appropriate assumption that the emigration rate is the same as the immigration rate one infected period ago. This results in a unique delay differential equation epidemic model with the delay equal to the infected period. Hamer’s mass action law for epidemiology is modified to resemble its chemistry precursor—the law of mass action. Constructing the model for an isolated population that exists on a surface bounded by the extent of the population’s movements permits compartment density to replace compartment size. The STR reduces to a SIR model in a timescale that negates the delay—the transmissible timescale. This establishes that the SIR model applies to an isolated population in the disease’s transmissible timescale. Cyclical social interactions will define a rhythmic timescale. It is demonstrated that the geometric mean maps transmissible timescale properties to their rhythmic timescale equivalents. This mapping defines the hybrid incidence (HI). The model validation demonstrates that the HI-STR can be constructed directly from the disease’s transmission dynamics. The basic reproduction number (\documentclass[12pt]{minimal}
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\begin{document}$${\mathcal{R}}_0$$\end{document}R0) is an epidemic impact property. The HI-STR model predicts that \documentclass[12pt]{minimal}
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\begin{document}$${\mathcal{R}}_0 \propto \root \mathfrak{B} \of {\rho_n}$$\end{document}R0∝ρnB where \documentclass[12pt]{minimal}
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\begin{document}$$\rho_n$$\end{document}ρn is the population density, and \documentclass[12pt]{minimal}
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\begin{document}$${\mathfrak{B}}$$\end{document}B is the ratio of time increments in the transmissible- and rhythmic timescales. The model is validated by experimentally verifying the relationship. \documentclass[12pt]{minimal}
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\begin{document}$${\mathcal{R}}_0$$\end{document}R0’s dependence on \documentclass[12pt]{minimal}
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\begin{document}$$\rho_n$$\end{document}ρn is demonstrated for droplet-spread SARS in Asian cities, aerosol-spread measles in Europe and non-airborne Ebola in Africa.
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Melnik LI, Garry RF. Enterotoxigenic Escherichia coli Heat-Stable Toxin and Ebola Virus Delta Peptide: Similarities and Differences. Pathogens 2022; 11:pathogens11020170. [PMID: 35215114 PMCID: PMC8878840 DOI: 10.3390/pathogens11020170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 01/27/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) STb toxin exhibits striking structural similarity to Ebola virus (EBOV) delta peptide. Both ETEC and EBOV delta peptide are enterotoxins. Comparison of the structural and functional similarities and differences of these two toxins illuminates features that are important in induction of pathogenesis by a bacterial and viral pathogen.
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Affiliation(s)
- Lilia I. Melnik
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA;
- Viral Hemorrhagic Fever Consortium, New Orleans, LA 70112, USA
- Correspondence: ; Tel.: +1-(504)988-3818
| | - Robert F. Garry
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA;
- Viral Hemorrhagic Fever Consortium, New Orleans, LA 70112, USA
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Melnik LI, Guha S, Ghimire J, Smither AR, Beddingfield BJ, Hoffmann AR, Sun L, Ungerleider NA, Baddoo MC, Flemington EK, Gallaher WR, Wimley WC, Garry RF. Ebola virus delta peptide is an enterotoxin. Cell Rep 2022; 38:110172. [PMID: 34986351 DOI: 10.1016/j.celrep.2021.110172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/27/2021] [Accepted: 12/03/2021] [Indexed: 12/21/2022] Open
Abstract
During the 2013-2016 West African (WA) Ebola virus (EBOV) outbreak, severe gastrointestinal symptoms were common in patients and associated with poor outcome. Delta peptide is a conserved product of post-translational processing of the abundant EBOV soluble glycoprotein (sGP). The murine ligated ileal loop model was used to demonstrate that delta peptide is a potent enterotoxin. Dramatic intestinal fluid accumulation follows injection of biologically relevant amounts of delta peptide into ileal loops, along with gross alteration of villous architecture and loss of goblet cells. Transcriptomic analyses show that delta peptide triggers damage response and cell survival pathways and downregulates expression of transporters and exchangers. Induction of diarrhea by delta peptide occurs via cellular damage and regulation of genes that encode proteins involved in fluid secretion. While distinct differences exist between the ileal loop murine model and EBOV infection in humans, these results suggest that delta peptide may contribute to EBOV-induced gastrointestinal pathology.
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Affiliation(s)
- Lilia I Melnik
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Shantanu Guha
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Jenisha Ghimire
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Allison R Smither
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Brandon J Beddingfield
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Andrew R Hoffmann
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Leisheng Sun
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | | | - Melody C Baddoo
- Tulane Cancer Center, Tulane University, New Orleans, LA 70112, USA
| | | | - William R Gallaher
- Department of Microbiology, Immunology and Parasitology, LSU Health Sciences Center, New Orleans, LA 70112, USA; Mockingbird Nature Research Group, Pearl River, LA 70452, USA
| | - William C Wimley
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
| | - Robert F Garry
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA; Zalgen Labs, Germantown, MD 20876, USA.
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Boonprasert K, Punyapornwithaya V, Tankaew P, Angkawanish T, Sriphiboon S, Titharam C, Brown JL, Somgird C. Survival analysis of confirmed elephant endotheliotropic herpes virus cases in Thailand from 2006 - 2018. PLoS One 2019; 14:e0219288. [PMID: 31276571 PMCID: PMC6611605 DOI: 10.1371/journal.pone.0219288] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 06/20/2019] [Indexed: 11/19/2022] Open
Abstract
The elephant endotheliotropic herpesvirus (EEHV) has been a known cause of death of young elephants in Thailand for over a decade. In this study, we report on the demography, disease characteristics and mortality of 58 elephants with confirmed EEHV hemorrhagic disease between January 2006 and August 2018 using retrospective data subjected to survival analysis. Median age of EEHV presentation was 29 months, and the mortality rate was 68.97% with a median survival time of 36 h. Most EEHV cases occurred in the north of Thailand, the region where most of the country’s captive elephants reside. The hazard ratio analysis identified application of medical procedures and antiviral medications as being significant factors correlated to the risk of death. Our results indicate a need to focus EEHV monitoring efforts on young elephants and to follow current protocols that advise starting treatments before clinical signs appear.
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Affiliation(s)
| | - Veerasak Punyapornwithaya
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
- Department of Food Animal Clinic, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Pallop Tankaew
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
| | - Taweepoke Angkawanish
- Elephant Hospital, National Elephant Institute, Forest Industry Organization, Lampang, Thailand
| | - Supaphen Sriphiboon
- Department of Large Animal and Wildlife Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen Campus, Nakornpathom, Thailand
| | - Chatchote Titharam
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
- Department of Companion Animal and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Janine L. Brown
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, United State of America
| | - Chaleamchat Somgird
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
- Department of Companion Animal and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
- * E-mail:
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Garbern SC, Yam D, Aluisio AR, Cho DK, Kennedy SB, Massaquoi M, Sahr F, Perera SM, Levine AC, Liu T. Effect of Mass Artesunate-Amodiaquine Distribution on Mortality of Patients With Ebola Virus Disease During West African Outbreak. Open Forum Infect Dis 2019; 6:ofz250. [PMID: 31281856 PMCID: PMC6602760 DOI: 10.1093/ofid/ofz250] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 05/22/2019] [Indexed: 11/13/2022] Open
Abstract
Background Experiments in vitro have shown that the drug amodiaquine may inhibit Ebola virus activity. During the Ebola virus disease (EVD) epidemic in West Africa in 2014-2016, 2 mass drug administrations (MDAs) of artesunate-amodiaquine (ASAQ) were implemented to decrease the burden of malaria. The objective of this study was to assess the effect of the ASAQ MDAs on the mortality of patients with EVD. Methods A retrospective cohort design was used to analyze mortality data for patients with EVD admitted to 5 Ebola treatment units in Liberia and Sierra Leone. Patients admitted to the ETUs during the time period of ASAQ's therapeutic effect from areas where the MDA was implemented were matched to controls not exposed to ASAQ, using a range of covariates, including malaria co-infection status, and a logistic regression analysis was performed. The primary outcome was Ebola treatment unit mortality. Results A total of 424 patients with EVD had sufficient data for analysis. Overall, the mortality of EVD patients was 57.5%. A total of 22 EVD patients were exposed to ASAQ during the MDAs and were found to have decreased risk of death compared with those not exposed in a matched analysis, but this did not reach statistical significance (relative risk, 0.63; 95% confidence interval, 0.37-1.07; P = .086). Conclusions There was a non-statistically significantly decreased risk of mortality in EVD patients exposed to ASAQ during the 2 MDAs as compared with EVD patients not exposed to ASAQ. Further prospective trials are needed to determine the direct effect of ASAQ on EVD mortality.
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Affiliation(s)
- Stephanie C Garbern
- Department of Emergency Medicine, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Derrick Yam
- Department of Biostatistics, Center for Statistical Sciences, Brown University School of Public Health, Providence, Rhode Island
| | - Adam R Aluisio
- Department of Emergency Medicine, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | | | | | | | - Foday Sahr
- Sierra Leone Ministry of Defense, Freetown, Sierra Leone
| | | | - Adam C Levine
- Department of Emergency Medicine, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Tao Liu
- Department of Biostatistics, Center for Statistical Sciences, Brown University School of Public Health, Providence, Rhode Island
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