scholarly journals Modelling and determination of the transmission contact rate for contagious bovine pleuropneumonia

2005 ◽  
Vol 133 (2) ◽  
pp. 337-342 ◽  
Author(s):  
T. BALENGHIEN ◽  
K. CHALVET-MONFRAY ◽  
D. J. BICOUT ◽  
P. SABATIER
Keyword(s):  
Vaccine Trial ◽  
Sub Saharan Africa ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Contact Rate ◽  
Contagious Bovine Pleuropneumonia ◽  
Contact Rates ◽  
Spreading Dynamics ◽  
Sub Saharan ◽  
Cattle Health

Contagious bovine pleuropneumonia (CBPP) is a cattle respiratory disease that represents one of the major threats to cattle health and production in sub-Saharan Africa. The transmission contact rate of CBPP plays a key role in the spreading dynamics of the disease. We have developed an approach based on the combination of a SEIR model describing the spread of CBPP with the dynamic of seroconversion to determine the transmission contact rate for CBPP. This method has been subsequently applied to serological diagnostic data obtained from an experimental vaccine trial. As a result, we find that the transmission contact rates for subclinical, clinical and chronic infective states are respectively, 0·084/N, 0·45 and 0·14/N per animal per day, where N is the herd population size, and the basic reproductive number corresponding to this trial (N=28) is R0=27.

scholarly journals Dynamics analysis of an online gambling spreading model on scale-free networks

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Yu Kong ◽  
Tao Li ◽  
Yuanmei Wang ◽  
Xinming Cheng ◽  
He Wang ◽  
...  
Keyword(s):  
Network Topology ◽  
Negative Impact ◽  
Online Gambling ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Scale Free ◽  
Spreading Model ◽  
Spreading Dynamics ◽  
Scale Free Networks ◽  
Gambling Policy

AbstractNowadays, online gambling has a great negative impact on the society. In order to study the effect of people’s psychological factors, anti-gambling policy, and social network topology on online gambling dynamics, a new SHGD (susceptible–hesitator–gambler–disclaimer) online gambling spreading model is proposed on scale-free networks. The spreading dynamics of online gambling is studied. The basic reproductive number $R_{0}$ R 0 is got and analyzed. The basic reproductive number $R_{0}$ R 0 is related to anti-gambling policy and the network topology. Then, gambling-free equilibrium $E_{0}$ E 0 and gambling-prevailing equilibrium $E_{ +} $ E + are obtained. The global stability of $E_{0}$ E 0 is analyzed. The global attractivity of $E_{ +} $ E + and the persistence of online gambling phenomenon are studied. Finally, the theoretical results are verified by some simulations.

scholarly journals PO 8581 ZOONOTIC VIRAL ANTIGENS SURVEILLANCE IN HEALTHY POPULATIONS LIVING IN LAMBARÉNÉ, GABON

2019 ◽  
Vol 4 (Suppl 3) ◽  
pp. A58.2-A58
Author(s):  
Emmanuel Bache ◽  
Marguerite M Loembe ◽  
Selidji T Agnandji
Keyword(s):  
Disease Transmission ◽  
Disease Surveillance ◽  
Vaccine Trial ◽  
Viral Rna ◽  
Sub Saharan Africa ◽  
Surveillance Systems ◽  
Rt Pcr ◽  
Zoonotic Infections ◽  
Viral Antigens ◽  
Sub Saharan

BackgroundWorldwide, viral zoonotic infections such as filoviruses, flaviviruses, nairoviruses and arenaviruses cause self-limiting to severe diseases. They are endemic in sub-Saharan Africa, causing sporadic outbreaks warranting the development of sustainable surveillance systems. In Gabon, Ebola outbreaks occurred from 1994 to 2002 causing 214 human cases and 150 deaths, while Dengue, Zika and Chikungunya virus outbreaks occurred between 2007 and 2010. Beyond these outbreaks, little is known about the epidemiology. Recently, in collaboration with the Japanese government, the Research and Health Ministries of Gabon supported the implementation of a biosecurity level-3 (BSL-3) laboratory at CERMEL in Lambaréné as a zoonotic disease surveillance unit. Start-off involved antigen detection and characterisation of circulating antibodies to targeted viral antigens in healthy populations. This study reports data from healthy participants (18–50 years) in a phase I rVSV-ZEBOV-GP Ebola vaccine trial.MethodsHundred-six (106) baseline samples were screened for Ebola, Dengue (serotypes) 1–4 and Chikungunya viral RNA by RT-PCR on serum. IgG ELISA on plasma was used to identify antibodies against: Zaire-Ebola-(EBOV-GP and EBOV-VP40), Marburg-(MARV-GP and MARV-VP40), Crimean Congo Haemorrhagic Fever-(CCHFV-GP), Lasa-(LASV-GPC and LASV-NP), Yellow Fever-(YFV-NS1), West-Nile-(WNV-NS1), Zika virus-(ZIKV-NS1), Chikungunya-(CHIKV-VLP) and Dengue-(DENV1-NS1,DENV2-NS1,DENV3-NS1,DENV4-NS1) virus antigens.ResultsNo viral RNA was isolated by RT-PCR in 106 samples. About 9% (10/106), 3% (3/106), 6% (6/106), 24% (25/106), 51% (54/106), 38% (40/106) and 36% (38/106) participants were seropositive for antibodies specific to EBOV-GP, MARV-GP, CCHFV-GP, YFV-NS1, WNV-NS1, ZIKV-NS1 and CHIKV-VLP, respectively. Twelve percent (12%; 13/106) of participants possessed antibodies specific to Zika, Chikungunya and Dengue 1–4 antigens. Six percent (6%; 6/106) of participants were seropositive for EBOV-GP and CCHFV-GP.ConclusionWe found antibodies to viral zoonotic infections among our healthy volunteers. Further assays, including neutralisation assays are being performed to ascertain the specificity of the antibodies. These findings, once confirmed, will provide insights into disease surveillance, vaccine trial designs, evaluation of post-vaccine immune responses, variability in adverse events and overall disease transmission patterns.

scholarly journals Development of a Novel Cocktail Enzyme-Linked Immunosorbent Assay and a Field-Applicable Lateral-Flow Rapid Test for Diagnosis of Contagious Bovine Pleuropneumonia

2016 ◽  
Vol 54 (6) ◽  
pp. 1557-1565 ◽  
Author(s):  
Martin Heller ◽  
Nimmo Gicheru ◽  
Georgina Tjipura-Zaire ◽  
Cecilia Muriuki ◽  
Mingyan Yu ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Rapid Test ◽  
Lateral Flow ◽  
Sub Saharan Africa ◽  
Enzyme Linked Immunosorbent Assay ◽  
Contagious Bovine Pleuropneumonia ◽  
Serum Samples ◽  
Content Type ◽  
Mycoplasma Mycoides ◽  
Sub Saharan

Contagious bovine pleuropneumonia (CBPP) is a severe respiratory disease that is widespread in sub-Saharan Africa. It is caused byMycoplasma mycoidessubsp.mycoides, a bacterium belonging to theMycoplasma mycoidescluster. In the absence of an efficient CBPP vaccine, improved and easy-to-use diagnostic assays for recurrent testing combined with isolation and treatment of positive animals represent an option for CBPP control in Africa. Here we describe the comprehensive screening of 17 immunogenicMycoplasma mycoidessubsp.mycoidesproteins using well-characterized bovine sera for the development of a novel cocktail enzyme-linked immunosorbent assay (ELISA) for laboratory use. Two recombinantMycoplasmaimmunogens, MSC_0136 and MSC_0636, were used to set up a standardized cocktail ELISA protocol. According to the results from more than 100 serum samples tested, the sensitivity and specificity of the novel cocktail ELISA were 85.6% and 96.4%, respectively, with an overall diagnostic accuracy comparable to that of the Office International des Epizooties (OIE)-prescribed serological assays. In addition, we provide a proof of principle for a field-applicable, easy-to-use commercially produced prototype lateral-flow test for rapid (<30-min) diagnosis of CBPP.

scholarly journals Population density and basic reproductive number of COVID-19 across United States counties

2020 ◽  
Author(s):  
Karla Therese L. Sy ◽  
Laura F. White ◽  
Brooke Nichols
Keyword(s):  
Population Density ◽  
Transmission Probability ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Main Mode ◽  
Cross Sectional ◽  
Rate Of Spread ◽  
Contact Rates ◽  
Random Intercept ◽  
Private Transportation

AbstractThe basic reproductive number (R0) is a function of contact rates among individuals, transmission probability, and duration of infectiousness. We sought to determine the association between population density and R0 of SARS-CoV-2 across U.S. counties, and whether population density could be used as a proxy for contact rates. We conducted a cross-sectional analysis using linear mixed models with random intercept and fixed slopes to assess the association of population density and R0. We also assessed whether this association was differential across county-level main mode of transportation-to-work percentage. Counties with greater population density have greater rates of transmission of SARS-CoV-2, likely due to increased contact rates in areas with greater density. The effect of population density and R0 was not modified by private transportation use. Differential R0 by population density can assist in more accurate predictions of the rate of spread of SARS-CoV-2 in areas that do not yet have active cases.Article Summary LineU.S. counties with greater population density have greater rates of transmission of SARS-CoV-2, likely due to increased contact rates in areas with greater density.

scholarly journals Translating transmissibility measures into recommendations for coronavirus prevention

2020 ◽  
Vol 54 ◽  
pp. 43 ◽  
Author(s):  
Fredi Alexander Diaz-Quijano ◽  
Alfonso Javier Rodriguez-Morales ◽  
Eliseu Alves Waldman
Keyword(s):  
Preventive Measures ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Contact Rate ◽  
Rate Reduction ◽  
Clinical Cases

The rapid increase in clinical cases of the new coronavirus disease, COVID-19, suggests high transmissibility. However, the estimates of the basic reproductive number reported in the literature vary widely. Considering this, we drew the function of contact-rate reduction required to control the transmission from both detectable and undetectable sources. Based on this, we offer a set of recommendations for symptomatic and asymptomatic populations during the current pandemic. Understanding the dynamics of transmission is essential to support government decisions and improve the community’s adherence to preventive measures.

scholarly journals Recent Developments in Vaccines for Bovine Mycoplasmoses Caused by Mycoplasma bovis and Mycoplasma mycoides subsp. mycoides

Vaccines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 549
Author(s):  
Katarzyna Dudek ◽  
Ewelina Szacawa ◽  
Robin A. J. Nicholas
Keyword(s):  
Vaccine Coverage ◽  
Sub Saharan Africa ◽  
Economic Losses ◽  
Mycoplasma Bovis ◽  
Contagious Bovine Pleuropneumonia ◽  
Cattle Industry ◽  
Mycoplasma Mycoides ◽  
Recent Developments ◽  
Sub Saharan ◽  
Cattle Rearing

Two of the most important diseases of cattle are caused by mycoplasmas. Mycoplasma bovis is a world-wide bovine pathogen that can cause pneumonia, mastitis and arthritis. It has now spread to most, if not all, cattle-rearing countries. Due to its increasing resistance to antimicrobial therapy, vaccination is the principal focus of the control of infection, but effective vaccines are currently lacking. Despite being eradicated from most parts of the world, Mycoplasma mycoides subsp. mycoides, the cause of contagious bovine pleuropneumonia (CBPP), continues to plague sub-Saharan Africa, affecting at least 25 countries. Numerous new experimental vaccines have been developed over the last 20 years to improve on protection afforded by the T1/44, a live vaccine in continuous use in Africa for over 60 years, but none so far have succeeded; indeed, many have exacerbated the disease. Tools for diagnosis and control are adequate for eradication but what is necessary are resources to improve vaccine coverage to levels last seen in the 1970s, when CBPP was restricted to a few countries in Africa. This paper summarizes the results of the main studies in the field of experimental mycoplasma vaccines, reviews data on commercially available bacterin vaccines and addresses issues relating to the search for new candidates for effective vaccines to reduce economic losses in the cattle industry caused by these two mycoplasmas.

scholarly journals Population density and basic reproductive number of COVID-19 across United States counties

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249271
Author(s):  
Karla Therese L. Sy ◽  
Laura F. White ◽  
Brooke E. Nichols
Keyword(s):  
United States ◽  
Population Density ◽  
Disease Transmission ◽  
Household Income ◽  
The United States ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Main Mode ◽  
Contact Rates ◽  
Mode Of Transportation

The basic reproductive number (R0) is a function of contact rates among individuals, transmission probability, and duration of infectiousness. We sought to determine the association between population density and R0 of SARS-CoV-2 across U.S. counties. We conducted a cross-sectional analysis using linear mixed models with random intercept and fixed slopes to assess the association of population density and R0, and controlled for state-level effects using random intercepts. We also assessed whether the association was differential across county-level main mode of transportation percentage as a proxy for transportation accessibility, and adjusted for median household income. The median R0 among the United States counties was 1.66 (IQR: 1.35–2.11). A population density threshold of 22 people/km2 was needed to sustain an outbreak. Counties with greater population density have greater rates of transmission of SARS-CoV-2, likely due to increased contact rates in areas with greater density. An increase in one unit of log population density increased R0 by 0.16 (95% CI: 0.13 to 0.19). This association remained when adjusted for main mode of transportation and household income. The effect of population density on R0 was not modified by transportation mode. Our findings suggest that dense areas increase contact rates necessary for disease transmission. SARS-CoV-2 R0 estimates need to consider this geographic variability for proper planning and resource allocation, particularly as epidemics newly emerge and old outbreaks resurge.

THRESHOLD AND STABILITY RESULTS FOR AN SIRS EPIDEMIC MODEL WITH A GENERAL PERIODIC VACCINATION STRATEGY

2005 ◽  
Vol 13 (02) ◽  
pp. 131-150 ◽  
Author(s):  
I. A. MONEIM ◽  
D. GREENHALGH
Keyword(s):  
Epidemic Model ◽  
Vaccination Strategy ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Contact Rate ◽  
Globally Asymptotically Stable ◽  
Epidemic Dynamics ◽  
Sirs Epidemic Model ◽  
Sirs Model ◽  
Periodic Disease

An SIRS epidemic model with general periodic vaccination strategy is analyzed. This periodic vaccination strategy is discussed first for an SIRS model with seasonal variation in the contact rate of period T = 1 year. We start with the case where the vaccination strategy and the contact rate have the same period and then discuss the case where the period of the vaccination strategy is LT, where L is an integer. We investigate whether a periodic vaccination strategy may force the epidemic dynamics to have periodic behavior. We prove that our SIRS model has a unique periodic disease free solution (DFS) whose period is the same as that of the vaccination strategy, which is globally asymptotically stable when the basic reproductive number R0 is less than or equal to one in value. When R0 > 1, we prove that there exists a non-trivial periodic solution of period the same as that of the vaccination strategy. Some persistence results are also discussed. Threshold conditions for these periodic vaccination strategies to ensure that R0 ≤ 1 are derived.

scholarly journals Cholera outbreaks in sub-Saharan Africa during 2010-2019: A Descriptive Analysis

2021 ◽  
Author(s):  
Qulu Zheng ◽  
Francisco J Luquero ◽  
Iza Ciglenecki ◽  
Joseph F Wamala ◽  
Abdinasir Abubakar ◽  
...  
Keyword(s):  
Universal Access ◽  
Descriptive Analysis ◽  
Case Fatality ◽  
Sub Saharan Africa ◽  
Reproductive Number ◽  
Outbreak Management ◽  
Incidence And Mortality ◽  
Sub Saharan ◽  
Administrative Units ◽  
Case Fatality Risk

Background: Cholera remains a public health threat, but is inequitably distributed, especially affecting areas without universal access to safe water and sanitation, including much of sub-Saharan Africa. Lack of standardized reporting and inconsistent outbreak definitions limit our understanding of cholera outbreak epidemiology. Methods: We curated a database of cholera incidence and mortality from sub-Saharan Africa from 2010 to 2020 and developed methods to reconstruct epidemic curves. We then described the distribution of key outbreak metrics, including outbreak size and duration. Results: We identified 999 suspected cholera outbreaks in 744 unique regions across 25 sub-Saharan Africa countries, and outbreak periods accounted for 1.8 billion person-months (2% of the total during this period) from January 2010 through January 2020. Among the 692 outbreaks reported from second-level administrative units (e.g., districts), the median attack rate was 0.8 per 1,000 people (IQR, 0.3-2.4 per 1,000), the median epidemic duration was 13 weeks (IQR, 8-19), and the median early outbreak reproductive number was 1.8 (range, 1.1-3.5). Rural outbreaks had more than twice the case fatality risk than urban ones (median of 1.8% versus 0.8%). Larger attack rates were associated with longer times to outbreak peak, longer epidemic durations, and lower case fatality risks. Conclusions: Despite reporting gaps and the limitations of analyzing outbreaks by administrative units, this work provides a baseline from which to monitor progress towards cholera control and essential statistics to inform outbreak management and emergency response in sub-Saharan Africa.

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