scholarly journals Rapid transmission of respiratory infections within but not between mountain gorilla groups

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Robin E. Morrison ◽  
Yvonne Mushimiyimana ◽  
Tara S. Stoinski ◽  
Winnie Eckardt
Keyword(s):  
Disease Transmission ◽  
Respiratory Infections ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Wild Populations ◽  
Gorilla Beringei Beringei ◽  
The Social ◽  
Gorilla Beringei ◽  
Rapid Transmission ◽  
Range Overlap

AbstractMinimizing disease transmission between humans and wild apes and controlling outbreaks in ape populations is vital to both ape conservation and human health, but information on the transmission of real infections in wild populations is rare. We analyzed respiratory outbreaks in a subpopulation of wild mountain gorillas (Gorilla beringei beringei) between 2004 and 2020. We investigated transmission within groups during 7 outbreaks using social networks based on contact and proximity, and transmission between groups during 15 outbreaks using inter-group encounters, transfers and home range overlap. Patterns of contact and proximity within groups were highly predictable based on gorillas’ age and sex. Disease transmission within groups was rapid with a median estimated basic reproductive number (R0) of 4.18 (min = 1.74, max = 9.42), and transmission was not predicted by the social network. Between groups, encounters and transfers did not appear to have enabled disease transmission and the overlap of groups’ ranges did not predict concurrent outbreaks. Our findings suggest that gorilla social structure, with many strong connections within groups and weak ties between groups, may enable rapid transmission within a group once an infection is present, but limit the transmission of infections between groups.

scholarly journals Social fluidity mobilizes contagion in human and animal populations

2017 ◽  
Author(s):  
Ewan Colman ◽  
Vittoria Colizza ◽  
Ephraim M. Hanks ◽  
David P. Hughes ◽  
Shweta Bansal
Keyword(s):  
Disease Transmission ◽  
Social Bonds ◽  
Group Living ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Animal Populations ◽  
Social Mixing ◽  
The Social ◽  
Group Members ◽  
Social Fluidity

Humans and other group-living animals tend to distribute their social effort disproportionately. Individuals predominantly interact with a small number of close companions while maintaining weaker social bonds with less familiar group members. By incorporating this behaviour into a mathematical model we find that a single parameter, which we refer to as social fluidity, controls the rate of social mixing within the group. We compare the social fluidity of 13 species by applying the model to empirical human and animal social interaction data. To investigate how social behavior influences the likelihood of an epidemic outbreak we derive an analytical expression of the relationship between social fluidity and the basic reproductive number of an infectious disease. For highly fluid social behaviour disease transmission is revealed to be density-dependent. For species that form more stable social bonds, the model describes frequency-dependent transmission that is sensitive to changes in social fluidity.

Modeling and stability analysis of the spread of novel coronavirus disease COVID-19

2021 ◽  
pp. 2150035
Author(s):  
A. George Maria Selvam ◽  
Jehad Alzabut ◽  
D. Abraham Vianny ◽  
Mary Jacintha ◽  
Fatma Bozkurt Yousef
Keyword(s):  
Fractional Order ◽  
Disease Transmission ◽  
Equilibrium Points ◽  
Sufficient Conditions ◽  
Basic Reproductive Number ◽  
Phase Portraits ◽  
Transmission Model ◽  
Reproductive Number ◽  
Discrete Version ◽  
Novel Coronavirus

Towards the end of 2019, the world witnessed the outbreak of Severe Acute Respiratory Syndrome Coronavirus-2 (COVID-19), a new strain of coronavirus that was unidentified in humans previously. In this paper, a new fractional-order Susceptible–Exposed–Infected–Hospitalized–Recovered (SEIHR) model is formulated for COVID-19, where the population is infected due to human transmission. The fractional-order discrete version of the model is obtained by the process of discretization and the basic reproductive number is calculated with the next-generation matrix approach. All equilibrium points related to the disease transmission model are then computed. Further, sufficient conditions to investigate all possible equilibria of the model are established in terms of the basic reproduction number (local stability) and are supported with time series, phase portraits and bifurcation diagrams. Finally, numerical simulations are provided to demonstrate the theoretical findings.

scholarly journals Differential effects of intervention timing on COVID-19 spread in the United States

2020 ◽  
Vol 6 (49) ◽  
pp. eabd6370 ◽  
Author(s):  
Sen Pei ◽  
Sasikiran Kandula ◽  
Jeffrey Shaman
Keyword(s):  
United States ◽  
Disease Transmission ◽  
Human Mobility ◽  
The United States ◽  
Control Measures ◽  
Basic Reproductive Number ◽  
Transmission Model ◽  
Reproductive Number ◽  
Mobility Data ◽  
Nonpharmaceutical Interventions

Assessing the effects of early nonpharmaceutical interventions on coronavirus disease 2019 (COVID-19) spread is crucial for understanding and planning future control measures to combat the pandemic. We use observations of reported infections and deaths, human mobility data, and a metapopulation transmission model to quantify changes in disease transmission rates in U.S. counties from 15 March to 3 May 2020. We find that marked, asynchronous reductions of the basic reproductive number occurred throughout the United States in association with social distancing and other control measures. Counterfactual simulations indicate that, had these same measures been implemented 1 to 2 weeks earlier, substantial cases and deaths could have been averted and that delayed responses to future increased incidence will facilitate a stronger rebound of infections and death. Our findings underscore the importance of early intervention and aggressive control in combatting the COVID-19 pandemic.

scholarly journals The rules and the reality of mountain gorilla Gorilla beringei beringei tracking: how close do tourists get?

Oryx ◽  
2006 ◽  
Vol 40 (4) ◽  
pp. 428-433 ◽  
Author(s):  
Chris Sandbrook ◽  
Stuart Semple
Keyword(s):  
Disease Transmission ◽  
National Park ◽  
Gorilla Gorilla ◽  
Mountain Gorilla ◽  
Close Encounters ◽  
Gorilla Beringei Beringei ◽  
Gorilla Beringei ◽  
Risk Of Disease ◽  
Gorilla Gorilla Beringei ◽  
First Time

Mountain gorilla Gorilla beringei beringei tracking tourism generates important revenue for conservation efforts but brings with it the threat of disease transmission into the gorilla population. This study quantifies for the first time aspects of encounters between gorillas and tourists at Bwindi Impenetrable National Park that are likely to contribute to the risk of disease transmission. These include how close tourists get to gorillas, how close encounters are initiated, how long they last, and the age class of gorillas involved. Tourists got significantly closer to gorillas than the park rules allow (a mean of 2.76 m, compared to the rule of 7 m), and remained close for long periods. Contacts with the gorillas most vulnerable to disease, the juveniles, were closer but of shorter duration than those with adults. Contacts initiated by gorillas were closer but shorter than those initiated by tourists. Taken together these results demonstrate that the present rules are failing, and that the risk of disease transmission may be greater than previously believed.

scholarly journals Epidemic spreading model in heterogeneous conditions

2021 ◽  
pp. 1-12
Author(s):  
Andrey Viktorovich Podlazov
Keyword(s):  
Equilibrium Position ◽  
Sir Model ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Epidemic Spread ◽  
Epidemic Spreading ◽  
Oscillatory Dynamics ◽  
Spreading Model ◽  
Multiple Contacts ◽  
The Social

I propose two modifications of the SIR model of the epidemic spread, taking into account the social and space heterogeneity of the population. Social hetero¬geneity associated with differences in the intensity of paired contacts between people qualitatively changes the basic reproductive number. Space heterogeneity associated with differences in the intensity of multiple contacts between people significantly shifts the equilibrium position, increases the characteristic times and leads to the emergence of oscillatory dynamics of finite duration.

scholarly journals Behavioral responses around conspecific corpses in adult eastern gorillas (Gorilla beringei spp.)

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6655 ◽  
Author(s):  
Amy Porter ◽  
Winnie Eckardt ◽  
Veronica Vecellio ◽  
Katerina Guschanski ◽  
Peter Philip Niehoff ◽  
...  
Keyword(s):  
Social Relationships ◽  
Disease Transmission ◽  
National Park ◽  
Democratic Republic Of Congo ◽  
Behavioral Responses ◽  
Mountain Gorilla ◽  
Adult Females ◽  
Gorilla Beringei Beringei ◽  
Gorilla Beringei ◽  
Group Members

Humans were once considered unique in having a concept of death but a growing number of observations of animal responses to dying and dead conspecifics suggests otherwise. Complex arrays of behaviors have been described ranging from corpse removal and burial among social insects to quiet attendance and caregiving among elephants and primates. Less frequently described, however, are behavioral responses of individuals from different age/sex classes or social position toward the death of conspecifics. We describe behavioral responses of mountain gorillas (Gorilla beringei beringei) to the deaths of a dominant silverback and a dominant adult female from the same social group in Volcanoes National Park in Rwanda and the responses of Grauer’s gorillas (Gorilla b. graueri) to the corpse of an extra-group silverback in Kahuzi-Biega National Park, Democratic Republic of Congo. In gorillas, interactions between groups or with a lone silverback often result in avoidance or aggression. We predicted that: (i) more individuals should interact with the corpses of same-group members than with the corpse of the extra-group silverback; (ii) adult females with infants should avoid the corpse of the extra-group silverback; and (iii) in the mountain gorilla cases, individuals that shared close social relationships with the dead individual should spend more time with the corpse than other individuals in the group. We used a combination of detailed qualitative reports, photos, and videos to describe all occurrences of affiliative/investigative and agonistic behaviors observed at the corpses. We observed similar responses toward the corpses of group and extra-group individuals. Animals in all three cases showed a variety of affiliative/investigative and agonistic behaviors directed to the corpses. Animals of all age/sex classes interacted with the corpses in affiliative/investigative ways but there was a notable absence of all adult females at the corpse of the extra-group silverback. In all three cases, we observed only silverbacks and blackbacks being agonistic around and/or toward the corpses. In the mountain gorilla cases, the individuals who spent the most time with the corpses were animals who shared close social relationships with the deceased. We emphasize the similarity in the behavioral responses around the corpses of group and extra-group individuals, and suggest that the behavioral responses were influenced in part by close social relationships between the deceased and certain group members and by a general curiosity about death. We further discuss the implications close interactions with corpses have for disease transmission within and between gorilla social groups.

Dynamics of a Food Chain Model with Two Infected Predators

2021 ◽  
Vol 31 (02) ◽  
pp. 2150019
Author(s):  
Xin-You Meng ◽  
Ni-Ni Qin ◽  
Hai-Feng Huo
Keyword(s):  
Food Chain ◽  
Disease Transmission ◽  
Sufficient Conditions ◽  
Geometric Approach ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Chain Model ◽  
Number Formula ◽  
Manifold Theory ◽  
Food Chain Model

In this paper, the dynamics of a three-species food chain model with two predators infected by an infectious disease is investigated. The positivity and boundedness of the system, the existence of the equilibria and the basic reproductive number are given. Sufficient conditions for the local stability of all equilibria are obtained by analyzing the corresponding characteristic equations. By constructing suitable Lyapunov functions and taking the geometric approach, the global stability of all equilibria is proved. According to the center manifold theory, this model undergoes the phenomenon of backward and forward bifurcations in a certain range of the basic reproductive number [Formula: see text]. By taking the disease transmission coefficient of predator as bifurcation parameter, Hopf bifurcation emerges in the neighborhood of the endemic equilibrium. Furthermore, the optimal control of the disease is discussed by the Pontryagin’s maximum principle. Various simulations are given to support the analytical results.

scholarly journals Estimation of the Outbreak Severity and Evaluation of Epidemic Prevention Ability of COVID-19 by Province in China

2020 ◽  
Vol 110 (12) ◽  
pp. 1837-1843
Author(s):  
Yilei Ma ◽  
Xuehan Liu ◽  
Weiwei Tao ◽  
Yuchen Tian ◽  
Yanran Duan ◽  
...  
Keyword(s):  
Emergency Response ◽  
Disease Transmission ◽  
Initial Period ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Linear Mixed Effects Model ◽  
Linear Mixed Effects ◽  
Imported Cases ◽  
And Control ◽  
Case Data

Objectives. To compare the epidemic prevention ability of COVID-19 of each province in China and to evaluate the existing prevention and control capacity of each province. Methods. We established a quasi-Poisson linear mixed-effects model using the case data in cities outside Wuhan in Hubei Province, China. We adapted this model to estimate the number of potential cases in Wuhan and obtained epidemiological parameters. We estimated the initial number of cases in each province by using passenger flowrate data and constructed the extended susceptible–exposed–infectious–recovered model to predict the future disease transmission trends. Results. The estimated potential cases in Wuhan were about 3 times the reported cases. The basic reproductive number was 3.30 during the initial outbreak. Provinces with more estimated imported cases than reported cases were those in the surrounding provinces of Hubei, including Henan and Shaanxi. The regions where the number of reported cases was closer to the predicted value were most the developed areas, including Beijing and Shanghai. Conclusions. The number of confirmed cases in Wuhan was underestimated in the initial period of the outbreak. Provincial surveillance and emergency response capabilities vary across the country.

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.

ASSESSING THE EFFECTS OF TEMPERATURE AND DENGUE VIRUS LOAD ON DENGUE TRANSMISSION

2015 ◽  
Vol 23 (04) ◽  
pp. 1550027 ◽  
Author(s):  
LOURDES ESTEVA ◽  
HYUN MO YANG
Keyword(s):  
Disease Transmission ◽  
Basic Reproductive Number ◽  
Effect Of Temperature ◽  
Reproductive Number ◽  
Vector Population ◽  
Dengue Transmission ◽  
Mosquito Mortality ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Nonzero Equilibrium

In this study, we propose a model to assess the effect of temperature on the incidence of dengue fever. For this, we take into account the dependence of the entomological and epidemiological parameters of the transmitter vector Aedes aegypti with respect to the temperature. The model consists of an ODE system that describes the transmission between humans and mosquitoes considering the aquatic stage of the vector population. The qualitative analysis of the model is made in terms of the parameters [Formula: see text] and [Formula: see text], which represent the basic offspring of mosquitoes, and the basic reproductive number of the disease, respectively. If [Formula: see text] mosquito population extinguishes while for [Formula: see text] it tends asymptotically to a nonzero equilibrium. Analogously, the disease transmission is eliminated if [Formula: see text], and it approaches an endemic equilibrium for [Formula: see text]. Using entomological data of mosquitoes as well as experimental data of disease transmission we evaluate [Formula: see text] and [Formula: see text] at different temperatures, obtaining that around [Formula: see text]C both parameters attain their maximum. Sensitivity analysis reveals that infection rates and mosquito mortality are the parameters for which [Formula: see text] is more sensitive.

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