Ebola Virus Disease Transmission Research Articles

Modeling Ebola Dynamics with a Φ-Piecewise Hybrid Fractional Derivative Approach

Ebola virus disease (EVD) is a severe and often fatal illness posing significant public health challenges. This study investigates EVD transmission dynamics using a novel fractional mathematical model with five distinct compartments: individuals with low susceptibility (S1), individuals with high susceptibility (S2), infected individuals (I), exposed individuals (E), and recovered individuals (R). To capture the complex dynamics of EVD, we employ a Φ-piecewise hybrid fractional derivative approach. We investigate the crossover effect and its impact on disease dynamics by dividing the study interval into two subintervals and utilize the Φ-Caputo derivative in the first interval and the Φ-ABC derivative in the second interval. The study determines the basic reproduction number R0, analyzes the stability of the disease-free equilibrium and investigates the sensitivity of the parameters to understand how variations affect the system’s behavior and outcomes. Numerical simulations support the model and demonstrate consistent results with the theoretical analysis, highlighting the importance of fractional calculus in modeling infectious diseases. This research provides valuable information for developing effective control strategies to combat EVD.

Community perspectives of Ebola Viral Disease in high-risk transmission border regions of Tanzania: a qualitative inquiry

BackgroundTanzania faces ever-rising concerns due to the recurrence of the Ebola Virus Disease (EVD) in neighbouring Democratic Republic of Congo (DRC) and Uganda. This necessitates a better understanding of the community perspectives in high-risk regions for effective risk communication and preparedness.MethodsThis rapid ethnographic assessment study used explorative qualitative methods to collect data. People from diverse backgrounds participated in 59 in-depth interviews, 57 Key Informant interviews, and 35 focus group discussions. Data was analysed using a thematic analysis approach.FindingThe study revealed existence of awareness of EVD and its symptoms, with radio and television being the main sources of information. However, there were varied perceptions of EVD’s cause and transmission, some attributed it to bats, monkeys, and wild animal meat, while others associated it with high fever, a dirty environment, changing dietary patterns, and the COVID-19 virus. Physical contact with an infected person’s body fluids and eating meat from infected animals were perceived as EVD transmission routes. Women, school children, boda-boda (motorcycle) riders, and fishermen were considered the most susceptible to EVD infections due to their daily activities. Preventive measures included avoiding physical contact, touching fluids, and refraining from eating wild animal meat. Prompt reporting of suspected cases to health facilities was deemed crucial for earlier outbreak identification and containment.ConclusionThe high-risk regions of Tanzania had a high level of awareness and perceived susceptibility to EVD, coupled with varying degrees of misperception about the etiology and its transmission. To improve community perspectives and preparedness in the case of an outbreak, there is a need for ongoing risk communication and participation in EVD prevention and responses.

Development of a clinical prediction score for Ebola virus disease screening at triage centers in the Democratic Republic of the Congo.

The 2018-2020 Ebola virus disease (EVD) outbreak in the Democratic Republic of the Congo (DRC) was the largest since the disease's discovery in 1976. Rapid identification and isolation of EVD patients are crucial during triage. This study aimed to develop a clinical prediction score for EVD using clinical and epidemiological predictors. We conducted a retrospective cross-sectional study using surveillance data from EVD outbreak, collected during routine clinical care at the Ebola Transit Center (ETC) in Beni, DRC, from 2018 to 2020. The Spiegelhalter and Knill-Jones method was used for score development, including potential predictors with an adjusted likelihood ratio above 2 or below 0.50. Validation was performed using a dataset previously published in PLOSOne by Tshomba et al. Among 3725 patients screened, 3698 fulfilled the inclusion criteria, with 571 (15.4%) testing positive for EVD via RT-PCR Test. Seven predictive factors were identified: asthenia, sore throat, conjunctivitis, bleeding gums, hematemesis, contact with a sick person, and contact with a traditional healer. The prediction score achieved an Area under the receiver operating characteristic (AUROC) of 0.764, with 81.4% sensitivity and 53.6% specificity at a -1 cutoff. External validation demonstrated an AUROC of 0.766, with 80.8% sensitivity and 41.4% specificity at the -1 cutoff. Our study developed a screening tool to assess the risk of suspected patients developing EVD and being admitted to ETUs for RT-PCR testing and treatment. External validation results affirmed the model's reliability and generalizability in similar settings, suggesting its potential integration into clinical practice. Given the severity and urgency of EVD as well as the risk nosocomial EVD transmission, it is essential to continuously update these models with real-time data on symptoms, disease progression, patient outcomes and validated RDT during EVD outbreaks. This approach will enhance model accuracy, enabling more precise risk assessments and more effective outbreak management.

Mathematical Analysis of an Ebola Differential Infectivity Model

West Africa and the Democratic Republic of Congo have in the recent years experienced majority of the Ebola Virus Disease (EVD) burden. Deaths from EVD occur yearly but naturally peak during the dry season. The average EVD fatality rate is approximated at 50%. Studies done on the dynamics of EVD transmission have not captured the differential infectivity aspects of the disease. In this work, a nonlinear differential infectivity model with variation in infectiousness that captures the dynamics of EVD to assess the role of varied infectivity on EVD with possible intervention measures is formulated. Stability analysis of the model shows that the model is conditionally locally and globally stable. The model is also shown to exhibit hopf bifurcation, which shows that the transmission dynamics of the disease are periodic in nature. Numerical simulation results showed that intervention measures to control the disease is more efficient at the onset of the infection to reduce the spread of the disease. The findings are significant in designing intervention measures aimed at reducing infections.

Quarantine Model on the Transmission of Ebola Virus Disease in the Human Population with Infectious Dead Class

Quarantine Model on the Transmission of Ebola Virus Disease in the Human Population with Infectious Dead Class

A community-based contact isolation strategy to reduce the spread of Ebola virus disease: an analysis of the 2018–2020 outbreak in the Democratic Republic of the Congo

IntroductionDespite tremendous progress in the development of diagnostics, vaccines and therapeutics for Ebola virus disease (EVD), challenges remain in the implementation of holistic strategies to rapidly curtail outbreaks. We investigated...

Characterization of Ebola Virus Mucosal Challenge Routes in Cynomolgus Macaques.

Zaïre ebolavirus (EBOV) causes Ebola virus disease (EVD), a devastating viral hemorrhagic fever in humans. Nonhuman primate (NHP) models of EVD traditionally use intramuscular infection with higher case fatality rates and reduced mean time-to-death compared to contact transmission typical of human cases of EVD. A cynomolgus macaque model of oral and conjunctival EBOV was used to further characterize the more clinically relevant contact transmission of EVD. NHPs challenged via the oral route had an overall 50% survival rate. NHPs challenged with a target dose of 1 × 102 PFU or 1 × 104 PFU of EBOV via the conjunctival route had 40% and 100% mortality, respectively. Classic signs of lethal EVD-like disease were observed in all NHPs that succumbed to EBOV infection including viremia, hematological abnormalities, clinical chemistries indicative of hepatic and renal disease, and histopathological findings. Evidence of EBOV viral persistence in the eye was observed in NHPs challenged via the conjunctival route. IMPORTANCE This study is the first to examine the Kikwit strain of EBOV, the most commonly used strain, in the gold-standard macaque model of infection. Additionally, this is the first description of the detection of virus in the vitreous fluid, an immune privileged site that has been proposed as a viral reservoir, following conjunctival challenge. The oral and conjunctival macaque challenge model of EVD described here more faithfully recapitulates the prodrome that has been reported for human EVD. This work paves the way for more advanced studies to model contact transmission of EVD, including early events in mucosal infection and immunity, as well as the establishment of persistent viral infection and the emergence from these reservoirs.

Modeling the potential influence of economic migration on Ebola virus disease transmission dynamics

IntroductionThe good health of the economy of developed countries is an attracting factor for economic migrants from poorer countries whose movements can be associated with the spread of diseases such as the Ebola virus disease.MethodsIn this paper, we formulate a model of Ebola virus disease that considers two patches with different economic statuses represented by the respective gross-national incomes of the two patches. First, we consider a one-directional movement from a poorer patch to a rich patch. Second, we consider a two-way migration model where people move between patches.ResultsThe steady states of the model are determined and analyzed. The analysis shows also that the disease free and the endemic equilibrium points are locally stable. The analysis also shows that a unique endemic equilibrium point exists in the poor patch when the reproduction number in this patch is greater than one and multiple endemic equilibria exist in the rich patch when the reproduction number in the poor patch is less than one. The model dynamics of the rich patch present a backward bifurcation which does not facilitate easy Ebola virus disease control. Sensitivity analysis is carried out to determine the most sensitive parameters that must be carefully estimated for the successful control of the Ebola virus disease.DiscussionNumerical simulations indicate a decrease in the number of infected individuals in the rich patch when movements of populations are limited through the improvement of the economy in the poor patch. So, the improvement of the economy of poorer countries may be critical in avoiding potential outbreaks of Ebola virus disease.

Mathematical analysis of sensitive parameters due to dynamic transmission of Ebola virus disease

Mathematical analysis of sensitive parameters due to dynamic transmission of Ebola virus disease

Mathematical analysis of a model of Ebola disease with control measures

The re-emergence of the Ebola virus disease has pushed researchers to investigate more on this highly deadly disease in order to better understand and control the outbreak and recurrence of epidemics. It is in this perspective that we formulate a realistic mathematical model for the dynamic transmission of Ebola virus disease, incorporating relevant control measures and factors such as ban on eating bush-meat, social distancing, observance of hygiene rules and containment, waning of the vaccine-induced, imperfect contact tracing and vaccine efficacy, quarantine, hospitalization and screening to fight against the spread of the disease. First, by considering the constant control parameters case, we thoroughly compute the control reproduction number [Formula: see text] from which the dynamics of the model is analyzed. The existence and stability of steady states are established under appropriate assumptions on [Formula: see text]. Also, the effect of all the control measures is investigated and the global sensitivity analysis of the control reproduction number is performed in order to determine the impact of parameters and their relative importance to disease transmission and prevalence. Second, in the time-dependent control parameters case, an optimal control problem is formulated to design optimal control strategies for eradicating the disease transmission. Using Pontryagin’s Maximum Principle, we derive necessary conditions for optimal control of the disease. The cost-effectiveness analysis of all combinations of the control measures is made by calculating the infection averted ratio and the incremental cost-effectiveness ratio. This reveals that combining the four restrictive measures conveyed through educational campaigns, screening, safe burial and the care of patients in health centers for better isolation is the most cost-effective among the strategies considered. Numerical simulations are performed to illustrate the theoretical results obtained.

Risk factors for Ebola virus disease among household care providers, Sierra Leone, 2015.

Household contacts who provide care to an Ebola virus disease (EVD) case have a 3-fold higher risk of EVD compared with contacts who do not provide care. We enrolled persons with confirmed EVD from December 2014 to April 2015 in Freetown, Sierra Leone, and their household contacts. Index cases and contacts were interviewed, and contacts were followed for 21 days to identify secondary cases. Epidemiological data were analysed to describe household care and to identify risk factors for developing EVD. Of 838 contacts in 147 households, 156 (17%) self-reported providing care to the index case; 56 households had no care provider, 52 a single care provider and 39 multiple care providers. The median care provider age was 29 years, 68% were female and 32% were the index case's spouse. Care providers were more likely to report physical contact, contact with body fluids or sharing clothing, bed linens or utensils with an index case, compared with non-care providers (P <0.01). EVD risk among non-care providers was greater when the number of care providers in the household increased (odds ratio: 1.61; 95% confidence interval: 1.1, 2.4). In multivariable analysis, factors associated with care provider EVD risk included no piped water access and absence of index case fever, and protective factors included age <20 years and avoiding the index case. Limiting the number of care providers in a household could reduce the risk of EVD transmission to both care providers and non-care providers. Strategies to protect care providers from EVD exposure are needed.

Qualitative evidence syntheses of attitudes and preferences to inform guidelines on infant feeding in the context of Ebola Virus Disease (EVD) transmission risk.

BackgroundBreast-feeding holds considerable potential to reduce infant mortality. Feeding choices, already complex, take on additional complexity against a backdrop of the risk of transmissible Ebola Virus. This review describes the factors that influence infant feeding and attitudes of pregnant women, mothers, family members and health practitioners, policy makers and providers (midwives) concerning infant feeding when there is a risk of Mother-to-Child (MTC) transmission of Ebola Virus Disease (EVD).MethodologyA systematic review of qualitative studies identified through rigorous searches of thirteen online databases and additional citation searches of included studies was undertaken. Search terms included breast-feeding, breast-feeding, infant feeding; Ebola; and qualitative, interview(s) and findings. Independent extraction of data by two reviewers using predefined extraction forms. Studies were assessed using the CASP Qualitative checklist.Principal findings5219 references were screened. 38 references related specifically to Ebola, and five papers met the inclusion criteria with data gathered from two settings: Guinea and Sierra Leone. The EVD outbreak had a significant impact on beliefs, attitudes, and resources to support infant feeding practices negatively affecting the nutritional status of children. The evidence from these studies highlight the need for guidance and appropriate psychosocial support need to be available to mothers who display symptoms and become infected and to front-line staff who are giving advice. Communities need to be engaged because stigma and fear may hinder uptake of appropriate interventions. The EVD outbreak caused multi-level system disruption akin to that seen following a natural disaster, meaning that logistics and coordination are critical and need adequate resourcing. Food production and distribution, and malnutrition screening are also disrupted and thereby compounding compromised nutritional status. The limited number of relevant studies highlights the need for further primary research, particularly in translation of messages to local settings.ConclusionsAn EVD outbreak causes multi-level disruption that negatively impacts infant feeding and child care practices. Negative impacts have multiple causes and successful planning for Ebola outbreaks requires that nutrition of infants and young children is a priority. Lessons from the Ebola pandemic have wider applicability to other pandemic contexts including Covid-19.

Ebola virus disease nosocomial infections in the Democratic Republic of the Congo: a descriptive study of cases during the 2018–2020 outbreak

To describe the characteristics of nosocomial cases of Ebola virus disease (EVD) in the Democratic Republic of the Congo between July 2018 and May 2020 in order to inform future interventions. Nosocomial cases of EVD were identified during outbreak response surveillance, and a retrospective analysis of cases was conducted according to demographic characteristics and type of health facility (HF). Of 3481 cases of EVD, 579 (16.6%) were nosocomial. Of these, 332 cases occurred in women (57.3%). Patients and visitors accounted for 419 cases (72.4%), of which 79 (18.9%) were aged 6-≤18years and 108 (25.8%) were aged ≤5years. Health workers (HWs) accounted for the remaining 160 (27.6%) nosocomial cases. The case fatality rate (CFR) for HWs (66/160, 41.3%) was significantly lower than the CFR for patients and visitors (292/419, 69.7%) (P<0.001). The CFR was higher among cases aged 6-≤18years (54/79, 68.4%) and ≤5years (89/108, 82.4%). Referral HFs (>39beds) had the highest prevalence of nosocomial EVD (148/579, 25.6%). Among HFs with at least one case of nosocomial infection, 50.0% (98/196) were privately owned. Nurses and traditional healers should be targeted for infection prevention and control training, and supportive supervision should be provided to HFs to mitigate EVD transmission.

Impact of COVID‐19 on wild meat trade in Nigerian markets

Impact of <scp>COVID</scp>‐19 on wild meat trade in Nigerian markets

Economic evaluation using dynamic transition modeling of ebola virus vaccination in lower-and-middle-income countries

Background With the increasing occurrence of infectious diseases in lower-and-middle-income countries (LMICs), emergency preparedness is essential for rapid response and mitigation. Economic evaluations of mitigation technologies and strategies have been recommended for inclusion in emergency preparedness plans. We aimed to perform an economic evaluation using dynamic transition modeling of ebola virus disease (EVD) vaccination in a hypothetical community of 1,000 persons in the Democratic Republic of Congo (DRC). Method Using a modified SEIR (Susceptible, Exposed, Infectious, Recovered, with Death added [SEIR-D]) model that accounted for death and epidemiological data from an EVD outbreak in the DRC, we modeled the transmission of EVD in a hypothetical population of 1,000. With our model, we estimated the cost-effectiveness of an EVD vaccine and an EVD vaccination intervention. Results The results showed vaccinating 50% of the population at risk prevented 670 cases, 538 deaths, and 22,022 disability-adjusted life years (DALYs). The vaccine was found to be cost-effective with an incremental cost-effectiveness ratio (ICER) of $95.63 per DALY averted. We also determined the minimum required vaccination coverage for cost-effectiveness to be 40%. Sensitivity analysis showed our model to be fairly robust, assuring relatively consistent results even with variations in such input parameters as cost of screening, as well as transmission, infection, incubation, and case fatality rates. Conclusion EVD vaccination in our hypothetical population was found to be cost-effective from the payer perspective. Our model presents an efficient and reliable approach for conducting economic evaluations of infectious disease interventions as part of an emergency preparedness plan.

Assessing the determinants of Ebola virus disease transmission in Baka Community of the Tropical Rainforest of Cameroon

BackgroundEbola virus disease (EVD) is a severe, often fatal illness in humans and nonhuman primates caused by the Ebola virus. The recently approved rVSV-EBOV vaccine is not available in many high-risk countries hence prevention is paramount. The design of effective prevention interventions requires an understanding of the factors that expose communities at risk. It was based on this that we investigated the Baka community of Abong-Mbang Health District in tropical rain forest of Cameroon.MethodsA cross-sectional study was conducted with participants randomly selected from 13 villages in Abong-Mbang by multi-stage cluster sampling. A questionnaire was administered to them to collect demographic information, data on knowledge of EVD, their feeding and health-seeking behaviour. Data was analyzed using the chi-square test. Knowledge of EVD was assessed using an 8 item Morisky Scale. An adapted Threat Capability Basic Risk Assessment Guide was used to determine their risk of exposure to infection.ResultsA total of 510 participants, most of whom were hunters (31.4%), farmers (29.8%), and had primary education (62.7%), were included in this study. Although 83.3% participants had heard of EVD, most (71%) did not know its cause. Their source of information was mainly informal discussions in the community (49%). Misconceptions were identified with regards to the cause and mode of transmission. Only 43.1% accepted EVD could be transmitted from human-to-human. Generally, participants’ knowledge of EVD was poor. Demographic factors such as level of education, occupation and ethnic group significantly affected knowledge of EVD. The majority of participants were at a very high risk of exposure to infection as they consumed various forms of bush meat and were involved in other risky practices such as scarification and touching of corpses. Although over half of participants seek medical care, most of them preferred traditional medicine. Socio-cultural and service-related factors were deterrent factors to medical care.ConclusionParticipants generally had poor knowledge of EVD and were at high risk of infection. We recommend rigorous sensitization campaigns in the study area to educate the population on EVD and clarify the misconceptions identified. EVD surveillance is recommended particularly as outbreaks have often been reported in the Congo Basin.

Effect of quarantine on transmission dynamics of Ebola virus epidemic: a mathematical analysis

In this paper, a nonlinear model called susceptible–exposed–infected–quarantined–recovered is developed to study the transmission of Ebola virus disease (EVD). In the proposed model, an additional class of quarantined humans is incorporated to investigate the impact of quarantine strategy for exposed population. A comprehensive mathematical analysis of this model is carried out to understand the dynamical behavior of EVD. Equilibrium points $$F^{0}$$ , $$F^{1}$$ and the threshold parameter $${\mathcal {R}}_{0}$$ of the model are evaluated. An analytic stability analysis of equilibrium points with the help of $${\mathcal {R}}_{0}$$ is performed. It is observed that $$F^{0}$$ is both locally and globally asymptotically stable when $${\mathcal {R}}_{0}$$ is strictly less than unity which means that there will be no epidemic. Moreover, $$F^{0}$$ is not stable and $$F^{1}$$ is both locally and globally asymptotically stable when $${\mathcal {R}}_{0}$$ is strictly greater than unity which indicates a uniform spread of disease among individuals. Global stability of both equilibria is established by employing theory of Lyapunov functions. To validate theoretical results thus obtained, the system of ODEs is solved by employing three well-known different numerical methods such as Euler method, Runge–Kutta method of order 4 (RK4), and the nonstandard finite difference (NSFD) method. It is worth mentioning that the Euler and RK4 numerical schemes converge conditionally, whereas the proposed NSFD scheme converges unconditionally and is dynamically consistent with the continuous model. A quantitative analysis of the proposed model at endemic point $$F^{1}$$ for different quarantine levels is also presented. We have studied the effect of different quarantine coverage levels on threshold parameter $${\mathcal {R}}_{0}$$ to draw our conclusions. Numerical results drawn using MATLAB validate our claim that EVD could be eradicated faster if quarantine measures with proper awareness at various coverage levels are adopted. Global asymptotical stability of equilibrium points is shown by 3D plots. Finally, the joint variability of populations is executed to assess the impact of quarantine measures on the transmission dynamics of a disease.

Development of a Skills-Based IPC Supervisor Course During the 2018-19 DRC Ebola Virus Disease Outbreak

Background: With &gt;3,000 cases and 2,000 deaths, the current outbreak of Ebola virus disease (EVD) in the Democratic Republic of the Congo (DRC) is the second-largest reported EVD outbreak in history. Healthcare-associated transmission of EVD has been a persistent amplifier of transmission due, in part, to fragility of the healthcare system, lack of basic infection prevention and control (IPC) infrastructure, and large number of healthcare facilities (HCFs). A central component of the strategy to rapidly strengthen IPC in HCFs is the provision of IPC supervisors to oversee standardized risk assessments and improvements and provide mentorship to HCF staff. To support these activities, we designed skills based training for IPC supervisors. Methods: Staff recruited by the Ministry of Health (MoH) to strengthen IPC are part of an outbreak-specific cadre known as IPC supervisors. IPC supervisors, who originally lacked technical knowledge and mentoring experience, were trained to provide technical support and mentorship to staff at HCFs, with the objective of improving IPC-related processes and behaviors. A competency-based training course was designed by conducting informal assessments of IPC supervisors during daily tasks to identify areas for performance improvement. We developed competencies based on activities designated for IPC supervisors according to MoH guidelines. We planned an iterative training rollout to allow for continuous, real-time modifications based on lessons learned throughout the implementation phase. Results: Although IPC supervisors displayed technical knowledge of IPC recommendations, we observed large gaps in implementation. IPC supervisors frequently failed to recognize behaviors that are high-risk for infection transmission. In addition, IPC supervisors lacked the ability to develop prioritized action plans and to implement interventions aimed at rapidly improving IPC practices. The course, designed as an interactive, skills-based training, is rooted in instructional design principles and addresses 4 key competencies: risk recognition and prioritization, IPC assessment completion, action plan development, and effective leadership and communication. The course will be pilot tested in the DRC to an audience of 25 IPC supervisors. Conclusions: In an outbreak setting, strong mentorship and problem-solving skills are needed to support effective implementation of IPC quality improvement. Trainings that are informed by field experiences and teach problem-solving, coaching, and communication skills are critical and can be developed rapidly. The strategy employed by the Ministry of Health to rapidly achieve IPC capacitation at HCFs might be adapted for use in future outbreaks.Funding: NoneDisclosures: None

Historical epidemiology and global health history.

The subdiscipline of historical epidemiology holds the promise of creating a more robust and more nuanced foundation for global public health decision-making by deepening the empirical record from which we draw lessons about past interventions. This essay draws upon historical epidemiological research on three global public health campaigns to illustrate this promise: the Rockefeller Foundation's efforts to control hookworm disease (1909-c.1930), the World Health Organization's pilot projects for malaria eradication in tropical Africa (1950s-1960s), and the international efforts to shut down the transmission of Ebola virus disease during outbreaks in tropical Africa (1974-2019).

Responding to the Challenge of the Dual COVID-19 and Ebola Epidemics in the Democratic Republic of Congo-Priorities for Achieving Control.

.As of June 11, 2020, the Democratic Republic of the Congo (DRC) has reported 4,258 COVID-19 cases with 90 deaths. With other African countries, the DRC faces the challenge of striking a balance between easing public health lockdown measures to curtail the spread of SARS-CoV-2 and minimizing both economic hardships for large sectors of the population and negative impacts on health services for other infectious and noninfectious diseases. The DRC recently controlled its tenth Ebola virus disease (EVD) outbreak, but COVID-19 and a new EVD outbreak beginning on June 1, 2020 in the northwest Équateur Province have added an additional burden to health services. Although the epidemiology and transmission of EVD and COVID-19 differ, leveraging the public health infrastructures and experiences from coordinating the EVD response to guide the public health response to COVID-19 is critical. Building on the DRC’s 40 years of experience with 10 previous EVD outbreaks, we highlight the DRC’s multi-sectoral public health approach to COVID-19, which includes community-based screening, testing, contact-tracing, risk communication, community engagement, and case management. We also highlight remaining challenges and discuss the way forward for achieving control of both COVID-19 and EVD in the DRC.