Virus Disease Epidemics Research Articles

Viral Threats to Fruit and Vegetable Crops in the Caribbean.

Viruses pose major global challenges to crop production as infections reduce the yield and quality of harvested products, hinder germplasm exchange, increase financial inputs, and threaten food security. Small island or archipelago habitat conditions such as those in the Caribbean are particularly susceptible as the region is characterized by high rainfall and uniform, warm temperatures throughout the year. Moreover, Caribbean islands are continuously exposed to disease risks because of their location at the intersection of transcontinental trade between North and South America and their role as central hubs for regional and global agricultural commodity trade. This review provides a summary of virus disease epidemics that originated in the Caribbean and those that were introduced and spread throughout the islands. Epidemic-associated factors that impact disease development are also discussed. Understanding virus disease epidemiology, adoption of new diagnostic technologies, implementation of biosafety protocols, and widespread acceptance of biotechnology solutions to counter the effects of cultivar susceptibility remain important challenges to the region. Effective integrated disease management requires a comprehensive approach that should include upgraded phytosanitary measures and continuous surveillance with rapid and appropriate responses.

Indirect Effects of Ebola Virus Disease Epidemics on Health Systems in the Democratic Republic of the Congo, Guinea, Sierra Leone and Liberia: A Scoping Review Supplemented with Expert Interviews.

Ebola Virus Disease (EVD) epidemics have been extensively documented and have received large scientific and public attention since 1976. Until July 2022, 16 countries worldwide had reported at least one case of EVD, resulting in 43 epidemics. Most of the epidemics occurred in the Democratic Republic of Congo (DRC) but the largest epidemic occurred from 2014–2016 in Guinea, Sierra Leone and Liberia in West Africa. The indirect effects of EVD epidemics on these countries’ health systems, i.e., the consequences beyond infected patients and deaths immediately related to EVD, can be significant. The objective of this review was to map and measure the indirect effects of the EVD epidemics on the health systems of DRC, Guinea, Sierra Leone and Liberia and, from thereon, draw lessons for strengthening their resilience vis-à-vis future EVD outbreaks and other similar health emergencies. A scoping review of published articles from the PubMed database and gray literature was conducted. It was supplemented by interviews with experts. Eighty-six articles were included in this review. The results were structured based on WHO’s six building blocks of a health system. During the EVD outbreaks, several healthcare services and activities were disrupted. A significant decline in indicators of curative care utilization, immunization levels and disease control activities was noticeable. Shortages of health personnel, poor health data management, insufficient funding and shortages of essential drugs characterized the epidemics that occurred in the above-mentioned countries. The public health authorities had virtually lost their leadership in the management of an EVD response. Governance was characterized by the development of a range of new initiatives to ensure adequate response. The results of this review highlight the need for countries to invest in and strengthen their health systems, through the continuous reinforcement of the building blocks, even if there is no imminent risk of an epidemic.

Global Plant Virus Disease Pandemics and Epidemics.

The world’s staple food crops, and other food crops that optimize human nutrition, suffer from global virus disease pandemics and epidemics that greatly diminish their yields and/or produce quality. This situation is becoming increasingly serious because of the human population’s growing food requirements and increasing difficulties in managing virus diseases effectively arising from global warming. This review provides historical and recent information about virus disease pandemics and major epidemics that originated within different world regions, spread to other continents, and now have very wide distributions. Because they threaten food security, all are cause for considerable concern for humanity. The pandemic disease examples described are six (maize lethal necrosis, rice tungro, sweet potato virus, banana bunchy top, citrus tristeza, plum pox). The major epidemic disease examples described are seven (wheat yellow dwarf, wheat streak mosaic, potato tuber necrotic ringspot, faba bean necrotic yellows, pepino mosaic, tomato brown rugose fruit, and cucumber green mottle mosaic). Most examples involve long-distance virus dispersal, albeit inadvertent, by international trade in seed or planting material. With every example, the factors responsible for its development, geographical distribution and global importance are explained. Finally, an overall explanation is given of how to manage global virus disease pandemics and epidemics effectively.

Disease Pandemics and Major Epidemics Arising from New Encounters between Indigenous Viruses and Introduced Crops.

Virus disease pandemics and epidemics that occur in the world’s staple food crops pose a major threat to global food security, especially in developing countries with tropical or subtropical climates. Moreover, this threat is escalating rapidly due to increasing difficulties in controlling virus diseases as climate change accelerates and the need to feed the burgeoning global population escalates. One of the main causes of these pandemics and epidemics is the introduction to a new continent of food crops domesticated elsewhere, and their subsequent invasion by damaging virus diseases they never encountered before. This review focusses on providing historical and up-to-date information about pandemics and major epidemics initiated by spillover of indigenous viruses from infected alternative hosts into introduced crops. This spillover requires new encounters at the managed and natural vegetation interface. The principal virus disease pandemic examples described are two (cassava mosaic, cassava brown streak) that threaten food security in sub-Saharan Africa (SSA), and one (tomato yellow leaf curl) doing so globally. A further example describes a virus disease pandemic threatening a major plantation crop producing a vital food export for West Africa (cacao swollen shoot). Also described are two examples of major virus disease epidemics that threaten SSA’s food security (rice yellow mottle, groundnut rosette). In addition, brief accounts are provided of two major maize virus disease epidemics (maize streak in SSA, maize rough dwarf in Mediterranean and Middle Eastern regions), a major rice disease epidemic (rice hoja blanca in the Americas), and damaging tomato tospovirus and begomovirus disease epidemics of tomato that impair food security in different world regions. For each pandemic or major epidemic, the factors involved in driving its initial emergence, and its subsequent increase in importance and geographical distribution, are explained. Finally, clarification is provided over what needs to be done globally to achieve effective management of severe virus disease pandemics and epidemics initiated by spillover events.

Methanol Fixation, but not Giemsa Staining, Inactivates Ebola and Lassa Viruses in Peripheral Blood Smears Made on Plastic Microscope Slides

Diseases caused by many highly pathogenic viruses, including Ebola virus (EBOV) and Lassa virus (LASV), present with nonspecific signs and symptoms that overlap with common tropical diseases such as malaria. Initial diagnostic tests performed on patients under investigation for viral hemorrhagic fevers routinely include analysis of peripheral blood smears to detect and quantify Plasmodium species. In light of recent and ongoing Ebola virus disease and Lassa fever epidemics, clinical laboratories around the world require protocols for dealing with highly infectious specimens from patients with suspected or confirmed high-consequence diseases. Few validated protocols for safe analysis of peripheral blood smears are available, revealing a need for further research. In this study, we evaluated the performance of two plastic microscope slide types that offer safe alternatives to glass slides, determined the temporal parameters required to inactivate EBOV and LASV in thin blood smears by methanol fixation, and assessed the virucidal activity of Giemsa stain. Both types of plastic microscope slides performed optimally; there were no significant differences in blood cell morphology or tinctorial properties nor were differences noted in Plasmodium ovale morphology or staining, when compared with glass slides. For both EBOV and LASV, viable viruses were not detected in thin blood smears following fixation in absolute methanol for at least 2 minutes. By contrast, viable EBOV and LASV were recovered from all Giemsa-stained thick blood smears.

COVID-19 Outbreak in Africa: Lessons and Insights from the West African Ebola Virus Disease Epidemics

Over the years, the African continent has had to battle several outbreaks of infectious diseases in different countries. Some of the most deadly were the Ebola virus disease (EVD) outbreaks that occurred in West Africa between 2014 and 2016 affecting Guinea, Liberia, and Sierra Leone and, more recently, from 2018 to 2020 in the Democratic Republic of Congo (DRC). In the era of the COVID-19 pandemic, it is important that as a continent, we draw lessons and insights from our past experiences to guide outbreak response strategies being deployed to curb the latest onslaught. The Ebola outbreaks have shown that disease outbreaks should not be seen only as medical emergencies, but as full blown humanitarian crises, because oftentimes, their socio-economic impacts are more devastating than the more obvious cost to life. In this mini-review, we explore the possible humanitarian costs of the COVID-19 pandemic on the African continent by looking through the lens of our past experiences with the EVD outbreaks, highlighting how the current pandemic could significantly affect the African economy, food security, and vulnerable demographics, like children and the sexual and reproductive health and rights of women and girls. We then proffer recommendations that could be instrumental in preventing a double tragedy involving the devastating health consequences of the virus itself and the deadly fallout from its multi-sectoral knock-on effects in African countries. Keywords: COVID-19, SARS-CoV-2, Ebola Virus Disease, Coronavirus.

The 2013-2016 Ebola epidemic: evaluating communication strategies between two affected countries in West Africa.

Ebola is a haemorrhagic disease with high fatality rates between 25 and 90%. The 2013-16 Ebola outbreak in West Africa was the largest to date with >28 000 cases and >11 000 fatalities. This outbreak exposed inadequacies in public health agencies and has spurred health officials to re-evaluate the way Ebola virus disease (EVD) epidemics are co-ordinated and communicated. This project compares, using the systematic review method, differences in the communication of EVD in Nigeria and Liberia with data from selected articles analyzed using thematic analysis. The most successful communication strategies were community engagement and targeted health-communication to the most at-risk groups. We also highlight the importance of a multi-modal strategy to effectively communicate prevention and management of EVD to affected communities. Secondary to these findings included the relevance of the media, particularly social media tools in managing such serious outbreak situations. This study provides the basis for the development of a theory-based framework to effectively communicate EVD and reduce the negative outcomes observed during the 2013-16 EVD outbreak.

Antibody-mediated protection against Ebola virus.

Recent Ebola virus disease epidemics have highlighted the need for effective vaccines and therapeutics to prevent future outbreaks. Antibodies are clearly critical for control of this deadly disease; however, the specific mechanisms of action of protective antibodies have yet to be defined. In this Perspective we discuss the antibody features that correlate with in vivo protection during infection with Ebola virus, based on the results of a systematic and comprehensive study of antibodies directed against this virus. Although neutralization activity mediated by the Fab domains of the antibody is strongly correlated with protection, recruitment of immune effector functions by the Fc domain has also emerged as a complementary, and sometimes alternative, route to protection. For a subset of antibodies, Fc-mediated clearance and killing of infected cells seems to be the main driver of protection after exposure and mirrors observations in vaccination studies. Continued analysis of antibodies that achieve protection partially or wholly through Fc-mediated functions, the precise functions required, the intersection with specificity and the importance of these functions in different animal models is needed to identify and begin to capitalize on Fc-mediated protection in vaccines and therapeutics alike.

Efficacy of Human Monoclonal Antibody Monotherapy Against Bundibugyo Virus Infection in Nonhuman Primates.

The 2013-2016 Ebola virus disease (EVD) epidemics in West Africa highlighted a need for effective therapeutics for treatment of the disease caused by filoviruses. Monoclonal antibodies (mAbs) are promising therapeutic candidates for prophylaxis or treatment of virus infections. Data about efficacy of human mAb monotherapy against filovirus infections in preclinical nonhuman primate models are limited. Previously, we described a large panel of human mAbs derived from the circulating memory B cells from Bundibugyo virus (BDBV) infection survivors that bind to the surface glycoprotein (GP) of the virus. We tested one of these neutralizing mAbs that recognized the glycan cap of the GP, designated mAb BDBV289, as monotherapy in rhesus macaques. We found that recombinant mAb BDBV289-N could confer up to 100% protection to BDBV-infected rhesus macaques when treatment was initiated as late as 8 days after virus challenge. Protection was associated with survival and decreased viremia levels in the blood of treated animals. These findings define the efficacy of monotherapy of lethal BDBV infection with a glycan cap-specific mAb and identify a candidate mAb therapeutic molecule that could be included in antibody cocktails for prevention or treatment of ebolavirus infections.

Plant Virus Epidemiology: Applications and Prospects for Mathematical Modeling and Analysis to Improve Understanding and Disease Control.

In recent years, mathematical modeling has increasingly been used to complement experimental and observational studies of biological phenomena across different levels of organization. In this article, we consider the contribution of mathematical models developed using a wide range of techniques and uses to the study of plant virus disease epidemics. Our emphasis is on the extent to which models have contributed to answering biological questions and indeed raised questions related to the epidemiology and ecology of plant viruses and the diseases caused. In some cases, models have led to direct applications in disease control, but arguably their impact is better judged through their influence in guiding research direction and improving understanding across the characteristic spatiotemporal scales of plant virus epidemics. We restrict this article to plant virus diseases for reasons of length and to maintain focus even though we recognize that modeling has played a major and perhaps greater part in the epidemiology of other plant pathogen taxa, including vector-borne bacteria and phytoplasmas.

Ebola Virus Disease and Pregnancy: A Retrospective Cohort Study of Patients Managed at 5 Ebola Treatment Units in West Africa.

Reliable data are lacking on pregnancy outcomes during Ebola virus disease (EVD) epidemics. We aimed to characterize symptoms and outcomes among pregnant women admitted to Ebola treatment units (ETUs) with suspected and confirmed EVD to better inform obstetric management. We analyzed a retrospective cohort of reproductive-aged women presenting to 5 West African ETUs from September 2014 to September 2015. We compared clinical symptoms, risk of EVD diagnosis, and mortality between pregnant and nonpregnant women. Of 729 reproductive-aged women admitted to study ETUs, 44 (6%) reported pregnancy. Thirteen of 44 pregnant women (30%) tested EVD positive; 6 of 13 (46%) died. Pregnant women were less likely than nonpregnant women to report anorexia, asthenia, diarrhea, fever, myalgias/arthralgias, nausea, or vomiting (P < .05) at admission. Pregnant women with suspected EVD had the same risk, however, of laboratory-confirmed EVD (30% vs 24%, P = .38). While pregnant women with confirmed EVD had similar Ebola viral loads on presentation to nonpregnant women, as measured by initial cycle threshold (26.4 vs 23.2, P = .16), they were less likely to have myalgias/arthralgias (P< .001) and vomiting (P = .02). Both all-cause mortality (14% vs 19%, P = .39) and EVD-specific mortality (46% vs 54%, P = .60) were not significantly different between pregnant and nonpregnant women. Two neonates born live in the ETU died within 8 days. We find no evidence to support a difference in the risk of death between pregnant women with suspected or confirmed EVD compared to nonpregnant women. Limited data suggest poor fetal and neonatal outcomes in EVD-affected pregnancies.

A systematic review of early modelling studies of Ebola virus disease in West Africa.

Phenomenological and mechanistic models are widely used to assist resource planning for pandemics and emerging infections. We conducted a systematic review, to compare methods and outputs of published phenomenological and mechanistic modelling studies pertaining to the 2013-2016 Ebola virus disease (EVD) epidemics in four West African countries - Sierra Leone, Liberia, Guinea and Nigeria. We searched Pubmed, Embase and Scopus databases for relevant English language publications up to December 2015. Of the 874 articles identified, 41 met our inclusion criteria. We evaluated these selected studies based on: the sources of the case data used, and modelling approaches, compartments used, population mixing assumptions, model fitting and calibration approaches, sensitivity analysis used and data bias considerations. We synthesised results of the estimated epidemiological parameters: basic reproductive number (R 0), serial interval, latent period, infectious period and case fatality rate, and examined their relationships. The median of the estimated mean R 0 values were between 1·30 and 1·84 in Sierra Leone, Liberia and Guinea. Much higher R 0 value of 9·01 was described for Nigeria. We investigated several issues with uncertainty around EVD modes of transmission, and unknown observation biases from early reported case data. We found that epidemic models offered R 0 mean estimates which are country-specific, but these estimates are not associating with the use of several key disease parameters within the plausible ranges. We find simple models generally yielded similar estimates of R 0 compared with more complex models. Models that accounted for data uncertainty issues have offered a higher case forecast compared with actual case observation. Simple model which offers transparency to public health policy makers could play a critical role for advising rapid policy decisions under an epidemic emergency.

Response of Undergraduates to Institutional Emergency Strategies on Ebola Virus Disease (EVD) in Kwara State University, Nigeria

ABSTRACT Background: The challenge of Ebola Virus Disease (EVD) outbreak prompted the need for the development and implementation of strategic alertness and emergency response intervention in prevention and containment of future threats and epidemics. Objective: This work was designed to assess knowledge, perception, attitude, behavioural practices, risk vulnerability and effectiveness of some selected surveillance interventions strategic responses and measures among undergraduate students in prevention and containment of Ebola Virus Disease epidemics. Also, to analyse the associations amongst root causes, vulnerability, risk factors, mode of spread, symptoms, prevention, and response patterns. Materials and Methods: The study employed a carefully-structured, closed-ended, interviewer-administered, paper-based questionnaire designed to capture information on socio-demographic characteristics, active knowledge on EVD, perception, behavioural attitude and responses from undergraduate students to selected strategic surveillance and intervention measures towards containment of EVD in Kwara State University, Nigeria. This is expected to enhance qualitative understanding of perceived misconceptions, and bottlenecks in relation to EVD root causes, mode of transmission, prevention and control programs and strategies. Data were entered and analysed using IBM® SPSS® Statistics Version 22. Descriptive statistics were reported as frequencies and percentages, and presented graphically using bar graphs and pie charts. Data were analysed further with Pearson Chi-Square test to determine associations between variables from which inferences were drawn and reported at a significance level of p

Ebola Virus Disease in Children, Sierra Leone, 2014–2015

Little is known about potentially modifiable factors in Ebola virus disease in children. We undertook a retrospective cohort study of children <13 years old admitted to 11 Ebola holding units in the Western Area, Sierra Leone, during 2014-2015 to identify factors affecting outcome. Primary outcome was death or discharge after transfer to Ebola treatment centers. All 309 Ebola virus-positive children 2 days-12 years old were included; outcomes were available for 282 (91%). Case-fatality was 57%, and 55% of deaths occurred in Ebola holding units. Blood test results showed hypoglycemia and hepatic/renal dysfunction. Death occurred swiftly (median 3 days after admission) and was associated with younger age and diarrhea. Despite triangulation of information from multiple sources, data availability was limited, and we identified no modifiable factors substantially affecting death. In future Ebola virus disease epidemics, robust, rapid data collection is vital to determine effectiveness of interventions for children.

Ebola Virus Disease in Children, Sierra Leone, 2014–2015

Abstract Little is known about potentially modifiable factors in Ebola virus disease in children. We undertook a retrospective cohort study of children <13 years old admitted to 11 Ebola holding units in the Western Area, Sierra Leone, during 2014–2015 to identify factors affecting outcome. Primary outcome was death or discharge after transfer to Ebola treatment centers. All 309 Ebola virus–positive children 2 days–12 years old were included; outcomes were available for 282 (91%). Case-fatality was 57%, and 55% of deaths occurred in Ebola holding units. Blood test results showed hypoglycemia and hepatic/renal dysfunction. Death occurred swiftly (median 3 days after admission) and was associated with younger age and diarrhea. Despite triangulation of information from multiple sources, data availability was limited, and we identified no modifiable factors substantially affecting death. In future Ebola virus disease epidemics, robust, rapid data collection is vital to determine effectiveness of interventions for children.

Future Scenarios for Plant Virus Pathogens as Climate Change Progresses.

Knowledge of how climate change is likely to influence future virus disease epidemics in cultivated plants and natural vegetation is of great importance to both global food security and natural ecosystems. However, obtaining such knowledge is hampered by the complex effects of climate alterations on the behavior of diverse types of vectors and the ease by which previously unknown viruses can emerge. A review written in 2011 provided a comprehensive analysis of available data on the effects of climate change on virus disease epidemics worldwide. This review summarizes its findings and those of two earlier climate change reviews and focuses on describing research published on the subject since 2011. It describes the likely effects of the full range of direct and indirect climate change parameters on hosts, viruses and vectors, virus control prospects, and the many information gaps and deficiencies. Recently, there has been encouraging progress in understanding the likely effects of some climate change parameters, especially over the effects of elevated CO2, temperature, and rainfall-related parameters, upon a small number of important plant viruses and several key insect vectors, especially aphids. However, much more research needs to be done to prepare for an era of (i) increasingly severe virus epidemics and (ii) increasing difficulties in controlling them, so as to mitigate their detrimental effects on future global food security and plant biodiversity.

Principles to guide a regional agenda on the right to health.

Principles to guide a regional agenda on the right to health.

Distribution in Australia and Seed Transmission of Tobacco streak virus in Parthenium hysterophorus.

Tobacco streak virus (TSV) was found to commonly occur in Parthenium hysterophorus, as symptomless infections, in central Queensland, Australia across a large area infested with this weed. Several isolates of TSV collected across the geographic range of P. hysterophorus were found to share identical coat protein sequence with each other and with TSV from crop plants in the same area. Seed transmission of TSV in P. hysterophorus was found to occur at rates of 6.8 to 48%. There was almost no change in the rate of TSV seed transmission when P. hysterophorus seed was stored for up to 24½ months. Implications of this relationship between TSV and P. hysterophorus for the development of virus disease epidemics in surrounding crops are discussed.

The role of plant biosecurity in preventing and controlling emerging plant virus disease epidemics

A number of research strategies have been initiated over the last decade to enhance plant biosecurity capacity at the pre-border, border and post-border frontiers. In preparation for emerging plant virus epidemics, diagnostic manuals for economically important plant viruses that threaten local industries have been developed and validated under local conditions. Contingency plans have also been prepared that provide guidelines to stakeholders on diagnostics, surveillance, survey strategies, epidemiology and pest risk analysis. Reference collections containing validated positive virus controls have been expanded to support a wide range of biosecurity sciences. Research has been conducted to introduce high throughput diagnostic capabilities and the design and development of advanced molecular techniques to detect virus genera. These diagnostic tools can be used by post entry quarantine agencies to detect known and unknown plant viral agents. Pre-emptive breeding strategies have also been initiated to protect plant industries if and when key exotic viruses become established in localized areas. With the emergence of free trade agreements between trading partners there is a requirement for quality assurance measures for pathogens, including viruses, which may occur in both the exporting and importing countries. These measures are required to ensure market access for the exporting country and also to minimize the risk of the establishment of a damaging virus epidemic in the importing country.

Early Warning of Ross River Virus Epidemics

Ross River virus disease is spread by mosquitoes, and an average of 5000 people are infected each year in Australia. It is one of the few infectious diseases for which climate-based early warning systems could be developed. The aim of this study was to test whether supplementing routinely collected climate data with mosquito surveillance data could increase the accuracy of disease prediction models. We focused on a temperate region of Western Australia between July 1991 and June 1999. We developed "early" and "later" warning logistic regression models to test the sensitivity of data on climate (tide height, rainfall, sea surface temperature) and mosquito counts for predicting epidemics of disease. Climate data on their own were moderately sensitive (64%) for predicting epidemics during the early warning period. Addition of mosquito surveillance data increased the sensitivity of the early warning model to 90%. The later warning model had a sensitivity of 85%. We found that climate data are inexpensive and easy to collect and allow the prediction of Ross River virus disease epidemics within the time necessary to improve the effectiveness of public health responses. Mosquito surveillance data provide a more expensive early warning but add substantial predictive value.