Epidemiology and control of the 2014 ebola virus disease outbreak in western africa: A narrative review of literature

The disease rendered wide spread devastation in the Sub Region causing the death of several thousands of infected cases before it was subsequently brought under control, draining significant resources. This study reviewed existing literature using the PRISMA statement for reporting systematic review as a guide. It sorts to describe the epidemiological and socio-economic factors that affected the Ebola Virus Disease (EVD) outbreak and to highlight the control measures implemented during the period.

JOURNAL OF MEDICAL RESEARCH EPIDEMIOLOGY AND CONTROL OF THE 2014 EBOLA VIRUS DISEASE OUTBREAK IN WESTERN AFRICA: A NARRATIVE REVIEW OF LITERATURE Ninsawu Nicholas Nakpan, 2Stanley Gordon Fenwick Le Minh Giang, 4Pham Quang Thai, 5Prosper Mandela Amaltinga Institute of Preventive Medicine and Public Health, Hanoi Medical University, Vietnam Fenwick Tufts University, United States; 3Department of Global Health-Hanoi Medical University, Vietnam; National Institute of Hygiene and Epidemiology, Vietnam; Clinical Nursing Department, Nyaho Clinic-Ghana The 2014 West Africa Ebola outbreak was the largest outbreak of the disease on the continent and the globe at large, beginning December 2013 in Guinea The disease rendered wide spread devastation in the Sub Region causing the death of several thousands of infected cases before it was subsequently brought under control, draining significant resources This study reviewed existing literature using the PRISMA statement for reporting systematic review as a guide It sorts to describe the epidemiological and socio-economic factors that affected the Ebola Virus Disease (EVD) outbreak and to highlight the control measures implemented during the period Human interaction with the vegetation created exposure to the EVD and males had an overall incidence slightly higher than females whilst being a child was a significant risk of dying from the infection A weak health system and inadequate infrastructure in affected countries contributed largely to early spread International organizations’ collaborating with local partners formed an immense component to controlling the outbreak Effective collaboration is required at international and national levels of the world to remain prepared for future outbreaks It calls for a ‘One Health’ approach to tackling future events Keywords: Epidemiology, socio-economic factors, control, containment, implementation, West Africa I INTRODUCTION outbreak started in December 2013 in Guinea, The world has been confronted in recent followed by its spread in subsequent months years with a host of infectious diseases that to neighboring Liberia and Sierra Leone The are either emerging or reemerging They have infection was later reported in Senegal, Mali, included the zika virus infection, Mers-Cov, Nigeria and outside the African Region to SARS, Avian influenza and lastly, Ebola Virus Europe (Spain, Italy and England) and the Disease (EVD) which gave the world a scare USA [2; 3] during its outbreak in West Africa The former Ebola virus disease (EVD) is a rare and Director General of the World Health Organi- fatal disease [4] of zoonotic origin believed to zation (WHO) described the 2014 Ebola virus have originated in a reservoir of fruit bats of disease as the family Pteropodidae So far there is no “unquestionably the most severe acute public specific treatment for this deadly infection health emergency in modern times” [1] The First observed in humans in 1976, EVD has outbreak in West Africa caused around 25 outbreaks to date [5; 6]; Corresponding author: Ninsawu IPMPH, Hanoi Medical University Email: nakpan4@yahoo.com Received: 12/7/2018 Accepted: 18/11/2018 JMR 116 E3 (7) - 2018 Nicholas Nakpan, however, a yet to be licensed vaccine (rVSVZEBOV) is being administered to prevent transmission as is in the case of the ongoing outbreak in Democratic Republic of Congo 101 JOURNAL OF MEDICAL RESEARCH (DRC) declared on May 8, 2018 [7] Epidemics as was in the case of Senegal and DRC in have also occurred in Sudan, Gabon and 2017 [14] Uganda A non-human type of the virus known This article aims to describe the as Ebola Reston Virus has also been found epidemiological present in the Philippines, affecting other changes that affected the 2014 Ebola virus primates rather than humans [8] The Ebola outbreak and highlight the control measures virus is transmitted to humans through contact implemented during the West Africa Ebola with infected living or dead animals, and its outbreak from a review of existing literature and socio-economical propagation in the human population occurs through human-to-human transmission of the II METHODS virus The most recent outbreak to have This study conducted a narrative review caused significant devastation occurred in using the PRISMA statement for reporting sys- West Africa with deaths totaling 11,300 as of early September 2015 [6; 9; 10] EVD is associated with a case fatality rate of 30% to 90%, depending on the virus species [8] The index case of the West Africa EVD outbreak was identified to have originated in an under year old boy in Meliandou, Guinea [4; 5] Prompt international response provided by the World Health Organization, Médecins Sans Frontières (MSF) and the Center for Disease Control during the early part of 2014 seemed to have helped in controlling the outbreak It, however, circulated rapidly across borders due to ineffective tracking [11] The recent outbreak in DRC starting in Bikoro has recorded a total of 55 cases as of June 28, 2018 It includes 38 confirmed cases, 15 probable cases and suspected cases, while 29 have died [12] tematic reviews as a guide [15] To develop this study, 52 published articles were reviewed, published from 2013 to 2017 Articles selected for retrieval were assessed for methodological validity prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute (JBI) Assessment and Review Instrument for an observational, qualitative and quantitative study The review focused on full-text articles published in English and French with an option to translate into English It also examined the reports of conferences and meetings of organizations and stakeholders The articles extracted were biased to those that have been published during the past years to enable it to capture the most recent development in the field When the titles of the retrieved articles During the West Africa Ebola outbreak, were insufficient to determine eligibility, the about $2.2 billion was lost in GDP in the three abstracts were read to determine if they could worst affected countries, according to the be included A thorough search was extended World Bank The disease resulted in lower to the websites of major international agencies investment and a substantial loss in private such as the World Health Organization, the sector growth, with declining agricultural pro- US Centers for Disease Control (CDC), the duction among other negative consequences Pan African Medical Journal (PAMJ) and bibli- [13] An effective preparedness plan has been ographies of indexed papers Search terms the hallmark of rapid containment and controls comprised 102 epidemiology, EVD, socio- JMR 116 E3 (7) - 2018 JOURNAL OF MEDICAL RESEARCH economic factors, and containment and con- Out of a total of 872 articles identified, 490 trol efforts A specific search for appropriate articles were duplicated and 382 non-duplicate articles began with a few of the keywords articles were screened further for inclusion above to include a large collection of articles 216 articles were further excluded after title It then narrowed the search using the following and abstract screening was done These did key syno- not meet the inclusion criteria because they nyms: Epidemiological factors AND socio- covered information of the Ebola virus out- economic factors AND control measures OR break that occurred in other places outside of containment AND Implemented AND Ebola West Africa Sixty articles were excluded after Virus Outbreak OR Ebola hemorrhagic fever full text screening because the information did AND West Africa Information obtained from not relate specifically to the epidemiology and the search databases and other sources were control of the EVD outbreak in 2014 Thirty- saved using the Zotero software two (32) were excluded because they focused search terms and their 775 articles were identified from the data- only on describing the clinical features of the base search which related to the topic in addi- disease; 14 articles focused only on Socio- tion to 97 articles from bibliographies, agency economic aspect of the Ebola outbreaks that websites and grey literature (Figure 1) The occurred in other parts of Africa rather West inclusion criteria included articles with informa- Africa; articles were non-specific in describ- tion on Ebola epidemiology or its control in ing control programs implemented during the West Africa The exclusion criteria included all outbreak in 2014 in West Africa Fifty-two (52) articles with information other than the Ebola studies were finally included in this review due outbreak in West Africa, its epidemiology and to it having relevant information on the epide- control measures implemented during 2014 miology and control of EVD outbreak in 2014 The prisma flow chart Figure PRISMA Flow diagram for systematic review [15] JMR 116 E3 (7) - 2018 103 JOURNAL OF MEDICAL RESEARCH III RESULTS ing and consuming fruit bats is suspected as the likely way humans were exposed to the Epidemiological factors affecting the 2014 West African EVD outbreak infection in Guinea [16] In a study in 2014, [10], the authors agreed that biological and investigations ecological factors may drive emergence of the have been conducted in affected countries to virus from the forest, but suggested that socio- provide a better understanding of the disease political landscape dictated where the virus and to institute mechanisms to contain or con- went next Several epidemiological trol the disease The basis of such investigations has often been demonstrated to be nec- 1.2 The distribution of Ebola virus disease essary in making available information for In Conakry, Guinea and surrounding pre- clinical and preventive decisions fectures, a descriptive study analyzed data 1.1 The vegetation involving 1355 cases reported During the There are a number of studies that have study period, the overall number of EVD cases argued the role of ecological forces in sparking per 100,000 persons was 33.2 in Conakry, outbreaks of Ebola [9 - 10] The environment 89.3 in Coyah, 37.5 in Dubreka, 136.9 in Fore- provides a special space for interaction be- cariah, and 24.6 in Kindia [17] (See Table 2) tween animals Cumulative incidence was slightly higher Gue´cke´dou in Guinea’s remote southeast- among males (46.8 cases/100.000 persons) ern forest region is thought to be the epicenter than females (45.3 cases/100.000 persons) of the Ebola virus infection that spans into Furthermore, incidence varied by sex in pre- various regions of Guinea as well as to fectures; incidence was higher among female neighboring Liberia and Sierra Leone [10] residents in Coyah, Forecariah and Kindia Ebola virus required two transmission proc- (Table 2) human population and esses for outbreaks to emerge It required an A descriptive retrospective study in Sierra initial spillover event referring to a zoonotic Leone, amongst other findings confirmed a transmission from either the primary Sylvan high infectivity among males than was ob- reservoir or from a secondary host for whom served in the opposite sex group [13] the virus is pathogenic It is then accompanied A descriptive study using 4.955 probable by a second process which is a person-to- and confirmed cases in the same country how- person spread from the index case occurring ever, showed a slightly contrasting finding [14; from the spillover infection [8] Human popula- 18] It showed that the ratio of male to female tion density and their interaction with sylvan EVD cases, irrespective of the district of origin, habitat creating pressure in the landscape was 1:1 This means there was an equal inci- may have opened a channel for EVD spillover dence between males and females It however into human communities The human popula- maintained that EVD affected all age groups tion’s interaction with the vegetation paved the with the most affected age groups being be- way for a zoonotic otic transmission [8] Hunt- tween 26-45 years old (Table 3) 104 JMR 116 E3 (7) - 2018 JOURNAL OF MEDICAL RESEARCH Table Ebola virus disease cases by prefecture and sex in Conakry and surrounding prefectures in Guinea, January 1, 2014 – March 29, 2015 [17] Table Aggregated age-specific case fatality in Western Area Region, Sierra Leone, June 2014 – November 2015 [14] Age group (years) Totals cases (N) %missing records N % Dead (N) Age-specific fatality (%)