scholarly journals Lassa Fever in post-Ebola Sierra Leone. Sociodemographics and case fatality rates of in-hospital patients admitted at the Kenema Government Hospital Lassa Fever Ward between 2016-2018

2019 ◽  
Author(s):  
Jia Bainga Kangbai ◽  
Fatima Kinto Kamara ◽  
Rosaline Chukwu Lahai ◽  
Fatmata Gebeh
Keyword(s):  
West Africa ◽  
Sierra Leone ◽  
Case Fatality ◽  
Lassa Fever ◽  
Control Measures ◽  
Government Hospital ◽  
Treatment History ◽  
Human Contact ◽  
Hospital Patients ◽  
Viral Illness

Abstract Background Lassa fever (LF) is a zoonotic acute viral illness mainly found in West Africa. The disease is endemic in some parts of West Africa including Sierra Leone, Liberia, Guinea and Nigeria; while other neighboring countries at high risk of its outbreak since the animal vectors are distributed throughout the region.Methods This is a retrospective mixed cohort study that analysed the treatment history containing the sociodemographic and clinical characteristics of 52 laboratory-confirmed LF cases that were admitted to the Kenema Government Hospital Lassa Fever Ward (KGHLFW) during 2016 to 2018; i.e. during the post Ebola outbreak in Sierra Leone. The LF patients whose treatment history we analysed came from either within or outside Kenema district were the KGHLFW is located.Results Majority (59.6%, n = 31/52) of the LF cases recorded during the period under review were adults; females (65.4%, n = 34/52). 2016 recorded more (40.4%, n = 21/52) LF cases; 2017 (28.8%, n = 15/52) and 2018(30.8%, n = 16/52).Conclusions We highlighted the significance of LF preventive and control measures that can target its seasonal epidemics. These measures could include strategies that can reduce human contact with the rodent vector as well as raise sensitization and awareness about LF among local residents especially those residing along the LF belt in eastern Sierra Leone.

scholarly journals Determining Ancestry between Rodent- and Human-Derived Virus Sequences in Endemic Foci: Towards a More Integral Molecular Epidemiology of Lassa Fever within West Africa

Biology ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 26 ◽  
Author(s):  
Ayodeji Olayemi ◽  
Adetunji Samuel Adesina ◽  
Thomas Strecker ◽  
N’Faly Magassouba ◽  
Elisabeth Fichet-Calvet
Keyword(s):  
West Africa ◽  
Sierra Leone ◽  
Evolutionary History ◽  
Epidemiological Studies ◽  
Lassa Fever ◽  
Clinical Samples ◽  
Ecological Studies ◽  
Emergence Patterns ◽  
Genetic Sequences ◽  
Virus Strains

Lassa fever is a viral hemorrhagic illness responsible for thousands of human deaths in West Africa yearly. Rodents are known as natural reservoirs of the causative Lassa mammarenavirus (LASV) while humans are regarded as incidental, spill-over hosts. Analysis of genetic sequences continues to add to our understanding of the evolutionary history, emergence patterns, and the epidemiology of LASV. Hitherto, the source of data in such investigations has mainly comprised human clinical samples. Presently, a rise in the quantity of virus strains accessed through ecological studies over the last 15 years now allows us to explore how LASV sequences obtained from rodents might affect phylogenetic patterns. In this study, we phylogenetically compared LASV sequences obtained from both rodents and humans across West Africa, including those from two localities highly endemic for the disease: Ekpoma in Nigeria and Kenema in Sierra Leone. We performed a time-calibrated phylogeny, using a Bayesian analysis on 198 taxa, including 102 sequences from rodents and 96 from humans. Contrary to expectation, our results show that LASV strains detected in humans within these localities, even those sampled recently, are consistently ancient to those circulating in rodents in the same area. We discuss the possibilities connected to this preliminary outcome. We also propose modalities to guide more comprehensive comparisons of human and rodent data in LASV molecular epidemiological studies.

scholarly journals Identification of Common CD8+ T Cell Epitopes from Lassa Fever Survivors in Nigeria and Sierra Leone

2020 ◽  
Vol 94 (12) ◽  
Author(s):  
Saori Sakabe ◽  
Jessica N. Hartnett ◽  
Nhi Ngo ◽  
Augustine Goba ◽  
Mambu Momoh ◽  
...  
Keyword(s):  
T Cell ◽  
West Africa ◽  
Sierra Leone ◽  
T Cell Responses ◽  
Lassa Fever ◽  
Health Concern ◽  
Lassa Virus ◽  
T Cell Epitopes ◽  
Virus Surface ◽  
Cell Responses

ABSTRACT Early and robust T cell responses have been associated with survival from Lassa fever (LF), but the Lassa virus-specific memory responses have not been well characterized. Regions within the virus surface glycoprotein (GPC) and nucleoprotein (NP) are the main targets of the Lassa virus-specific T cell responses, but, to date, only a few T cell epitopes within these proteins have been identified. We identified GPC and NP regions containing T cell epitopes and HLA haplotypes from LF survivors and used predictive HLA-binding algorithms to identify putative epitopes, which were then experimentally tested using autologous survivor samples. We identified 12 CD8-positive (CD8+) T cell epitopes, including epitopes common to both Nigerian and Sierra Leonean survivors. These data should be useful for the identification of dominant Lassa virus-specific T cell responses in Lassa fever survivors and vaccinated individuals as well as for designing vaccines that elicit cell-mediated immunity. IMPORTANCE The high morbidity and mortality associated with clinical cases of Lassa fever, together with the lack of licensed vaccines and limited and partially effective interventions, make Lassa virus (LASV) an important health concern in its regions of endemicity in West Africa. Previous infection with LASV protects from disease after subsequent exposure, providing a framework for designing vaccines to elicit similar protective immunity. Multiple major lineages of LASV circulate in West Africa, and therefore, ideal vaccine candidates should elicit immunity to all lineages. We therefore sought to identify common T cell epitopes between Lassa fever survivors from Sierra Leone and Nigeria, where distinct lineages circulate. We identified three such epitopes derived from highly conserved regions within LASV proteins. In this process, we also identified nine other T cell epitopes. These data should help in the design of an effective pan-LASV vaccine.

scholarly journals Phylogeography of Lassa Virus in Nigeria

2019 ◽  
Vol 93 (21) ◽  
Author(s):  
Deborah U. Ehichioya ◽  
Simon Dellicour ◽  
Meike Pahlmann ◽  
Toni Rieger ◽  
Lisa Oestereich ◽  
...  
Keyword(s):  
West Africa ◽  
Case Fatality ◽  
Hemorrhagic Fever ◽  
Lassa Fever ◽  
Future Research ◽  
Lassa Virus ◽  
Southeastern Part ◽  
Data Set ◽  
Content Type ◽  
Virus Strains

ABSTRACT Lassa virus is genetically diverse with several lineages circulating in West Africa. This study aimed at describing the sequence variability of Lassa virus across Nigeria and inferring its spatiotemporal evolution. We sequenced and isolated 77 Lassa virus strains from 16 Nigerian states. The final data set, including previous works, comprised metadata and sequences of 219 unique strains sampled between 1969 and 2018 in 22 states. Most of this data originated from Lassa fever patients diagnosed at Irrua Specialist Teaching Hospital, Edo State, Nigeria. The majority of sequences clustered with the main Nigerian lineages II and III, while a few sequences formed a new cluster related to Lassa virus strains from Hylomyscus pamfi. Within lineages II and III, seven and five sublineages, respectively, were distinguishable. Phylogeographic analysis suggests an origin of lineage II in the southeastern part of the country around Ebonyi State and a main vector of dispersal toward the west across the Niger River, through Anambra, Kogi, Delta, and Edo into Ondo State. The frontline of virus dispersal appears to be in Ondo. Minor vectors are directed northeast toward Taraba and Adamawa and south toward Imo and Rivers. Lineage III might have spread from northern Plateau State into Kaduna, Nasarawa, Federal Capital Territory, and Bauchi. One sublineage moved south and crossed the Benue River into Benue State. This study provides a geographic mapping of lineages and phylogenetic clusters in Nigeria at a higher resolution. In addition, we estimated the direction and time frame of virus dispersal in the country. IMPORTANCE Lassa virus is the causative agent of Lassa fever, a viral hemorrhagic fever with a case fatality rate of approximately 30% in Africa. Previous studies disclosed a geographical pattern in the distribution of Lassa virus strains and a westward movement of the virus across West Africa during evolution. Our study provides a deeper understanding of the geography of genetic lineages and sublineages of the virus in Nigeria. In addition, we modeled how the virus spread in the country. This knowledge allows us to predict into which geographical areas the virus might spread in the future and prioritize areas for Lassa fever surveillance. Our study not only aimed to generate Lassa virus sequences from across Nigeria but also to isolate and conserve the respective viruses for future research. Both isolates and sequences are important for the development and evaluation of medical countermeasures to treat and prevent Lassa fever, such as diagnostics, therapeutics, and vaccines.

Fifty years of imported Lassa fever: a systematic review of primary and secondary cases

2020 ◽  
Vol 27 (4) ◽  
Author(s):  
Timo Wolf ◽  
Regina Ellwanger ◽  
Udo Goetsch ◽  
Nils Wetzstein ◽  
Rene Gottschalk
Keyword(s):  
Systematic Review ◽  
Early Diagnosis ◽  
West Africa ◽  
Clinical Features ◽  
Case Fatality Rate ◽  
Case Fatality ◽  
Lassa Fever ◽  
Fatality Rate ◽  
Imported Cases ◽  
Epidemiological Characteristics

Abstract Rationale for Systematic Review Lassa fever is the most common cause of imported haemorrhagic fevers cases in non-endemic countries. As a disease with a high case fatality rate that has regularly caused clusters of nosocomial transmission in endemic areas, prompt diagnosis is vital. We conducted a systematic review of imported cases of the last 50 years with the aim of defining the clinical and epidemiological characteristics that will enhance early diagnosis, prompt initiation of treatment and an appropriate public health response to Lassa fever cases. Methods We performed a retrospective, systematic review of 36 primary and two secondary cases of Lassa fever in non-endemic countries outside West Africa by searching the PubMed database. This yielded 56 relevant publications that were included in our analysis. Results The case fatality rate of 35.1% for imported cases was higher than that reported for endemic countries. The majority of patients showed clinical features consistent with Lassa fever and had a typical exposure. There was a considerable delay in diagnosis in imported cases with high associated numbers of contacts. Ribavirin was rarely used for post-exposure prophylaxis. Only two secondary transmissions occurred. Thirty-one percent of patients received Lassa fever-specific treatment and five required intensive care. Conclusions Although importation of Lassa fever to non-endemic countries is a rare event, it has repeatedly happened over five decades. Suspicion of Lassa fever should be based on careful consideration of clinical features and exposure history in order to assist early diagnosis in returning travellers from West Africa.

scholarly journals Lassa fever in a UK soldier recently returned from Sierra Leone - e-alert 10 February

2003 ◽  
Vol 7 (6) ◽  
Author(s):  
Keyword(s):  
Infectious Diseases ◽  
West Africa ◽  
Sierra Leone ◽  
Stable Condition ◽  
Lassa Fever ◽  
Press Release ◽  
High Security

A case of Lassa fever has been confirmed in a British soldier returned from Sierra Leone, West Africa, it is reported in a press release issued today by the Royal Free Hampstead Hospital in London (1). The man, who became ill on 30 January, is being cared for at a high security infectious diseases unit in London and is in a stable condition.

scholarly journals Space-Time Trends in Lassa Fever in Sierra Leone by ELISA Serostatus, 2012–2019

2021 ◽  
Vol 9 (3) ◽  
pp. 586
Author(s):  
Jeffrey Shaffer ◽  
John Schieffelin ◽  
Mambu Momoh ◽  
Augustine Goba ◽  
Lansana Kanneh ◽  
...  
Keyword(s):  
Sierra Leone ◽  
Time Trends ◽  
Severe Disease ◽  
Case Fatality ◽  
Lassa Fever ◽  
Space Time ◽  
Dry Season ◽  
Sub Saharan Africa ◽  
Hemorrhagic Disease ◽  
Illness Onset

Lassa fever (LF) is a viral hemorrhagic disease found in Sub-Saharan Africa and is responsible for up to 300,000 cases and 5000 deaths annually. LF is highly endemic in Sierra Leone, particularly in its Eastern Province. Kenema Government Hospital (KGH) maintains one of only a few LF isolation facilities in the world with year-round diagnostic testing. Here we focus on space-time trends for LF occurring in Sierra Leone between 2012 and 2019 to provide a current account of LF in the wake of the 2014–2016 Ebola epidemic. Data were analyzed for 3277 suspected LF cases and classified as acute, recent, and non-LF or prior LF exposure using enzyme-linked immunosorbent assays (ELISAs). Presentation rates for acute, recent, and non-LF or prior LF exposure were 6.0% (195/3277), 25.6% (838/3277), and 68.4% (2244/3277), respectively. Among 2051 non-LF or prior LF exposures, 33.2% (682/2051) tested positive for convalescent LF exposure. The overall LF case-fatality rate (CFR) was 78.5% (106/135). Both clinical presentations and confirmed LF cases declined following the Ebola epidemic. These declines coincided with an increased duration between illness onset and clinical presentation, perhaps suggesting more severe disease or presentation at later stages of illness. Acute LF cases and their corresponding CFRs peaked during the dry season (November to April). Subjects with recent (but not acute) LF exposure were more likely to present during the rainy season (May to October) than the dry season (p < 0.001). The findings here suggest that LF remains endemic in Sierra Leone and that caseloads are likely to resume at levels observed prior to the Ebola epidemic. The results provide insight on the current epidemiological profile of LF in Sierra Leone to facilitate LF vaccine studies and accentuate the need for LF cohort studies and continued advancements in LF diagnostics.

SPATIOTEMPORAL TRANSMISSION DYNAMICS OF RECENT EBOLA OUTBREAK IN SIERRA LEONE, WEST AFRICA: IMPACT OF CONTROL MEASURES

2017 ◽  
Vol 25 (03) ◽  
pp. 369-397 ◽  
Author(s):  
PARIMITA ROY ◽  
RANJIT KUMAR UPADHYAY
Keyword(s):  
West Africa ◽  
Sierra Leone ◽  
Epidemic Model ◽  
Control Measure ◽  
Reaction Diffusion ◽  
Model System ◽  
Control Measures ◽  
Transmission Dynamics ◽  
Spatial Spread ◽  
The Impact

In this paper, we have formulated a compartmental epidemic model with exponentially decaying transmission rates to understand the Ebola transmission dynamics and study the impact of control measures to basic public health. The epidemic model exhibits two equilibria, namely, the disease-free and unique endemic equilibria. We have calculated the basic reproduction number through next generation matrix and investigated the spatial spread of the epidemic via reaction–diffusion modeling. Instead of fitting the model to the observed pattern of spread, we have used previously estimated parameter values and examined the efficacy of predictions of the designed model vis-à-vis the pattern of spread observed in Sierra Leone, West Africa. Further, we conducted a sensitivity analysis to determine the extent to which improvement in predictions is achievable through better parameterization.We performed numerical simulations with and without control measure for the designed model system. A significant reduction in infection and death cases were observed when proper control measures are incorporated in the model system. Two-dimensional simulation experiments show that infectious population and the number of deaths will increase up to one and a half years without control, but it will decline after two years. We have reported the numerical results, and it closely matches with the real situation in Sierra Leone.

Lassa fever in children in Sierra Leone, West Africa

1986 ◽  
Vol 80 (4) ◽  
pp. 577-582 ◽  
Author(s):  
P.A. Webb ◽  
J.B. McCormick ◽  
I.J. King ◽  
I. Bosman ◽  
K.M. Johnson ◽  
...  
Keyword(s):  
West Africa ◽  
Sierra Leone ◽  
Lassa Fever

scholarly journals Characteristics of Lassa Fever Outbreak in Ondo State, Nigeria, Year 2019

2021 ◽  
Vol 3 (1) ◽  
pp. 115-125
Author(s):  
Adaora Rosemary Ejikeme ◽  
Lois Olajide ◽  
Sola Sunday Thomas ◽  
Chimezie Anueyiagu ◽  
Gbetsere Aghogho ◽  
...  
Keyword(s):  
Case Fatality ◽  
Rapid Response Team ◽  
Lassa Fever ◽  
Control Measures ◽  
Contact Tracing ◽  
Suspected Case ◽  
Female Ratio ◽  
Emergency Operations Center ◽  
Response Team ◽  
Ondo State

Background: Lassa fever (LF) is an acute viral haemorrhagic illness of a 2–21-day incubation period that occurs in West Africa. It is endemic in Nigeria and peaks during the first 12 weeks of the year. On January 22, 2019, the Nigeria Centre for Disease Control (NCDC) declared an outbreak of LF following an upsurge of LF cases in the country. A total of 213 confirmed cases including 41 deaths were reported from sixteen states including Ondo State. A multi-sectoral national rapid-response-team (RRT) was deployed to Ondo State to characterise the outbreak, assess its determinants, and institute control measures. Methods: An Emergency Operations Center (EOC) was activated to coordinate activities. We defined a suspected case as anyone with one or more of the following symptoms: malaise, fever, headache, sore throat, cough, vomiting and either history of contact with rodents, or a probable or confirmed LF case in the past 21 days, or any person with inexplicable bleeding between January 1, 2019, to February 26, 2019, in Ondo State. A confirmed case was any suspected case with laboratory confirmation. We conducted active case search, collected data using the LF case investigation form and reviewed the existing line list. We conducted contact tracing in hospitals and affected Local Government Areas (LGA). Data was analysed using and Epi info 7.0. Results: We identified 287 LF suspected cases in 6 LGAs; 118 were confirmed with 21 deaths (case fatality rate: 17.8%). The mean age was 39.2 ±20 years with a male-to-female ratio of 1.3:1. Of the 1,269 contacts line-listed, 20 became symptomatic, while 14 (70.0%) were confirmed positive. The secondary attack rate was 1.1%. Conclusion: The confirmed cases were more of primary cases, hence the need to focus more on reducing rodent-to-human transmission of LF. We recommend continuous education on community and health facility infection prevention control, contact tracing and enforcement of environmental sanitation measures across the state to mitigate future outbreaks

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