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.

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 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.

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 An exploration of the protective effect of rodent species richness on the geographical expansion of Lassa fever in West Africa

2021 ◽  
Vol 15 (2) ◽  
pp. e0009108
Author(s):  
Kyung-Duk Min ◽  
Jusun Hwang ◽  
Maria Cristina Schneider ◽  
Yeonghwa So ◽  
Ju-Yeun Lee ◽  
...  
Keyword(s):  
Species Richness ◽  
West Africa ◽  
Credible Interval ◽  
Epidemiological Studies ◽  
Lassa Fever ◽  
Rodent Species ◽  
Ecological Data ◽  
Geographical Expansion ◽  
The One ◽  
High Level

Background Lassa fever (LF) is one of the most devastating rodent-borne diseases in West Africa, causing thousands of deaths annually. The geographical expansion of LF is also a concern; cases were recently identified in Ghana and Benin. Previous ecological studies have suggested that high natural-host biodiversity reduces the likelihood of spillover transmission of rodent-borne diseases, by suppressing the activities of reservoir species. However, the association of biodiversity with the geographical expansion of LF has not been the subject of epidemiological studies. Methodology/Principal findings We conducted a spatial analysis based on sociodemographic, geographical, and ecological data, and found that higher rodent species richness was significantly associated with a lower risk of LF emergence in West Africa from 2008 to 2017 (Odds Ratio = 0.852, 95% Credible Interval = 0.745–0.971). Conclusions/Significance The results reinforce the importance of the ‘One Health’ approach by demonstrating that a high level of biodiversity could benefit human health.

The Influence of Wharfs on School Children: A Case Study of Portee Wharf in Freetown, Sierra Leone

2019 ◽  
Vol 2 (3) ◽  
pp. 128-140
Author(s):  
Alhaji Bakar Kamara
Keyword(s):  
West Africa ◽  
Sierra Leone ◽  
School Children ◽  
Research Area ◽  
Background Information ◽  
Control Problems

The focus of this research is to investigate the influence of wharfs on school children. Therefore it will report the findings of the result on the influences of wharfs on school children with specific case on Portee Wharf in Freetown, Sierra Leone in West Africa. In this regard, the introduction describes the research area, stating the statement of the problem, the overall goal and specific objectives that will be attained in this study, justification for selecting the topic, problems to be encountered during the course of carrying out this research and major influences. Besides, an indication of the methods used to investigate the topic will also be highlighted. Moreover, the studies will analyze the actual responses of the respondents of the activities of the wharf on school-going children. It will address the questionnaire in accordance with the following: Background information of respondents, this investigated areas such as sex, age, religion, occupation and tribe; It enquires about the activities of the wharfs, reasons and consequences of children engaged in wharfs and strategies to control problems that may emanate from the wharf. The paper will show the findings, gives the summary, conclusion and recommendations of problems identified while carrying out the research.

scholarly journals Lassa Virus Circulation in Small Mammal Populations in Bo District, Sierra Leone

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Umaru Bangura ◽  
Jacob Buanie ◽  
Joyce Lamin ◽  
Christopher Davis ◽  
Gédéon Ngiala Bongo ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Sierra Leone ◽  
Small Mammal ◽  
Hemorrhagic Fever ◽  
Lassa Fever ◽  
Lassa Virus ◽  
Sierra Leonean ◽  
Bayesian Phylogenetic Analysis ◽  
Prevalent Species ◽  
Lineage Iv

Lassa fever is a viral hemorrhagic fever caused by the Lassa virus LASV, which was first isolated in the rodent Mastomys natalensis in 1974 in Kenema, Sierra Leone. As little is known about the abundance and the presence of LASV in rodents living in the Bo area, we carried out a small mammal longitudinal population survey. A standardized trapping session was performed in various habitats and seasons in six villages over two years (2014–2016) and samples collected were tested for arenavirus IgG and LASV. A Bayesian phylogenetic analysis was performed on sequences identified by PCR. A total of 1490 small mammals were collected, and 16 rodent species were identified, with M. natalensis (355, 24%) found to be the most prevalent species. Forty-one (2.8%) samples were IgG positive, and 31 of these were trapped in homes and 10 in surrounding vegetation. Twenty-nine of 41 seropositive rodents were M. natalensis. We detected four LASV by PCR in two villages, all found in M. natalensis. Phylogenetic analysis showed that the sequences were distributed within the Sierra Leonean clade within lineage IV, distinguishing a Bo sub-clade older than a Kenema sub-clade. Compared to other settings, we found a low abundance of M. natalensis and a low circulation of LASV in rodents in villages around Bo district.

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