Cases Of Lassa Fever Research Articles

A medical records and data capture and management system for Lassa fever in Sierra Leone: Approach, implementation, and challenges.

Situated in southeastern Sierra Leone, Kenema Government Hospital (KGH) maintains one of the world’s only Lassa fever isolation wards and was a strategic Ebola virus disease (EVD) treatment facility during the 2014 EVD outbreak. Since 2006, the Viral Hemorrhagic Fever Consortium (VHFC) has carried out research activities at KGH, capturing clinical and laboratory data for suspected cases of Lassa fever. Here we describe the approach, progress, and challenges in designing and maintaining a data capture and management system (DCMS) at KGH to assist infectious disease researchers in building and sustaining DCMS in low-resource environments. Results on screening patterns and case-fatality rates are provided to illustrate the context and scope of the DCMS covered in this study. A medical records system and DCMS was designed and implemented between 2010 and 2016 linking historical and prospective Lassa fever data sources across KGH Lassa fever units and its peripheral health units. Data were captured using a case report form (CRF) system, enzyme-linked immunosorbent assay (ELISA) plate readers, polymerase chain reaction (PCR) machines, blood chemistry analyzers, and data auditing procedures. Between 2008 and 2016, blood samples for 4,229 suspected Lassa fever cases were screened at KGH, ranging from 219 samples in 2008 to a peak of 760 samples in 2011. Lassa fever case-fatality rates before and following the Ebola outbreak were 65.5% (148/226) and 89.5% (17/19), respectively, suggesting that fewer, but more seriously ill subjects with Lassa fever presented to KGH following the 2014 EVD outbreak (p = .040). DCMS challenges included weak specificity of the Lassa fever suspected case definition, limited capture of patient survival outcome data, internet costs, lapses in internet connectivity, low bandwidth, equipment and software maintenance, lack of computer teaching laboratories, and workload fluctuations due to variable screening activity. DCMS are the backbone of international research efforts and additional literature is needed on the topic for establishing benchmarks and driving goal-based approaches for its advancement in developing countries.

A cluster of nosocomial Lassa fever cases in a tertiary health facility in Nigeria: Description and lessons learned, 2018

BackgroundLassa fever is an acute viral haemorrhagic disease endemic in Nigeria. The 2018 Lassa fever outbreak in Nigeria was unprecedented, with 8% of all cases occurring among healthcare workers (HCWs). A disproportionately high number of these infections occurred in HCWs working in a tertiary health facility in Nigeria. This paper describes the cluster of Lassa fever infections among HCWs in a treatment centre and the lessons learnt. MethodsWe analysed clinical, epidemiological and laboratory data from surveillance and laboratory records kept during the 2018 outbreak. Interviews were conducted with surviving HCWs using a questionnaire developed specifically for the investigation of Lassa fever infections in HCWs. Descriptive analysis of the data was performed in Microsoft excel. ResultsThe index case was a 15-year-old male who presented at the health facility with fever and uncontrolled nasopharyngeal bleeding, following a recent uvulectomy by a traditional healer. Overall, 16 HCWs were affected (15 confirmed and 1 probable) with five deaths (CFR-31.6%). Of the 15 confirmed cases, five (33.3%) were asymptomatic. Nine HCWs were direct contacts of the index case; the remaining six HCWs had no direct contact with the index case. HCW interviews identified a low index of suspicion for Lassa fever leading to inadequate infection prevention and control (IPC) practices as possible contributing factors to nosocomial transmission. ConclusionMaintaining a high index of suspicion for Lassa fever in all patients, especially in endemic areas, is essential in adhering to adequate IPC practices in health facilities in order to prevent nosocomial transmission of Lassa fever among HCWs. There is a need to continually train and sensitise HCWs on strict adherence to IPC measures while providing care, irrespective of a patient’s provisional diagnosis.

Potential for Seasonal Lassa Fever Case Exportation from Nigeria

The largest epidemic of Lassa fever in recent history occurred in Nigeria in 2018. We assessed the potential for cases of Lassa fever originating in Nigeria to arrive at international destinations via air travel using a probabilistic model. We estimated no exported cases in 62% of 1,000 model simulations. In 30% of simulations, a single exported case was projected. Greater than 40% of outbound travelers from Nigeria arrived in the United States, the United Kingdom, and Ghana, placing these countries at greatest risk for receiving an exported case. There was a wide range in the capacity of highly connected countries to respond to infectious disease threats, as measured by the Infectious Disease Vulnerability Index. Although we quantified a low probability of case exportation during this outbreak, countries with the greatest connectivity to Nigeria should be alert to the potential risks of Lassa fever importation and be prepared to manage infected individuals.

Lassa Fever in Travelers from West Africa, 1969-2016.

Lassa virus is a rodentborne arenavirus responsible for human cases of Lassa fever, a viral hemorrhagic fever, in West Africa and in travelers arriving to non–Lassa-endemic countries from West Africa. We describe a retrospective review performed through literature search of clinical and epidemiologic characteristics of all imported Lassa fever cases worldwide during 1969–2016. Our findings demonstrate that approximately half of imported cases had distinctive clinical features (defined as fever and >1 of the following: pharyngitis, sore throat, tonsillitis, conjunctivitis, oropharyngeal ulcers, or proteinuria). Delays in clinical suspicion of this diagnosis were common. In addition, no secondary transmission of Lassa fever to contacts of patients with low-risk exposures occurred, and infection of high-risk contacts was rare. Future public health investigations of such cases should focus on timely recognition of distinctive clinical features, earlier treatment of patients, and targeted public health responses focused on high-risk contacts.

Genetic characterization of Lassa virus strains isolated from 2012 to 2016 in southeastern Nigeria.

Lassa virus (LASV) is endemic in parts of West Africa where it causes Lassa fever (LF), a viral hemorrhagic fever with frequent fatal outcomes. The diverse LASV strains are grouped into six major lineages based on the geographical location of the isolated strains. In this study, we have focused on the lineage II strains from southern Nigeria. We determined the viral sequences from positive cases of LF reported at tertiary hospitals in Ebonyi and Enugu between 2012 and 2016. Reverse transcription-polymerase chain reaction (RT-PCR) showed that 29 out of 123 suspected cases were positive for the virus among which 11 viral gene sequences were determined. Phylogenetic analysis of the complete coding sequences of the four viral proteins revealed that lineage II strains are broadly divided into two genetic clades that diverged from a common ancestor 195 years ago. One clade, consisting of strains from Ebonyi and Enugu, was more conserved than the other from Irrua, although the four viral proteins were evolving at similar rates in both clades. These results suggested that the viruses of these clades have been distinctively evolving in geographically separate parts of southern Nigeria. Furthermore, the epidemiological data of the 2014 outbreak highlighted the role of human-to-human transmission in this outbreak, which was supported by phylogenetic analysis showing that 13 of the 16 sequences clustered together. These results provide new insights into the evolution of LASV in southern Nigeria and have important implications for vaccine development, diagnostic assay design, and LF outbreak management.

Genomic Analysis of Lassa Virus during an Increase in Cases in Nigeria in 2018

SummaryDuring 2018, an unusual increase in Lassa fever cases occurred in Nigeria, raising concern among national and international public health agencies. We analyzed 220 Lassa virus genomes from infected patients, including 129 from the 2017–2018 transmission season, to understand the viral populations underpinning the increase. A total of 14 initial genomes from 2018 samples were generated at Redeemer’s University in Nigeria, and the findings were shared with the Nigerian Center for Disease Control in real time. We found that the increase in cases was not attributable to a particular Lassa virus strain or sustained by human-to-human transmission. Instead, the data were consistent with ongoing cross-species transmission from local rodent populations. Phylogenetic analysis also revealed extensive viral diversity that was structured according to geography, with major rivers appearing to act as barriers to migration of the rodent reservoir.

Descriptive features of Lassa fever in Bauchi, Northeastern Nigeria - a retrospective review

Objective: Nigeria records it largest outbreak of Lassa fever in 2018, with 416 confirmed cases by 22nd April 2018 affecting 22 states and the Federal Capital Territory (FCT). This study determines the descriptive features of Lassa fever in Bauchi, Northeastern Nigeria.Methods: A retrospective study that encompasses all the suspected and confirmed cases of Lassa fever managed in Abubakar Tafawa Balewa University Teaching Hospital (ATBUTH), Bauchi, between October 2016 and April 2018. Clinical notes of these patients were used to source information including sociodemographic features, clinical characteristics of the presenting illness, laboratory investigations results, working diagnosis, line of management, and treatment outcomes.Results: A total 127 suspected cases records were reviewed out of which 27(21%) were positive for Lassa fever Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) test. Thirteen (48%) of the confirmed cases were males and fourteen (51.9%) females giving a male to female ratio of 1:1.08. their ages ranged from 1 to 60 years with a mean age of 27.5. Most cases were seen between October and April. Fever was the most common clinical presentation, occurring in 23 cases (85%) at presentation. Other clinical features were headache 20 cases (74%), bleeding 19 cases (70%), abdominal pain 14 cases (52%), Nausea/Vomiting 12 cases (44%), Diarrhoea 11 cases (41%), cough 11 cases (41%), encephalitis 9 cases (33%), Chest pain 8 cases (30%), Hypotension 7 cases (26%), Sore throat 5 cases (19%) and Facial and or Neck swelling 3 cases (11%). Mortality among the confirmed cases was (44.4%) with all deaths occurring within 72hours of presentation and had bleeding and or encephalitis as presenting symptoms.Conclusion: Lassa fever is relatively common in Bauchi state and affects people of all age groups and sexes. Late presentation, bleeding and encephalitis were common features among mortality cases.Keywords: Lassa Fever, clinical features, mortality, Nigeria

Descriptive analysis of Lassa fever outbreak data in Edo State, Nigeria, 2016

Background: Lassa fever is an acute viral hemorrhagic disease endemic in West Africa. It is transmitted to humans via contact with food or household items contaminated by rodent, Mastomys natalensis urine or droppings. Human-to-Human transmission can occur in communities or hospitals with poor infectious control practices. The burden of Lassa fever is not known because it's asymptomatic in 80% of cases in addition to non-specific symptoms. The objective of the study is to describe the cases in person, place and time which will help inform decision making. Methods & Materials: We obtained the suspected Lassa fever cases data for all 18 Local Government Areas (LGA) in Edo State for the period of January to December, 2016. Data abstraction was done to obtain socio-demographic, clinical and laboratory information. A descriptive study was done and Data was analyzed using Epi Info to determine frequencies and proportions. Bivariate analysis was done to determined factors associated with outcome using confidence interval set at 95%. Results: Out of 946 suspected cases, 49(5.2%) were laboratory confirmed (RT-PCR positive). Modal age group was 20-29 years, 15 (30.6%) and 27 (55.1%) were males. Esan-West, 12(24.5%) and Etsako-West, 13(26.5%) Local Government Areas had most cases. More cases were recorded between January to April with peak in February 17(35.4%). Case fatality rate (CFR) among the 39 cases with known outcome was 51.3%. CFR among the suspected cases was 8%. Late confirmation of illness (>7days of onset) was associated with death [OR = 2.5 (95%CI 0.6–11.3)]. Conclusion: The peak of the outbreak was in February. Case fatality rate of the outbreak was high with cases detected early having better outcome.

Variation in lineage 2 strain of Lassa fever virus in Nigeria

Background: Nigeria is one of four countries endemic for Lassa fever (LF) in West Africa and harbours three of the four established lineages (strains) of LF. Lineages 2 and 3 occur dominantly in the southern and Northern regions of the country respectively. In the southern region, the South central (S.C) and South east (S.E) axes are most endemic for LF in the southern region. The disparity in complications, morbidity and subsequent mortality (CFR of 30% of S.C cases versus 48% of S.E cases) raised the question; Are there any variations in the LF strains in the SC and SE axes? Methods & Materials: Following the 2014 epidemic with fifteen positive cases in the SE axes, genomic studies elucidating their nucleic acid sequences were conducted in NUITM. A ten year study of nucleic acid sequences of lineage two strains of LF from Nigeria covering the period 2004-2014 gleaned from the GENBANK pool was conducted. To this was added the fifteen positive samples of 2014, totalling 79 LF glycoprotein precursor (GPC) gene sequences. Using MEGA 6 software, phylogenetic and BLAST analysis of the homologous identity of all the 79 strains were conducted. Results: Fifty of the 79 LF lineage two strains were of SC origin while 29 were of SE. Three distinct clades of the SE strain were observed and clustered around Nig 05-SE40, Nig 08-04 and Nig 11-186 strains. Diversity among the clades of the SE strains ranged between 18 – 21%. Perhaps there is a new clade developed every three years in the SE axis. The SC strains were essentially of one clade and exhibited good homologous identity of 97-100%. This suggests less diversity of the SC strains than the SE strains. The SC and SE strains strains exhibited diversity of up to 20%. Conclusion: The Lineage 2 strain has four clades, with 3 of the clades belonging to the strain from the SE axis. This may explain the worse CFR of LF cases in SE axes. The SC strains are essentially of one clade. There is need to evaluate for Ribavirin resistance and/or mutation among clades of SE origin

A Case of Lassa Fever Diagnosed at a Community Hospital-Minnesota 2014.

In April 2014, a 46-year-old returning traveler from Liberia was transported by emergency medical services to a community hospital in Minnesota with fever and altered mental status. Twenty-four hours later, he developed gingival bleeding. Blood samples tested positive for Lassa fever RNA by reverse transcriptase polymerase chain reaction. Blood and urine samples were obtained from the patient and tested for evidence of Lassa fever virus infection. Hospital infection control personnel and health department personnel reviewed infection control practices with health care personnel. In addition to standard precautions, infection control measures were upgraded to include contact, droplet, and airborne precautions. State and federal public health officials conducted contract tracing activities among family contacts, health care personnel, and fellow airline travelers. The patient was discharged from the hospital after 14 days. However, his recovery was complicated by the development of near complete bilateral sensorineural hearing loss. Lassa virus RNA continued to be detected in his urine for several weeks after hospital discharge. State and federal public health authorities identified and monitored individuals who had contact with the patient while he was ill. No secondary cases of Lassa fever were identified among 75 contacts. Given the nonspecific presentation of viral hemorrhagic fevers, isolation of ill travelers and consistent implementation of basic infection control measures are key to preventing secondary transmission. When consistently applied, these measures can prevent secondary transmission even if travel history information is not obtained, not immediately available, or the diagnosis of a viral hemorrhagic fever is delayed.

Pre-clinical development of a vaccine against Lassa fever.

Lassa virus (LASV) is a persistent global health threat that causes about half a million cases of Lassa fever each year in Western Africa. Although most cases are mild, the disease can cause significant morbidity and results in as many as 5,000 deaths per year. Since 2015, Nigeria has been experiencing a severe and extended outbreak of Lassa fever, raising concerns that it could spill over into other countries and reach a magnitude similar to the West African Ebola outbreak of 2013-2016. Despite the burden that Lassa fever places on public health, both in Africa and around the world, there are still no clinically-approved therapeutics or vaccines to treat or prevent it. Nevertheless, a number of promising candidate vaccines have been developed over the last several years, and there is a growing political and social determination to drive at least one of these candidates towards licensure. This paper describes a LASV vaccine candidate that is being developed at Canada's National Microbiology Laboratory. Based on the same live attenuated vesicular stomatitis virus (VSV) vaccine platform that was used to produce the successful Ebola virus vaccine, the VSV-based LASV vaccine has been shown to elicit a potent and protective immune response against LASV. The vaccine shows 100% protection in the "gold-standard" nonhuman primate model of Lassa fever, inducing both humoral and cellular immune responses. Moreover, studies have shown that a single vaccination may offer universal protection against numerous different strains of the virus, and additional studies have shown that immunization with the VSV platform appears to be unaffected by pre-existing immunity to VSV. The next step in the development of the VSV-based LASV vaccine is phase I human clinical trials to assess vaccine safety and dosage.

Lassa fever: A recurring decimal in Plateau state, Nigeria

Background: Since the first reported case of Lassa fever (LF) in Jos, Plateau state Nigeria in the early 70’s, the state has been plagued with increasing number of cases. This could be due to poor environmental practices, food and personal hygiene. By the end of August 2017 there were 42 reported cases with 15 confirmed cases. Sadly, over the years there have been challenges with reporting and investigation of cases. This could be due to weak health systems commonly seen in developing countries.Methods and Materials: We reviewed 2012-2016 surveillance data from the State Ministry of Health (SMoH) using Microsoft Excel. Descriptive analysis was conducted on the reported LF cases in the state.Results: Between the years 2012 – 2016 there were 109 reported LF cases, with 57 (52.3%) males and 52 (47.7%) females. The mean age of the reported cases was 27.9± 13.6 years. Out of these, 23 (21.1%) were confirmed cases: 1 (4.5%) in 2012, none in 2013, 2014 and 2015, and 21 (91.3%) in 2016.The male: female ratio was10 (43.5%): 13 (56.5%). Six (26.1%) of the confirmed cases were health workers. The case fatality rate of the confirmed cases was 52.2%. Even though there is significant association between LF and death (P-value = 0.003) the odds ratio, 0.215 (95% CI) is low. The reporting years show consistent increasing trend from 2012 to 2016, except for 2015 where there was a decline in the number of reported cases. In 2016 there were 74 (67.9%) cases, 5 (4.6%) in 2015, 15 (13.7%) in 2014, 12 (11.0%) in 2013 and 3 (2.6%) in 2012.Conclusion: Even though reported cases are increasing, there are still gaps observed in the surveillance system of the SMoH. The annual recurrence of LF outbreak in the state without reciprocal preventive efforts on ground to combating it has exposed the populace and health workers to ill-health and death.

Knowledge of Lassa fever and use of infection prevention and control facilities among health care workers during Lassa fever outbreak in Ondo State, Nigeria.

IntroductionHospital-acquired infections of Lassa fever (LF) have been described in many West African countries. We assessed the availability of Infection Prevention and Control (IPC) measures and their use in the health centres (HCs) at the affected Local Government Areas (LGAs) during an ongoing LF outbreak in Ondo State, Nigeria.MethodsWe included all primary and secondary HCs and their healthcare workers (HCWs) in the affected Ose and Owo LGAs. We collected data from respondents using self-administered questionnaires and used a checklist to assess the IPC measures at the HCs. We generated frequencies and proportions and tested associations using odds ratios at 95% CI.ResultsOne hundred and ninety HCWs from 59 HCs were surveyed of which 34 (57.6%) were located in Owo LGA. All HCs had soap for handwashing, 57(96.6%) had wash-hand basins but only 52(88.1%) had water. While 57(96.6%) had gloves and 53(89.8%) had sharps boxes, only 16(27.1%) had an isolation room. Only 44(23.2%) respondents had been trained in IPC. The majority, 144 (91.6%) always had gloves available for their use, 79(41.6%) always had facemask/shield and 71(37.4%) always had full personal protective equipment. At the last patient contact, only 151 (79.8%) washed their hands before the contact, 188(98.9%) washed their hands after and 183 (96.2%) wore gloves. While there was no association between availability of gloves and its use (OR: 0.21, 95%CI 0.04-1.17), there was significant association between having had training in basic universal precautions and having used gloves (OR: 3.64, 95%CI 1.21-19.40) and having washed hands after last patient contact (OR: 2.31, 95%CI 1.67-12.30).ConclusionAmong these HCs that serve as point of first contact with possible cases of LF in these endemic LGAs, none met the minimum standard for IPC. We recommend that IPC committee for each LGA and the whole state should be set up and IPC trainings made mandatory.

A review of lassa fever outbreaks in Nigeria from 1969 to 2017: Epidemiologic profile, determinants and public health response

Introduction : Lassa fever outbreaks have occurred in Nigeria since the 1969 till date. This is in spite of the fact that the reservoir and modes of transmission have been known for all these years. This review aimed at describing the epidemiology and determinants of the Lassa fever outbreaks in Nigeria from 1969 to 2017 and the public health response to these outbreaks. Method : The guidelines for the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were used to conduct the review between May 2017 and January, 2018. We searched PubMed, Science direct, WHO library databases and Google Scholar for articles published from 1970 till January 2018. Other relevant websites such as those of the World Health Organization, Nigeria Centers for Disease Control and Prevention were searched for Lassa fever outbreak reports. Results : Twenty-six articles and reports were included in the final review. These described twenty-one outbreaks involving 5442 suspect cases, 768 confirmed cases and 631 deaths from suspected or confirmed Lassa fever. Thirty-two states and the Federal Capital Territory have ever recorded outbreaks of Lassa fever. Lassa fever cases now occur in various states in Nigeria all year round with dry season peaks. Nosocomial transmission has remained a consistent determinant. Public health responses have changed over time starting from predominantly case management in initial outbreaks to a centrally coordinated response supporting states and institutions over the years. Conclusion ; Lassa fever outbreaks have increased in frequency and geographic spread with case fatality ratio remaining unacceptably high. The same determinants have persisted with nosocomial transmission a consistent factor. Public health response has consistently improved with the last two years showing the most coordinated response. We recommend that the definition of Lassa fever in the Nigerian Integrated Disease Surveillance and Notification System (IDSR) be revised to reflect the current reality to ensure better Lassa fever control. Key words : Lassa fever, Outbreak, Viral haemorrhagic fevers, Nigeria.

2016/2017 Lassa fever outbreak in Nigeria: age and sex have no effect on treatment outcome

Introduction : lassa fever is an endemic Viral Hemorrhagic Fever (VHF) in Nigeria. Improvements in case detection and treatment outcome could be achieved by understanding the transmission dynamics better and applying the lessons from previous outbreaks considering the resource constrained setting. This study assessed age-sex disparities in treatment outcome using data from 2016/2017 lassa fever outbreak surveillance in Nigeria. Methods : lassa fever surveillance and outcome data from December 2016 to May 2017 from 14 States was extracted from the VHF platform. Univariate and bivariate analysis were carried out using Epi info 7 for socio-demographics and treatment outcome. Possible association between treatment outcome and selected variables (age, sex) were analyzed using Chi square at 0.05 level of significance. Results : there were 168 confirmed cases of Lassa fever during the study period, data was complete for 139 (82.7%). More men were affected (56%), as 61 of the 139 patients (46%) were female. The median age for all the patients treated was 32 years (IQR 25 - 44). Symptoms at presentation prior to treatment included fever (67%), nausea and vomiting (34.5%), diarrhea (14.4%), and intense fatigue (39%) while only 10.8% experienced unexplained bleeding. A total of 75 (54%) patients were treated and discharged alive, while 64 (46%) died. No significant association was found between gender and treatment outcome (p value = 0.976). Although survival was higher among patients aged 15 to 24 years (72%) and lowest among patients who were 45 years and above (35%), age of the patient was not significantly associated with the adverse treatment outcome (p-value = 0.06). Conclusion : for the 2016/2017 lassa fever outbreak in Nigeria, age and sex did not influence the treatment outcome of the recorded cases. There is a need for further analysis and more large scale studies on Lassa fever treatment outcomes.

Lassa fever outbreak and challenges of effective infection control in an isolation ward, Edo State, 2016

Introduction : lassa fever (LF) is an epidemic-prone viral haemorrhagic disease caused by the Lassa virus. However, prompt patients’ isolation, good infection control practices and contact tracing are important in outbreak control. On January 8, 2016, the Nigeria Federal Ministry of Health was alerted of an ongoing outbreak of Lassa fever across states including Edo State. We investigated to establish the existence of the outbreak, contact tracing, monitoring, described the outbreak and assessed infection control measures in Edo State. Methods : we did a descriptive study of confirmed LF cases of Edo State from 23rd December 2015 to February 2016. Active contact tracing and laboratory surveillance were used to detect suspected and confirmed Lassa fever cases. Infection prevention and control checklist was used to assess infection control of the Lassa fever institute isolation ward. Patients’ bio-data were collected from structured questionnaires applied on patient’s relatives, Lassa fever laboratory register and survey forms. Data was analyzed with Epi Info 7 and the outbreak described by person, place and time. Univariate analysis was expressed as frequency distribution, percentages, median, interquartile range, and rate. Results : a total of 359 suspected cases were screened of which 29 (8%) tested positive for Lassa virus. Case fatality rate was 9 (31%). The median age of cases was 30 years (IQR = 25 - 47), 17 (58.6%) were males, and 13 (44.8%) were students. Ten LGAs were affected including Etsako West LGA 12(41%) of cases. During the outbreak period, 179 contacts were monitored. Clinical presentations included redness of the eyes (79%), haematuria (69%), and facial oedema (52%). Infection control assessment of 15 items revealed 7 (46.7%) not available in the isolation ward. Conclusion : good infection prevention and control at the isolation ward challenged by an initial unavailability of some infection control items. Active contact tracing, prompt patients’ isolation, and surveillance helped in control and detection of the outbreak. Continuous community awareness, good infection control practices, and active surveillance may prevent and detect early outbreaks.

Descriptive characterization of the Lassa fever outbreak in Nigeria, 2016

Introduction : Lassa hemorrhagic fever is caused by the Lassa virus. The disease is endemic in Nigeria and many West African countries. Nigeria recorded outbreak of Lassa fever from late 2015 to 2016. We described the Lassa fever outbreak in Nigeria to highlight the trend of morbidity and mortality, and make recommendation for future prevention. Methods : we did a retrospective secondary data analysis of line listed cases from affected LGAs from epidemiologic weeks 1-38 of 2016. Data was obtained from Epid division of the Nigeria Center for Disease Control (NCDC). Results : a total of 837 cases and 98 deaths were recorded within this period. This gives a case fatality rate of 11.7%. The Lassa fever outbreak affected 28 of the 36 States of Nigeria. Out of the 774 LGAs in the country, 135 (17%) reported Lassa fever cases within the same period. The attack rate (AR) was highest at Esan central LGA of Edo State with 240.8 cases per 100,000 population, followed by Muya LGA in Niger State with 38 cases per 100,000 population, while Ikorodu and Kosofe LGAs of Lagos State had the least AR of 0.1 cases per 100,000 population. The CFR ranges from as high as 100% in some LGAs to zero in others. Only 83 (9.9%) cases were confirmed by laboratory diagnosis. Conclusion : Nigeria had a protracted Lassa fever outbreak through most part of 2016. The outbreak affected more than half of the states in the country. Though the CFR was generally low, very high mortality levels were recorded in several LGAs. We recommend enhanced surveillance and improved laboratory diagnostic capacity for Lassa fever across the country.

Lessons Learnt from Epidemiological Investigation of Lassa Fever Outbreak in a Southwest State of Nigeria December 2015 to April 2016.

Introduction: An outbreak of Lassa Fever (LF) reported and confirmed in Ondo state, Southwest Nigeria in January 2016 was investigated. This paper provides the epidemiology of the LF and lessons learnt from the investigation of the outbreak.Methods: The incidence management system (IMS) model was used for the outbreak coordination. Cases and deaths were identified through the routine surveillance system using standard definitions for suspected and confirmed cases and deaths respectively. Blood specimens collected from suspect cases were sent for confirmation at a WHO accredited laboratory. Active case search was intensified, and identified contacts of confirmed cases were followed up for the maximum incubation period of the disease. Other public health responses included infection prevention and control, communication and advocacy as well as case management. Data collected were analysed using SPSS 20, by time, place and persons and important lessons drawn were discussed. Results: We identified 90 suspected LF cases of which 19 were confirmed by the laboratory. More than half (52.6%) of the confirmed cases were females with majority (73.7%) in the age group ≥ 15 years. The Case Fatality Rate (CFR) of 63.2% among the laboratory-confirmed positive cases where 9 of 19 cases died, was significantly higher compared to the laboratory confirmed negative cases where 6 of the 65 cases died ( CFR; 8.5%) p ≤ 0.05. Two hundred and eighty-seven contacts of the confirmed cases were identified, out of which 267(93.0%) completed the follow-up without developing any symptoms and 2 (0.7%) developed symptoms consistent with LF and were confirmed by the laboratory. More than half of the contacts were females (64.5%) with most of them (89.2%) in the age group ≥ 25 years. Discussion: One key lesson learnt from the investigation was that the confirmed cases were mainly primary cases; hence the needs to focus on measures of breaking the chain of transmission in the animal-man interphase during Lassa fever epidemic preparedness and response. In addition, the high case fatality rate despite early reporting and investigation suggested the need for a review of the case management policy and structure in the State. Key Words: Lassa fever, Outbreak Response, Incident Management System, Nigeria

Mortality Among Confirmed Lassa Fever Cases During the 2015-2016 Outbreak in Nigeria.

To determine factors associated with mortality among confirmed Lassa fever cases. We reviewed line lists and clinical records of laboratory-confirmed cases of Lassa fever during the 2016 outbreak in Nigeria to determine factors associated with mortality. We activated an incident command system to coordinate response. We documented 47 cases, 28 of whom died (case fatality rate [CFR] = 59.6%; mean age 31.4 years; SD = ±18.4 years). The youngest and the oldest were the most likely to die, with 100% mortality in those aged 5 years or younger and those aged 55 years or older. Patients who commenced ribavirin were more likely to survive (odds ratio [OR] = 0.1; 95% confidence interval [CI] = 0.03, 0.50). Fatality rates went from 100% (wave 1) through 69% (wave 2) to 31% (wave 3; χ2 for linear trend: P < .01). Patients admitted to a health care center before incident command system activation were more likely to die (OR = 4.4; 95% CI = 1.1, 17.6). The only pregnant patient in the study died postpartum. Effective, coordinated response reduces mortality from public health events. Attention to vulnerable groups during disasters is essential. Public Health Implications. Activating an incident command system improves the outcome of disasters in resource-constrained settings.

Immunobiology of Ebola and Lassa virus infections.

Two of the most important contemporary emerging viruses that affect human health in Africa are Ebola virus (EBOV) and Lassa virus (LASV). The 2013-2016 West African outbreak of EBOV was responsible for more than 11,000 deaths, primarily in Guinea, Sierra Leone and Liberia. LASV is constantly emerging in these and surrounding West African countries, with an estimate of more than 500,000 cases of Lassa fever, and approximately 5,000 deaths, annually. Both EBOV and LASV are zoonotic, and human infection often results in a severe haemorrhagic fever in both cases. However, the contribution of specific immune responses to disease differs between EBOV and LASV. This Review examines innate and adaptive immune responses to these viruses with the goal of delineating responses that are associated with protective versus pathogenic outcomes.