Lassa virus lasv, the causative agent of lassa fever, is estimated to be responsible for up to 300,000 new infections and 5000 deaths each year across western africa. Morphologically, eosinophilic necrosis of hepatocytes was the most frequent finding and focal necroses, often. Humans usually become infected with lassa virus from exposure to urine and faeces of infected mastomys rats. Lassa fever, a zoonotic viral infection, is endemic in west africa. Epidemiologic and clinical features of lassa fever outbreak.
As stated above, lassa virus consists of four lineages. Lassa virus, which spreads from rodents to humans, infecting about half a million people every year, can lead to deadly hemorrhagic fever. As of 19 february 2016, there have been 72 cases 6 confirmed, 12 probable and 54 suspected cases. The symptoms of lf are often protean and nonspecific. A free powerpoint ppt presentation displayed as a flash slide show on id. Symptoms of lassa fever typically occur 221 days after coming into contact with the virus. However, it remains a very little known disease by healthcare workers. Apr 20, 2020 nigerian health officials have declared an outbreak of lassa fever in nigeria.
The different lasv strains are grouped into lineages based on the geographical location of the isolated strains. Lassa fever article about lassa fever by the free dictionary. Some cases are severe and require going to a hospital. Download premium images you cant get anywhere else. Lassa fever is mostly found in west africa, specifically in sierra lione, guinea, liberia, and nigeria. Lassa fever virus lasv is a member of the family arenaviridae arena means sand in latin root 16, 17. Lassa fever was discovered in 1969 after two nurses died from the disease. The disease was first described in the 1950s, and the virus was.
It is endemic in west african countries, especially sierra leone, the republic of guinea, nigeria, and. Lassa fever is named after lassa village in borno state, northeast nigeria where it was first discovered in 1969. Molecular confirmation and phylogeny of lassa fever virus in benin. The lassa fever virus spreads by an animal reservoir, or host, known as the multimammate rat mastomys natalensis. Lassa fever is a disease that is spread primarily by rats. Lassa fever was first recognized in lassa, nigeria, in 1969 and is endemic to west africa. Transmission occurs through contact with urine and faeces of. The multimammate mouse mastomys natalensis is the only known nonhuman host for lassa virus monath et al.
The aim of our study was to characterize the lineage ii strains in southern nigeria. Lassa fever is endemic in regions of west africa, including guinea, liberia, nigeria, and sierra leone, but cases have been exported to other countries by infected travelers. Lassa fever is a viral infection found in east africa, including sierra leone, liberia, guinea, and nigeria. Viral haemorrhagic fevers can be caused by viruses from several different families, all of which have the potential to cause disease with haemorrhagic features. The lack of specificity of its clinical manifestations makes its diagnosis difficult even in an epidemic context. Lassa fever in nigeria watch level 1, practice usual. Lassa fever spreads to humans most often through ingestion or inhalation of virus. Cases of lassa fever in the netherlands ex sierra leone ecdc. To date no lasv vaccine candidates have undergone clinical evaluation. It is endemic in parts of west africa including sierra leone, liberia, guinea and nigeria. Lassa fever simple english wikipedia, the free encyclopedia. Lassa fever lf is a viral hemorrhagic disease caused by the lassa virus lasv and endemic in. As a major impediment to vaccine development, delayed and weak neutralizing antibody nab responses represent.
Lassa fever is a hemorrhagic illness caused by lassa virus. Neighboring countries are also at risk, as the animal vector for lassa virus, the multimammate rat mastomys natalensis is distributed throughout the region. Lassa fever outbreak hits nigeria infectioncontrol. Lassa fever lf is an epidemicprone zoonotic disease prevalent in nigeria and ebonyi state is a high burden area in nigeria. Lassa fever virus was first identified in 1969 in nigeria. Brief history, diagnosing, and symptoms of lassa fever. Lassa fever, a viral haemorrhagic fever with symptoms similar to those of ebola virus disease, is endemic in much of west africa and usually sparks a seasonal outbreak from december to march. The disease is mainly spread to humans through contamination with the urine or feces of infected rats 3,4. Like many viruses, lassa virus binds to cell surface receptors. What you need to know about lassa fever 6 april 6 april 6 april 6 april 6 april 6 april 6 april estimated number of lassa fever cases in west africa each year death rate from ebola death rate from lassa fever estimated number of deaths lassa fever is caused by a virus that is found in west africa. Infection with lassa virus in humans may take many forms. How lassa and ebola are similar but different msnbc. Lassa virus can also be transmitted via sexual contact or via contact with skin lesions. Lassa fever fact sheet pennsylvania department of health.
Possible importation of lassa fever and the potential for the use of lassa virus as an agent of bioterrorism mandate clinicians in israel and other countries to be vigilant and familiar with the. Lassa virus is an arenavirus transmitted to humans by inhalation of or exposure to mastomys natalensis excreta, but it can also be transmitted persontoperson through virus infected bodily fluids. A, time line of major lassa fever research programs and initiatives at kenema government hospital prior to the emergence of ebola virus ebov disease in west africa. When symptoms occur they typically include fever, weakness, headaches, vomiting, and muscle pains. As of 19 february 2016, there have been 72 cases 6 confirmed, 12 probable and 54 suspected cases, and 27 people have died cfr 33%. The lassa virus is so named because, in 1969, it was first isolated and correlated as the causative agent of lassa fever in a small town called lassa in northeastern nigeria. The virus is a member of the arenavirus family and is spread primarily by rodents. The lassa virus is transmitted to humans mainly through handling rats, food or household items contaminated by rats urine and. Once infected, this rodent is able to excrete virus in urine. Outbreak of ebola virus disease in the lassa fever zone the. Pdf understanding lassa fever virus and diversification of the. Lassa fever lf is a febrile infectious disease caused by lassa virus.
It is a serious public health problem in this region of africa where it is endemic in several countries. Lassa virus, which is a member of the arenaviridae virus family, causes acute viral hemorrhagic fever. The disease is highly contagious and spread like wild fire. Sequential serum samples, beginning on the day of hospital admission, from three patients with lassa fever were tested for the presence of lassa virus antigens and antibodies by means of an enzyme. Infection with lassa virus can result in a range of outcomes from a mild or asymptomatic infection to lassa fever, a severe and often fatal viral haemorrhagic fever. Mastomys natalensis, a multimammate, peridomestic rat is the reservoir. Lassa fever is a viral illness that occurs in west africa. Current and historical conditions indexed list of current and historical nationally notifiable conditions. Lassa fever lf is a viral hemorrhagic fever caused by lassa virus lasv. The virus can be cultured in 7 to 14 days, after which virus can be detected by rtpcr andor ifa, c. It is most common in a large region of west africa, and is named after the nigerian town where it was.
It has also been reported in europe and north america. For 40 years, the natal multimammate rat, mastomys natalensis, has been assumed to be the sole host of lasv. Lassa fever is a virus disease of man characterized by generalized organ involvement resulting in manifestations of myositis, myocarditis, pneumonitis, encephalopathy, and signs of kidney involvement. Lassa fever, a significant cause of morbidity and mortality, while lassa fever is mild or has no observable symptoms in about eighty per cent of people infected with lassa virus. The pathology of human lassa fever pubmed central pmc. Clinical research on lassa fever needs to integrate the priority of care and the imperative of research. Lassa fever can be diagnosed using enzymelinked immunosorbent serologic assays elisa or ifa, which detect igm and igg antibodies andor lassa antigen. Lesson learned from the investigation and response of lassa fever.
Lassa fever lf is an epidemicprone zoonotic viral haemorrhagic disease caused by lassa fever virus lfv, a member of the arenaviridae family. Lassa virus entry requires a triggerinduced receptor. Case of human lassa virus infection with robust acute tcell. Lassa fever is endemic in regions of west africa, including guinea, liberia, nigeria, and sierra leone, but cases have been exported to other countries by infected. Viral hemorrhagic fever caused by the arenavirus lassa. It is an acute febrile viral illness lasting one to four weeks, and it occurs in west africa and some areas beyond. Less commonly there may be bleeding from the mouth or gastrointestinal tract. Lassa fever is an epidemicprone zoonotic viral haemorrhagic disease it is caused by lassa fever virus lfv member of the arenaviridae family reservoir. While lassa fever is mild or has no observable symptoms in about 80% of people infected with the virus, the remaining 20% have a more severe multisystem disease. Dec 17, 2018 lassa fever is one of the most lethal neglected tropical diseases in west africa.
Lf is endemic in nigeria, liberia, sierra leone, benin, ghana, guinea and mali. Lassa mammarenavirus lasv is an arenavirus that causes lassa hemorrhagic fever, a type of viral hemorrhagic fever vhf, in humans and other primates. This book was very fascinating and real to me because i lived in nigeria at the time when lassa fever was prevalent. Lassa virus causes lassa fever, an acute viral haemorrhagic fever vhf. A recombinant vesicular stomatitis virus based lassa fever vaccine protects guinea pigs and macaques against challenge with geographically and. Find highquality lassa fever stock photos and editorial news pictures from getty images. Lassa fever must be differentiated from other diseases that cause hemorrhagic fever, diarrhea, muscle fatigue, such as ebola infection, typhoid fever, malaria, diphtheria, legionellosis, congohemorrhagic fever, yellow fever, and shigellosis. We investigated the knowledge and risk perception of residents towards lf and determined the factors influencing their risk perception in communities that have reported confirmed. Jul 12, 2017 the natural reservoir of the lassa virus is the multimammate rat mastomys natalensis, a rodent found commonly in rural areas of tropical africa that often colonises in or around human homes where food is stored. Such infections are often asymptomatic, but in those who become ill, the disease can range from an uncomplicated fever of unknown origin to a fulminating hemorrhagic disease. In studies of lassa fever in sierra leone, the prevalence. Nigerian health officials have declared an outbreak of lassa fever in nigeria.
The virus is found in west africa in areas overlapping with the geography of its animal reservoir. Lassa virus, a member of the arenaviridae family, is an enveloped virus with a bisegmented, linear, single. Determining ribavirins mechanism of action against lassa. The animal reservoir, or host, of lassa virus is a rodent of the genus mastomys, commonly known as the multimammate rat. Jeannette troup, one of the main characters in fever, had died from this awful virus. National guidelines for lassa fever case management 1 nigeria centre for disease control foreword the large lassa fever outbreak in nigeria between january and may 2018, increased our awareness of the need to have welldetailed and easily accessible guidelines, for response. Laboratory diagnosis of lassa fever journal of clinical. It is clear that humans who do not develop an appropriate cellmediated immune response are much more likely to succumb to lassa fever, and that neutralizing antibodies do not play an important role early in infection, if at all. Lassa fever is a zoonotic disease, meaning that humans become infected from contact with infected animals. One wonders why borno state is usually home to a lot of things. Caused by an rna virus, it remains a priority disease for immediate notification by health authorities. Many of the characters in this book i knew personally. I was shocked when the news came to our mission station that dr. The animal reservoir of the lassa fever virus is a rat, mastomys natalensis.
Nigeria is in the midst of its largest ever outbreak of lassa fever. The lassa virus is a member of the arenaviridae family of viruses. Report of a fatal case of lassa fever in parakou in 2018. Mastomys natalensis, the multimammate, peridomestic rat endemic in nigeria, liberia, sierra leone, and guinea circulating in mali and cote divoire 3. Caused by an arenavirus the lassa virus, it is characterized by high fever, weakness, headaches, mouth ulcers, hemorrhages under the skin, heart and kidney failure, and a high mortality rate. Jun 02, 2017 lassa virus can cause a hemorrhagic disease called lassa fever and is endemic to western africa. The disease was first described in nigeria in 1969. Prospective study of the epidemiology and ecology of lassa fever. Progress and challenges of lassa fever control in nigeria. Lassa fever is an acute viral illness that occurs in west africa. Lassa fever, a new virus disease of man from west africa. Ppt lassa fever powerpoint presentation free to view.
Viral culture must be performed only in a high containment bsl4. Travelers to nigeria should avoid contact with rats, especially rat urine and feces, and keep their accommodations or campsites clean. Lassa fever is an animalborne, or zoonotic, acute viral illness. The prevalence of antibodies to the virus is 822%9 in sierra leone, 455% in guinea,12 and 21% in nigeria. Redeemers varsity develops 10mins lassa fever testkit. Lassa fever or lassa hemorrhagic fever lhf is a fever caused by the lassa virus. This is so called because at some point in the disease the patient bleeds. Lassa fever clinical course and setting a standard of care. The disease causes annual wide spread morbidity and mortality in africa, and can be imported by travelers. Rodents, particularly mastomys natalensis, are considered the natural hosts of the virus.
Lassa fever was first documented in nigeria, in lassa village of borno state. Lassa fever in nigeria, benin, togo, germany and usa reliefweb. Nigerias largest lassa fever outbreak sparked by rats. Lassa fever is a viral illness that typically occurs in west africa. Morphologically, eosinophilic necrosis of hepatocytes was the most frequent finding and focal necroses, often extensive, were present in most cases. Lassa fever is a member of the arenaviridae virus family. The first challenge is biosafety, as the lassa virus belongs to the group 4 of dangerous pathogens and therefore needs to be handled in at least biosafety level 3 bsl3 laboratories. Mar 14, 2016 lassa fever infects an estimated 100,000 to 300,000 individuals in west africa each year and around 5,000 result in death.
Baseline mapping of lassa fever virology, epidemiology and. Late rainy and early dry season affects all age groups and both sexes 3. The reservoir, or host, of lassa virus is a rodent known as the multimammate rat mastomys natalensis. Liberia and sierra leone were downloaded from the national center for. The reservoir of the lassa virus is a rodent of the genus mastomys known as multimammate rat. May 03, 2016 lassa virus lasv causes a deadly haemorrhagic fever in humans, killing several thousand people in west africa annually. Seroprevalence and risk factors for lassa fever infection. Aug 23, 2018 lassa fever is a viral hemorrhagic fever caused by an rna virus of the arenavirus family. The illness was discovered in 1969 when two missionary nurses died of it in nigeria. Lassa virus, an arenavirus first isolated in 1969 in jos, nigeria, is the cause of lassa fever, an acute viral illness that affects 100,000 to 300,000 persons per year based on 1970s estimates.
Low risk perceptions have been reported to prevent appropriate preventive behaviours. The nigeria centre for disease control ncdc has said that these statistics should not mask the progress made in the control of lassa fever in the worlds worst hit country. Outside of the case at emory university hospital, there have been six other cases of lassa fever reported in the united states. Pdf nigeria is presently suffering from another lassa fever epidemic. Lassa fever or lassa hemorrhagic fever lhf is an acute viral hemorrhagic fever caused by the lassa virus and first described in 1969 in the town of lassa, in borno state, nigeria. The number of lassa fever virus infections per year in west africa is estimated at about 300,000 to 500,000 with approximately 5000 deaths world health organization, 2005. Late rainy and early dry season affects all age groups and both sexes. An acute, highly communicable exotic infection that is endemic in western africa. Epidemiologic and clinical features of lassa fever.
As of march 3, nigeria has confirmed 420 cases of lassa fever and 93 deaths in 2019, suggesting the 2018 record of the most cases reported in a single year will be surpassed. The lassa virus is transmitted to humans mainly through food or household items contaminated by infected rats urine and faeces and by handling infected rats. Pathophysiology and treatment of lassa fever springerlink. General facts viral hemorrhagic fever caused by the arenavirus lassa transmitted from rodents to humans discovered in nigeria, 1969 endemic in portions of west africa seasonal clustering. Lassa mammarenavirus is an emerging virus and a select agent, requiring biosafety level 4equivalent containment. Benin co lassa fever update situation in numbers highlights unicef benin is scaling up its emergency response to the ongoing lassa fever outbreak. Key events during the development of the lassa fever program at kenema government hospital and important locations of the 202016 west african ebola outbreak.
Lassa fever is a zoonotic disease that commonly manifests as an acute viral hemorrhagic fever. Lassa fever full recovery without ribavarin treatment. Against the backdrop of the raging lassa fever virus, the redeemers university, run, ede, osun state, has developed a test kit known as pan lassa rapid diagnostics test pl rdt, that allows. Lassa fever is spread by rodents, which carry the virus in their excrement and urine, sometimes for the rest of their lifespan. Lassa virus, the causative agent of lassa fever, is a member of the family arenaviridae. Sep 15, 2017 lassa fever lf is a severe and often fatal hemorrhagic disease caused by lassa virus lasv, a member of the arenaviridae virus family. Lassa fever disease lassa fever is viral illness that occurs in west africa. The 2016 ebola virus disease epidemic was an unprecedented event, not only in terms of illness and death but also for showing the frailties of international preparedness for infectious disease outbreaks. Lassa fever is spread through direct contact with the urine and droppings of the mastomys natalensis, or multimammate rat, as well as through contact with the blood, tissue or secretions of a person infected with the lassa fever virus. Pathological findings have been described in only a small number of cases of lassa fever since the virus was first isolated in 1969. Structure of the lassa virus nucleoprotein reveals a dsrna.
Lassa virus article about lassa virus by the free dictionary. Lassa fever is part of a group of conditions known as viral haemorrhagic fevers. Lassa fever is an illness caused by lassa virus, a singlestranded rna hemorrhagic fever virus from the family arenaviridae. Rats fuelled the largest outbreak of deadly lassa fever in nigeria this year, according to the most extensive and rapid genomic analysis of the lassa virus. Testing of samples for lassa virus should be performed under bsl4. Genetic characterization of lassa virus strains isolated. Mastomys rats infected with lassa virus do not become ill, but they can shed the virus in their urine and faeces. The arenaviral nucleoprotein np has been implicated in suppression of the host innate immune system, but the mechanism by which this occurs has remained elusive. Many of those infected by the virus do not develop symptoms. The centers for disease control and prevention estimates that up to 300,000 lassa virus infections occur each year. The lassa fever virus lfv was named after the town where the first cases occurred. It was first reported in 1969 in the town of lassa, in borno state, nigeria. Details of lassa virus structure could inform development of.
Two outbreaks of lassa fever november 2014 and january 2016 in the. Lassa fever virus, a member of the family arenaviridae, is a highly endemic category a pathogen that causes 300,000500,000 infections per year in western africa. It was first described in northeastern nigeria in 1969, and it is endemic in west africa 1. Get a printable copy pdf file of the complete article 547k, or click on a page image below to browse page by page. Lassa fever, also known as lassa hemorrhagic fever lhf, is a type of viral hemorrhagic fever caused by the lassa virus. Lassa fever is a significant cause of death and disease in. Persontoperson spread may occur during the acute febrile phase when the virus is present in the throat3.
The reservoir of the lassa virus is a rodent of the genus mastomys known as. Lassa fever is endemic in parts of west africa, including sierra leone, liberia, guinea, and nigeria fig 1. Natal multimammate mouse is the primary reservoir of lassa virus, found in subsaharan africa. Lassa virus can be excreted in urine for 39 weeks from the onset of illness. Sufficient capacity exists in the eu for testing purposes, however given the wide genetic diversity of circulating lassa viruses, laboratory protocols.
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