Lassa virus was discovered in 1969 by a team led by dr. Lassa fever infects an estimated 100,000 to 300,000 individuals in west africa each year and around 5,000 result in death. Pathogenesis of lassa fever in cynomolgus macaques virology. Lassa fever virus often causes deafness, and this complication may be noted in latestage disease and during recovery periods. Neighboring countries are also at risk, as the animal vector for lassa virus, the multimammate rat mastomys natalensis is distributed throughout the region. Sequence variability and geographic distribution of lassa. We tested favipiravir in lassa virusviremic macaques and found that 300 mgkg daily for 2 weeks successfully treated infection. Lassa virus diversity and feasibility for universal. The very diverse lasv genome has 4 major lineages associated with different geographic locations. The lassa virus is one of several viruses identified by who as a likely cause of a future epidemic. Clinical sequencing uncovers origins and evolution of lassa virus. Jun 02, 2017 lassa virus can cause a hemorrhagic disease called lassa fever and is endemic to western africa. Clinical research on lassa fever needs to integrate the priority of care and the imperative of research. Viral hemorrhagic fever vhf 2011 case definition recommend on facebook tweet share compartir note.
The virus can spread between people through direct contact with the body fluids of a person infected with lassa fever, as well. Lassa virus is a singlestranded rna virus that can quickly overwhelm the immune system. The virus, a member of the virus family arenaviridae, is a singlestranded rna virus and is zoonotic, or animalborne. Lamp1 increases the efficiency of lassa virus infection by. Lassa virus is a singlestranded rna virus that is enveloped in lipid with glycoprotein spikes protruding from the outside surface. Lasv infection of humans can cause lassa fever lf, a disease associated with high morbidity and significant mortality. Increasing international travel and the possibility of use of the lassa virus as a. Lassa virus, the cause of lassa fever in humans, is endemic to west africa. Lassa virus infects all tissues, but infection of the liver is especially typical. 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. Lassa virus is a member of the old world arenaviruses, and, as such, is endemic in western africa.
Biochemical characterization of the lassa virus l protein. Lassa virus can cause a hemorrhagic disease called lassa fever and is endemic to western africa. Lassa fever or lassa hemorrhagic fever lhf is a fever caused by the lassa virus. Lassa antibody and antigen were found in 96 11% and 46 5%, respectively, of 884 tested mastomys demby et al. It is the causative agent of lassa fever, a potentially fatal viral hemorrhagic fever in humans for which only limited treatment options and no licensed vaccine are available. Gradual onset of fever, malaise and general weakness after a few days. Once infected, this rodent is able to excrete virus in urine. Apr 28, 2018 we evaluated the impact of manmade conflict events and climate change impact in guiding evidencebased community one health epidemiology and emergency response practice against reemerging epidemics. Increasing evidence of emerging and reemerging zoonotic diseases including recent lassa fever outbreaks in almost 20 states in nigeria led to 101 deaths and 175 suspected and confirmed. 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 virusinfected bodily fluids.
May 03, 2016 lassa virus in hylomyscus pamfi, nigeria. A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Outside of the case at emory university hospital, there have been six other cases of lassa fever reported in the united states. Lassa fever is an animalborne, or zoonotic, acute viral illness. Free fulltext pdf articles from hundreds of disciplines, all in one place lassa fever encephalopathy. Of 10 specimens captured in kako, southwestern nigeria, during this period, 4 were lasv positive table 1. The illness was discovered in 1969 when two missionary nurses died in nigeria. Lassa fever lf is a viral hemorrhagic disease caused by the lassa virus lasv and endemic in west. Sufficient capacity exists in the eu for testing purposes, however given the wide genetic diversity of circulating lassa viruses, laboratory protocols. Case of human lassa virus infection with robust acute t. This work illuminates phdriven conformational changes in both receptorbinding and fusion subunits of lassa virus, illustrates the unique assembly of the arenavirus glycoprotein spike, and provides a muchneeded template for vaccine design against these threats to global health. Lassa fever simple english wikipedia, the free encyclopedia. Pdf immunobiology of ebola and lassa virus infections.
Lassa fever is a frequently severe human disease that is endemic to several countries in west africa. Morphologically, eosinophilic necrosis of hepatocytes was the most frequent finding and focal necroses, often. 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. Late rainy and early dry season affects all age groups and both sexes. Only 1% of all lassa virus infections overall are fatal. Lassa fevercaused by infection with the lassa virusis named after the town in nigeria where the first identified cases occurred. The incubation period for lassa ranges from 6 days to 3 weeks. Increasing evidence of emerging and reemerging zoonotic diseases including recent lassa fever outbreaks in almost 20 states in nigeria led to. Lassa virus lasv is endemic to parts of west africa and causes highly fatal hemorrhagic fever. Pathophysiology and treatment of lassa fever springerlink. Lassa fever in nigeria watch level 1, practice usual. 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. Pdf lassa virus, an old world arenavirus family arenaviridae, is the etiological agent of lassa fever, a severe human disease that is. Virus is shed in urine and droppings of the chronically infected animal host, the multimammate rat mastomys rodent species.
Welcome to cdc stacks use of favipiravir to treat lassa. The lassa virus is transmitted to humans mainly through handling rats, food or household items contaminated by rats urine and faeces. But 15% to 20% of those treated for the disease in hospitals. Pdf on jan 1, 2018, aude lalis and others published mice and men. Instructions for use realstar lassa virus rtpcr kit 1. Jan 31, 2019 lassa virus lasv is a highly prevalent mammarenavirus in west africa and is maintained in nature in a persistently infected rodent host, mastomys natalensis, which is widely spread in subsaharan africa. The virus is a member of the arenavirus family and is spread primarily by rodents. Lassa virus lasv 4 belongs to the old world clade of the family of arenaviridae. Instead of only 1 lassa virus laboratory for edo and ondo and 1 in lagos, 2 additional laboratories in eb. Lassa fever, also known as lassa hemorrhagic fever lhf, is a type of viral hemorrhagic fever caused by the lassa virus. The multimammate mouse mastomys natalensis is the only known nonhuman host for lassa virus monath et al. How lassa and ebola are similar but different msnbc. Persistent and latent infections occur if viral genome becomes integrated into the host cell genome.
Infection with lassa virus in humans may take many forms. Introduction to lassa fever world health organization. They therefore list it for urgent research and development to develop new diagnostic tests, vaccines, and medicines. 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. It is endemic in parts of west africa including sierra leone, liberia, guinea and nigeria. Pathological findings have been described in only a small number of cases of lassa fever since the virus was first isolated in 1969. Lassa virus consists of four lineages, which have a strain variation of 27% in relation to their nucleotides and 15% in relation to their amino acids. The reservoir, or host, of lassa virus is a rodent known as the multimammate rat mastomys natalensis. With 472 confirmed cases to date and 121 deaths,9 2018 has seen nigeria battle its largest documented outbreak of lassa virus on record. Lassa fever clinical course and setting a standard of care.
However, the full extent of lassas endemicity is unknown due to poor mean of contact and communication with the rural villages where lassa is surely seen, a factor that prevents both reporting and treatment of infection. Lassa virus lasv infection causes an acute and sometimes fatal hemorrhagic disease in humans and nonhuman primates. Etiology lassa virus l asv is a bisegmented, negativesense, single stranded rna virus belonging to the old world complex, genus arenavirus, family arenaviridae. Lassa virus, which is a member of the arenaviridae virus family, causes acute viral hemorrhagic fever. The virus is named after the town in nigeria where the first cases occurred. In october 2008 and march 2009, a preliminary screening for arenaviruses was conducted during the process of describing the african wood mouse h. Constraints in the diagnosis and treatment of lassa fever and the. Most human infections result from zoonotic transmission. We evaluated the impact of manmade conflict events and climate change impact in guiding evidencebased community one health epidemiology and emergency response practice against reemerging epidemics. Some cases are severe and require going to a hospital.
Lassa mammarenavirus lasv is an arenavirus that causes lassa hemorrhagic fever, a type of viral hemorrhagic fever vhf, in humans and other primates. Natal multimammate mouse is the primary reservoir of lassa virus, found in subsaharan africa. Lassa fever by carly brown discovery john frame 1969 collaborated with yale arbovirus research unit typestructure arenaviridae family spherical lipid membrane singlestranded rna transportation zoonotic hostmultimammate rat genus mastomys person to person transportationcont. Protection from lethal lassa disease can be achieved both. Details of lassa virus structure could inform development.
The lack of specific antiviral therapies for lassa fever drives an urgent need to identify druggable targets, and interventions that block infection at the entry stage are particularly attractive. Lassa fever is a hemorrhagic disease caused by lassa virus, and the increasing occurrence of this disease has highlighted lassa virus as an important pathogen that can lead to 90% perinatal. Lassa virus, the causative agent of lassa fever, is a member of the family arenaviridae. The assay includes a heterologous amplification system internal control to identify. Viruses that cause human hemorrhagic fevers, such as ebola, marburg and lassa, are classified as bl4 agents due to their high fatality rates and lack of effective. Lassa fever is an acute viral illness that occurs in west africa. Hepatitis may be mild or severe, and laboratory tests may not reflect the level of injury. Many of those infected by the virus do not develop symptoms. Jan 03, 2020 the nigeria center for disease control has declared an outbreak of lassa fever in nigeria due to an increase in the number of cases reported across the country since the beginning of the year. The results suggest that the mechanism by which lassa virus causes infection is. Treatment of lassa fever is primarily supportive, although ribavirin has shown limited efficacy if administered early during infection.
When symptoms occur they typically include fever, weakness, headaches, vomiting, and muscle pains. The multimammate rat mastomys natalensis is the only known reservoir of lasv. Lassa virus is one of more than 25 causative viruses of viral hemorrhagic fever table 4. Lassa virus in cerebrospinal fluid but not in serum pdf. Less commonly there may be bleeding from the mouth or gastrointestinal tract. Morphologically, eosinophilic necrosis of hepatocytes was the most frequent finding and focal necroses, often extensive, were present in most cases. Lassa mammarenavirus is an emerging virus and a select agent, requiring biosafety level 4equivalent containment. The pathology of human lassa fever pubmed central pmc. Jun 27, 2014 the lassa virus, endemic to west africa, uses an unexpected twostep process to enter cells, research has shown. Product description the realstar lassa virus rtpcr kit 1. Lassa virus lasv is a highly prevalent mammarenavirus in west africa and is maintained in nature in a persistently infected rodent host, mastomys natalensis, which is widely spread in subsaharan africa.
Unless you live in or have visited certain parts of western africa, or have had close contact with someone who does or has, your likelihood of contracting lassa fever is very low. To date, no licensed vaccines are available to prevent lassa virus lasv infection, even though lassa fever is thought to be an important disease contributing to mortality and both acute and chronic morbidity. It was first reported in 1969 in the town of lassa, in borno state, nigeria. Case of human lassa virus infection with robust acute tcell. In 2007, siga technologies, studied a medication in guinea pig with lassa fever. The nigeria center for disease control has declared an outbreak of lassa fever in nigeria due to an increase in the number of cases reported across the country since the beginning of the year. The virus is found in west africa in areas overlapping with the geography of its animal reservoir.
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. Lassa virus is a virulent and highly transmissible rna virus that belongs to the arenavirus group. The lassa virus, endemic to west africa, uses an unexpected twostep process to enter cells, research has shown. Current and historical conditions indexed list of current and historical nationally notifiable conditions.
Lassa virus is the most clinically important member of the arenaviridae, a family that includes six additional biosafety level 4 bsl4 hemorrhagic fever viruses. Lasv, which primarily causes infection in humans, was originally isolated from a missionary nurse in lassa, nigeria in 1969. Six cynomolgus monkeys were experimentally infected with. Jul 12, 2017 lassa fevercaused by infection with the lassa virusis named after the town in nigeria where the first identified cases occurred. Lassa fever was discovered in 1969 after two nurses died from the disease.
However, in 2018, many changes occurred in nigeria regarding lassa virus surveillance and treatment. Lassa fever lf is an acute haemorrhagic viral infection caused by the lassa virus, which is endemic in the lf belt of west africa. Lassa mammarenavirus is an emerging virus and a select agent, requiring biosafety level 4. Six cynomolgus monkeys were experimentally infected with lasv. Increase in lassa fever cases in nigeria, januarymarch 2018. Lassa fever is a viral illness that typically occurs in west africa. Lassa virus or lassa viral haemorrhagic fever is an acute illness of 14 weeks duration that occurs in west africa. Details of lassa virus structure could inform development of.
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