Routine barrier nursing precautions probably protect against transmission of lassa virus in most circumstances. Lassa mammarenavirus is an emerging virus and a select agent, requiring biosafety level 4equivalent containment. Gradual onset of fever, malaise and general weakness after a few days. Morphologically, eosinophilic necrosis of hepatocytes was the most frequent finding and focal necroses, often extensive, were present in most cases. Constraints in the diagnosis and treatment of lassa fever and the. Rodents, particularly mastomys natalensis, are considered the natural hosts of the virus 2. Caused by an rna virus, it remains a priority disease for immediate notification by health authorities. Lassa fever is a viral illness that typically occurs in west africa. Difference between ebola and lassa fever ebola vs lassa. Fever and malaise generally appear 10 days after infection. It was first described in northeastern nigeria in 1969, and it is endemic in west africa 1. Lassa fever lf is a zoonotic disease associated with acute and potentially fatal hemorrhagic illness caused by the lassa virus lasv, a member of the family arenaviridae. Lassa fever is a disease that is spread primarily by rats. Lassa fever is a zoonotic disease that commonly manifests as an acute viral hemorrhagic fever.
The ebola virus is mainly carried by fruit bats or transmitted through humantohuman contact. Kent campbell, an epidemiologist at the at lanta center, developed a. 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. Lassa fever is part of a group of conditions known as viral haemorrhagic fevers. Lassa fever is a viral illness that occurs in west africa. Lassa fever, an acute viral hemorrhagic disease, is found mostly in west africa. Neighboring countries are also at risk, as the animal vector for lassa virus, the multimammate rat mastomys natalensis is distributed throughout the region. It has been known since the 1950s, but the virus was not identified until 1969, when two missionary nurses died from it in the town of lassa in nigeria.
Determining ribavirins mechanism of action against lassa. 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 fever full recovery without ribavarin treatment. Lassa virus is easily isolated from the blood during the febrile stage of the illness, and cf, ifa, and elisa may all be used for detecting viral antibodies. When symptoms occur they typically include fever, weakness, headaches, vomiting, and muscle pains. Lassa fever lf is a severe and often fatal hemorrhagic disease caused by lassa virus lasv, a member of the arenaviridae virus family. Lassa mammarenavirus lasv is an arenavirus that causes lassa hemorrhagic fever, a type of viral hemorrhagic fever vhf, in humans and other primates. Lassa fever is named after lassa village in borno state, northeast nigeria where it was first discovered in 1969. Lassa fever lf is an epidemicprone zoonotic viral haemorrhagic disease caused by lassa fever virus lfv, a member of the arenaviridae family 1.
The illness was discovered in 1969 when two missionary nurses died in nigeria. Lassa fever virus was first identified in 1969 in nigeria. Lassa fever is spread by rodents, which carry the virus in their excrement and urine, sometimes for the rest of their lifespan. The lassa virus is transmitted to humans mainly through handling rats, food or household items contaminated by rats urine and faeces. The virus is a member of the arenavirus family and is spread primarily by rodents. It has also been reported in europe and north america. Lesson learned from the investigation and response of lassa fever. Epidemiologic and clinical features of lassa fever.
Details of lassa virus structure could inform development. Since 2015, major increases in lassa fever attack rate and in the casefatality rate have occurred in this state. The number of lassa virus infections per year in west africa is estimated at 100,000 to 300,000, with approximately 5,000 deaths. Ebola and lassa fever are both types of viral hemorrhagic fever caused by different viruses. The animal reservoir of the lassa fever virus is a rat, mastomys natalensis. Lassa fever is caused by infection with the lassa virus. Health, general animal carriers of disease research animals as carriers of disease arenaviruses hemorrhagic fever hemorrhagic fevers lassa fever. Lassa fever, also known as lassa hemorrhagic fever lhf, is a type of viral hemorrhagic fever caused by the lassa virus. Current and historical conditions indexed list of current and historical nationally notifiable conditions.
The disease was first recognized in lassa, nigeria, in 1969. Outside of the case at emory university hospital, there have been six other cases of lassa fever reported in the united states. It is endemic in parts of west africa including sierra leone, liberia, guinea and nigeria. The virus is spread by a rat that lives in large numbers in west, central, and east africa.
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. Lassa fever is a zoonotic disease, meaning that humans become infected from contact with infected animals. Cases of lassa fever in the netherlands ex sierra leone ecdc. Transmission occurs through contact with urine and faeces of. Lassa virus, which is a member of the arenaviridae virus family, causes acute viral hemorrhagic fever. Lassa fever, on the other hand, is carried and transmitted by the natal multimammate mouse. Lassa fever virus lasv causes acute viral haemorrhagic fever with symptoms similar to those. The virus can spread between people through direct contact with the body fluids of a person infected with lassa fever, as well as contaminated bedding and clothing.
Since the first epidemic was discovered in 2014 in the department of atacora, benin experienced its fourth epidemic of lassa hemorrhagic fever in january 2018, with an average lethality. Health workers may be infected by direct contact with blood, body fluids, urine, or stool of a patient with lassa fever. Benin co lassa fever update situation in numbers highlights unicef benin is scaling up its emergency response to the ongoing lassa fever outbreak. Viral haemorrhagic fevers can be caused by viruses from several different families, all of which have the potential to cause disease with haemorrhagic features. Ebola virus disease and the result turned negative. Lassa fever in nigeria watch level 1, practice usual. 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%. Travelers to nigeria should avoid contact with rats, especially rat urine and feces, and keep their accommodations or campsites clean. Viral hemorrhagic fever vhf 2011 case definition recommend on facebook tweet share compartir note. Diagnostics are key to effective prevention and control of lassa fever virus lasv, a who. Lassa fever virus article about lassa fever virus by the. Pdf understanding lassa fever virus and diversification of the. Nigerian health officials have declared an outbreak of lassa fever in nigeria.
Pathophysiology and treatment of lassa fever springerlink. Lassa fever, on the other hand is caused by the lassa virus. As the disease progresses, increased fever and myalgia are typical, accompanied by severe prostration. How lassa and ebola are similar but different msnbc. Lassa fever is caused by a single stranded rna virus healing and gopal, 2001. Lassa fever is an animalborne, or zoonotic, acute viral illness. Lassa fever is a haemorrhagic disease caused by lassa virus, a member of the mammarenavirus genus in the family arenaviridae. Increasing international travel and the possibility of use of the lassa virus as a.
The mobile unit was used once before, in an outbreak of lassa fever in sierra leone in 1972, when dr. Natal multimammate mouse is the primary reservoir of lassa virus, found in subsaharan africa. Sufficient capacity exists in the eu for testing purposes, however given the wide genetic diversity of circulating lassa viruses, laboratory protocols. A surveillance case definition is a set of uniform criteria used to define a.
The centers for disease control and prevention estimates that up to. They carry the virus in their urine and droppings and live in homes and areas where food is stored. Lassa fever outbreak hits nigeria infectioncontrol. People can get lassa fever through people with lassa fever are not believed to be contagious before they. The pathology of human lassa fever pubmed central pmc. Report of a fatal case of lassa fever in parakou in 2018.
Pdf on jun 16, 2015, bibiana nonye egenti and others published understanding lassa fever virus and diversification of the rodent. The main feature of this fatal infection is impaired or delayed cellular immunity leading to fulminant viraemia, usually starting as fever of unknown origin chen and cosgriff, 2000. It was first reported in 1969 in the town of lassa, in borno state, nigeria. Lassa fever lf is a febrile infectious disease caused by lassa virus. The virus, a member of the virus family arenaviridae, is a singlestranded rna virus and is zoonotic, or animalborne. Baseline mapping of lassa fever virology, epidemiology and. 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. 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 virus was first discovered in nigeria in 1969 1 and later detected in liberia in 1972. Infection with lassa virus in humans may take many forms. Lf is endemic in nigeria, liberia, sierra leone, benin, ghana, guinea and mali. Lassa fever is caused by a single stranded rna virus and is a disseminated systemic.
Less commonly there may be bleeding from the mouth or gastrointestinal tract. The virus is spread to humans via the rats urine in airborne droplets. 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 and hemorrhagic diathesis. The areas where lassa is found are the areas where this rat is. It is endemic in west african countries, especially sierra leone, the republic of guinea, nigeria, and liberia, where the annual. Mastomys rats infected with lassa virus do not become ill, but they can shed the virus in their urine and faeces. However, for added safety, patients suspected to have lassa fever should be cared for under specific isolation precautions, which include the wearing of protective clothing such as masks, gloves. 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 symptoms of lf are often protean and nonspecific. Lassa fever is one of the hemorrhagic fever viruses like ebola virus, marburg virus, and others unlike ebola virus, lassa fever is not as contagious person to person, nor as deadly lassa virus is typically transmitted by the urine or feces of mastomys rats to humans. Lassa fever is a viral haemorrhagic fever transmitted by rats. Found predominantly in west africa, 1 it has the potential to cause tens of thousands of deaths.
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. Lassa fever is an acute viral illness that occurs in west africa. I was shocked when the news came to our mission station that dr. Mastomys natalensis, a multimammate, peridomestic rat is the reservoir. Abstract lassa fever is an acute viral zoonotic illness caused by lassa virus, an arenavirus known to be responsible for a severe haemorrhagic fever characterised by fever, muscle aches, sore throat, nausea. We report the epidemiology of lassa fever in bauchi state, a diseaseendemic region, in nigeria. The causative virus is an arenavirus and is harbored by a rat, mastomys natalensis. The exposure is usually to a multimammate rat mastomys natalensis. Many of those infected by the virus do not develop symptoms. Introduction to lassa fever world health organization. Many of the characters in this book i knew personally. With 472 confirmed cases to date and 121 deaths,9 2018 has seen nigeria battle its largest documented outbreak of lassa virus on record. The virus is named after the town in nigeria where the first cases occurred. Discovered in 1969 in a nigerian nurse from the town of lassa in the state of borno, the arenavirus named lassa virus is one of the viruses responsible for deadly epidemics of hemorrhagic fever in africa.
Epidemiology of lassa fever and factors associated with. Virus is shed in urine and droppings of the chronically infected animal. The most recent 2018 and 2019 nigerian outbreaks featured alarmingly high fatality rates of up to 25. The animal reservoir, or host, of lassa virus is a rodent of the genus mastomys, commonly known as the multimammate rat.
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