Lassa virus febrility is a disease that is really common and endemic in West Africa which harmonizing to the CDC infects 100,000-300,000 per twelvemonth with about 5,000 deceases [ 1 ] . This extremely contagious and highly deadly viral disease was foremost discovered in a town in the Yedseram river vale called Lassa ( which is where it got its name from ) in Borno province, Nigeria. Its first instance was recorded in 1969 after two nurses died in a infirmary in Lassa town. It is an acute viral hemorrhagic febrility that is endemic non merely in Nigeria, but to other West African states like Congo, Liberia, Sierra Leone and Guinea [ 2 ] . At least two instances have occurred in the United States, both of which of class both persons traveled to states endemic to this disease. Lassa virus is zoonotic but it can besides be transmitted from individual to individual. No vaccinum has been developed for this virus but merely one drug is known and used to successfully handle the disease.
Lassa virus is a member of the Old World composite and is classified under the household of Arenaviridae. The genus categorization is arenavirus and its species is its name ; Lassa virus. It belongs to Group five ( V ) in the Baltimore categorization of viruses alongside Ebola, rubeolas, hydrophobias and grippe. Viruses in this class are negative-sense individual stranded RNA genomes and have sandy visual aspects due to the presence of ribosomes [ 3 ] . The virions are spherical and comprise of an envelope and two nucleocapsids which have fibrils that form a circle. The mirid bug is enveloped. The envelope contains glycoproteins that station translationally cleave to Glycoprotein1 and 2 ( GP2 ) . GP2 interacts with nucleocaspid protein to assemble virion. It besides acts as the viral merger protein under acidic conditions [ 4 ] . Other proteins found in the cell include nucleocapsid protein which is the most abundant and the first protein that is expressed in an septic cell. The 2nd protein that is expressed is the viral RNA-dependent- RNA polymerase which can be detected in virions. Its genome is composed of two strands viz. S-RNA and L-RNA. S-RNA is ambisense and codifications for two proteins ; glycoprotein and nucleoprotein while L-RNA is a negative sense RNA and codifications for Zinc RING-finger motive protein ( Z ) and Viral RNA dependent RNA polymerase ( L ) [ 4 ] .
The life rhythm of a typical Lassa virus starts when the virion comes in contact with the cell. The virus takes over the cell mechanism and uses it to its advantage by using the cell ‘s reproduction machinery to do more viruses that will do infection in other cells. The cellular receptor called alpha-dystroglycan binds with the viral receptor called GP1 and infects the cell. The virus enters the cell through endocytosis which is rare with enveloped viruses [ 5 ] . The mirid bug is uncoated due to low Ph ( sourness ) of the endosome and so transported to the cytosol. Reproduction is really rapid. Transcripts of the messenger RNA subtraction sense genomes are made and these genomes so make viral complementary RNA transcripts of itself which are plus sense. Nuclear proteins are expressed in big measures followed by the reproduction of L and S strands being ensued. Enveloped glycoprotein is expressed and this differentiates into GP1 and GP2 which so migrate to the surface of the cell. Nucleocapsid proteins unite with genomic RNA to organize strings of bead-like constructions. The nucleocapsid proteins cross-links to the carboxy end point of GP2. The virus is assembled in the cytol after which it egresses the cell by budding out [ 5 ] .
Lassa virus is zoonotic which means that humans become infected when they come in contact with an animate being that is infected. The animate being in this instance is a gnawer called Mastomys natalensis normally known as multimammate rat. Infected rats are symptomless to this disease but they shed it in their piss and dungs and besides release it in their spit, all which can be aerosolized [ 1 ] . Humans get infected from direct contact with these stuffs like ingestion of contaminated nutrient, touch septic objects and even inspiration of bantam septic atoms. It can besides be tramsmitted from individual to individual. This can happen if a individual comes in contact with eliminations, blood, and secernments of an septic individual. Lassa virus affects about all the tissues in the human organic structure, get downing with the mucous membrane and finally the vascular system. Arenaviruss are able to infect macrophages and perchance do the release of go-betweens of cell and vascular harm. T-cell induced immunopathologic effects significantly exacerbate tissue devastation. Once infected, the virus can happen its manner into the human organic structure through different mediums like the respiratory piece of land, the blood watercourse and/or lymph vass. It so duplicates in the reticuloendolethial cells doing capillary lesions. These lesions farther lead to platelet and erythrocyte loss and sometimes do bleeding in assorted variety meats [ 6 ] .
Approximately 80 % of people infected with this virus are symptomless. After and incubation period of about 21 yearss, symptoms that are non specific like febrility, thorax hurting, sickness, purging unease, abdominal hurting and coughing Begin to happen. Some patients experience symptoms like diarrhoea, protein in the piss, facial puffiness, phrenitis, ictuss, facial puffiness, shudder and freak out may happen in the late phases. If foetal or left untreated, it can take to decease. Mortality rate is about 15-20 % among hospitalized patients and about 95 % among pregnant adult females. However, abortion reduced decease among pregnant adult females because the virus has a high affinity for the placenta and the endurance of the foetus in 10 % regardless of any step taken [ 1 ] . The most common long term effect of Lassa febrility after recovery is deafness which occurs in tierce of the instances. Deafness could run from mild to severe and could go lasting. Spontaneous abortion is another common effect. It is frequently diagnosed by utilizing ELISA which detects IgG, IgM antibodies and besides Lassa antigens. This viral infection can non be cleared by the immune system because it is systemic and do haemorrhagic febrility.
Ribavirin, an antiviral drug is the lone drug that is used to handle Lassa virus in its early phases. It works by interfering with the viral reproduction by barricading RNA-dependent nucleic acid synthesis [ 7 ] . Patients should have supportive attention which includes care of appropriate organic structure fluid, oxygenation and intervention of timeserving and complicating infections. No vaccinum is available for this diease. Lassa virus can be prevented if contact can be avoided between worlds and the multimammate rat particularly in parts when eruptions are known to happen. Proper storage of nutrient in rodent-proof containers is extremely recommended. Besides, maintaining places clean, disposing rubbish far off from family, maintaining cats and utilizing rat traps in order to avoid attractive force of these vectors can greatly cut down susceptibleness [ 2 ] . The complete obliteration of Mastomys is about impossible because these rodent reservoirs are widely distributed and are really abundant in endemic countries. Peoples caring for patients with Lassa febrility should avoid direct individual to individual reach particularly with blood and bodily fluids of patients. Other safeguards like utilizing sterilised equipments, have oning masks, protective vesture, baseball mitts, face shields, closed-toe places and goggles should be worn before coming in contact with septic patients. Septic patients should be isolated from clean patients as good. Educating people in endemic countries on ways to cut down rodent population in their places and milieus, personal hygiene, developing more rapid diagnostic trials and besides doing Ribavirin readily available to the population can assist to turn to the menace of this disease.
Lassa virus infects males, females and even kids of all age groups. Peoples who are at hazard of undertaking the infection include those that live in or often visit countries that have a high population of Mastomys who are infected with the virus. This includes topographic points with hapless sanitation and/or overcrowded living conditions. Those that work at wellness attention installations are besides at hazard if proper precautionary steps are non taken. Studies show that 300,000 – 500,000 instances of Lassa febrility occur yearly and out of which 5,000 deceases are recorded. Death normally occurs with 14 yearss of happening in foetal instances. This disease is foetal in adult females who are late in gestation and mortality rate is every bit high as 80 % in the 3rd trimester. In Liberia and Sierra Leone, 10-16 % of patients that are admitted in their infirmaries suffer from Lassa febrility which expresses the impact of this dieases in those countries. The most promising attack to developing a vaccinum so far is Vaccinia vectored Lassa cistrons. They have been successfully tested on guinea hogs and Primatess but it has non been tested on worlds.
Lassa virus is an acute viral hemorrhagic febrility that is extremely endemic in West Africa. It is a zoonotic disease that is transmitted to worlds when they come in contact with urine, dungs or elimination of waste merchandises from Mastomys Natalensis normally known as the ‘multimammate rat ‘ . The virus does non impact the rats. Infected rats serve as bearers of the Lassa virus because they are symptomless throughout their life clip. Lassa virus affects about all the tissues in the human organic structure. Person to individual transmittal can besides happen if proper cautiousness is non maintained. Symptoms of this disease scope from febrility to encephalitis and if foetal, decease can happen. Mortality rate is from 15-20 % , nevertheless, it is significantly higher in pregnant adult females. Deafness is a common long term effect of this disease after recovery. Ribavirin is the lone drug that is known to handle this disease and it is merely successful if used when the infection is in its early phases. No vaccinum is available. Preventive steps to avoid this being infected this disease include avoiding contact with rodent vectors, proper storage of nutrient and H2O, isolation of septic patients and taking proper precautional steps when wellness attention workers treat septic patients. Lassa virus affects people of all ages. It is about impossible to eliminate this viral infection because the multimammate rat is abundant in endemic countries.
Work Cited Pages
[ 1 ] The Center for Health and Disease. hypertext transfer protocol: //www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/lassaf.htm. 3rd December 2004. 4th November 2010
[ 2 ] World Health Organization. hypertext transfer protocol: //www.who.int/mediacentre/factsheets/fs179/en/ . April 2005. 4th November 2010
[ 3 ] Ogbu O, Ajuluchukwu E, Uneke CJ ( 2007 ) . “ Lassa febrility in West African sub-region: an overview ” .A Journal of vector borne diseasesA pages 1-11.
[ 4 ] hypertext transfer protocol: //www.ictvdb.org/ICTVdb/00.003.0.01.003.htm. 25th April 2006. 4th November 2010
[ 5 ] Cordell, Ryan. “ The Molecular Biology and General Background of the Lassa Virus ” Powerpoint slide 17-19
[ 6 ] hypertext transfer protocol: //www.tarakharper.com/v_lassa.htm # diethylstilbestrols. 2004. 4th November 2010
[ 7 ] Crotty S, Cameron C, Andino R ( 2002 ) . “ Ribavirin ‘s antiviral mechanism of action: deadly mutagenesis? “ .A J. Mol. Med.A 80A ( 2 ) : 86-95.