LASSA Fever Lassa hemorrhagic fever (LHF)
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LASSA FeverLassa hemorrhagic fever (LHF)
Basic InformationIntroAcute viral illness that occurs in west Africa. The virus is named after the town in Nigeria where the first cases occurred. A single-stranded RNA virus and is zoonotic, or animal-borne.
TransmissionHost of Lassa virus is a rodent known as the Multimammate Rat /Mastomys rodents.Once infected, the virus will always be in the animal, for its life time.Transmission of LASSA virus to uhumans occurs most commonly through ingestion or inhalation.Mastomys rodents shed the virus in urine and droppings and direct contace with these materials, through touching soiled objects, eating contaminated food, or exposure to open cuts or sores, can lead to infection.
TransmissionSigns and SymptomsSigns and symptoms of Lassa fever typically occur 1-3 weeks after the patient comes into contact with the virus. Sore throat Back painCoughAbdominal painVomitingDiarrheaFacial swelling mucosal bleedingSlight feverGeneral malaiseWeaknessHeadacheRespiratory distressRepeated vomitingFacial swellingPain in the chest, back, abdomenShockConjunctivitis (Red eyes)
LASSA VirusLassa virus is an emerging virus and a select agent, requiring Biosafety Level 4-equivalent containment.Recently, going on nowEffects both human and agriculture as a threatEnvelopedSingle-strandedBisegmented Ambisense RNA virusesstructure
The genes are oriented in both negative and positive senses on the two RNA segmentsDiameter from 50 to 300 nm.
Lassa virus enters the cell via the receptor molecule alpha-dystroglycan.
Once in the body, it reacts with the macrophage-monocyte cells and dendritic cells.
Replicates and sent throughout the entire body of the victum.
Decrease platelet counts, decrease leukocyte counts, and increase clotting time in patients.
NDeath RateIn West AfricaNotEstimated at 15% to 20%. Some studies estimate mortality as high as 45%.Less than 1% of all infections in result in fatal disease.The mortality rates for Lassa appear to be much higher in people of non-African stock. 92% for fetuses in early pregnancy, 75% for fetuses in the third trimester, and 100% in the neonatal period for full-term babies. pregnantTreatmentRibavirinantiviral drugmost effective when given early in the course of the illnessmaintenance of appropriate fluid and electrolyte balance, oxygenation and blood pressure, as well as treatment of any other complicating infections.
stop viral RNA synthesis and viral mRNA capping
In 1972 it was reported that ribavirin was active against a variety of RNA and DNA viruses in culture and in animals, without undue toxicity.No vaccine is currently available. However, the most promising approach to developing a vaccine appears to be via vaccinia-vectored Lassa genes. These have been protective in both guinea pigs and nonhuman primates. First recognized in 1969 in Lassa, Nigeria. Subsequent outbreaks occurred in Nigeria, Liberia, and Sierra Leone.
In some parts of Sierra Leone and Liberia, 10% to 16% of all patients admitted to hospitals have Lassa fever.
Some Lassa fever cases have been "imported" into the U.S. and U.K. through viremic travelers who acquired the disease elsewhere.Out Breaks
- 1969, northern Nigeria - first recognized outbreak of the disease.- 1970 to present, Liberia. Most cases were hospital workers who acquired the disease in the hospital from the index patient.- 1970 to present, Sierra Leone. It is estimated that 6% of all residents in the initial endemic area have antibodies to Lassa Fever, even though only 0.2% were recognized as clinically ill.Estimated 100,000-300,000 infections per year in West Africa. At the beginning of 2012, WHO was noti-fied by The Federal Ministry of Health in Nigeria of an outbreak of Lassa fever. Total of 623 cases and 70 deaths