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Viral Hemorrhagic Fevers: Lassa, Machupo, Junin

Viral Hemorrhagic Fevers: Lassa, Machupo, Junin. Remy Schneider Jazmin Jerez. Arenavirus Structure. Single-stranded, bi-segmented RNA genome Large segment (7200nt), small one (3500nt) Lipid envelope with 8-10nm club-shaped projections. South American Fever Viruses Background.

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Viral Hemorrhagic Fevers: Lassa, Machupo, Junin

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  1. Viral Hemorrhagic Fevers:Lassa, Machupo, Junin Remy Schneider Jazmin Jerez

  2. Arenavirus Structure • Single-stranded, bi-segmented RNA genome • Large segment (7200nt), small one (3500nt) • Lipid envelope with 8-10nm club-shaped projections

  3. South American Fever VirusesBackground • Junin Virus : Argentine hemorrhagic fever (AHF) • 1950’s emergence plagued the Buenos Aires region • The peak frequency is during corn harvesting between March and June • Case fatality rate of 20% • Machupo Virus: Bolivian hemorrhagic fever (BHF) • First documented in 1959 and first isolated in 1963 • Case fatality rate is 20%

  4. Reservoir • Junin virus • Calomys laucha or Calomys musculinus • 75% of infected people are male agricultural workers • Contaminated by inhalation of infected aerosols or from rodents caught in mechanical harvesters • Machupo virus • Calomys callosus

  5. Symptoms • Junin/Machupo virus: • Incubation 7-16 days with slow onset of symptoms • First symptoms: fever, malaise, headache, muscular pains, anorexia, nausea and vomiting • Between third and fifth day: dehydration, hypotension, infrequent urination, bradycardia • Hemorrhagic phase: • Begins with petechiae (blood spots) on upper trunk and oral mucosa • Hemorrhaging starts from nose, gums, stomach and intestines where severe blood loss results in hypotensive shock and neurological crisis

  6. Remedies • Junin • Immune plasma therapy • Herbal: NDGA-compound in Larra divaricata leaf resin & aromatic plant oils from Argentina • Candid 1, live-attenuated vaccine • Induces neutralizing antibody response • Developes virus-specific antibody-dependant cellular cytotoxicity • Machupo • immune plasma therapy from survivors • Ribavirin • Candid 1 gives some protection from BHF

  7. Lassa Fever Virus • Background • Discovered in 1969 when two missionary nurses died in Lassa, Nigeria, W. Africa • It expands to Guinea, Liberia, Sierra Leone • 100 to 300 thousand cases per year with approx. 5,000 deaths

  8. Case Study • New Jersey, 2004 • Liberia-born US resident travels to West Africa. He begins to feel feverish, with chills, severe soar throat, diarrhea, and back pain. He travels back to Newark, is then admitted to a hospital in Trenton where he eventually dies.

  9. Primary Means of Diagnosing Arenaviruses

  10. Reservoir/Transmission • Multimammate rat (Mastomys natalensis) • High breed frequency • Virus shed in urine and feces • Instinctual scavengers • Person to person contact through exchange of bodily fluids only • Nosocomial transmission

  11. Symptoms • Incubation period of 6-21 days • 80% of human infections are asyptomatic • Onset is slow: fever, weakness, & malaise • Few days: headache, pharyngitis, muscle pain, retrostinal & abdominal pain, nausea, vomiting, conjunctivitis, diarrhea, cough, & proteinuria • Severe cases: • facial swelling, lung cavity fluid, hemorrhaging, hyopotension, • Neurological problems: tremors, encephalitis, hair loss, gait disturbance, deafness • 95% deathrate among pregnant women & spontaneous abortion

  12. Remedies • Antiviral therapy (Ribavirin) • Acts via lethal mutagenesis • 1989 study: Rhesus monkeys injected with mopeia & vaccinia (V-LSGPC) viruses and escaped death • Non-Specific control: fluid replacement (electrolyte balance), blood transfusion, fighting of hypotension • Hemmorrhaging treated with clotting factor and/or platelet repacement • Promising vaccine • Developed by USAMDRID (2005) • Attentuated recombinant stomatitis virus vector expressing the Lassa viral glycoprotein

  13. Prevention • Nosocomial: Complete equipment sterilization & protective clothing • House to house rodent trapping • Better food storage & hygiene • Cautious handling of rodent if used as food source

  14. References • http://en.wikipedia.org/wiki/Lassa_fever_virus • http://en.wikipedia.org/wiki/Machupo_virus • http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/lassaf.htm • http://www.who.int/mediacentre/factsheets/en/ • S. P. Fisher-Hoch; J. B. McCormick; D. Auperin; B. G. Brown; M. Castor; G. Perez; S. Ruo; A. Conaty; L. Brammer; S. Bauer. Proceedings of the National Academy of Sciences of the United States of America, Vol. 86, No. 1. (Jan. 1, 1989), pp. 317-321 • Duschatzky CB; Possetto ML; Talarico LB; García CC; Michis F; Almeida NV; de Lampasona MP; Schuff C; Damonte Ebf. Antiviral chemistry & chemotherapy. [Antivir Chem Chemother] 2005; Vol. 16 (4), pp. 247-51 • MMWR: Morbidity & Mortality Weekly Report, 10/1/2004, Vol. 53 Issue 38, p894

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