Lassa

Although the term nucleoside was once limited to the compounds in Table 28.2 and a few others, cunent use is more permissive. Pyrimidine derivatives of D-arabinose, for exfflnple, occur in the free state in certain sponges and are called spongonticleosides. The powerful antiviral drug ribavirin, used to treat hepatitis C and Lassa fever, is a synthetic nucleoside analog in which the base, rather than being a pyrimidine or purine, is a triazole. 

Lassa Fever W. Africa Rodent Aerosol, Fomites ... 

Drugs Available Prophylactic ribavirin may be effective for Crimean-Congo hemorrhagic fever, Lassa fever, and Rift Valley fever. 

Lassa Fever Aerosol Low to moderate High 10-14 days 1-4 weeks Unknown Relatively stable No Effective Experi- mental... 

Viruses (smallpox, encephalitis, and hemorrhagic fevers like Ebola, Lassa and Rift Valley fevers)... 

Treatments with immune globulin vaccines are useful against Crimean Congo hemorrhagic fever, Rift Valley fever, Bolivian hemorrhagic fever, and Lassa fever Yellow fever vaccine is the only established and licensed vaccine for a hemorrhagic fever several others are under development... 

Viral A hemor hagic fevers (Ebola, Marburg, Lassa) Animals— rodents, ticks 4-21 days Yes Contact Fever, massive hemor hage, malaise, facial/ ho ax fl ushing, HA, V/D, hypotension Fatal w/in 2 weeks Supportive, fluid replacement ribavirin for Congo-Crimean HF/arenavi ruses... 

Although ribavirin monotherapy is ineffective against HCV, oral ribavirin in combination with inter-feron-a (Rebatron) is approved for this indication and is effective in patients resistant to interferon therapy alone. Intravenous ribavirin may be useful in the therapy of Hantaan virus infection, Crimean or Congo virus hemorrhagic fever, Lassa fever, and severe adenovirus infection. 

Intravenous ribavirin decreases mortality in patients with Lassa fever and other viral hemorrhagic fevers if started early. High concentrations inhibit West Nile virus in vitro, but clinical data are lacking. Clinical benefit has been reported in cases of severe measles pneumonitis and certain encephalitides, and continuous infusion of ribavirin has decreased virus shedding in several patients with severe lower respiratory tract influenza or parainfluenza infections. At steady state, cerebrospinal fluid levels are about 70% of those in plasma. 

Rhabdo Arena RNA RNA ss ss 6 175x 75 85-120 Bullet shaped Roughly spherical Helical Helical + + VSV Lassa... 

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