Zoonotic viruses Flashcards
What is a zoonotic virus?
Biruses that normally exist within animal reservoirs and cause disease when transmitted to humans
Newly emerging vs re-emerging
Newly- wasn’t in a population previously
What are two of the most devestating pandemics caused by zoonotic viruses
1918 flu
HIV
Factors that contribute to emergence or
re-emergence of viral diseases
Environmental changes Deforestation Globalization (rapid air travel) Microbial evolution Altered ecosystem Expanding populations
Which zoonotic viruses transmit from animals to humans but do not exhibit human to human transmission under natural conditions
Rabies virus
Sin nombre virus
West Nile virus
Which zoonotic viruses transmit from animals to humans and can cause limited cycles of human to human transmission
Ebola
Nipah virus
Which zoonotic viruses originated or persist in animals but can cause self-sustaining chains of transmission in humans (human to human OR vector to human)
Influenza SARS HIV Yellow Fever Dengue Zika
Rabies
Transmitted from the bite of a rapid animal (usually dog)
Uniformly fatal without treatment
30-50% of cases are children living in poverty
Immunization and post-exposure prophylaxis
Low incidence in US (but found in wildlife). No canine rabies in US.
Rhabsoviridae
Negative strand RNA genome
CONTAINS A LIPID ENVELOPE
Each host has a different virus variant (skunk, bat, foxes, etc) so we can find the source of infection
1-3 months prolonged incubation phase (why post-exposure prophylaxis helps)
Two forms of rabies
- Furious (encephalitic form) 80%-
difficulty swallowing, hydrophobia
Terror and excitation with spasm of inspiratory muscles,
larynx, and pharynx precipitated by attempts to drink
Episodes of hallucination
Hypersalivation
Brain stem dysfunction-coma-death - Paralytic form (20%)
• Lack of major features of furious form
• Quadriparesis
• Multiple organ failure-death
Rabies pathogenesis
Virus replicates initially at site of wound
Infects neurons unnervation site of wound
Infection spreads retrograde through axons to CNS (no viremia)
Behavioral changes/symptoms develop
Post-exposure prophylaxis for rabies
- Treatment of animal wound- immediately wash with soap and water (helps because of lipid envelope)
- Human rabies virus immunoglobulin- passive-immunization around the area of wound
- Rabies virus vaccine (4 dose schedule)
Hantavirus
Bunnyaviridae
Segmented, negative sense, ssRNA genome
Human infection primarily due to exposure to aerosols of rodent urine (persistent infection with no symptoms in rodents)
Example: Sin Nombre
Causes:
Hemorrhagic fever with renal syndrome (HFRS)
Hantavirus pulmonary syndrome (HPS)
Hantavirus pulmonary syndrome (HPS)
Fever, myalgia at first
No cough at onset, but develops later
Later: HA, cough, rapid respiratory failure and death in young, fit people
Low platelet count, neutrophilia, elevated LDH and AST
Sin nombre virus in deer mice
Outbreak in Yosemite in 2012
Treatment of HPS
No specific antiviral therapy available
Supportive care
Support for breathing, ICU hospitalization, early recognition
Filovirus
Ebola, marburgvirus
Non-segmented; negative-sense RNA
Historically associated with sporadic outbreaks in remote Africa
