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Infectious Disease: Unit 2 > Zoonotic Viral Diseases > Flashcards

Flashcards in Zoonotic Viral Diseases Deck (15):
1

Characteristics of emerging nad reemerging infectious diseases around the world

1. Emerging infections are a global problem and occur in both temperate and tropical regions

2. Most emerging and re-emerging infectious diseases are zoonotic diseases

3. Incredible diversity in types of zoonotic pathogens and the diseases they cause in humans

2

Factors that contribute to emergence/re-emergence of viral diseases

  •  Improved detection and dx: “Emerging Dx”
  •  Viral genetic changes: alters properties such as virulence, tropism, transmission
    • Mutations in the spike glycoprotein of SARS-CoV enhanced human infection
  • • Human susceptibility to infection
  • International travel and commerce
    • Global spread of Ae. albopictus mosquitoes in old tires
  • • Changes in populations of reservoir hosts or vectors
  •  • Human demographics (e.g. population density, activity)
  •  Poverty
  • • Climate, changing ecosystems
  • • Changing land use and agricultural practices

3

Zoonotic viruses that are also human pathogens

  • Rabies virus
  • Hantaviruses (Sin Nombre)
  • Filoviruses (Ebola & Marburg)
  • Arenaviruses (Junin, Machupo, & Lassa)
  • Paramyxoviruses (Nipah & Hendra)
  • Arboviruses
  • HIV
  • Influenza virus
  • MERS-CoV

4

Common zoonotic diseases present in CO

  • Rabies
  • Hantavirus
  • Colorado Tick Fever
  • West Nile Virus

5

Characteristics of Rabies

  • Global Distribution 
  • Disease transmitted to humans via the bite of a rabid animal
  • Without treatment = Uniformly fatal
  • Rabies is completely preventable both before and after infection • Immunization and post-exposure prophylaxis

6

Rabies prevention

  •  Vaccination of companion animals:
    • • Annual turnover of dog population necessitates revaccination of millions of animals each year
    • ==> elimination of canine rabies in US
  • Animal control programs and surveillance
  • Maintenance of rabies laboratories
  • Avoiding common reservoirs
    • bats
    • skunks
    • racoons

7

Clinical presentation of Rabies

  • Prolonged incubation phase  1-3 months 
  • Two major forms: Both begin with nonspecific symptoms (fever, headache, nausea)
  • • Furious (encephalitic) form (80%) •
    • Difficulty swallowing
    • Hydrophobia
    • Episodes of hallucination
    • Hypersalivation
    • Brain stem dysfunction-coma-death
  • Paralytic form (20%) • Lack of major features of furious form • Quadriparesis • Multiple organ failure-death

8

Tx of Rabies

  • Treatment of animal wounds:
    • • Immediately wash with soap (detergent) and water
  •  Human rabies virus immunoglobulin (HRIG)
    • • Passive-immunization around area of wound—neutralize virus
  • • Rabies virus vaccine (4 dose vaccine schedule)
    • Inactivated vaccine
    • • Administered IM at different site than HRIG
    • • Additional doses at days 3, 7, and 14 (New 2010 recommendations)

9

Algorithm for rabies tx

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10

Hantavirus characteristics

  • Human infection primarily due to exposure to aerosols of rodent urine
  • Causative agents of two major diseases in humans: • Hemorrhagic fever with renal syndrome (HFRS) • Hantavirus pulmonary syndrome (HPS)
  • Family of viruses ==> disease
  • Common virus in N.A. = "Sin Nombre" and is carried by deer mouse

 

11

Clinical presentaiton of hantavirus pulmonary sydnrome

  • Prodromal phase characterized by: Fever Chills Myalgia
  • Clinical recognition of HPS prodrome:
    • Pain in legs and back can be very severe
    • Presence of productive cough at onset of illness is NOT consistent with HPS
    • Laboratory findings:
      • • Low platelet count
      • • Neutrophilia
      • • Elevated LDH and AST
    • • Rodent exposure:  increase in mouse populations around their residence or exposure to mice-infested areas

12

Treatment of HPS

  •  No specific anti-viral therapy or vaccines available
  • • Treatment options limited
    • • Supportive Care
    • • Assisted Respiration
    • • Blood oxygenation in severe cases •
  • Outcomes significantly improved when:
    • • Early recognition of disease (symptoms + rodent exposure)
    • • Immediate hospitalization in ICU
    • • Adequate support for breathing

13

Zoonotic viruses that transmit from animals to humans and can cause limited cycles of human to human transmission 

  • Lassa fever virus
  • Machupo virus
  • Ebola virus
  • Marburg virus
  • Nipah virus
  • Monkeypox

14

Major zoonotic viruses that have some person-person transmission + region + host + disease

  • Lassa virus (Arenaviridae virus)
    • W. Africa
    • Rodent host
    • ==> hemorrhagic fever
  • Ebola (filoviridae virus)
    • Africa
    • Bat host
    • ==> hemorrhagic fever

  • Nipah (paramyxociridae virus)

    • Asia

    • Bat host

    • ==> respiratory/neurologic syndrome

15

Originated or persist in animals but can cause self-sustaining chains of transmission in humans (human to human OR vector to human) 

  • HIV
  • Influenza virus
  • SARS- and MERS-CoV
  • Yellow Fever virus
  • Dengue virus
  • Chikungunya virus