Ectoparasites and other blood feeding insects as vectors of virus spread

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Ectoparasites and other blood feeding insects as vectors of virus spread
2015-01-07 12:45:51
Ectoparasites Viruses Vectors

Vet Med - Module 7
Show Answers:

  1. What is an ectoparasite?
    A parasite that lives on or in the skin but not within the body
  2. What is a zoonosis?
    A disease/infection naturally transmitted between vertebrate animals and humans
  3. What is a dead end host?
    A host from which infectious agents are not transmitted to other susceptible hosts
  4. What is viraemia?
    The presence of virus in the blood
  5. What is the difference between biological and mechanical vectors?
    In biological vectors the virus multiplies within the host whereas in mechanical vectors the virus does not multiply within the host
  6. What is an arbovirus?
    Arthropod-borne viruses are viruses which are maintained in nature through biological transmission between vertebrae hosts by arthropods.  They multiply and produce viraemia in the vertebrates, multiply in the tissues of the arthropods and are passed on to new vertebrates by the bite of arthropods
  7. List examples of diseases caused by arboviruses
    • Bluetongue virus
    • African Swine Fever virus
    • West Nile Virus
    • Louping ill virus
  8. How is arbovirus transmitted between vertebrates and arthropods?
    • Can be passed on at different stages of arthropod life cycle
    • By venereal transmission between arthropods
    • By close feeding on vertebrate hosts (in low viraemic hosts)
  9. In which species does Bluetongue cause disease?
    It causes clinical disease in sheep (and sometimes cattle)
  10. What is the vector for Bluetongue?
  11. Is Bluetongue an RNA or DNA virus?
  12. What are the clinical signs of Bluetongue?
    Fever, changes to the mucous linings of the mouth, nose and coronary band, reproductive disorder, vascular disease
  13. True or false: Bluetongue is a notifiable disease in the UK?
  14. How is Bluetongue transmitted?
    It is transmitted by midge vectors - the virus is in their saliva
  15. In which species does African Swine Fever virus cause disease?
    It causes clinical disease in domestic and wild pigs
  16. What is the vector for African swine fever virus?
    Soft tick
  17. How is african swine fever virus transmitted?
    Primarily by the tick/natural host cycle (sylvatic cycle) but also by pig/pig cycle in some areas (domestic cycle)
  18. What type of virus is african swine fever virus?
    An arbovirus (only DNA arbovirus)
  19. Describe the tick/natural host cycle of infection in african swine fever virus
    The tick acquires the virus on feeding or in ova, develops persistent infection.  The virus may then be transmitted to a new host during the next feeding.
  20. Describe the pathology of african swine fever
    African swine fever causes acute haemorrhagic disease.  Pigs have a grossly enlarged spleen, haemorrhagic lymph nodes and haemorrhagic skin lesions.
  21. True or false: african swine fever is a notifiable disease in the UK?
  22. Describe the domestic cycle of infection in african swine fever
    The virus can be passed on through uncooked pigment, domestic pigs, fomites (environmental contamination) via the oronasal route.  It can also be transmitted by mechanical transmission of biting flies and ticks (although ticks are not always associated with domestic cycle persistence).
  23. How do you control African swine fever virus?
    There is no treatment or successful vaccine so the best measures are to: prevent contact with carrier pigs, tick control, and trying to maintain a disease free status through control of pigs/pig meat imports, slaughter policies in events of outbreaks, boiling of swill.
  24. In which species does West Nile Virus cause disease?
    It causes clinical disease in horses and man
  25. What is the vector for west nile virus?
  26. Which species is the dead end host for west nile virus: horses or man?
  27. What type of virus is west nile virus?
    A flavivirus
  28. True or false: west nile virus is a zoonotic disease?
  29. List some measures for general arthropod control
    • Insect zappers in housing facilities
    • Dips
    • Habitat control
    • Insecticides
    • Release of sterile males
    • Release of 'good' arthropods