Tabanidae

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Tabanidae

• Tabanids as transmitters of pathogens.
• Anautogeny - must have blood meal for development
  of eggs
• Telmophagy feeding habit - pool of blood that can
  receive pathogenic organisms.
• Large blood meals (feed for long time)
• Intermediate feeding (from organism to organism)

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Black Deer Fly Chrysops
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Glossina - The Tsetse Fly

• Day feeders, attracted to moving objects.
• Both males and females feed on blood.
• Larviparous giving birth to larvae ready to
  pupate. The larva is deposited in loose, dry
  soil, and soon completes development.
• Attracted to chemicals found in human sweat (1st
  column, 580)

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Glossina - The Tsetse Fly

• Important vectors of Trypanosoma gambiense and T.
  rhodiense, causative agents for African Sleeping
  Sickness
• Glossina morsitans is one example of many

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African Sleeping Sickness

• Caused by Trypanosoma gambiense and T. rhodiense.
• T. gambiense causes a chronic form that is found
  in west central and central Africa.
• Attacks CNS, often fatal
• Wild animals do not serve as reservoir hosts
• T. rhodiense causes an acute form in east central
  and central Africa.
• Wild animals serve as reservoir hosts.

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Muscidae

• Musca domestica - the house fly
• Why is it so important?
• Synarthropy - close relationship with man -
  frequent table and outhouse.
• A male and female fly inApril. All flies survive
  and reproduce offspring. How many flies in
  August?
• 1.9 X10 20 in August (cover the surface of the
  earth 47 feet deep)

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Myiasis

• Infestation of tissue with maggots
• Cochliomyia hominovorax (primary screw worm) is
  the most important producer of human and
  domesticated animal myiasis.
• Eradicated in U.S. by releasing of sterile male
  flies.
• Female flies only mate once, if mate with sterile
  male, will not mate again.

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Medically Important Arachnids

• The ticks and the mites
• General statements
• Ticks and mites are important because they cause
  harm to animals they infest and because they are
  important vectors for other diseases.
• Ticks are ectodermal parasites of vertebrate
  hosts during larval, nymphal and adult stages
• Mites are found on the skin or in the respiratory
  system or other organs of hosts.

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Medically Important Ticks and Mites

• Morphology
• Segmentation is reduced externally.
• Anterior gnathostoma or capitulum (jawed mouth or
  head) and idiosoma which makes up the body of the
  organism
• The capitulum consists of feeting apendages
  surrounding the mouth. Chelicera or pincher like
  feeding structures are characteristic
• Usually contain 4 pair of legs although some
  mites have less than 4 pair of functioning legs.

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Order Ixodida the ticks

• Several ways they are important to man
• Exsanguination - excessive loss of blood
• Dermatosis - breakdown of dermal tissue
• Paralysis - Paralysis resulting from secretions
  of the tick. Reversed when tick is removed.
• Otoacariasis - Infestation of the ear with ticks
• Transmitters of other pathogenic organisms.

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One, Two, and Three Host Ticks
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Ixodidae (hard ticks) and Argasidae (soft
ticks)
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Family Ixodidae Hard ticks

• Characteristics of hard ticks
• Capitulum is terminal and can be seen from the
  dorsal view
• Scutum is present and eyes when present are on
  the scutum
• Pedipalps are rigid and not leg like
• Marked sexual dimorphorism
• Posterior margin of opisthosoma may be divided
  into sclerites called festoons

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Scutum
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Family Ixodidae Hard ticks

• The family of hard ticks is divided into three
  subfamilies.
• Subfamily Ixodinae with the single genus Ixodes
• Subfamily Amblyominae containing Amblyomma,
  Haemaphysalis, Aponomma and Dermacentor.
• Subfamily Rhipicephalinae containing
  Rhipicphalus, Anocentor, Hytalomma, Boophilus,
  and Margaropus

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Dermacentor variabilis

• American Dog Tick
• Principal vector of Rocky Mountain Spotted Fever
• Causes tick paralysis and transmits tularemia
• Family Ixodidae - hard tick

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Dermacentor andersoni

• Rocky Mountain Wood Tick
• Vector for several diseases in man.

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Amblyomma americanum

• Lone Star Tick
• Wide variety of hosts
• Transmits Rocky Mountain Spotted Fever and
  Tularemia
• Family Ixodidae - hard

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Ixodes scapularis

• Blacklegged tick
• Common In Eastern U.S.
• Family Ixodidae hard tick

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Rhipicephalus sanguineus

• Brown Dog Tick
• Transmits East Coast Fever in Cattle
• Family Ixodidae hard tick

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Other ticks

• Ixodes dammini - important vector for Lyme
  disease. Caused by spirochaete Borrelia
  burgdorferi
• Boophilus annulatus - American cattle tick.
  Transmits Texas Cattle Fever. First evidence of
  arthropod as a vector

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Family Argasidae the soft ticks

• Characteristics
• Capitulum is subterminal and can not be seen from
  the dorsal view
• No festoons or scutum
• Sexual dimorphorism is slight
• Pedipalps are freely articulated and leg like
• Other characteristics see text page 614 second
  column
• There are 5 genera of Soft ticks
• Argas, Ornithodoros, Otobius, Nothoaspis, and
  Antricola

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Scutum
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Otobius megnini

• Spinose ear tick
• Soft tick belonging to the FamilyArgasidae
• May be found in ears
• Adults do not feed

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Argas persicus

• Poultry tick
• Soft tick belonging to the family Argasidae
• Can be very destructive to fowl.

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Mites

• Dermanyssus gallinae the chicken mites -
  Nocturnal feeders that will aggressively feed on
  humans can cause severe dermititis.
• Dermadox folliculorum - hair follicle mite of
  humans (fig 40.9, page 617)
• Family Trombiculidae - the chigger mites
• Sarcoptes scabiei - the itch mite causes
  sarcoptic mange or scabies.

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Dermodex folliculorum

• Human hair follicle mite
• 20 of people under 20 are infected and nearly
  100 of older people.

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Sarcoptes scabiei

• Sarcoptic mange or scabies mite.
• Skin parasites of homoiotherms. What are
  homoiotherms?
• 7 year itch or Norwegian Itch, or scabies.
• May see it.

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Dermanyssus gallinae

• Chicken Mite
• Very destructive to chickens
• Can be very painful to humans.