ticks 1

• TICKS General importance Major cause of disease and production loss

   • Blood losses (large numbers → anaemia)

   • Tick worry (prevent animals feeding) 

  • Disease transmission 

  • Tick paralysis (ascending motor paralysis) • Secondary infection / blowfly strike (at bite site)

   • Production losses (farm animals)\
• Ticks are arthropod parasites - arcarnia
• TICKS Divided on the basis of their MORPHOLOGY into:

   • HARD ticks Important in temperate and warmer climates -but found globally.

  • SOFT ticks More important in warmer climates only
• male hard ticks identify

  scutum - hard dorsal covering > prominent mouth parts > festoons > colour

  A) mouth

  B) scutum

  C) festoons

  
• female hard ticks

  scutum is smaller > mouth part and festoons > BODY WALL - convoluted to accommodate blood meal (esp. female ticks)

  for egg production
• soft ticks

   Scutum – ABSENT

  → Mouthparts – NOT visible from dorsal surface

  → Do NOT swell much (feed little and often)
• TICKS Mouthpart - soft ticsk

  s • CHELICERAE: puncture skin

   • PALPS: (red arrows) sensory organs 

  • HYPOSTOME: (green arrows) tube for sucking host blood, backward pointing teeth- difficult to remove tick

  A) HYPOSTOME: (green arrows) tube for sucking host blood,

  B) palps

  
• TICKS

   Feeding

  → • Tick stands upright

  → Chelicerae cut through skin → pool of blood

  → Hypostome inserted deep into skin

  → Mouthparts CEMENTED in place

  → • Tick feeds continuously + injects saliva (contains substances that decrease   host inflammatory response, increases  permeability of blood vessels → free flow of blood)

  → biological active substance to stop a clot from forming 

  → release their grip and life cycle continues 
• palps sensors co2 and cows are main targets since the transmit
• TICK LIFE CYCLE (months – years) depending on tick .eggs> larva > larvae(6 legs) > nymphs (8 legs) > adult tick
• TICK LIFE CYCLES Hard ticks

  → Classified according to number of different hosts to which they attach during their life cycle: → ONE-host ticks: each stage (larva + nymph + adult) feed on one host, e.g. Boophilus

  → • TWO-host ticks: larvae + nymphs feed on one host; adult ticks on a second host, e.g. Hyalomma 

  → • THREE-host ticks: each stage feeds + develops on a different host, i.e. three hosts, e.g. Ixodes
• soft ticks not classified like hard ticks
• Trans-STADIAL transmission

  • Infectious agent ingested during feeding by larva

   • Passed on as it grows from one host to the next (in 2- & 3-host ticks) as tick develops to nymph + adult

   • NOT passed onto next generation via the egg, not mother to child > but each host get infected
• Trans-OVARIAL transmission

   • Infectious agent is passed from one generation to the next through the egg, e.g. Babesia spp.

  → objects found inside red blood cells transmitted by ticks

  adult > eggs> eggs are infected with agent > eggs develop into larva > larvae > nymphs > adult and passes on agent to hosts > more infection and more ticks that are infected
• HARD TICKS - UK

  → Ixodes spp. (3-host ticks)

  I.ricinus
• →   I. ricinus, most important tick in UK 

  →  Distribution: western UK (mainly) 

  → Wide host range

  • Vector for HUMAN disease: Lyme disease (humans, dogs)

   • Vector for ANIMAL disease: Bovine babesiosis, louping ill, tickborne fever & tick pyaemia

   • Paralysis in humans, dogs (warmer climates only)

  • hard tick
• Epidemiology (Ixodes ricinus)

  • THREE-host tick

   • Life cycle: 3 years (range, 2-7 years) 

  • Ticks feed for a few DAYS each year 

  • MOST of the time – on the ground 

  • Need high RH (>90%) – in matted vegetation (e.g. rough grazing, hedgerows)- rough grazing
• Epidemiology (Ixodes ricinus)

  • Tick activity seasonal, e.g. spring (and autumn)

   • Dependent on temperature + relative humidity

  late spring and summer and early autumn if war, speeds up development
• SOFT TICKS

  Argas spp

  • Infect birds in warmer climates (also humans)

  • Feeds at night → production loss + death (large numbers)

   • Found on migratory birds in temperate regions

  • Infect birds in warmer climates (also humans)
• SOFT TICKS

  Argas spp

   ticks is really dependent on rainfall.

  → And if there's rainfall on and off all year round, well, ticks will be active all year round because it's that much warmer than in temperate climates.

  • Ticks may be active all year round 

  • If limited vegetation mat → activity influenced by seasonal rainfall + vegetation transpiration ( RH)
• Kill ticks on ground

  →  By altering microclimate: pasture improvement, e.g. cultivation, drainage 

  →  By starving: “spelling” pasture (livestock removed); useful only if ticks don’t feed on other hosts 

  →  By burning: e.g. during dry period before rainy season
• Separate host from infection

  → • Stock management: remove stock from tick-infected areas when ticks are active 

  →  Fencing: fence off infested pastures
• Kill ticks on host

  → Acaricides: dipping, spraying, pour-on formulations
• → Enhance host resistance

  • Stock hybridisation: e.g. Bos indicus (humped breeds) x Bos taurus (European breeds). Heritability of resistance to ticks is higher in humped breeds than European breeds
• Enhance host resistance (cont.)

  → • Vaccination: a vaccine is now used in Australia for Boophilus microplus control
• Tick antigens are never introduced into the host while the tick is feeding
• Hidden antigens are injected through theor saliva with tick proteins foreign to the cow
• The cow's immune system will make antibodies against these proteins
• Unfortunately, pretty well all of these antibodies confer no protective effect against future attack
• To vaccinate the cows with the hidden antigen
• Hidden antigens trigger antibody production by the host


  When the tick feeds, these antibodies will be taken straight up into the gut
• Antibodies interact with the hidden antigen


  In the gut of the tick