prevent disease, disability and premature death. relate the biology of ticks to appropriate control...
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Prevent Disease, Disability and Premature Death
Tick Biology & Control Tick Biology & Control
Prevent Disease, Disability and Premature Death
Relate the biology of ticks to appropriate control measures.
Objectiveهدف
Prevent Disease, Disability and Premature Death
Characteristics
Life Cycle
Habits
Disease Agent Transmission
Surveillance and Control Measures
Overviewمرور
Prevent Disease, Disability and Premature Death
Ticks are arachnids:cousins of spiders and scorpions
Represent a very important group of vectors of arthropod-borne diseases.
These diseases include:Rickettsiae: Boutonneuse Fever, Q-Fever, etc.Spirochetes: Relapsing fever, etc.Other bacteria: tularemia, mycobacterium, etc.Viruses: Crimean-Congo HFProtozoa: Babesia, Theileria, trypanosomes, etc.
Prevent Disease, Disability and Premature Death
Disease Agents Transmitted By Ticks
Worldwide, they rank number two behind mosquitoes as vectors of disease.All life stages are obligate blood feeders Hosts can come from virtually any vertebrate group including mammals, reptiles, birds, and amphibians.Ticks are divided into two distinct families—hard ticks (Ixodidae) and soft ticks (Argasidae).
Prevent Disease, Disability and Premature Death
GENERAL TICK MORPHOLOGY AND BIOLOGY
Hard ticks & soft ticks are very different in appearance,biology, and behavior.
Illustration available on-line at www.howstuffworks.com
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Which is which?Mouthparts NOT
visible from above
Mouthparts visible from
above
Soft Tick Hard Tick
Prevent Disease, Disability and Premature Death
Hard Ticks (Family Ixodidae)Have a stiff, leathery cuticle on their back called a scutum
Covers entire back of the maleA small plate on back of female
Mouthparts project off the front of the tick and are visible from above
Males are smaller than females
Prevent Disease, Disability and Premature Death
HARD TICKS (FAMILY IXODIDAE)
• Sexual Dimorphism: males are smaller than females
Left to Right: Attached male, attached gravid female, attached gravid & engorged female
Sexual dimorphism is the systematic difference in form between individuals of different sex within the same species.
Prevent Disease, Disability and Premature Death
Life cycle of hard ticks
• Egg• Larva -- 6 legs• Nymph -- 8 legs, but
sexually immature• Adult -- 8 legs, sexually
mature• Molt (shed skin) only
once between each successive life stage
Prevent Disease, Disability and Premature Death
Life cycle of hard ticks
• Female lays thousands of eggs at one time
Prevent Disease, Disability and Premature Death
Life cycle of hard ticksLarval ticks emerge seemingly all at once and only have six legs during this stage
Prevent Disease, Disability and Premature Death
Life cycle of hard ticks
After molting and developing their last pair of legs, nymphal ticks seek a blood meal from smaller animals.
Prevent Disease, Disability and Premature Death
Life cycle of hard ticks• Nymphal ticks molt into
adults, and seek out larger animals for a blood meal.
• Adults attach tightly to host and feed over a period of hours, days, or weeks.
Prevent Disease, Disability and Premature Death
Life cycle of hard ticks
• Adults mate on the host, usually reproduce only once.
• Adult female falls to the ground, lays eggs, and dies shortly thereafter.
Prevent Disease, Disability and Premature Death
Soft Ticks (Family Argasidae)
Males and females are very similar in appearance
Lacks a scutum
Body ranges from fleshy to leathery in texture
Mouthparts are located underneath the body towards the front, and are not visible from above
Prevent Disease, Disability and Premature Death
Soft Ticks (Family Argasidae)
Ventral side of a soft tick.
Note that the mouthparts are
tucked underneath
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Egg -- Very hardyLarva -- 6 legsNymph -- 8 legs, but sexually immature
Molt 5-7 times during nymphal life stage
Adult -- 8 legs, sexually mature
LIFE CYCLE OF SOFT TICKS
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Mate off the host, reproduce several times.Attach to host only to feed
Loosely attach & feed rapidly
Hide in cracks & crevices of host’s nest, bedding, or home
LIFE CYCLE OF SOFT TICKS
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High vector potentialGreat Reproductive Capability
Can lay a tremendous number of eggs
Production of several thousand eggs isn’t uncommon
Persistent Bloodfeeders
If they’re not feeding on a host, they’re looking for one
Ticks climb vegetation and “grabs” the host as it passes. This is known as “questing.”
Prevent Disease, Disability and Premature Death
High vector potential
Relative Freedom from Natural Enemies
There’s not too many things that eat ticks
Fire ants seem to like them fine
Encyrtid Wasp only known parasitoid
Photo by: Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services, Bugwood.org
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High vector potentialSlow Feeding
Hard ticks take up to 2 hours to find an attachment point.
Usually requires 4 - 24 hours of feeding before the pathogens leave the tick and enter host
A hard tick may take 5 - 7 days to feed
Prevent Disease, Disability and Premature Death
Wide Host Range1-, 2-, or 3- host ectoparasites. Risk of disease transmission greatly increases with multiple host ticksE.g., the black-legged tick feeds on mice as a larva, larger animals like raccoon as a nymph, and deer as an adult.
HIGH VECTOR POTENTIAL
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Longevity
Hard ticks may live 3 - 5 years
Soft ticks may live 15 - 20 years
Transovarial Transmission Of Pathogens
Pathogen is passed from the female tick to the embryonic egg
When the eggs hatch, the larvae emerge already infected with the pathogen
Ticks are thus reservoirs for diseases
HIGH VECTOR POTENTIAL (HARD TICKS)
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Hard Ticks“Transitional Zones”
Deep woods
Shrubby areas
Shorter grasses and weeds
Vegetation along animal trails
On the host
Soft Ticks
Cracks and crevices of host’s burrow
Abandoned dwellings and caves infested by animal hosts
TICK HABITAT
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Drag Cloth Method
TICK SURVEILLANCE
Flannel Sheet & Dry Ice
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Vegetation ReductionCut-back or totally remove habitats
Host ExclusionConstruct physical barriers to keep tick-infested hosts out of areas where personnel will inhabit.
TICK CONTROL
Prevent Disease, Disability and Premature Death
Pesticides General area application for hard ticks is impractical since they spend most of time on host
Treatment is only temporaryMay serve well as a barrier treatment around tents or areas requiring protection against ticks
TICK CONTROL
Prevent Disease, Disability and Premature Death
Personal Protection from Ticks
Avoidance
Refrain from entering areas that are known to be infested with ticks.
Reduce activities in those areas when complete avoidance is impractical.
Prevent Disease, Disability and Premature Death
Proper Wear of Clothing
This includes wearing clothing that will prevent ticks from reaching your skin, such as long sleeves and long pants.
Tuck your shirt into your pants and your pant cuffs into your socks or boots.
Personal Protection From Ticks
Prevent Disease, Disability and Premature Death
Personal Protection from Ticks
Tape Barriers Wrap double-sided tape or regular tape with the adhesive side out to form a sticky barrier which will form an external barrier on your uniform. Ticks are “unidirectional” (travel in one way—upward) and will get stuck as they climb up your pants.
Prevent Disease, Disability and Premature Death
Repellents (covered in detail in PPE lecture)Permethrin (Aerosol or IDA kit) treatment of uniform.
DEET lotion for skin.
Personal Protection from Ticks
Prevent Disease, Disability and Premature Death
Tick removal
Search for and remove ticks as soon as possible
The longer the tick remains attached, the more engorged and difficult it becomes to remove
The longer the tick remains attached, the more likely the chance of infection, disease transmission, or tick paralysis
Prevent Disease, Disability and Premature Death
Tick removal
DON’T “bare hand” ticksTicks may shed pathogens in their feces at any time, and these may contaminate cuts or abraded skin
Fingers contaminated with infected feces may introduce pathogens (especially viruses & rickettsias) through the mucus membrane of the nose or eyes
Prevent Disease, Disability and Premature Death
Tick removal
DON’T use VaselineWON’T WORK!!!Ticks cannot be suffocated (Acquires oxygen needs from your blood)Tick leaves only when it has finished feedingThe longer it remains attached, the greater chance for disease transmission
Prevent Disease, Disability and Premature Death
Tick removal
DON’T use Fingernail Polish
WON’T WORK!!!Ticks cannot be suffocated (acquires oxygen needs from your blood)Tick leaves only when it has finished feedingSolvent in fingernail polish may irritate tickIrritated tick may regurgitate gut contents and pathogens into your blood…increasing chance of infection
Prevent Disease, Disability and Premature Death
Tick removal
DON’T use Matches/Fire
WON’T WORK!!!Tick might be killed and will never leaveAt the very least, tick will be irritatedIrritated tick may regurgitate gut contents and pathogens into your blood…increasing chance of infectionPotential damage to skin may enhance pathogen transfer into body
Prevent Disease, Disability and Premature Death
Tick removal
DON’T use Gadgets/PliersUsually Don’t Work!!!Tick will be crushed or at least squishedSquished tick will have gut contents and pathogens squished into your blood
May cut the tick from its mouthparts, leaving the mouthparts in the wound and causing possible infection
Prevent Disease, Disability and Premature Death
Tick removal
USE Fine-Pointed ForcepsGrasp tick by mouthparts as close to skin as possible (Figure 1)Using slow & steady pressure, gradually pull tick from skin (Figure 2). Skin may stretch a bit, but that is okay.
Prevent Disease, Disability and Premature Death
Tick removal
USE Fine-Pointed ForcepsAfter tick detaches, check the mouthparts (Figure 3)
If clump of your skin attached, you got the whole tickIf no clump of skin attached, mouthparts broke off in skinSecondary infection possible if mouthparts not removed
Prevent Disease, Disability and Premature Death
Summary
Characteristics
Life Cycle
Habits
Disease Agent Transmission
Surveillance and Control Measures
Prevent Disease, Disability and Premature Death
Questions?
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