Lecture 22 (Ticks)

Made by Harley Chase and Kylee Wood

What is associated with Class Arachnida?

Ticks, Mites, Spiders

What is a common outdoor nuisance associated with pets and humans that play an important role in transmission of infectious disease?

Ticks

What can be caused by Ticks?

Tick Paralysis, Inflammation and infection at site of tick bite

• Lyme Disease

• Rocky Mtn. Spotted Fever

• Canine Babesiosis

What are different Tick-borne Diseases?

• Encephalitides & hemorrhagic fevers

• Rocky Mtn. Spotted Fever

• Boutonneuse Fever

• Queensland Tick Typhus

• Siberian Tick Typhus

• Q Fever

• Tick-borne Relapsing Fever

• Lyme Disease

• Tularemia (Rabbit Fever)

• Babesiosis (Texas Cattle Fever)

What is associated with Ixodid or the Family Ixodidae?

Hard Ticks

Ticks are macroparasites meaning what?

They are visible without a microscope

Ticks have a fused 2-piece body plan including what?

• Fused head/thorax (cephalothorax)

• Abdomen (opisthosoma)

Is there constriction between the head and body in ticks?

No

How is the skeleton/appearance of a tick described?

Chitinous exoskeleton w/ hard scutum and have toothed hypostome

How many legs do adults and nymphs have?

8 legs

How many legs do larvae have?

6 legs

T or F: All ticks are parasitic in all lifecycle stages.

True

T or F: Not all ticks suck blood.

False

*All ticks suck blood

What type of feeders are all stages of ticks?

Obligate blood feeders

What type of life cycle do most ticks have?

A 3 host life cycle

What is there variable expression of among species of ticks?

Nest dwelling (nidicolous) and host seeking (questing)

T or F: Ticks are able to withstand starvation for long periods between hosts.

True

What plays an important role in the infectious disease transmission cycle of ticks?

Wildlife Reservoirs

What is the basic life cycle of the tick?

Eggs → Larva → Nymph → Adult (male/female) → Female acquires host and gets blood meal then lays cluster of eggs

What are the tick life cycle variations?

• 1 host - uses 1 host for entire lifecycle

• 2 host - uses 2 hosts to complete lifecycle (Not common in U.S.)

• 3 host - uses 3 hosts to complete lifecycle

What is the only reason a 1 host tick will leave?

A female will leave to lay her eggs

What does it mean to be a 1 host tick?

It completes the entire lifecycle on a single animal

Where are 1 host tick eggs deposited (oviposition)?

Off the host

Where do 1 host ticks molt to each life-stage (instar)?

On the host

T or F: 1 host ticks are highly susceptible to control efforts.

True

What is the only route of infectious disease transmission associated with 1 host ticks?

Trans-ovarial (Vertical transmission)

Trans-ovarial is the only mechanism for 1 host ticks to do what?

Vector disease

What occurs in Trans-ovarial transmission for 1 host ticks?

Infectious agent is passed to progeny through the ovaries

2 host ticks require 2 hosts for completion of the lifecycle - at what point does the host change?

• Larvae and nymph feed on same host

• Adults acquire new host

Where does oviposition of 2 host ticks occur?

Off the host

Where are 2 host ticks commonly found?

Africa

What is the only route of infectious disease transmission associated with 2 host ticks?

Interstadial

What occurs in interstadial transmission for 2 host ticks?

Infectious agent acquired by larvae/nymph from host and passed to adult stage

How many times does a 3 host tick acquire a new host?

3 times - larvae, nymph, adult

Where does oviposition occur?

Off of the host

How common is the 3 host tick lifestyle in North America tick species?

It is the most common

What is the only route of infectious disease transmission associated with 3 host ticks?

Interstadial

What occurs in Interstadial transmission for 3 host ticks?

Infectious agent acquired by larvae or nymph from host and passed to successive stages — larva to nymph or nymph to adult

What are the 3 primary tick species associated with zoonotic disease?

• Ixodes scapularis

• Amblyomma americanum

• Dermacentor varriabilis

What disease is associated with Ixodes scapularis?

Lyme Disease

What disease is associated with Amblyomma americanum?

• STARI

• Ehrlichiosis

What disease is associated with Dermacentor varriabilis?

RMSF

What is the top arrow?

Capitulum

What is the middle arrow?

Scutum (Dorsal shield)

What is the bottom arrow?

Festoons

What ticks are included in the Dermacentor spp.?

• D. varriabilis

• D. albipictus

• D. andersoni

• D. occidentalis

• D. nitens

What is Dermacentor varriabilis also known as?

American Dog Tick

What type of lifecycle does D. varriabilis have?

3 host lifecycle

Where are D. varriabilis adults found?

On larger vertebrates

What diseases are associated with D. varriabilis or the American Dog Tick?

• RMSF

• Tularemia

• Q Fever

• Tick Paralysis

Where is Dermacentor albipictus found?

Cananda, Northern US, Appalachian Mtns

What type of lifecycle does D. albipictus have?

1 host lifecycle

What species are D. albipictus typically associated with?

• Deer

• Elk

• Moose

What impact does D. albipictus have on the host?

Hair loss/lose body condition in winter

What is Dermacentor albipictus also known as?

The “Winter Tick”

What is Dermacentor andersoni also known as?

Rocky Mtn Wood Tick

What type of lifecycle does D. andersoni have?

3 host lifecycle

Where are D. andersoni adults found?

On larger vertebrates

What is Dermacentor occidentalis also known as?

Pacific Coast TickW

What type of lifecycle does D. occidentalis have?

3 host life cycle

Where are D. occidentalis adults found?

On larger vertebrates

What diseases are associated with D. occidentalis or the Pacific Coast Tick?

• Bovine Anaplasmosis

• Tularemia

• Q Fever

• Tick Paralysis

Where is Dermacentor nitens found?

South Florida and Texas

What type of life cycle does D. nitens have?

1 host life cycle

What disease is associated with Dermacentor nitens?

Equine Babesiosis

What is an acute disease associated with Rickettsial infection by Dermacentor varriabilis?

Rocky Mountain Spotted Fever

What are the initial signs associated with Rocky Mtn. Spotted Fever?

Non-specific muscle aches and fever

What occurs 2-5 days post tick exposure with Rocky Mtn. Spotted Fever?

Rash appears

When is Rocky Mtn. Spotted Fever typically seen?

April - September

How is Rocky Mtn. Spotted Fever treated?

Easily treated with antibiotics - But early diagnosis is key

This canine presented for a spay and a petechial rash was noticed on the abdomen. What does she most likely have?

Rocky Mountain Spotted Fever

What is a tickborne disease associated with the neurotoxic salivary component of ticks?

Tick Paralysis

What can the rapid ascending paresis of tick paralysis lead to?

Respiratory and fatality if untreated

T or F: Tick paralysis can be caused by a single tick.

True

Although other species can be involved, what is tick paralysis often associated with?

Dermacentor varriabilis (American Dog Tick)

What is Amblyomma americanum also known as?

The Lonestar Tick

What are the characteristics that allows you to differentiate the lonestar tick or Amblyomma americanum?

• Long mouthparts (Palps)

• Prominent white spot (“Lonestar”) on dorsal scutum

• Festoons along distal margin

What tick is seen in the following image?

The “Lonestar” Tick - Amblyomma americanum

How can you differentiate a male and female Amblyomma americanum tick?

The scutum in the male is not obvious while the margin of the scutum in the female encircles a white “Lonestar”

What disease is associated with the bite of the Lonestar Tick?

STARI - Southern Tick Associated Rash Illness

Has the etiologic agent for STARI been isolated?

No

What is an acute disease of humans and animals where gram negative bacteria invade white blood cells leading to a low white blood cell count or low platelets?

Ehrlichiosis

What is the principle vector of Ehrlichiosis?

Amblyomma americanum

How many human cases of Ehrlichiosis are seen annually?

> 1200 cases

What is Rhipicephalus sanguineus also known as?

Brown Dog Tick

What type of lifecycle does Rhipicephalus sanguineus have?

3 host lifecycle

Rhipicephalus sanguineus have a tropical distribution including what?

• Adapted to living indoors

• Central heating offers optimal temperature and humidity

• Semi-nidicolous behavior w/ eggs in bedding/residential environment

What does the rapid lifecycle of Rhipicephalus sanguineus facilitate?

The development of huge populations

• Short as 2 months and may require household fumigation

What is Rhipicephalus sanguineus or the Brown Dog Tick a disease vector for?

• Babesia canis, B. gibsoni

• Hepatozoon canis

• RMSF (Rickettsia rickettsii)

What species of tick is associated with the following image?

Dermacentor

What species of tick is associated with the following image?

Rhipicephalus

How would you describe the “neck” of Dermacentor?

Rectangular shaped

How would you describe the “neck” of Rhipicephalus?

Diamond shaped

What is Haemaphysalis longicornus also known as?

The Longhorn Tick

What is an invasive 3 host tick species that is native to Eastern Asia with recent recognition in New Jersey (Aug. 2017) and has been in the U.S. since 2010?

The Longhorn Tick - Haemaphysalis longicornus

What significant vector potential does Haemaphysalis longicornus or the Longhorn Tick have?

• Theileriosis

• Babesiosis

• Anaplasmosis

• Ehrilichiosis

• Lyme borreliosis

• Various viral diseases

How do Haemaphysalis longicornus ticks reproduce?

Parthenogenically - males are rare and unnecessary

What should Haemaphysalis longicornus be differentiated from?

H. leporispalustris - native species on rabbits

T or F: Haemaphysalis longicornus is reportable to the State Vet/USDA.

True

Who is Haemaphysalis longicornus found on?

Cattle, Dogs or Cats