Ixodidae Ticks & Tick-borne DiseasesMichael Lehrke

Ixodidae Ticks

• Ixodidae ticks are hard ticks• Taxonomy:• Kingdom: Animalia• Phylum: Arthropoda • Class: Arachnida (Eight legs)• Subclass: Acari (Ticks & Mites)• Superorder: Parasitiformes (Parasitic ticks)• Order: Ixodida• Family Ixodidae (Hard ticks)

• 702 species in 14 genera

Notable Species

• Amblyomma americanum• The lone star tick

• Dermacentor andersoni• Wood tick

• Dermacentor variabilis• American dog tick

• Ixodes scapularis (Ixodes dammini)• Black-legged deer tick

• Rhipicephalus sanguineus• Brown dog tick

General Morphology

• Hard scutum or shield, on females it is partial on males it is full

• A capitulum (mouth parts) that projects from the body• Opposed to soft ticks in which the

head is beneath the body

A. americanum Morphology

• Red-brown color, females have white spot posterior to scutum, males have more than one spot around body

• Mouth parts are particularly long

• Festoons are present

Dermacentor Morphology

• Females have a white scutum and brown body, males are brown with white markings (D. variabilis has more white)

• Eleven festoons

• Basis capituli is straight

• Coxae get larger from anterior to posterior

I. scapularis Morphology

• They have reddish bodies with black scutum, males are usually mostly black

• Lack of festoons

• Have anal groove on ventral side, anterior to the anus

• Adults are “1/2 sesame” sized and nymphs are “poppy seed” sized

R. sanguineus Morphology

• Brown abdomen and scutum

• Festoons present

• Hexagonal basis capituli

• Coxae remain same size

Morphology

Amblyomma americanum• Definitive hosts: Cats, cattle, sheep, goats, horses, rodents,

primates

• Intermediate hosts: Cats, rodents, rabbits

• It is a three-host tick

• Southern US and Mexico

Dermacentor andersoni• Definitive hosts: Dogs, cattle, sheep, goats, horses, primates,

raccoons

• Intermediate hosts: Rodents, rabbits

• It is a three-host tick

• Western North America and Canada

Dermacentor variabilis• Definitive hosts: Dogs, cats, cattle, rodents, primates, raccoons

• Intermediate hosts: Rabbits

• It is a three-host tick

• Central and Eastern US

Ixodes scapularis• Definitive hosts: Dogs, cats, cattle, rodents, horses, pigs,

rabbits, birds, primates

• Intermediate hosts: Rabbits, rodents, snakes/turtles

• It is a three-host tick

• Central, Midwest and Eastern US

Rhipicephalus sanguineus• Definitive hosts: Dogs, rodents, rabbits, primates

• Intermediate hosts: Dogs, rodents, rabbits

• It is a three-host tick

• Entire US (your dog is not safe!!)

Life Cycle

• Three host tick: feeds on three hosts during life cycle• Can be all different or the same individual

• Molt in between feedings

• Usually winter before each feeding and after molting

• Progress from Egg -> Larvae -> Nymph -> Adult• Larvae, aka rebels, have 6 legs (nymphs keep it real

with 8 again)

Life Cycle

Life Cycle

Pathology

• Usually asymptomatic, like a normal insect bite• Tick cuts into skin (can take 10 min to 2 hours to prepare),

inserts feeding tube, and secrete anesthetic saliva! (Sucks, literally)

• Dermacentor and Ixodes have been implicated with tick paralysis• Acute, ascending, flaccid motor paralysis, can result in

death• Thought to be caused by toxins

• Ticks can transmit diseases!

Treatment/Control

• Remove the tick, duh• DO NOT use ointments/Vaseline or heat, ticks

vomit, possibly forcing pathogens into you!

• Avoid tick infested areas

• Repellent (DEET)

Tick-borne Diseases

• Anaplasmosis

• Babesiosis

• Ehrlichiosis

• Lyme disease

• Rocky Mountain Spotted Fever

Anaplasmosis• Formerly human granulocytic ehrlichiosis (HE), now referred to human

granulocytic anaplasmosis

• Caused by bacteria Anaplasma phagocytophilum, transmitted by Ixodes scapularis

• Symptoms include fever, headache, chills, muscle aches usually 1-2 weeks after bite

• Diagnosed on symptoms and can be confirmed by lab tests, treated with doxycycline

Babesiosis

• Caused by blood parasite Babesia microti, transmitted by Ixodes scapularis

• Usually asymptomatic, can cause flu-like symptoms, dangerous to immunocompromised people

• Diagnosed with blood smears, visualizing “Maltese-cross” formations, treated, usually clears itself or can be treated with drug combinations

Ehrlichiosis

• Caused by Ehrlichia species of bacteria, transmitted by lone-star tick

• Flu-like symptoms, malaise, confusion, rash, red eyes

• Diagnosed on clinical signs and lab tests, treated with doxycycline

Rocky Mountain Spotted Fever• Caused by the bacteria

Rickettsia rickettsi, transmitted by Dermacentor variabilis, Dermacentor andersoni, and Rhipicephalus sanguineus

• Flu-like symptoms, spotted rash, can be deadly if not treated

• Suspicion, blood tests, platelet count, treated with doxycycline

Lyme Disease

• NOT “Lyme’s Disease” – Named after

• Caused by the spirochete bacteria Borrelia burgdorferi, transmitted by Ixodes scapularis

• Acute: Flu-like symptoms, erythema migrans (bull’s-eye rash), Bell’s palsy, joint pain, fatigue• Chronic: Arthritis, neurological issues, persistent fatigue• Post-treatment: fatigue, sleep disturbance, cognitive

defects, joint problems

Lyme Disease

• Diagnosed with blood tests (after several weeks), treated with doxycycline, Ceftin, or amoxicillin

Lyme Disease

• Prevalent on the East Coast and in the Midwest (particularly around this area and Wisconsin)

• Prevalence is dramatically climbing• In 2000 MN had 465 cases, in 2010 that rose to

1293 (270% increase)!• In 2000 WI had 631 cases, which rose to 2505

in 2010 (400% increase)!

Lyme Disease

Lyme Disease

Lyme Disease

Prevention

• These diseases can be prevented by avoiding ticks, using repellents (DEET), and promptly removing ticks

Questions?