Ectoparasites III- Other Tick-Borne Pathogens Flashcards
How long do most hard ticks attach and feed?
Days
Why do immature and adult female ticks take day to complete feeding/engorge?
They have an incomplete scutum
What is feeding like for soft ticks?
Feed quickly and often
Usually go back to same host repeatedly
What are methods of direct disease?
Tick bites
Paralysis (toxicosis)
…red meat allergy
What are methods of indirect disease?
Transmission of pathogens
- -viruses
- -bacteria
- -protozoa
What is the clinical presentation of direct disease from tick bites?
Pain and inflammation at site Possible complications (anemia, secondary infections, "tick worry")
What are methods of treatment and prevention for direct disease from tick bites?
Manual removal vs. acaricide
Year-round control
What is an example of a severe direct disease due to bites?
Dermacentor albipictus (Winter Tick) is a 1-host tick known for causing hair and blood loss primarily in moose
What is tick paralysis (direct disease) caused by?
Toxin in tick saliva
Often female hard ticks
Why do female ticks often cause tick paralysis?
They stay on longer
What are the tick species that can cause tick paralysis?
Argasid: Argas persicus
Ixodid: Dermacentor* variabilis, Ambylomma maculatum, A. americanum
What is the clinical presentation of tick paralysis?
Acute ascending flaccid paralysis
What is Red Meat Allergy?
Direct disease
Allergic reaction to pork, beef, lamb
Described in humans
IgE antibodies to galactose-α-1,3-galactose (α-gal)
What is galactose-α-1,3-galactose (α-gal)?
Oligosaccharide blood group component found in non-primate species
What are the 2 processes that that transmission via vectors can occur with indirect disease?
Biological transmission (most vector-borne diseases) with reproduction or developmental changes in pathogen Mechanical transmission without reproduction or developmental changes in pathogen
What makes a tick a good vector?
Persistent blood-feeder Wide host range Few natural enemies High reproductive potential Pathogen can be maintained in tick populations
What makes up the tick-host-pathogen system?
Vector competency
Reservoir host
What is vector competency?
Capable of acquiring, maintaining, and transmitting an infectious agent
What is a reservoir host?
Capable of acquiring, maintaining, and transmitting infectious agents
May be the vertebrate host or arthropod vector
What was the first described vector-borne disease?
Texas cattle fever (1893), Babesia/Rhipicephalus
What is the time line for the first VBD described?
1893: Texas cattle fever, Babesia/Rhipicephalus
1905: relapsing fever (Africa), Borrelia/Ornithodoros)
1906: Rocky mountain spotted fecer, Rickettsia/Dermacentor
Describe tick-borne encephalitis
Powassan Encephalitis:
Vector(s)- Ixodes spp.
Clinically affected: humans
Mainly midwestern, northeastern US; Canada
Describe tick-borne hemorrhagic disease
Nairobi sheep disease
Vector(s)- various hard tick species
Hemorrhagic gastroenteritis- small ruminants
Africa; Asia
Describe tick-borne systemic disease
African Swine Fever: Vector(s)- Ornithodoros Systemic hemorrhagic disease Domestic swine; warthogs- asymptomatic reservoirs Africa Colorado Tick Fever: Human cases
What are vectors of Lyme disease?
Ixodes scapularis (eastern US) Ixodes pacificus (western US)
What is the agent of Lyme disease?
Borrelia burgdorferi
What are the reservoir hosts for Lyme disease?
Rodents (white-footed mouse; reservoir for bacteria)
White-tailed deer (required host for tick only)
Where is Lyme disease commonly found?
Northeastern and north-central US
How do the most exposed dogs to Lyme disease appear?
Clinically normal
What are the clinical signs and pathogenesis of lyme disease in dogs?
Shifting leg lameness, fever, anorexia, lymphadenopathy
Polyarthritis, renal disease
What are sentinels for Lyme disease risk in humans?
Dogs
What are lyme-like illnesses in humans in the south often associated with?
Lone star tick bite
What are vectors of tularemia?
Dermacentor variabilis
Amblyomma americanum
What is the agent of tularemia?
Francisella tularensis
What is the pathology of tularemia in wild and domestic animals?
Abscesses in liver and spleen
What are the clinical signs of tularemia in humans?
Ulcerated lesions
Fever
Headache
What causes rickettsial diseases?
In general, obligate intracellular, gram negative bacteria
Rickettsia spp., Ehrliche spp., Anaplasma spp.
What are the signs that Rickettsial infections usually cause?
Nonspecific signs
How are Rickettsiae transmitted?
Transstadially
Transovarially
What are Rickettsial disease treatable with?
Tetracyclines
What are vectors of Heartwater disease?
Amblyomma app where endemic
A. maculatum– experimentally
What is the causative agent of Heartwater disease?
Ehrlichia ruminantium
What is the vector of tropical canine pancytopenia?
Rhipicephalius sanguineus
What is the causative agent of tropical canine pancytopenia?
Ehrlichia canis
What are the acute clinical signs of tropical canine pancytopenia?
Fever
Anorexia
Lethargy
What are the sublicnical signs of tropical canine pancytopenia?
E. canis in blood
What are the chronic signs of tropical canine pancytopenia?
Ocular, neurologic abnormalities Scrotal/limb edema Hemorrhage Weight loss Death
What is tropical canine pancytopenia common in?
German Shepherds
What is the vector if canine granulocytic ehrlichiosis?
Ambylomma americanum
What is the causative agent of canine granulocytic ehrlichiosis?
Ehrlichia ewingii
What is the vector of canine cyclic thrombocytopenia?
Rhipicephalus sanguineus
What is the causative agent of canine cyclic thrombocytopenia?
Anaplasma platys
What is the vector of granulocytic anaplasmosis?
Ixodes scapularis
I. pacificus
What is the causative agent of granulocytic anaplasmosis?
Anaplasma phagocytophilum
What are the clinical signs of granulocytic anaplasmosis in equine hosts?
Usually mild/subclinical
Fever, lethargy, stocking edema, petechiae
What are the clinical signs of granulocytic anaplasmosis in dogs and cats?
May be asymptomatic or have nonspecific or acute signs
What is the vector of bovine anaplasmosis?
Dermacentor adersoni– mechanical transmission
What is the causative agent of bovine anaplasmosis?
Anaplasma marginale
What are the clinical signs of bovine anaplasmosis in cattle?
Fever,hemoltic anemia
Severity increases with age (up to 50% mortality in adults)
What are the vectors Rocky Mountain Spotted Fever?
Dermacentor variabilis
D. andersoni
What is the causative agent of Rocky Mountain Spotted Fever?
Rickettsia rickettsii
What are the clinical signs of Rocky Mountain Spotted Fever?
Fever Lymphadenopathy Polyarthritis Edema Petechiae Ocular lesions
What are examples of bacterial diseases with soft tick vectors?
Epizootic bovine abortion
Relapsing fever
What is the vector of epizootic bovine abortion?
Ornithodoros coriaceus
What is the causative agent of epizootic bovine abortion?
Deltaproteobacterium
Where does epizootic bovine abortion occur?
California
What is the vector of relapsing fever?
Ornithodoros spp.
What is the causative agent of relapsing fever?
Borrelia spp.
Where does relapsing fever occur?
Western US, Texas, Florida
What are causes of canine hepatozoonosis (protozoal disease)?
Hepatozoon americium, H. canis
What is the cause of feline cytauxzoonosis (protozoal disease)?
Cytauxzoon felis
What are causes of canine piroplasmosis (protozoal disease)?
Babesia canis vogeli
B. gibsoni
B. conradae
What are causes of bovine piroplasmosis (protozoal disease)?
Babesia bigemina
B. bovis
What are causes of equine piroplasmosis?
Theileria equi
Babesisa caballi
