Rickettsial Diseases
4-H Veterinary Science
Extension Veterinary Medicine
Texas AgriLife Extension Service
College of Veterinary Medicine and Biomedical Sciences
Texas A&M System
http://aevm.tamu.edu
Objectives
 Discuss arthropod transmission of rickettsiae
 Describe a rickettsial disease of cattle
 Decribe a rickettsial disease of swine
 Describe a rickettsial disease of horses
 Describe two rickettsial diseases of dogs
Review
 Infectious diseases
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Bacterial diseases
Viral diseases
Fungal diseases
Parasitic diseases
Rickettsial diseases
 Infectious -
Rickettsiae
 Definition
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A genus of small, rod-shaped, round to
pleomorphic microorganisms in the order
Rickettsiales. They are true bacteria, gramnegative, and cultivable only in living tissues.
Transmitted by lice and ticks, they cause
disease in humans and domestic animals but
are also found in the cytoplasm of tissue cells
of lice, fleas, ticks and mites, which may act as
reservoirs and vectors
 Symptoms
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Fever
Anemia
Edema
Icterus (jaundice)
Hemorrhages of mucous membranes
Enlarged spleen
Death
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Acute
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Young animals
Summer during vector season
Chronic
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Older animals
Stressful events
 Transmission
 Biological
 Examples
 Ticks
 Sucking lice
Live inside arthropods for months
Mechanical
 Examples
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 Biting flies
 Instruments
 Blood transfusions
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Live short time outside of host
Types
 Anaplasmosis (Gall sickness)
 Affects ruminants
 Transmission
 Mechanical
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Horseflies
Deerflies
Instruments
Ticks
Non-contagious
Treatable
Prevention
 Vaccinate
 Biosecurity
 Eperythrozoonosis (Epe)
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Affects swine
Transmission
Mechanical and biological
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Sucking lice
Instruments
Prevention is best treatment
 Ehrilichiosis (Tick fever)
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Affects
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Dogs
Transmission
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Brown dog tick
Instruments
Blood transfusion
 Rocky mountain spotted fever
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Affects
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Dogs
Transmission
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American god tick
Instruments
Blood transfusion
 Ehrlichiosis
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Affects
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Horses
Transmission
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Unknown
Diagnosis
 Blood smears
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Anaplasma
Eperythrozoon
Ehrlichia rickettsial
 Serological
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Rocky mountains spotted fever