Tick Borne Diseases

Question 1

what are the vectors of most vector borne diseases

Answer 1

arthropods
- ticks, mosquitoes, fluke, lice, fleas

Question 2

can vector borne pathogens exist outside of the vector or host

Answer 2

NO - obligate intra-host pathogens

can live in either definitive or intermediate hosts

Question 3

what are the top clinical signs of vector borne disease in all hosts

Answer 3

fever
thrombocytopenia

Question 4

what are the clinical signs and findings of vector borne disease in dogs

Answer 4

CS: fever, polyarthritis, vasculitis, myocarditis, glomerulonephritis, petechiae, GI bleeds

Labs: pancytopenia, thrombocytopenia, anemia

Question 5

what are the clinical signs and findings of vector borne disease in cattle

Answer 5

CS: fever, CNS signs (hyperesthesia), peracute death, petechiae/ecchymosis

Labs: thrombocytopenia, hemolytic anemia, icterus

Question 6

what are the clinical signs and findings of vector borne disease in horses

Answer 6

CS: fever, anorexia, depression, CNS signs (ataxia), vasculitis, petechiae

Labs: thrombocytopenia, icterus, anemia

Question 7

what are rickettsial organisms

Answer 7

small bacteria that are:
- gram negative
- aerobic
- obligate intracellular

Question 8

what are the two families and species of rickettsial organisms

Answer 8

1. anaplasma: anaplasma, ehrlichia, neorickettsia
2. rickettsia: rickettsia

Question 9

characteristics of rickettsia

Answer 9

• obligate intra host and intracellular
• replicate via binary fission within phagosomes of infected cells
• form morula clusters

pathogenicity and clinical signs depend on cell target

Question 10

what are rickettsial organisms treated with

Answer 10

tetracyclines

Question 11

what diagnostics are used for canine ehrlichiosis

Answer 11

1. serology: ELISA SNAP test, IFA
2. PCR
3. cytology: blood smear

Question 12

what might cause false negative ELISA SNAP test

Answer 12

acute infections

double check with pCR

Question 13

what diagnostics are used for heartwater

Answer 13

1. cytology
2. post mortem histopathology of CNS tissue

Question 14

what diagnostics are used in anaplasma

Answer 14

1. cytology
2. serology: ELISA
3. PCR

Question 15

what mechanisms are used by intracellular pathogens to enter host cells

Answer 15

bind to host cell membrane receptors to facilitate transport into cells

Question 16

what are some mechanisms that intracellular pathogens use to persist within host

Answer 16

1. antigenic variation
2. enzyme production - degrades phagosome to survive in cytoplasm
3. hijacking host cell processes - using actin to transport and inhibiting apoptosis

Question 17

what are mechanisms that intracellular pathogens use to evade host immune defenses

Answer 17

antigenic diversity - decreases ability of immune system to recognize and destroy the pathogen

allows for development of CHRONIC infections

Question 18

what immune response do hosts mount to intracellular pathogens

Answer 18

strong HUMORAL response
- also requires cell mediated

antibodies target surface proteins on antigen

Question 19

what virulence factors are used by intracellular pathogens

Answer 19

1. endotoxin (LPS)
2. stimulates immune complex formation (type III hypersensitivity)
3. stimulates antibody production (type II hypersensitivity)