Exam 3 - Vector-borne Diseases Flashcards
when is the overall prevalence of tick infestation highest in the USA?
may & June – second peak in October
what replication-incompetent bacteria relies on fleas & ticks to be transmitted?
bartonella spp.
what protozoal parasite uses an insect as both vector & definitive host?
hepatozoon
what agents are obligate intracellular parasites?
ehrlichia, anaplasma, rickettsia spp.
genus borrelia spirochetes
T/F: obligate intracellular parasites can’t survive outside of the host or vector & therefore, aren’t directly contagious
true – extremely well-adapted to survive
because you typically can’t culture obligate intracellular pathogens to diagnose them, what tests are used instead?
serology or molecular diagnostics
how are infections caused by obligate intracellular parasites treated?
must get drugs into the cells to kill the pathogen – or prevent the transmission in the first place
general tick-borne syndrome involves what agents?
ehrlichia, rickettsia, anaplasma, & borrelia
what is the common presentation of general tick-borne syndrome?
tick was attached for 48 hours or more – clinical signs appear 7-21 days later
what are the common initial signs associated with general tick-borne syndrome?
fever, lethargy, lameness, shifting leg lameness, polyarthritis, polymyositis, acute thrombocytopenia, & may wax/wane in severity
acute signs associated with general tick-borne syndrome are generally rapidly responsive to what antibiotic?
doxycycline
why is shifting leg lameness seen in animals with general tick-borne syndrome?
muscle stiffness, soreness, or pain from systemic inflammatory disease or just achiness
true neutrophilic polyarthritis – may be reactive to systemic inflammatory disease or may be direct spread within connective tissues
what 3 mechanisms are associated with acute thrombocytopenia in animals with general tick-borne syndrome?
- increased consumption – fever, inflammatory cascade during bacteremia/parasitemia, vasculitis
- concurrent immune-mediated destruction in some cases – could be specific or bystander
- impaired function also likely – bleeding occurs at platelet counts higher than typically seen with spontaneous bleeding
T/F: anemia is a common feature of general tick-borne syndrome
false – but when present, anemia of chronic inflammatory disease & is non-regenerative
what major clinical syndromes are associated with vector-borne diseases in humans?
spotted fever group, STAR, tick-borne relapsing fever (borrelia turicatae), r. typhi, & r. prowazekii
what is the primary vector of rickettsia rickettsii?
dermacentor species
what are the possible reservoirs for rickettsia rickettsii?
dermacentor, small mammals, rodents, & birds
where is the highest seropositivity of dogs with rickettsia rickettsii?
eastern time zones
where are human cases of rocky mountain spotted fever most prevalent?
southeast united states
rickettsia rickettsii causes clinical disease in what species?
dogs & people
what are the target cells of r. rickettsii?
vascular endothelial cells – ‘spotted’ appearance
typically, mild thrombocytopenia – likely immune-mediated or secondary to vasculitis
diffuse vasculitis often progresses to DIC
what is the prognosis of rocky mountain spotted fever?
acute disease only!!!
dead or better in days to weeks – extremely rapidly treatment responsive
T/F: in rocky mountain spotted fever, exposure-induced immunity is protective for 3 years or more
true
what ticks transmit ehrlichia canis?
r. sanguineus & d. variabilis