Term
| What is the disease caused by Rickettsia? |
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Definition
| Rocky Mountain Spotted Fever |
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Term
| What order and family is the genus Rickettsia classified under? |
|
Definition
Order: Rickettsiales
Family: Rickettsiaceae |
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Term
| Are Rickettsiales organisms intracellular or extracellular parasites? |
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Definition
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Term
| How do Rickettsiales stain with gram stain? |
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Definition
| Gram-negative cell wall (red) |
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Term
| How do you stain Rickettsiales? |
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Definition
Use small, special stains
(like Gimenz) |
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Term
| How are Rickettsiales transmitted? |
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Definition
|
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Term
| Describe the host range of Rickettsiales. |
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Definition
|
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Term
| What do the different Rickettsiales diseases reflect? |
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Definition
| The type of cell that is parasitised (i.e. endothelial, WBC, RBC) |
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Term
| What antibiotic should be used with Rickettsiales? |
|
Definition
|
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Term
| What are some escape mechanisms of Rickettsiaceae (Rickettsia sp.)? |
|
Definition
|
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Term
| Where does Rickettsiaceae replicate? |
|
Definition
|
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Term
| What does Rickettsiaceae utilize most in catabolism? |
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Definition
| Glutamate (little or not glycolysis) |
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Term
| Why does Rickettsiaceae utilize mostly glutamate? |
|
Definition
| Leaky membranes that preferentially exchange ADP for host ATP |
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Term
| With serum agglutination tests, what will Rickettsiaceae show? |
|
Definition
| Cross-reaction with Enterobacteriaceae agents |
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Term
| What type of cells do Rickettsiaceae mostly infect? |
|
Definition
| Vascular endothelial cells |
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Term
| What are the vectors of Rickettsiaceae? |
|
Definition
| Ticks, lice, fleas, & mites |
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Term
| What are the vectors of Rickettsia (RMSF)? |
|
Definition
- Dermacentor variablis (American Dog Tick)- eastern u.s.
- Dermacentor andersonii (Wood Tick) - western u.s.
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|
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Term
| What is the transmission cycle of Rickettsia in the ticks? |
|
Definition
| Transovarian & transtadial |
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Term
| Is there a high or low incidence of Rickettsia infectio in ticks of endemic areas? |
|
Definition
| Low (requires high levels of rickettsemia) |
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Term
| What happens to animals that are infected with non-pathogenic Rickettsial species? |
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Definition
| May die or become resistent to infection |
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Term
| What is required for transmission of Rickettsia via a tick bite? |
|
Definition
Prolonged attachment (5-20 hours)
but can be also from direct mucous
membrane contact |
|
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Term
| What are the signs of RMSP in humans? |
|
Definition
- Incubation period ~1 wk.
- Fever, severe headache, muscle pain
- Rash on extremities ~3-5 days after symptom onset
- Can be fatal involving CNS, heart, & kidneys
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Term
| Where is the primary growth of R. rickettsia inside host, and what does that cause? |
|
Definition
| Endothelium of small-medium blood vessels (causes cell death & vasculitis) |
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Term
| What are the RMSF signs in dogs? |
|
Definition
- Incubation 2-14 days
- Fever 3-5 days post bite
- Inconsistent rash (12 days post bite)
- Skin lesions
- Edema hyperemia of extremities
- Petechial hemorrhage on mucosal surfaces (seen on fundic exam)
- Neurologic abnormalities (depression, stupor, behavior changes)
- Other (dyspnia, arthralgia, etc)
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Term
| What are the outcomes of RMSF? |
|
Definition
- Sometimes subclinical
- Rapid complete recovery if mild & treated
- Death in acute stages from hemorrhage or thrombosis in vital organs
- Permanent organ damage w/n ~1-2 wks of acute infection (heart, CNS, kidneys, necrosis of extremeties)
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Term
| What do you look for in diagnosing RMSF? |
|
Definition
- Young dog <2-3 yrs
- Seasonal (Mar. - Oct.)
- History of recent tick habitat exposure
- Thrombocytopenia
- Positive serology test (not immediately useful)
- Titers may rise 4-fold over 2-4 wks
- IgM anitbodies
- Direct detection
- Direct FA on biopsy/necropsy tissues
- PCR on blood tissues
- Culture in live animals or tissue culture
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|
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Term
|
Definition
- Tetracycline
- Treat immediately after getting samples for diagnostic testing
- Supportive care
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Term
|
Definition
- No available vaccines
- Tick control
- Prompt tick removal
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