Rickettsiales Flashcards
Rickettsiales description
Family Anaplasmataceae & Family Rickettsiaceae - Obligate intracellular gram negative bacteria -
Family Anaplasmataceae
Anaplasma - Ehrilichia - Neorickettsia
Anaplasma spp
Survive in cytoplasmic vacuoles of erythrocytes, phagocytes, platelets & myeloid cells
Ehrlichia spp.
Survive in phagocytic cells
Neorickettsia spp
Survive in macrophages & mononuclear cells
Family Rickettsiaceae
Rickettsiae spp: R. rickettsia, wolbackia, oreintia
Rickettsiae spp
Survive in vascular endothelium
Anaplasma spp description
Gram negative, small coccoid-ellipsoid
Anaplasma spp list
A. marginale, centrale, ovis, bovis, platys, phagocytophilum
A. marginale
REPORTABLE, transmission with hard ticks (Ixodes), infects ruminants - Bovine anaplasmosis
Bovine anaplasmosis
A. marginale - undulating febrile disease - Long-term carriage.
When I say Bovine anaplasmosis, you say,
Anaplasma marginale!
A. marginale pathogenesis in bovine
Bovine anaplasmosis! Erythrocytes engulf bacteria–> multiplication & release of new –> indiscriminate erythrocyte removal by host’s macrophage system–> anemia, icterus, splenomegaly, hepatomegaly –> DESTRUCTION OF RBC!!
Anaplasma platys
Infectious canine cyclic thrombocytopenia - Cycles of 1-2 week interval -
Tick species that transmit Anaplasma platys
Rhiphicephalus & Dermacentor
Anaplasma phagocytophilum
Tick borne fever in ruminants, human, equine - Canine granulocytic anaplasmosis - Transmitted by rodents & ixodes (hard ticks)
What species causes canine granulocytic anaplasmosis?
A. phagocytophilum
What species causes Infectious canine cyclic thrombocytopenia?
A. platys
Rickettsiae - description
Small, gram negative, nonmotile (but hijacks actin in cells)
Rickettsiae pathogenesis
Enter endothelials –> escape phagosome & multiply in cytoplasm & nucleus
What disease is caused by Rickettsia rickettsia?
Rocky Mountain Spotted Fever
What causes Rocky Mountain Spotted Fever?
Rickettsia rickettsia
What does Rickettsia felis cause?
Typhus group
What disease does Coxiella burnetii cause?
Q fever
What causes Q fever?
Coxiella burnetii
Rocky Mountain Spotted fever - Reservoir
Dogs & people, small mammals
Rocky Mountain Spotted fever transmission
Dermecentor (Wood tick, American dog tick) (also transovarial & transtadial)
Rickettsia ricketsii - Pathogenesis
In tick: replicate in epithelium–> to salivary glands & ovarian tissues - In vertebrate: Tick injects bacteria–> bacteria to endothelium, damage cell membrane –> vasculitis & thrombosis
Rocky Mountain Spotted fever pathology
Rickettsia ricketsii - Severe necrosis in extremities, severe fatal disease (from vasculitis & thrombosis)
Rocky Mountain Spotted fever DDx
Ehrlichiosis - Babesiosis - Baorreliosis
Rocky Mountain Spotted fever prevention
Tick control, Tx with chloramphenicol, fluroquinolones, tetracyclines
Coxiella burnetii General info
Survives in environment - have endospore-like growth phase - Can disseminate airborne - Bioweapon!! REPORTABLE
Coxiella burnetii Hosts
Ticks, mites, lice, fleas ; Mammals
Coxiella burnetii in humans
Q fever! subclinical influenza-like occupational disease - Endocarditis in chronic presentations
Coxiella burnetii pathogenesis
inhalation/ingestion/arthropod bite –> vascular endothelium/renal & respiratory epithelia –> multiplies within phagosome - Persistent in lactating mammary gland and pregnant uterus
Ehrlichiae general
WBC obligate intracellular bacteria - multiply within membrane lined intracytoplasmic vesicles
Ehrlichiae genus
Ehrlichia & Neorickettsia - Tick transmitted species - Transtadially not transovarially
Ehrlichiae spp Tx
Tetracyclines, imodocarb dipropionate - Doxy & steroid for late-stage, poor prognosis
Ehrlichia canis Dz & transmission
Canine monocytic ehrlichiosis - Transmitted by Rhiphicephalus (brown dog tick)
Ehrlichia canis pathogenesis
Inoculation by tick bite–> incubation –> severe acute dz develops, progresses to chronic (tropical canine pancytopenia) - Thrombocytopenia, leukopenia, anemia, secondary infections
E. chaffensis
Human monocytic ehrlichiosis - Dermacentor (american dog tick) - Deer=reservoir
What is the species of tick that transmits E. chaffensis
Dermacentor (American dog tick)
E. ewingii
Canine granulocytic ehrlichiosis - Transmitted by Ambylomma americanum (Lone Star Tick)
E. ruminantium
Africal heartwater - REPORTABLE - Ruminants in africa & caribbean - Some cattle breeds resistant
E. ruminantium transmission
Amblyomma vector - parenteral introduction to blood
E. ruminantium pathogenesis
Inoculation–> multiplication in reticuloendothelial cells lining lymph node sinusoids–> vascular dissemination & endothelial colonization –> vasculitis, pericardial effusion
E. ruminatium Signs
Fever, followed by neurological signs (collapse & convulsions)
Neorickettsia description
Small, non-motile, coccoid, intracytoplasmic vacuoles - In monocytes, macrophages, enterocyte - Vectors=Flukes
Neorickettsia helminthoeca diseases
Salmon poisoning disease - Elokomin fluke fever (mild form)
Neorickettsia helminthoeca - Pathogenesis
Dog ingests fluke-contaminated fish (encysted in salmon–> attachment & penetration of duodenal mucosa by trematode –> hemorrhagic enteritis w/bacterial spread to lymph node, spleen, liver, lungs, brain, thymus
Neorickettsia helminthoeca - Life with the helminth
N. helminthoeca maintained by transovarial passage in the helminth, found throughout life cycle of the fluke - Only obligatory helminth borne pathogenic bacteria!
Neorickettsia helminthoeca target cells
Canine mononuclear cells
Neorickettsia helminthoeca Dx
Location, detection of fluke eggs, history of dog health
Neorickettsia helminthoeca Prevention
Don’t let dogs eat raw fish!
Neorickettsia risticii
Potomac Horse Fever! - Equine monocytic ehrlichiosis - Equine sours
When I say equine sours, you say
Neorickettsia risticii
When I say Potomac horse fever, you say…
Neorickettsia risticii
Neorickettsia risticii Target cells
Affinity for blood monocytes, tissue macrophages, intestinal epithelial cells
Neorickettsia risticii - Reservoir
Infectious life cycle involves intermediate snail reservoir & trematode cercaria (proximity to bodies of water, summertime)
Neorickettsia risticii clinical signs
Diarrhea
Aegyptianellosis
Aegyptianella pullorum - Poultry & wild birds - Tick: Argus! - Lesions: hepatosplenomegaly, punctiform hemorrhages on serosal surfaces