Rickettsias And Coxiella Flashcards
What are rickettsias?
Obligate, intracellular bacteria
Gram negative- two membranes with no lipopolysaccharides
some have absence of peptidoglycan
What is the intracellular lifecycle of rickettsiales
- Ricketssia enters
- Phagosome lysis
- Replication throughout the cytoplasm
- Then either direct transfer into the adjacent cell or host cell lysis and release
What are the two main pathogenic species of Anaplasmataceae
Ehrlichia & Anaplasma
- they cycle between animal and tick hosts
What kind of host cells do anaplasmatacae target?
- Eythrocytes
- Platelets
- Neutrophils, eosinophils,
- monocytes, macrophages, lymphocytes
- vascular endothelium
What happens when the rickettsia are in the dense core?
They are infectious but not-dividing
What happens when the rickettsia are in the reticulate part of the developmental cycle?
They are dividing but not infectious
What are the three ticks that primarily transmis anaplasmatcae?
- Ixodes ricinus
- Dermacentor
- Amblyomma
What is the three-host tick cycle of rickettsia and coxiella?
- Hatches and quests on the grass
- attachment and feeding to a dog
- Drops off/ moults then attaches to cattle
- then drops off and attaches to a human/ deer
What are the symptoms of bovine anaplasmosis?
- anaemia
- fever #
- jaundice
- weight-loss
- breathlessness
- abortion
What causes bovine anaplasmosis?
- Type of ricketssia
- caused by anaplasma marginale
- transmitted by a variety of ticks- dermacenter and rhipcephalus
- infects erythrocytes
- leads to anaemia
- infected animals serve as a reservoir
- worldwide/ tropical/sub tropical
What is anaplasma centrale?
- Milder version of bovine anaplasmosis
- also affects sheep, wild ruminants
What is anaplasma centrale used as immunisation for?
A.marginale- does not prevent the disease but reduces symptoms
What is anaplasma platys?
- Causes cyclic thrombocytopenia
- targets platelets
What are the clinical signs of anaplasma platys?
- anaemia
- diarrhoea
- weight loss
What do anaplasma ovis and anaplasma bovis cause?
- A ovis causes ovine anaplasmosis in sheep, goats and wild ruminants
- targets erythrocytes
- A.bovis generally causes mild disease and targets monocytes
*they both have worldwide distribution
What is anaplasma phagocytophilum?
Combines E.equi, E.phagocytophillia and HGE agent
it is transmitted by hard ticks Ixodes
targets neutrophils, eosinophils, and sometimes monocytes
causes tick-borne fever (cattle, sheep, goats, equine anaplasmosis in the US)
it is characterised by high fever, neutropenia and leukopenia
What does infection of cells with A. phagocytophilum lead to?
Cell lysis
often combined with immunosupression and secondary infections
leads to abortion
can convert to a carrier state
What is the diagnosis and treatment of anaplasma infections?
- Clinical signs
- Microscopy
- immunofluorescence assays
- serology
- culture
- molecular tests
What is important about Ehrlichia species?
- Tick-borne
- targets a wide range of hosts
- targets white blood cells primarily
What does erhlichia canis cause?
- causes canine ehrlichosis, canine pancytopenia
- lethargy, inappetence, pancytopenia
- targets monocytes, macrophages and lymphocytes
What tick transmits Ehrlichia canis?
Rhipcephalus sanguineous
What are the clinical signs of canine Erhrlichiosis?
- fever, oedema, haemorrhage
- leukopenia, hypergammaglobulaemia
- there is presence of inclusion bodies (morula) in blood smears
- Growth in tick cell lines
Where is E. chaffensis primarily found?
primarily found in deer, can cause human ehrlichosis
similiar to E.canis
-monocytes, macrophages, lymphocytes
What is the name of the tick that transmits E.chaffensis?
Amblyomma americanum
