10,008 bytes removed ,  20:14, 14 May 2010
Redirected page to Rickettsiales
Line 1: Line 1: −
{{unfinished}}
+
#REDIRECT[[Rickettsiales]]
 
  −
{{toplink
  −
|backcolour =
  −
|linkpage =Bacteria
  −
|linktext =BACTERIA
  −
|pagetype=Bugs
  −
}}
  −
<br>
  −
 
  −
===Overview===
  −
 
  −
*Cause systemic diseases in animals
  −
*Usually use arthropod vectors
  −
*Host and cell type specificity
  −
*Q fever and Rocky Mountain spotted fever are zoonoses
  −
 
  −
 
  −
 
  −
===Characteristics===
  −
 
  −
*Non-motile, pleomorphic Gram-negative organisms
  −
*Obligate intracellular pathogens
  −
*Require live cells for culture such as tissue culture cells or embryonated eggs
  −
*Require Romanowsky stains
  −
 
  −
*Include two families, ''Rickettsiaceae'' and ''Anaplasmataceae''
  −
*''Rickettsiaceae'' have cell walls that contain peptidoglycan; they target endothelial cells and leukocytes
  −
*''Anaplasmataceae'' lack cell walls; they target erythrocytes
  −
 
  −
 
  −
===Epidemiology===
  −
 
  −
*Rickettsiae replicate in gut epithelial cells of arthropod vectors and spread to other organs such as salivary glands and ovaries
  −
*Transmission occurs during feeding on the animal host
  −
*Transovarial or trans-stadial transmission occurs in the arthropod vectors
  −
*Most ricketsiae have limited survival in the environment, apart from ''Coxiella burnetii'', which undergoes aerosol transmission
  −
 
  −
 
  −
===Pathogenesis and pathogenicity===
  −
 
  −
*Many rickettsiae target endothelial cells of small blood vessels; they produce phospholipase which damages phagosome membranes, escaping into the cytoplasm
  −
*''Ehrlichia'' target leukocytes or platelets, and inhibit phagosome/lysosome fusion
  −
*''Anaplasmataceae'' localise within vacuoles or on the surface of red blood cells; they may alter red cell antigens causing immune-mediated damage.  Anaemia may result from haemolysis or removal of red blood cells
  −
 
  −
 
  −
===Identification===
  −
 
  −
*Giemsa-stained blood or tissue smears identify blue/purple organisms
  −
*Fluorescent antibody technique for specific identification
  −
*Isolation in embryonated eggs or tissue culture lines
  −
*Nucleic acid probes and PCR
  −
*Inoculation of susceptible animals
  −
 
  −
 
  −
===Rocky Mountain spotted fever===
  −
 
  −
*Caused by ''Rickettsia rickettsii''
  −
*Affects humans and dogs
  −
*Various tick vectors, which acquire the organism from small mammals
  −
*Transovarial and trans-stadial transmission within the tick population
  −
*Organisms replicate in endothelial cells of infected dogs, cause vasculitis, increased vascular permeability and haemorrhage
  −
 
  −
*Clinical signs
  −
**Incubation period 2-10 days; course less than 2 weeks
  −
*Fever, depression, conjunctivitis, retinal haemorrhage, muscle and joint pain, coughing, dyspnoea, oedema of extremities
  −
*Neurological signs in dogs include stupor, ataxia, neck rigidity, seizures and coma
  −
*Death from cardiovascular, neurological or renal damage in severely-affected animals
  −
*Gross pathology includes haemorrhage, splenomegaly and lymphadenopathy
  −
 
  −
*Diagnosis
  −
**Rising antibody titre during an indirect fluorescent antibody test or ELISA
  −
**Thrombocytopenia and leukopenia during early phase
  −
 
  −
*Treatment and control
  −
**Tetracycline therapy for two weeks
  −
**Tick removal from dogs
  −
 
  −
 
  −
===Canine monocytic ehrlichiosis===
  −
 
  −
*Generalised disease of dogs in tropical and subtropical regions
  −
*Caused by ''Ehrlichia canis''
  −
*The brown tick, ''Rhipicephalus sanguineus'', is the main vector
  −
*Dogs may carry the organism for 2 years after resolution of clinical signs
  −
 
  −
*Clinical signs
  −
**Incubation period of 3 weeks
  −
**Acute, subclinical or chronic phases
  −
**Acute phase: fever, thrombocytopenia, leukopenia and anaemia
  −
**Subclinical phase: low blood cell numbers but minimal clinical signs; can progress to a severe disease, tropical canine pancytopenia
  −
**Chronic phase: bone marrow depression, haemorrhages, neurological disease, peripheral oedema, emaciation and hypotensive shock
  −
 
  −
*Diagnosis
  −
**''E. canis'' morulae present in mononuclear cells in Giemsa-stained blood smears
  −
**Rising antibody titre detected by indirect immunofluorescence
  −
**Culture in canine macrophages
  −
 
  −
*Treatment and control
  −
**Doxycycline for 10 days
  −
**Fluid therapy or blood transfusion
  −
**Prophylactic tetracyclines
  −
 
  −
 
  −
===Canine cyclic thrombocytopenia===
  −
 
  −
*Caused by ''Ehrlichia platys''
  −
*Affects platelets
  −
*Recurrent thrombocytopenia, but dogs usually asymptomatic
  −
*Seroconversion detected by indirect immunofluorescence
  −
 
  −
 
  −
===Potomac horse fever===
  −
 
  −
*Caused by ''Ehrlichia risticii''
  −
*Occurs during the summer
  −
*Fluke vector
  −
*Infects epithelial cells of colon and [[Monocytes - WikiBlood]], macrophages and mast cells
  −
 
  −
*Clinical signs
  −
**Fever, anorexia, depression, diarrhoea, colic, leukopenia, laminitis
  −
*30% mortality
  −
*Can cause abortion
  −
*Hyperaemia of large intestine at post mortem
  −
 
  −
*Diagnosis
  −
**Seroconversion detected by indirect immunofluorescence or ELISA
  −
 
  −
*Treatment and control
  −
**Oxytetracycline for 1 week
  −
**Inactivated vaccines
  −
 
  −
 
  −
===Equine granulocytic ehrlichiosis===
  −
 
  −
*Caused by ''E. equi''
  −
*Clinical signs: fever, depression, ataxia, limb oedema, icterus and petechial haemorrhages
  −
*Low mortality
  −
*Diagnosis: presence of morulae in [[Neutrophils - WikiBlood|neutrophils]] during early disease; seroconversion; leukopenia
  −
*Treatment: tetracyclines
  −
 
  −
 
  −
===Bovine petechial fever===
  −
 
  −
*Caused by ''E. ondiri''
  −
*Disease of cattle in Kenya and other countries of East Africa
  −
*Tick vector
  −
*Clinical signs: intermittent fever, depressed milk yield, petechiation of mucous membranes and conjunctiva
  −
*Death from pulmonary oedema
  −
*Diagnosis: presence of organisms in Giemsa-stained blood smears
  −
*Treatment: tetracyclines
  −
 
  −
 
  −
===Tick-borne fever===
  −
 
  −
*Caused by ''E. phagocytophila''
  −
*Affects ruminants in Europe
  −
*The tick ''Ixodes ricinis'' is the main vector
  −
*Animals remain carriers for up to 2 years, but are immune to reinfection
  −
 
  −
*Clinical signs
  −
**Incubation period of 2 weeks; recovery in 2 weeks
  −
**Fever, anorexia, reduced growth rates in young animals
  −
**Reduced milk production, abortion, still birth
  −
**Leukopenia and thrombocytopenia
  −
**Causes immunosuppression in young lambs causing susceptibility to tick pyaemia and louping ill
  −
 
  −
*Diagnosis
  −
**Intracytoplasmic morulae in [[Neutrophils - WikiBlood|neutrophils]] of Giemsa-stained blood smears during acute phase
  −
**Seroconversion detected by immunofluorescence
  −
 
  −
*Treatment and control
  −
**Oxtetracycline
  −
**Tick control
  −
**Prophylactic tetracyclines for lambs during first few weeks of life
  −
 
  −
 
  −
===Heartwater===
  −
 
  −
*Severe disease of ruminants in sub-Saharan Africa caused by ''Cowdria ruminantium''
  −
*Vectors include ''Amblyomma'' ticks
  −
*Carrier status can occur for up to 8 months in adult cattle and wildebeest
  −
*Clinical disease in calves and lambs
  −
 
  −
*Clinical signs
  −
**Incubation period 4 weeks
  −
**Acute fever
  −
**Neurological signs including chewing, twitching of eyelids, circling, high-stepping gait, convulsions and recumbency; can be fatal
  −
**Subacute cases suffer from hydropericardium, hydrothorax and pulmonary oedema and congestion; splenomegaly and haemorrhages may occur
  −
 
  −
*Diagnosis
  −
**Clinical and post mortem findings in endemic areas suggestive
  −
**Orgnisms present in nuclei of endothelial cells in Giemsa-stained brain tissue
  −
**PCR, indirect immunofluorescence, ELISA and western blot
  −
 
  −
*Treatment and control
  −
**Tetracyclines during early disease
  −
**Immunisation using infected blood
  −
 
  −
 
  −
===Bovine anaplasmosis===
  −
 
  −
*Disease of cattle in tropical and sub-tropical regions caused by ''Anaplasma marginale''
  −
*Carrier status in endemic regions with clinical disease occuring in times of stress
  −
*High mortality rate in naive adult cattle
  −
*Morulae localise inside red blood cells close to the cell membrane
  −
*Transmitted via the ''Boophilus'' tick as well as flies and contaminated instruments
  −
 
  −
*Clinical signs
  −
**Inculbation period 2-12 weeks
  −
**Anorexia, fever, depression, reduced milk yield, weight loss
  −
**Anaemia and icterus
  −
**Sudden death from hypoxia can occur
  −
 
  −
*Diagnosis
  −
**Clinical signs and haematology suggestive
  −
**Organisms present in erythrocytes of Giemsa-stained blood smears
  −
**Immunofluorescence of blood smears, PCR, serology
  −
 
  −
*Treatment and control
  −
**Long-acting oxytetracycline or imidocarb early in the disease
  −
**Supportive therapy
  −
**Vaccination of animals being introduced into an endemic region
  −
 
  −
 
  −
===Feline infectious anaemia===
  −
 
  −
*Caused by ''Mycoplasma haemofelis ( ''until recently, known as'' Haemobartonella felis)
  −
*Organism found on surface of erythrocytes
  −
*Common in roaming tom-cats of 1-3 years old
  −
*Possibly transmitted via bite wounds or arthropods
  −
*Recoverd cats become carriers
  −
 
  −
*Clinical signs
  −
**Peracute disease is associated with severe anaemia and immunosuppression, and can be rapidly fatal
  −
**Fever, anaemia, depression, weakness and jaundice occur in the acute form
  −
**Anaemia, lethargy and weight loss occur in the chronic form
  −
**Recovery can occur with a regenerative bone marrow response
  −
**Severe feline infectious anaemia may occur in the presence of feline leukaemia virus
  −
 
  −
*Diagnosis
  −
**Organism intermittently seen on the surface of red blood cells in Giemsa-stained blood smears
  −
**Immunofluorescence of blood smears
  −
**Reduced packed cell volume; regenerative anaemia
  −
 
  −
*Treatment
  −
**Doxycycline for 3 weeks early in the course of the disease
  −
**Blood transfusion
  −
**Flea control
  −
 
  −
===Canine haemobartonellosis===
  −
 
  −
*Dogs infected with ''Haemobartonella canis'' usually asymptomatic
  −
*Acute haemolytic anaemia may occur in dogs after splenectomy, immunosuppressive drug therapy or immunosuppressive infections
  −
 
  −
 
  −
===Q fever===
  −
 
  −
*Caused by ''Coxiella burnetti''
  −
*Influenza-like disease of humans in contact with farm animals
  −
*Transmitted to humans by inhalation from parturient sheep, goats and cattle
  −
*Organisms replicate in female genital tract and mammary glands of ruminants
  −
*Shedding occurs in uterine discharges, foetal fluid and milk
  −
*Infections in animals usually subclinical
  −
*Sporadic abortions occur in sheep, goats, cattle, cats
  −
*Infertility may result in ruminants, as well as placentitis or endometritis
  −
*Hepatitis, myocarditis and interstitial pneumonia may occur in affected foetuses
  −
*Diagnosis: MZN-stained smears of placental tissue and uterine discharges; immunofluorescence; PCR; culture; serology
  −
*Control: disposal of infected placenta and separation of pregnant ruminants; inactivated vaccines
 
Author, Donkey, Bureaucrats, Administrators
53,803

edits