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| − | {{toplink
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| − | |backcolour =
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| − | |linkpage =Bacteria
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| − | |linktext =BACTERIA
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| − | |pagetype=Bugs
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| − | }}
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| − | <br>
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| − | ===Overview===
| + | #REDIRECT[[:Category:Spirochaetes]] |
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| − | *Two families exist, ''Leptospiraceae'' and ''Spirochaetaceae''
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| − | *''Leptospiraceae'' include the pathogens of the genus ''Leptospira''
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| − | *''Spirochaetaceae'' include the pathogens of the genera ''Borrelia'', ''Brachyspira'' and ''Treponema''
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| − | *Many cause zoonotic infections
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| − | ===Characteristics===
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| − | *Spiral or helical Gram-negative bacteria
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| − | *Motile organisms via endoflagella
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| − | *Poor survival in the environment and sensitive to dessication
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| − | *Stain poorly with Gram stain
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| − | *Most require specialised media for growth
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| − | *Serology required for identification
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| − | ===''Leptospira''===
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| − | *Motile, helical bacteria found in aquatic environments
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| − | *Require liquid media for culture
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| − | *Cause leptospirosis in all animals, which can range from mild urogenital tract infections to systemic diseases
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| − | *Organisms persist in kidney tubules or genital tract of carrier animals and are shed in urine
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| − | *Transmission via direct contact
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| − | *Serovars are fairly host-specific, causing mild disease in the maintenance host, with shedding in the urine
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| − | *Maintenance hosts may transmit the infection to incidental hosts, which are less susceptible to infection, but develop serious disease
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| − | * May cause severe systemic disease, resulting in [[Intestines Fibrinous/Haemorrhagic Enteritis - Pathology#Bacterial septicaemia and enteritis|enteritis]]
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| − | *Pathogenesis and pathogenicity
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| − | **Depends on virulence of the serovar and susceptibility of the host
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| − | **Leptospires invade tissues through moist skin or via mucous membranes, aided by their motility
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| − | **Leptospires may invade via receptor-mediated endocytosis
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| − | **They disseminate through the body via the blood stream
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| − | **Antibodies clear organisms from the blood stream after about 10 days of infection
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| − | **Organisms may persist in the renal tubules, uterus, eye or meninges
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| − | **Evade phagocytosis possibly via macrophage apoptosis
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| − | **Damage red blood cell membranes and endothelial and liver cells, leading to haemolytic anaemia, jaundice, [[General Pathology - Pigmentation and Calcification#Haemoglobin|haemoglobin pigmentation]], haemoglobinuria and haemorrhage in acute leptospirosis
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| − | *Diagnosis
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| − | **Clinical signs and history of exposure
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| − | **Dark-field microscopy of urine may detect organisms
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| − | **Isolation from blood or urine by culture or animal inoculation
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| − | **Identificaiton or certain serovars using DNA probes and serology
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| − | **FLuorescent antibody technique for identification in tissues
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| − | **Silver impregnation
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| − | **Molecular techniques such as PCR
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| − | **Serology using microscopic agglutination test or ELISA
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| − | *Clinical infections
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| − | **Cattle and sheep
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| − | ***Cattle are maintenance hosts for ''L. borgpetersenii'' serovar ''hardjo''
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| − | ***''L. interrogans'' serovar ''hardjo'' is host-adapted to cattle
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| − | ***Acute disease in susceptible heifers, with fever and agalactia of all quarters; abortion and stillbirth may occur
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| − | ***Diagnosed by rising antibody titre in paired serum samples
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| − | ***Infection in sheep may cause abortion and agalactia
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| − | ***Urinary excretion can be reduced by administering dihydrostreptomycin or amoxycillin
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| − | ***Incactivated vaccines are of questionable efficacy
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| − | ***Serovars ''pomona, grippotyphosa'' and ''icterohaemorrhagiae'' cause pyrexia, haemoglobinurea, jaundice, anorexia, uraemia due to renal damage and death in calves and lambs
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| − | **Horses
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| − | ***Clinical disease rare
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| − | ***May be maintenance host of serovar ''bratislava'', which causes abortion and stillbirth
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| − | ***Incidental hosts for serovar ''pomona'', suffering from abortion and renal disease
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| − | ***Chronic leptospirosis may cause an immune-mediated anterior uveitis
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| − | **Pigs
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| − | ***The rodent-adapted serovars ''icterohaemorrhagica'' and ''copenhagenii'' cause acute disease in pigs
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| − | ***Severe disease in young pigs
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| − | ***Serovar ''pomona'' is the host-adapted species, and may be shed in the urine
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| − | ***Infections may cause abortions and stillbirths
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| − | ***Pigs are maintenance hosts for serovars ''tarassovi'' and ''bratislava'', which may cause reproductive failure
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| − | **Dogs and cats
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| − | ***Serovars ''canicola'' and ''icterohaemorrhagica'' cause leptospirosis in dogs, but are vaccinated against
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| − | ***Serovars ''pomona'' and ''grippotyphosa'' are becoming important
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| − | ***The host-adapted serovar ''canicolar'' causes acute renal failure in puppies; a chronic uraemic syndrome may follow
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| − | ***Incidental infections with serovar ''icterohaemorrhagica'' or ''copenhagenii'' cause renal failure
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| − | ***''L. icterohaemorrhagiae'' may cause [[General Pathology - Pigmentation and Calcification#Hepatic (Toxic) Icterus|hepatic jaundice]]
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| − | ***Serovar ''bratislava'' causes abortion and infertility in dogs, which may be the maintenance host
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| − | ***Infections uncommon in cats
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| − | ===''Borrelia''===
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| − | *Longer, wider, helical spirochaetes with a linear chromosome and linear and circular plasmids
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| − | *Obligate parasites transmitted by arthropod vectors
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| − | *Lyme disease
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| − | **Caused by ''Borrelia burgdorferi''
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| − | **Reported in humans, dogs, horses, cattle, sheep
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| − | [[Brachyspira hyodysenteriae]]
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| − | [[Leptospira]] | |