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*Serology required for identification
*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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*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-mediatied 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, 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 renal failure in puppies
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[[Brachyspira hyodysenteriae]]
[[Brachyspira hyodysenteriae]]
[[Leptospira]]
[[Leptospira]]