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*Serology required for identification
*Serology required for identification
===''Leptospira''
*Motile, helical bacteria found in aquatic environments
*Require liquid media for culture
*Cause leptospirosis in all animals, which can range from mild urogenital tract infections to systemic diseases
*Organisms persist in kidney tubules or genital tract of carrier animals and are shed in urine
*Transmission via direct contact
*Serovars are fairly host-specific, causing mild disease in the maintenance host, with shedding in the urine
*Maintenance hosts may transmit the infection to incidental hosts, which are less susceptible to infection, but develop serious disease
*Pathogenesis and pathogenicity
**Depends on virulence of the serovar and susceptibility of the host
**Leptospires invade tissues through moist skin or via mucous membranes, aided by their motility
**Leptospires may invade via receptor-mediatied endocytosis
**They disseminate through the body via the blood stream
**Antibodies clear organisms from the blood stream after about 10 days of infection
**Organisms may persist in the renal tubules, uterus, eye or meninges
**Evade phagocytosis possibly via macrophage apoptosis
**Damage red blood cell membranes and endothelial and liver cells, leading to haemolytic anaemia, jaundice, haemoglobinuria and haemorrhage in acute leptospirosis
*Diagnosis
**Clinical signs and history of exposure
**Dark-field microscopy of urine may detect organisms
**Isolation from blood or urine by culture or animal inoculation
**Identificaiton or certain serovars using DNA probes and serology
**FLuorescent antibody technique for identification in tissues
**Silver impregnation
**Molecular techniques such as PCR
**Serology using microscopic agglutination test or ELISA
*Clinical infections
**Cattle and sheep
***Cattle are maintenance hosts for ''L. borgpetersenii'' serovar ''hardjo''
***''L. interrogans'' serovar ''hardjo'' is host-adapted to cattle
***Acute disease in susceptible heifers, with fever and agalactia of all quarters; abortion and stillbirth may occur
***Diagnosed by rising antibody titre in paired serum samples
***Infection in sheep may cause abortion and agalactia
***Urinary excretion can be reduced by administering dihydrostreptomycin or amoxycillin
***Incactivated vaccines are of questionable efficacy
***Serovars ''pomona, grippotyphosa'' and ''icterohaemorrhagiae'' cause pyrexia, haemoglobinurea, jaundice, anorexia, uraemia due to renal damage and death in calves and lambs
**Horses
***Clinical disease rare
***May be maintenance host of serovar ''bratislava'', which causes abortion and stillbirth
***Incidental hosts for serovar ''pomona'', suffering from abortion and renal disease
***Chronic leptospirosis may cause an immune-mediated anterior uveitis
**Pigs
***The rodent-adapted serovars ''icterohaemorrhagica'' and ''copenhagenii'' cause acute disease in pigs
***Severe disease in young pigs
***Serovar ''pomona'' is the host-adapted species, and may be shed in the urine
***Infections may cause abortions and stillbirths
***Pigs are maintenance hosts for serovars ''tarassovi'' and ''bratislava'', which may cause reproductive failure
**Dogs and cats
***Serovars ''canicola'' and ''icterohaemorrhagica'' cause leptospirosis in dogs, but are vaccinated against
***Serovars ''pomona'' and ''grippotyphosa'' are becoming important
***The host-adapted serovar ''canicolar'' causes renal failure in puppies
[[Brachyspira hyodysenteriae]]
[[Brachyspira hyodysenteriae]]
[[Leptospira]]
[[Leptospira]]