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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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| − | *Cause systemic infections in many animals and humans
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| − | *Slow growth in specialised culture media
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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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| − | **Ticks are the vector, which acquire the infection from small rodents, the reservoir hosts
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| − | **Ticks transmit the infection to large mammals such as deer and sheep
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| − | **''Ixodes ricinus'' is the most common tick vector in Europe
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| − | **Pathogenesis
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| − | ***Virulence of the borreliae requires a change in expression of an outer membrane protein following ingestion of blood by the tick
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| − | ***Borreliae multiply in the blood stream of susceptible hosts and disseminate throughout the body
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| − | ***Localisation in joints, brain, nerves, eyes and heart can occur
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| − | ***The associated lesions may be in part caused by the host immune response
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| − | **CLinical signs
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| − | ***May be subclinical in endemic areas
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| − | ***Clinical manifestation depends on the site of localisation of organisms
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| − | ***Disease in dogs may cause fever, lethargy, arthritis, cardiac, renal or neurological disturbance
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| − | ***Horses suffer similar clinical signs but also lameness, uveitis, nephritis, hepatitis and encephalitis
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| − | ***Cattle and sheep may suffer from lameness
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| − | **Diagnosis
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| − | ***Laboratory confirmation difficult due to low numbers of organisms and fastidious growth requirements
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| − | ***History of exposure to ticks in an endemic region and clinical signs
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| − | ***Rising antibody titre to ''Borrelia burgdorferi'' detected by ELISA
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| − | ***Immunofluorescence
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| − | ***Culture in Barbour-Stoenner-Kelly medium for 6 weeks under microaerophilic conditions
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| − | ***PCR
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| − | **Treatment and control
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| − | ***Amoxycillin and oxytetracycline in the acute phase; prolonged treatment in the chronic phase
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| − | ***Tick control and removal
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| − | ***Vaccines including whole cell bacterins and recombinant subunit vaccines available for dogs
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| − | ===Avian spirochaetosis===
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| − | *Caused by ''Borrelia anserina''
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| − | *Acute, endemic disease of birds in tropical and subtropical regions
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| − | *Chickens, turkeys, pheasants, ducks and geese susceptible
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| − | *Transmitted by soft ticks of the ''Argas'' family, but also via contact with infected material such as blood and tissues
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| − | *Transmitted transovarially and trans-stadially via the tick population
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| − | *Outbreaks during peak tick activity during warm, humid conditions
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| − | *Fever, anaemia and wight loss occurs, with development of paralysis later
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| − | *Immunity is serotype specific
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| − | *Diagnosis using dark-field microscopy of buffy coat smears or immunodluorescence of blood or tissues
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| − | *Giemsa-stained smears and silver impregnation of tissues
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| − | *Isolation of borreliae by inoculation of embryonated eggs or chicks
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| − | *Antibiotic treatment
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| − | *Inactivated vaccines available
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| − | ===''Brachyspira'' and ''Serpulina''===
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| − | *Anaerobic, intestinal spirochaetes, found in normal and diseased pigs
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| − | *Enterophogens of pigs
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| − | *''B. hyodysenteriae, B. pilosicoli, B. innocens, Serpulina intermedia'' and ''S. murdochii'' occur in pigs
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| − | *Carrier pigs shed ''B. hyodysenteriae'' for up to 3 months, acting as a source of infection for healthy pigs
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| − | *Demonstrated in stained faecal smears or silver-stained histopathology sections
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| − | *Cultured anaerobically on selective blood agar
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| − | *Spirochaetes differentiated by pattern of haemolysis on blood agar as well as molecular techniques
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| − | *Pathogenesis
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| − | **Motility in mucous allows colonisation of pig intestine
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| − | **Haemolytic and cytotoxic activiity important for virulence
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| − | **Attachment of ''B. pilosicoli'' to epithelial cells of colonic mucosa disrupts their function and leads to their shedding and oedema
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| − | *Clinical infections
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| − | **''B. hyodysenteriae'' causes [[Intestines Fibrinous/Haemorrhagic Enteritis - Pathology#Swine Dysentery|swine dysentery]]
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| − | **''B. pilosicoli'' causes porcine intestinal spirochaetosis
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| − | **Infection is acquired via contaminated faeces
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| − | **Disease spreads slowly through the herd
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| − | **Dogs, rats, mice and flies may act as transport hosts
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| − | **''B. hyodysenteriae'' survives several weeks in moist faeces
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| − | *Clinical signs
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| − | **''B. hyodysenteriae'' causes dysentry in weaned pigs 6-12 weeks old; pigs lose condition and become emaciated; appetite is decreased; large amount of mucous may be present in the faeces; low mortality; poor feed conversion ratio
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| − | **''B. pilosicoli'' causes less severe signs than swine dysentry; reduced feed conversion rates occur
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| − | *Diagnosis
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| − | **History, clinical signs and gross pathology
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| − | **Anaerobic culture on blood agar with added antibiotics for at least 3 days
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| − | **''B. hyodysenteriae'' causes complete haemolysis whereas other spirochaetes cause partial haemolysis
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| − | **Immunofluorescence, DNA probes and biochemical tests
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| − | **Serology using ELISA can be used on a herd basis
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| − | **PCR
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| − | [[Brachyspira hyodysenteriae]]
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