Leptospiraceae
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
- May cause severe systemic disease, resulting in enteritis
- 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-mediated 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, haemoglobin pigmentation, 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