Leptospira
G.HARIPRASAD M.Sc.,(Med micro),M.phil.,Lecturer in Microbiology Department of Microbiology Thoothukudi Govt. Medical College Thoothukudi
LEPTOSPIRA
• Spirochaetes possess numerous closely wound spirals with characteristic hooked ends.
• Actively motile
Classification
• Non-pathogen– L.biflexa –found in
waters.
• Human Pathogen- L. interrogans
• L.interrogans has 26 serogroups
e.g. - Icterohaemorrhagiae
- Canicola
- Australis
- Hebdomadis
- Andamana
Leptospira interrogans-Pathogenicity
Infection with leptospira – Leptospirosis
The primary reservoir is rodents because, once infected, they shed the organisms for life.
ANIMAL RESERVOIR FOR LEPTOSPIRA
• Humans gets infection by drinking water contaminated with Leptospira….
• Leptospires can also enter thro’ abraded skin…..
Incubation period – 6-8 days
• Leptospires enters blood & multiply for 1 wk • Then disappear from the blood and enters
into the liver, Kidney, spleen and meninges.• Persist mainly in kidney and excreted in
urine in later stages
WEIL’S DISEASE
Severe form of leptospirosis
Fever, conjunctivitis, albuminurea, jaundice and haemorrhage
Implicated group:
L.icterrohaemorrhagiae
Clinical symptoms
Laboratory diagnosis
Specimens:
1. Blood – in initial stage
2. Urine – in later stage
Blood should be examined during the first week of illness thereafter urine is examined.
DARK-GROUND MICROSCOPY
Gold standard method for detection of spirochetes including Leptospira
FONTANA’S STAIN
CULTURE
• Modified Korthof’s medium
• Fletcher’s semisolid medium
Incubated at 28-320C aerobically
Examined every 3rd day upto 6 weeks before discarding it as negative
ANIMAL INOCULATION
• Intraperitoneal inoculation into young guinea pigs
• On third day, the peritoneal fluid is examined daily by dark ground illumination.
SEROLOGICAL TESTS
• Useful method of diagnosis
• Antibodies begin to appear at the end of first week and continue to rise till the fourth week and then begin to decline.
Two types
• Screening tests
• Serotype specific tests
SCREENING TEST
• Identify genus i.e.Leptospira?????• Using antigen: L.biflexa (non-pathogen)
Test used: Complement-fixation test Haemagglutination test ELISA Agglutination Indirect immunofluorescence
Serotype specific tests
• Identify exact serotypes
Microscopic agglutination test
Macroscopic agglutination test
TREATMENT:• Penicillin • Tetracycline• Erythromycin
PROPHYLAXIS:
Rodent control
Disinfection of water
Wearing of protective clothes
No vaccines!!!!
Natural immunity develops after infection with corresponding serotype
