Leptospira

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