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Leptospirasaceae

Leptospirosis is a zoonotic disease affecting animals and humans, with major health implications in tropical regions. Learn about its epidemiology, modes of transmission, clinical manifestations, and diagnostic methods like microscopy and serological testing.

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Leptospirasaceae

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  1. Leptospirasaceae

  2. Leptospira causes Leptospirosis. • A zoonosis of global importance affecting both animals and humans and has veterinary, economic,and medical relevance. • Major public health problem in tropical countries, with epidemic outbreaks occurring in the rainy season and after floods.

  3. Synonyms • Mud / Swamp fever • Japanese 7 day fever • Rice Field Fever • Spirochete Jaundice / Leptospiral Jaundice. • Autumn Fever • Canicola Fever • Swineherd’s Disease

  4. Epidemiological factors • First description by Weil in 1886 India - Cases are reported from Kerala, Tamil Nadu, AP, Karnataka, Maharashtra, Gujarat & Andamans. Source - Animals (rodents and domestic animals) • Poor Sanitation; Inadequate drainage facilities.

  5. Risk Groups Walking/ working bare foot poses high risk. Occupational exposure • Farmers • Sewerage workers • Abattoirs, Butchers • Vetenarians, • Lab staff • Fishermen – Inland. Recreational activities: • Swimming, Sailing, Marathon runners, Gardening.

  6. Reservoirs of Infection • Rodents • (Rattus rattus, Rattus norvegicus, Mus musculus) • Dogs • Wild animals • Domesticated animals Leptospira are excreted in the urine

  7. Human infection is accidental No human to human transmisonn Modes of Transmission Reservoir Host Urine Infect 1. Direct contact with urine or tissue of infected animal Through skin abrasions, intact mucus membrane 2. Indirect contact Broken skin with infected soil, water or vegetation Ingestion of contaminated food & water 3. Droplet infection Inhalation of droplets of infected urine Rodents esp. Rats Splashing contaminated water/urine into eyes Leptospira sp. Urine Swallowing contaminated water/food Contaminated water/food/soil Contains Exposing open wounds (e.g cuts) to contaminated water/soil

  8. Organism in Enviroment Mucosal Penetration Systemic Circulation Low or Abscent antibodies Moderate no. of antibodies Multiplication leptospiremia Endotoxin release TNF,IL-1.IL-8 Mild leptospiremia Kidney (renal failure) Liver (jaundice) Cougulopathy Vascular damage Thrombocytopenia Mild / inapparentclininical signs Clinical disease Multiorgan failure Antibody titre ↑ weilssyndome Chronic active hepatitis Leptospira cleared from blood DEATH Elimination of organism Renal colonization Carrier state Chronic shedding No shedding

  9. Clinical syndromes Anicteric :Common (95% recover) < 2% Mortality Icteric ( Weil’s Syndrome)(rare, fatal) 15% Mortality

  10. Approach to Diagnosis Microscopy

  11. Direct Microscopy - Dark-field microscopy - Phase contrast microscopy - Silver staining - Immunostaining methods: . Direct immunofluorescence, and . Immunoperoxidase staining Specimen: • . Blood • . Urine • . CSF • . Body fluids and tissues

  12. Shortcomings of Direct microscopy • High risk of false-positive and False-negative diagnoses. • Results by microscopy of clinical material should always be confirmed by other tests.

  13. Culture • Isolation of leptospires: Media Ellinghausen- McCullough-Johnson-Harris (EMJH) medium, 1% bovine serum albumin, 10% Leptospira enrichment (or 8 - 10% rabbit serum) Tween 80 (source of long-chain fatty acids)

  14. Made selective by the addition of several antibiotics such as: 5-fluorouracil and neomycin sulphate, polymyxin B, nalidixic acid, rifampicin, vancomycin and amphotericin B. • Since urine is acid and decreases the viability of leptospires, should be inoculated into medium within 2 hours after voiding. Urine samples should be neutralized with sodium bicarbonate or using phosphate-buffered bovine serum albumin (BSA) solution.

  15. Opaque ring just below the surface of the media in the tube • Incubated between 28°C and 30°C. • The time required for detection of a positive culture varies with: Leptospiral serovar. Number of organisms present in the sample. • Less fastidious serovars (e.g. Pomona ): 7 - 10 days. • Other serovars (e.g. Hardjo ): 4 - 6 months.

  16. Serological Methods • Most appropriate diagnostic method. • Generally, seroconversion (first sample, no detectable titre, the second sample, positive, i.e. above the cut-off point) OR • A four-fold or higher rise in titre in successive serum samples is considered to be diagnostic proof of recent infection

  17. Microscopic Agglutination Test • Determines agglutinating antibodies in the serum of a patient by mixing it in various dilutions with live different leptospiral antigens. • The standard criteria for a positive MAT are a four-fold increase in antibody titre, or a conversion from seronegativity to a titre of 1/100 or 1/200. ADVANTAGES: • Sensitive • Highly specific and reliable assay when used by skilled personnel.

  18. DISADVANTAGES: Require meticulous culture of a collection of the strains used as antigen suspensions in the tests. Use of live organisms as antigen, it poses a danger to laboratory personnel and potentially biohazardous. Regular subculture, purity agglutination and maintenance of several leptospiral serovars may be; Difficult, Tedious, Expensive, and Time consuming.

  19. Enzyme-Linked Immunosorbent Assay Test (ELISA) Reported to be more sensitive than the conventional serological tests. • Latex Agglutination Test: useful screening procedure. Simple and Rapid + Latex particles with Leptospiral antigen LATEX PARTICLE Human Sera + SENSITIZED WITH LEPTOSPIRAL ANTIGEN Agglutination of the particles. L. biflexa serovar Patoc

  20. Lepto-Dipstick Test: Detects Leptospira-specific IgM antibodies in human sera. The highly stable reagents and simple implementation. Suitable for use in clinical and field laboratories in tropical countries Prepared from Leptospira biflexa serovar Patoc and coat.

  21. Molecular Diagnosis Polymerase Chain Reaction (PCR) Amplifying specific segments of leptospiral DNA in clinical samples such as blood or urine, cerebrospinal fluid and tissue samples (ante or postmortem). Real-Time Polymerase Chain (RT-PCR) Distinguish between pathogenic leptospires using melting curves and gives a result much quicker than conventional PCR and is less prone to contamination.

  22. Interpretation of Tests

  23. WHO Guide - Faine’s Criteria Score of 25 or more – Presumptive Diagnosis Score of 20 to 25 – Possible case of leptospirosis

  24. Treatment Oral Treatment 7 to 10 day IV Treatment 5 to 7 days Jarisch Herxheimer Reaction

  25. Special Measures

  26. Prevention

  27. Conjunctival suffusion Purpura Yellow discolouration conjuctiva Conjunctival hyperaemia

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