Resistance, antigens and toxins

RESISTANCE, ANTIGENS AND TOXINS

Resistance

  • Leptospira are highly susceptible to heat, being killed in 10 mts at 50ºC and in 10 sec at 60ºC.
  • They are also sensitive to acid and are destroyed by gastric juice in 30 mts. Bile destroys them rapidly.
  • They are also readily destroyed by most antiseptics and disinfectants.
  • They can survive for several days in alkaline water and only 12 –14 wks in sewage.
  • Dogs may shed leptospires in their urine for 2 to 6 months, cattle for 3 months and rats for longer periods.
  • Leptospira have remained viable for atleast 6 days in coagulated blood and also they remain viable in unfrozen kidneys for several days after the death of the animal.

Antigens and toxins

  • A lipopolysaccharide antigen appears to be present in all members of the genus.
  • Based on surface antigens, probably composed of protein-polysachharide complexes L. interrogans is divided into more than 190 different serovars, arranged into 25 major antigenically related serogroups. Animals and humans can be infected with wide variety of serovars.
  • The serovars causing disease in animals vary between countries and sometimes between regions in the same country.
  • Pathogenic leptospires produce haemolytic, lipolytic and cytotoxic substances.
Last modified: Monday, 4 June 2012, 5:42 AM