LEPTOSPIROSIS

  • It is also known as Weils disease, Stuttgarts disease, infectious disease, haemoglobinuria, rice field workers disease, swine handlers disease, canine typhus
  • It is an acute, febrile and septicemic disease characterised by septicaemia, interstitial nephritis, haemolytic anaemic and abortion.
  • It causes mastitis in cattle.

Aetiology

  • Leptospira pomona, Leptospira canicola, L. Grippotyphosa, L.icterohaemorrhagica, L.hardjo
  • It is a G+ve, long, flexible and filamentous bacteria made of fine spirals with hook shaped ends.
  • Cattle act as reservoir host for Icterohaemorrhagica

Mode of transmission

  • Urine act as chief source of contamination.
  • Drinking water contaminated with urine of rodents and wild infected animals act as source of infection.
  • Bathing or swimming in infected water may also cause disease. Organisms may enter through abraded skin, mucous membrane and conjuctiva.
  • Grazing animals get infection from pasteur and soil which gets contaminated from infected urine, aborted material or uterine discharge.
  • Trans-placental infection is also seen in case of cattle.
  • Calves may acquire disease from infected mother through suckling.
  • Ticks transmit the disease.
  • Carrier animals shed organisms through urine.

Clinical signs

  • Interrogans serovar icterohaemorrhagica causes severe septicemia.
  • Incubation period- 3-7 days
  • Interrogans serovar pomana- acute leptospirosis
  • Calves upto 1 month of age are more susceptible.
  • Causes septicemia with high fever upto 107°F
  • Signs are anorexia, pallor mucosa and petechial haemorrhages of mucosa are seen.
  • Acute haemolytic anemia and haemoglobinurea are seen.
  • Other symptoms include jaundice, increased heart rate with increased intensity of heart sound, prominent dyspnoea.
  • Pregnant animals may abort.
  • High mortality rate in affected animals.
  • Udder becomes soft and milk flow ceases. Blood clots are seen over udder.
  • Sub acute case
  • Mild fever 102-105°F
  • Signs like depression, dyspnoea, anorexia,haemoglobinurea are seen.
  • Abortion may occur 3-4 weeks later.
  • Milk yield decreases with presence of blood stain in milk.
  • Milk becomes thick.
  • No physical change in udder is observed.
  • Chronic case
  • Mild signs and symptoms
  • Abortion occurs in last trimester of pregnancy.

Abortion storm

  • interrogans serovar harjdo
  • Restricted to pregnant or lactating cows
  • Sudden onset of fever, anorexia, and abnormality
  • Agalctia, milk colour changes from yellow to orange colour and may contain clots.
  • Mastitis occurs.
  • Milk drop syndrome
  • Abortion occurs several weeks later.

Diagnosis

  • From history and clinical signs
  • Haematological examination- increased leucocytes, haemolytic anemia
  • Biochemical examination- increased serum bilirubin, BUN
  • Identify leptospira in clinical samples under dark field microscope
  • Histopathological examination using levaditis technique
  • Animal inoculation- materials from liver, spleen and brain are inoculated into mice
  • Rapid diagnostic kit- lepto dipstick
  • Culture using specific media like chang's, Fletcher's, Gillespie media.
  • For identification of organisms-
  • Immunoflouroscent staining, immunoperoxidase staining, radioimmunoassay, PCR, DNA probes
  • Other serological tests like-CFT, MAT, ELISA etc

Differential diagnosis

  • Bacillary Haemoglobinurea
  • Post parturient haemoglobinurea
  • Babesiosis
  • Anaplasmosis
  • Brucellosis
  • Infectious bovine rhinotracheitis
  • Milk drop syndrome- ketosis, mastitis etc.

Treatment

  • Benzathine penicillin@ 12000IU per kg bwt
  • Iron dextran @100-300 mg total dose for 2-3 wks
  • Haemostatics- Adrenocrome monosemicarbazone@ 20-25 mg total dose
  • Blood transfusion

Control

  • Avoid feeding contaminated feed and water
  • Strict sanitary measures should be followed in farms
  • Infected animals should be isolated from herd
  • Screening of suspected herd should be done in every 3 months
  • Water logging should be avoided and rodent control should be done effectively
  • Herd disinfection using sodium hypochlorate, calcium chloride and NaOH should be done

Vaccination

  • No cross protection between strains is seen so vaccinating animals does not yield very good result.
  • Vaccinating calves below 3 months of age is not very effective.
  • Vaccinating pregnant cows at late pregnancy yields good result.