Leptospirosis:

Synonym: Rice field worker’s disease, Weils disease, Sugarcane worker’s disease, Stuttgart disease

• It is an acute or chronic or clinically inapparent contagious disease of domesticated and wild animals as well as man.
• Disease is characterized by fever, anemia, haemoglobinuria, icterus and abortion.

Etiology:

• It is caused by Leptospira species.

Epidemiology:

• Cattle, buffalo, horse, donkey, sheep, goat, pig and dogs are susceptible.
• Disease is worldwide in distribution.
• Organisms usually remain motile in liquid media with flexing motion and rotation around their long axis.
• Organisms are readily destroyed by heat and disinfectants but survive for longer period of time in water and sewages.

Transmission:

• Through direct contact with infected urine of domestic animals
• Through ingestion of urine contaminated food and water
• Through drinking water contaminated by rodents or wild animals.
• Through abraded skin, mucus membrane or conjunctiva.
• Transplacental transmission is possible in cattle, pig and man.
• Dogs acquire infection through ingestion of infected carcasses.
• Vector transmission is possible.

Pathogenesis:

Clinical Signs:

Cattle and buffalo:

• Sudden onset, first sign is elevation of body temperature (2-5°C).
• Anorexia, lassitude, haemoglobinuria, dyspnoea, icterus, abortion.
• Hemoglobinuria is more common in calves than adult animals.
• Anemia along with icterus is common.
• In lactating dairy cattle, high rise of temperature may be accompanied by yellow clotted milk. It is followed by agalactia.
• Abortion and still birth in 5-9 months pregnant cattle.
• Oedema and hemorrhage of the conjunctiva.

Sub-acute/Mild form:

• This form lasts for few days.
• Anorexia, depression, hemoglobinuria, and colic.
• Reduction in milk yield.
• Blindness, cerebral ataxia, incoordination of hindquarters.

Chronic form:

• Symptoms are less marked but lasts for longer period of time.
• Abortion is most common feature.
• Acute nephritis or chronic nephritis is observed.
• Acute nephritis is characterized by hematuria and presence of cellular debris in urine.
• Anuria is observed in severe cases which terminates fatally.

Horse:

• Disease may appear as per-acute, acute or chronic form.

Per-acute form:

• Anorexia, depression, tachycardia
• Polypnoea, haemoglobinuria
• Depression of erythrocytic count and haemoglobin level.

Acute form:

• This form is characterized by high rise of temperature, anorexia, conjunctivitis, keratitis, photophobia, iridocyclitis, excessive lacrimation and jaundice.
• Abortion is observed in third trimester of pregnancy.
• Myalgia, stiff gait and paralysis
• Diarrhoea followed by constipation, colic, oliguria, red urine and necrotic skin.

Chronic form:

• Weakness, emaciation, intermittent fever along with subicterus and haemorrhages.

Sheep and goat:

• Per-acute form is characterized by sudden onset resulting to death.
• Acute cases may show anemia, haemoglobinuria, and jaundice with high temperature.
• Abortion is important signs beside icterus.
• High rise of temperature, icterus, anemia, haemoglobinuria and leptospiruria.

Pig:

• High rise of temperature, anorexia
• Conjunctivitis, jaundice and abortion
• There is abortion storm and early death of new born pigs
• Fetus shows signs of jaundice.
• Meningo-encephalitic signs like hyper irritability, epileptic form of convulsion, circling, incoordination, paralysis

Dog and cat:

• Signs in dog appears as per-acute, acute, subacute and chronic.
• Onset of disease is usually sudden.
• Per-acute form is characterized by hemorrhages of mucus membrane and death in one to few days.
• Acute form shows jaundice following pyrexial attack.
• Ulceration of buccal mucosa and tonsillar involvements cause foul breath.
• Concentration of urea in blood
• Fibrotic kidney in older dog.

PM Findings:

• Carcass of Leptospira affected cattle show icteric condition and multiple widespread haemorrhagic spots below mucus and serous membrane.
• Necrotic changes in liver cells.
• Retention of bile and mononuclear cell infiltration in the liver.
• Kidneys shows greyish white spots due to necrosis. Hemorrhages are noted on cortical surfaces.
• Changes are observed in uterus and aborted fetus show signs of focal hepatitis.
• Following abortion, fetal membrane shows hemorrhages and edema.
• Hemorrhages in lungs and cellular infiltration.

Dog:

• Ulceration of buccal mucosa, hemorrhagic and necrotic changes of GI tract
• Fatty degeneration of liver
• Haemorrhagic and cellular infiltrations of kidneys.
• Carcass of dog is often dehydrated and mouth and anus are soiled.
• GI hemorrhages are common.
• Lymph nodes are swollen and haemorrhagic.
• Stomach and intestinal contents are blood tinged and tarry.
• Pulmonary and myocardial hemorrhages.
• Liver and kidney show the signs of cloudy swelling and fatty degeneration.

Diagnosis:

• Based on history and clinical findings.
• Based on PM findings
• Based on laboratory findings; elevation of leucocytic count, signs of anemia, raise bilirubin values, raised BUN level
• Demonstration of organism in the blood or urine during the first 5-7 days of illness by dark field microscopy
• Culture of urine or blood or infected tissues
• Histopathological examination; liver, kidneys and brain tissues may be used for this purpose.
• Animal inoculation: Suspected materials from liver, spleen and brain may be inoculated into mice.
• Identification of organism through immunofluorescence staining, immuno peroxidase training
• PCR

Differential Diagnosis:

Bacillary haemoglobinuria: Adult cattle in pasture used to suffer. High rise of temperature, colic and haemoglobinuria. WBC will show leukopenia or leukocytosis.

Post-parturient haemoglobinuria: High-yielding dairy cows will suffer following parturition. No rise of temperature, No-red colored milk, marked haemoglobinuria, low blood phosphorus level.

Babesiosis: History of tick bite, high rise of temperature, yellowish urine, loose stool, haemoglobinuria. Demonstration of parasites in blood smear.

Anaplasmosis: Both calf and adult cows may suffer. It is transmitted by ticks. There are signs of jaundice. No hemoglobinuria, No signs of fever, Parasites in blood smear.

Treatment:

• IM injection of penicillin, ampicillin or doxycycline is recommended. Treatment should be continued for 5-7 days. Penicillin for dog @25000-40,000 Unit/kg, IM at 12 hours.
• Ampicillin @ 22mg/kg, every 8 hours IV
• Doxycycline @5mg/kg, SID
• Supportive treatment should be given to monitor the kidney function. Corticosteroid may be used to speed up the elimination of urea.
• It is self-limiting problem in bovine.

Control:

• All possible measures should be taken to avoid leptospires contamination made by the excreta of domestic and wild carrier animals.
• Strict sanitary measures should be adopted in a farm to avoid establishment of infection through urine.
• Infected animals must be segregated from the rest of the herd.
• Recovered animals should be kept separated for at least 2 months following clinical recovery.
• Animals with febrile reaction or positive to serotest should be isolated.
• Newly acquired animals should be purchased from non-infected farms.
• Pigs, sheep, and goats are to be kept separated from cattle.
• Adequate care should be made to prevent contamination of drinking water.
• Strict vigilance should be made to avoid contamination of drinking vessels, feeding trough and stored feeds by the urine of domestic and wild animals.
• Aborted fetus and fetal membrane must be destroyed. Overcrowding of animals in pasture, yards and sheds should be prevented.
• Disinfectants like sodium hypochlorate, calcium chloride and sodium hydroxide may be used.
• Rodents are main carriers of this disease. Rodent should be controlled in animal farms.
• Chick embryo attenuated vaccine has been used. Calves should be vaccinated after the age of 3 months.