Managing Leptospirosis (Proceedings)

Agent

• Spirochete with more than 200 “serovars.” The pathogenic serovars do not replicate outside animal hosts

• Leptospira interrogans

• Serovars: autumnalis, bratislava, canicola, icterohaemorrhagiae, pomona

• Leptospira kirshneri

• Serovar: gryppotyphosa

• Leptospira borgpetersenii

• Serovar: hardjo

• Specific serovars are “hosted-adapted” to certain reservoir species and generally do not cause disease in those hosts, e.g.:

• L. interrogans bratislava                                              pigs, rats, small mammals

• L. interrogans canicola                                                dogs

• L. interrogans icterohaemorrhagiae                             rats

• L. kirschneri grippotyphosa                                        voles, raccoons, small mammals

Epidemiology

• Animals are critical to the maintenance of pathogenic leptospires in a given area.

• Leptospires can persist in the renal tubules without causing disease, and can be excreted in the urine for prolonged periods of time.

• Leptospires evade immune responses while sequestered in renal tubules.

• Prevalence in dogs is increasing since 1983

• Risk factors

• Adult (4 – 7 years) intact male dogs

• Herding, working dogs, and hounds

• Enzootic worldwide

• Tropical and semitropical areas

• Alkaline soil

• Leptospires can survive in moist environments for months, but are killed by freezing

• Seasonality

• Summer or fall

• Rainy periods

Transmission

• Leptospires are eliminated by urine and enter the body through abraded skin and intact mucous membranes

• In dogs, leptospira concentrates in the liver and kidneys

• Clinical signs – 7 days post-exposure

• May clear the infection in 2 – 3 weeks

• May develop chronic renal failure or chronic active hepatitis

• In cats, infections are usually subclinical

• Cats can shed leptospira in the environment

Clinical Signs

• Many, if not most, Leptospira infections in dogs are subclinical

• L. interrogans icterohaemorrhagiae: Hepatic disease and hemorrhage occur mostly with (may also have sub-acute uremia)

• L. interrogans bratislava: Renal disease predominates with (liver changes also can be present)

• L. interrogans pomona: Renal and liver disease mostly

• L. kirschneri grippotyphosa: Renal and liver disease mostly

• L. interrogans canicola: Mostly renal changes

• Experimental infection

• L. interrogans pomona and L. interrogans bratislava causes hemorrhagic and inflammatory lesions in lungs kidneys and liver.

• Signs

• Fever

• Uveitis

• Vomiting, diarrhea

• Renal failure

• Liver failure

• Jaundice

• Muscle pain

Laboratory Abnormalities

• CBC

• Leukopenia (acute)

• Leukocytosis (subacute)

• Thrombocytopenia

• Renal failure

• Increased BUN and creatinine

• Cillindruria

• Pyuria

• Hematuria

• Liver disease

• Increased activity of ALT and Alkaline phosphatase

• ALP is usually higher than ALT

• Increased bilirubin

• Interstitial lung disease

Diagnosis

• Clinical Signs + Serology

• Detection of antibodies

• Antibodies from active infection, previous infection or vaccination

• Active infection

• MAT titer > 3200

• 4 fold increase in titer over 2 – 4 weeks

• Positive IgM ELISA

• Titers can be negative in acute infection

• Vaccine may induce antibodies against L. interrogans automnalis

• Demonstration of the organism

• Dark-field or phase-contrast microscopy in the urine

• Intermittent shedding leads to false-negative

• Culture

• Before antibiotics

• Place immediately in transport media

• To the laboratory ASAP

• Pre-treatment with furosemide may increase yield

• PCR (urine)

• Early positive

• Very sensitive

• May be positive for years after recovery

• 8% of dogs (regardless of health status) shed pathogenic leptospir

• Serology is a poor predictor of leptospiruria

• 22% sensitivity, 79% specificity

Therapy

• Fluid therapy

• Maintain hydration

• Preserve renal function

• Antibiotics

• Ampicillin or penicillin G

• Initially IV

• Doxycycline for 2 weeks after penicillin to eliminate the carrier phase

• Decreases shedding, but may not eliminate it

Prevention

• All serovars can potentially infect humans

• Wear gloves

• Vaccines

• Can reduce severity of the disease but do not eliminate the carrier state

• May not protect against all serovars

• Not necessary in geographic areas with low/absent risk

• The most reactogenic vaccines for the dog

• The duration of immunity is short (£ 1 year). 

• If risk of Leptospira disease is high

• Vaccines need to be given much more often than they are currently given

• 4-way lepto product

• 12 weeks, 15 weeks, 6 months, 1 year

• Then every 6 to 9 months if it remains at high risk

• Relative efficacy

• L. interrogans canicola: £ 75%

• L. kirshnerii grippotyphosa: £ 60%

• L. interrogans icterohaemorrhagiae: £ 90%

• L. interrogans pomoma: £ 60%

Public health

• Leptospirosis can occur as either sporadic cases or in epidemics

• Infection occurs through mucosal contact with water or soil contaminated with the urine of infected animals

• Risk occupations

• Veterinarians, farmers and abattoir workers

• Recreational activities in water

References

Adin CA & Cowgill LD. Treatment and outcome of dogs with leptsopirosis: 36 cases. JAVMA 216():371-5, 2000.

Bal AE et al. Detection of leptropires in urine by PCR for early diagnosis of leptospirosis. J Clin Microbiol 32(8):1894-8, 1994

Barr, S.C. et al. Serologic responses of dogs given a comme rcial vaccine against Leptospira interrogans serovar pomona and Leptospira kirschn eri serovar grippotyphosa. AJVR. 66:1780-1874. 2005

Birnbaum N et al. Naturally acquired leptospirosis in 36 dogs: serological and clinicopathological features. JSAP 39(5):231-6, 1998

Brown CA et al. Leptospira interrogans serovar grippotyphosa infection in dogs. JAVMA 209(7):1265-7, 1995. 

Forrest, L.J. et al. Sonographic renal finding s in 20 dog s with leptospirosis. Vet. Radiol. Ultrasound 39:337-340. 1998

Greenlee , J.J. et al. Clinical and pathologic comparison of acute leptospirosis in dogs caused by two strains of Leptospira kirschneri serovar grippotyphosa. AJVR. 65:1100-1107. 2004

Greenlee JJ. Experimental canine leptospirosis caused by Leptsopira interrogans serovars pomona or bratislava. AJVR 66(10):1816-22, 2005

Harkin KR & Gartrell CL. Canine leptospirosis in New Jersey and Michigan: 17 cases (1990-1995). JAAHA 32(6):495-501, 1996.

Harkin, K.R. et al. Clinical application of a polymerase chain reaction assay for diagnosis of leptospirosis in dogs. JAVMA. 222:1224-1229. 2003

Harkin, K.R. et al. Comparison of polymerase chain reaction assay, bacteriologic culture, and serologic testing in assessment of prevalence of urinary shedding of leptospires in dogs. JAVMA. 222:1230-1233. 2003

Levett, P.N. Leptospirosis. Clin. Microbiol. Rev. 14:296-326. 2001

Syjes J. et al 2010 ACVIM Small Animal Consensus Statement on Leptospirosis: Diagnosis, Epidemiology, Treatment, and Prevention. J Vet Intern Med. 25:1-13, 2011.

Ward, M.P. et al. Evaluation of environmental risk factors for leptospirosis in dogs: 36 cases (1997-2002). JAVMA. 225:72-77. 2004

Ward, M.P. et al. Prevalence of and risk factors for leptospirosis among dogs in the United States and Canada: 677 cases (1970-1998). JAVMA. 220:53-58. 2002

Ward, M.P. et al. Serovar-specific prevalence and risk factors for leptospirosis among dogs: 90 cases (1997- 2002). J.VMA. 224:1958-1963. 2004