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Managing Leptospirosis (Proceedings)

Article

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

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

 

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