Leptospira spp

From Cow
Aborted foetus as a consequence of L. interrogans infection in a cow

Leptospira spp are a parasitic spirochaete bacteria which are endemic in cattle throughout most parts of the world.

Leptospira spp are associated with renal and reproductive disorders and are of economic impact to both beef and dairy cattle industries and is a zoonotic disease in humans[1]. Although over 200 serovars of Leptospira spp have been recognized, a number of species have been regularly associated with disease in cattle, including:

  • L. pomona
  • L. hardjo - most common[2]
  • L. grippotyphosa
  • L. interrogans[3]
  • L. bratislava
  • L. icterohaemorrhagiae
  • L. canicola

Leptospires have a predilection for moist environments and infect cattle through ingestion of contaminated grass[4]. They acquire access to the host via penetration of damaged mucous membranes or skin. One to three weeks later, leptospires can be seen in circulation, following which they replicate in the liver, kidneys, lungs, genital tract, and nervous system. After this period of bacteremia, most cattle eliminate the bacteria, but some cattle remain maintenance hosts, with bacteria remaining in the renal tubules, genital tract and, more rarely, the eyes for up to many years[5].

Clinical signs

Most cases of leptospirosis remain subclinical, although some cattle present with fever and signs associate with acute nephritis. In subacute cases, severe bacteremias may result in hemolytic anemia, hemoglobinuria, jaundice, pulmonary congestion, occasionally meningitis, and death.

In carrier cattle, infertility, abortion and stillbirths are common. Drops in milk yield are reported in dairy herds.

Diagnosis

A suspicion of Leptospirosis can be made from historical evidence of the disease within the district, supported by clinical findings of stillbirths, abortions, low milk yields, serological titres and the presence of Leptospira spp cultured from milk, urine or placenta.

Antibody titers >1:800 in placental tissue, cow blood or foetal tissue at the time of abortion is considered evidence of leptospirosis[6]. Immunofluorescence, ELISA[7] and PCR testing of bovine urine are considered definitive methods of confirming leptospirosis in cattle[8][9]. Interference with some ELISA assays does occur in previously vaccinated cattle[10].

Treatment

Broad-spectrum antimicrobials such as tetracyclines are considered effective, although ceftiofur, tilmicosin, tulathromycin, erythromycin, tiamulin and tylosin are also effective[11].

Annual vaccinations with pentavalent vaccines are an effective method of control in herds where leptospirosis is endemic[12].

References

  1. Ngbede EO et al (2012) Serological prevalence of leptospirosis in cattle slaughtered in the Zango abattoir in Zaria, Kaduna State, Nigeria. Vet Ital 48(2):179-184
  2. Surujballi O et al (1997) Development of a monoclonal antibody-based competitive enzyme-linked immunosorbent assay for the detection of Leptospira borgpetersenii serovar hardjo type hardjobovis antibodies in bovine sera. Can J Vet Res 61:267–274
  3. Terpstra WJ et al (1987) Detection of Leptospira interrogans in clinical specimens by in situ hybridization using biotin-labelled DNA probes. Microbiol 133:911–914
  4. Ellis WA (1984) Bovine leptospirosis in the tropics: prevalence, pathogenesis and contro. Prev Vet Med 2:411–421
  5. Thiermann AB (1984) Leptospirosis: current developments and trends. J Am Vet Med Assoc 184:722–725
  6. Merck Vet Manual
  7. Joseph S et al (2012) Evaluation and comparison of native and recombinant LipL21 protein-based ELISAs for diagnosis of bovine leptospirosis. J Vet Sci 13(1):99-101
  8. Otaka DY et al (2012) Serology and PCR for bovine leptospirosis: herd and individual approaches. Vet Rec 170(13):338
  9. Talpada MD et al (2003) Prevalence of leptospiral infection in Texas cattle: implications for transmission to humans. Vector Borne Zoonotic Dis 3:141–147
  10. Naves JH et al (2012) Interference in diagnostic tests for brucellosis in cattle recently vaccinated against leptospirosis. J Vet Diagn Invest 24(2):283-287
  11. Alt DP et al (2001) Evaluation of antibiotics for treatment of cattle infected with Leptospira borgpetersenii serovar hardjo. J Am Vet Med Assoc 219:636–639
  12. Rinehart CL et al (2012) Efficacy of vaccination of cattle with the Leptospira interrogans serovar hardjo type hardjoprajitno component of a pentavalent Leptospira bacterin against experimental challenge with Leptospira borgpetersenii serovar hardjo type hardjo-bovis. Am J Vet Res 73(5):735-740