Bovis ISSN 2398-2993

Leptospira spp

Contributor(s): Veronica Fowler, Vetstream Ltd , Tammy Hassel

Introduction

Classification

Taxonomy

  • Order: spirochaetales.
  • Family: leptospiraceae.
  • Genusleptospira.

Etymology

  • Gk: lepto- thin, narrow; spira- a coil; leptospira- a fine coil.

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Clinical Effects

Epidemiology

Habitat

  • Leptospires can survive in rivers, surface water, mud and moist soil when environmental temperature is moderate. As such Leptospirosis is spread most often during the spring and summer months while cattle are at pasture.
  • Mixed grazing with sheep is not advised as sheep can carry and excrete Leptospires.

Lifecycle

  • The most likely sites of entry of Leptospires are the mucosa and broken skin and a generalized infection follows.
  • The host responds by producing antibodies that result in clearance of the bacteria from all tissues except the brain, eyes, and kidneys.
  • Leptospires surviving in the brain and eyes multiply slowly, if at all; however, in the kidneys they multiply and cause persistent infection (for weeks or even months) in the convoluted tubules and are shed in the urine.

Transmission

  • Leptospirosis can be transmitted both directly (animal to animal) and indirectly (from the environment).
  • Direct transmission can be through contaminated urine. Leptospire Hardjo serovars often produce a carrier state in the kidneys causing long term shedding of the bacteria in the urine.
  • Indirect transmission is usually through contaminated water sources or soil.

Pathological effects

  • The clinical presentation of infection with Leptospires differs depending on whether the particular serovar is ‘host adapted’ or ‘non-host adapted’.
  • Host adapted serovars (Hardjo) readily infect cattle and the disease symptoms are relatively mild or even subclinical. These serovars also produce a carrier state in the kidneys causing long term shedding of the bacteria in the urine. Clinical signs include:
    • Raised temperature.
    • Lethargy and loss of appetite.
    • Agalactia and the udder appear soft and flabby.
    • Persistent infection of the oviducts results in reduced fertility.
  • For non-host adapted serovars (grippotyphosa, pomona, icterohemorrhagia) cattle exhibit a low susceptibility to infection with these serovars with transmission to other animals being inefficient. In contrast the disease symptoms can be much more severe.
    • In calves:
      • High fever.
      • Anemia.
      • Red urine.
      • Jaundice.
      • Sometimes death occurs within three to five days.
    • In older cattle:
      • Fever.
      • Lethargy.
      • Agalactia Agalactiae.
      • Thick, discolored milk.
    • In pregnant cows:
      • Embryonic death, abortions, stillbirths Abortion & Stillbirths, retained Placenta Placenta, and the birth of weak calves.
      • Abortions usually occur three to ten weeks after infection.

Control

Control via animal

  • Isolate any affected animals.
  • Before introducing new animals to the herd consider treatment with Streptomycin Streptomycin 25mg/kg on two occasions 10-14 days.

Control via chemotherapies

  • A single intramuscular injection of Streptomycin Streptomycin/Dihydrostreptomycin Dihydrostreptomycin at 25mg/kg will eliminate infection from most cattle.
  • Streptomycin is added to semen from bulls held at artificial insemination centres.

Control via environment

  • Avoid co-grazing cattle with sheep. If sheep have previously been grazing on a pasture leave a period of approx 4 weeks before introducing cattle.
  • Prevent cattle accessing potentially contaminated watercourses.

Vaccination

  • The use of vaccines containing inactivated bacterial cells to stimulate an immune response is effective in the prevention of the disease circulating.
    • Two doses are given 4-6 weeks apart initially followed by annual boosters, usually in the spring, prior to turnout.

Diagnosis

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Ellis W A (2015) Animal leptospirosis. Curr Top Microbiol Immunol 387, 99-137.
  • Williams D & Winden S V (2014) Risk factors associated with high bulk milk antibody levels to common pathogens in UK dairies. Vet Rec 174 (23), 580 PubMed.
  • Hamond C, Martins G, Loureiro A P, Pestana C, Lawson-Ferreira R, Medeiros M A & Lilenbaum W (2014) Urinary PCR as an increasingly useful tool for an accurate diagnosis of leptospirosis in livestock. Vet Res Commun 38 (1), 81-5 PubMed.
  • Koizumi N & Yasutomi I (2012) Prevalence of leptospirosis in farm animals. Jpn J Vet Res 60, 55-8
  • Otaka D Y, Martins G, Hamond C, Penna B, Medeiros M A & Lilenbaum W (2012) Serology and PCR for bovine leptospirosis: herd and individual approaches. Vet Rec 170 (13), 338 PubMed.

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