Leptospirosis

Leptospirosis is a widespread disease in Ireland (>70% dairy and >80% beef herds[1]). Leptospira Hardjo is the serovar (group) that affects cattle in Ireland. There are two strains within this serovar, borgpetersenii (bovis) and interrogans (prajitno). The two strains have genetic variations but are indistinguishable on serological testing. There are two Leptospirosis Hardjo vaccines available in Ireland. Each of these vaccines contains a single strain of L. Hardjo.

• Clinical signs:
  • Milk drop
  • Abortion
  • Weak calves
• Vaccination of heifers prior to exposure to the leptospires can prevent kidney colonisation and carrier status.
• Vaccinate heifers as early as possible to prevent carrier status
• Two dose initial vaccination
• Annual booster thereafter

Leptospirosis is a zoonotic disease, which can cause clinical signs ranging from mild ‘flu like symptoms to severe, debilitating disease.

 

Spirovac® is a Leptospira Hardjo vaccine and contains the L. Hardjo borgpetersenii strain. Spirovac® is licensed to prevent kidney colonisation and shedding of L. Hardjo borgpetersenii and to reduce shedding from carrier animals. A strong serological cross reactivity has been demonstrated against L.Hardjo interrogans, the second strain in the serovar. This was sustained for at least 12 months following booster vaccination.

Early calf vaccination- now you can stop leptospirosis infection before it starts

Traditionally in Ireland, dairy cattle have been vaccinated for leptospirosis just prior to breeding to prevent infertility losses, abortions and the birth of weak calves associated with Leptospirosis infections, However, by this time in their life, they may already be infected. Seroconversion has been noted in younger animals, and we know that infected cattle can continue to shed leptospires in their urine.

‘Protection gap' following MDA

L. Hardjo maternal antibodies decline to zero at around 13 weeks of age. This creates a ‘protection gap', placing calves at risk of L. Hardjo infection- even in situations where calves are not reared close to adult cows.  It is important to remember that L. Hardjo can survive for up to six months in wet conditions.

Currently there are no available data to show that vaccines can clear infection in already infected animals i.e. vaccines have not been shown to have any therapeutic effect. However, if young cattle are vaccinated before they become infected, this will prevent those becoming carriers. Routine "early calf" vaccination is a logical and practical way to prevent new carriers developing in a herd and to optimise leptospirosis control.