Monday, May 5, 2014

Early  Vaccination for Lepto

How early can heifer calves be vaccinated for Lepto and be protected? That was one of the questions asked by the research team that reported their finding in Cortese, V.S. and Others, "Efficacy of a flexible schedule for administration of a Leptospira borgpetersenii serovar Hardjo bacterin to beef calves." American Journal of Veterinary Research 75:507-512, May 2014.

Very condense protocol: 55 calves in 3 treatments
1. Control - no vaccine
2. One dose of L. Hardjo vaccine (about 20-29 days of age)
3. Two doses of L. Hardjo vaccine (1st on between 20-29 days old, 2nd dose average 136 days after first)
22 days after the second vaccination all three groups were challenged with L. Hardjo pathogen.

Findings: Was it possible to isolate in either urine or kidneys the pathogen to which they were exposed in the challenge?

Control (no vaccination) had 10 out of 11 positive.
One vaccination between 20 and 29 days had 0 out of 21 positive
Two vaccinations (1st between 20-29 days, 2nd about 136 days later) had 0 out of 20 positive.

The authors conclude:
"Results of the present study indicated that administration of a single dose of L. borgpetersenii serovar Hardjo bacterin to young calves provides protective efficacy to 4 to 5 months and that administration of a second dose of the bacterin 4 to 5 months after the initial dose will elicit a substantial anamnestic response. [or, "4 to 5 months after the initial dose will significantly increase protection against infection]

Maybe it is time to dust off our vaccination protocol and see if any changes are needed?

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