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Barber pole vaccine works

In the last several months, several articles were published in the Veterinary Parasitology journal about the efficacy of Barbervax®, the vaccine that provides protection against the barber pole worm (Haemonchus contortus).

Continuous vaccination with Barbervax® was studied in Brazil. Lambs were vaccinated every 3 to 6 weeks until they reached adulthood (2 years of age). They received 23 vaccinations during this period. They responded with anti-vaccine specific antibodies, had 80% lower Haemonchus egg counts, and were less anemic compared to controls, which were not vaccinated. Eighty-eight percent of controls required drenching (3.1 drenches per treated animal), whereas. 57% of vaccinated sheep required salvage treatment (1.9 drenches per treated animal). There were no differences in body weight. Vaccination provided substantial year-round protection.

In Australia, the level of efficacy of the vaccine against different levels of infection was studied with trickle infections of Haemonchus larvae (L3). Lambs received 0, 300, 600, 1200, or 2400 L3 per week in split doses. Treatment groups were vaccinated at 8, 11, 15 and 22 weeks of age. Controls were not vaccinated. Vaccinated lambs had significantly lower fecal egg counts than untreated lambs. Vaccination reduced the number of lambs that required salvage anthelmintic treatment: 9.4 vs. 33.6 percent. The vaccination protection index (based on fecal egg count) was similar at all challenge levels, but deworming would be required at higher levels of Haemonchus larval challenge, stressing the importance of vaccination as part of an integrated program for worm control.

Australian researchers altered the pre-weaning vaccination schedule. Instead of being given three priming doses of the vaccine, 175 Merino lambs were vaccinated only at marking and weaning and were given a double dose of the vaccine at marking and/or weaning. Researchers hypothesized that reducing the interval between lamb marking and weaning to 6 weeks and providing a double dose of the vaccine would remove the need for the second priming and eliminate the need to muster the ewes/lambs a third time. As evidenced by fecal egg counts and antibody titers, the alternative regimes proved to be just as effective as the manufacturer's recommendation of three priming doses.

***Barbervax® is currently not available in the US.

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