Proceedings of the 10th International Colloquium on Paratuberculosis

#140 The <strong>the</strong>rapeutic effect <strong>of</strong> <strong>the</strong> immunization against paratuberculosis with a heat-killed
vaccine results in an increase <strong>of</strong> <strong>the</strong> productive life <strong>of</strong> vaccinated cattle
Marta Alonso-Hearn, Elena Molina, Marivi Geijo, Patricia Vazquez, Iker Sevilla, Joseba M Garrido, Ramon A
Juste, NEIKER-Tecnalia, Spain
The objective <strong>of</strong> this study was to evaluate <strong>the</strong> <strong>the</strong>rapeutic efficacy <strong>of</strong> a heat-killed Mycobacterium avium subspecies
paratuberculosis (Map) vaccine in six tuberculosis-free herds <strong>of</strong> dairy cattle. The prevalence <strong>of</strong> infection
with paratuberculosis in <strong>the</strong>se herds ranged from 2-10 %. Cattle from <strong>the</strong> 6 vaccinated farms (n=50) and
from 2 unvaccinated farms (n=50) were slaughtered due to paratuberculosis or to o<strong>the</strong>r reasons, and feces and
gastrointestinal tissues were taken and analyzed by bacteriological culture and histopathology. Clinical signs <strong>of</strong>
paratuberculosis were observed in 28 and 30 % <strong>of</strong> <strong>the</strong> vaccinated and control animals, respectively. Immunization
with <strong>the</strong> heat-killed vaccine reduced 23 % <strong>the</strong> overall mortality and 53 % <strong>the</strong> culling due to paratuberculosis
<strong>of</strong> <strong>the</strong> 3-4.5 years old vaccinated animals when compared with <strong>the</strong> control group; p=0.012 and p=0.047,
respectively. The peak <strong>of</strong> culling was between 4.5-5 years (21 %) in <strong>the</strong> vaccinated animals and between 3-4.5
years (60 %) in <strong>the</strong> control animals. Animals were culled at an average age <strong>of</strong> 4.7 and 3.7 years in vaccinated
and control farms, respectively. Thus, vaccination resulted in 1 year <strong>of</strong> increase in <strong>the</strong> productive life <strong>of</strong> <strong>the</strong>
vaccinated herds when compared with unvaccinated animals (p=0.038). In addition, vaccination diminished a
33 % <strong>the</strong> presence <strong>of</strong> paratuberculosis-associated lesions in gut tissues <strong>of</strong> <strong>the</strong> vaccinated animals (p=0.006)
and 24 % <strong>the</strong> development <strong>of</strong> severe lesions (p=0.002), multibacillary forms, when compared with <strong>the</strong> control
group. It also reduced a 38 % and 47 % <strong>the</strong> presence <strong>of</strong> bacteria in feces and in intestinal tissues <strong>of</strong> <strong>the</strong> vaccinated
animals, respectively. Although vaccinated animals are not fully protected, <strong>the</strong> clear regression <strong>of</strong> <strong>the</strong>
lesions and <strong>the</strong> substantially reduced Map load in <strong>the</strong>ir feces and gut tissues suggests that vaccination protects
against <strong>the</strong> infection by decreasing Map load, which provides important benefits to <strong>the</strong> farmers.
#148 The externalities associated with <strong>the</strong> cross-reactivity <strong>of</strong> Johne’s Disease vaccination
with tuberculosis in U.S. dairy cattle
Jonathan Dressler, Rebecca Smith, Loren Tauer, Ynte Schukken, Yrjo Grohn
Cornell University, USA
We conceptualize and construct a dairy herd model to capture <strong>the</strong> externalities associated with <strong>the</strong> crossreactivity
<strong>of</strong> MAP vaccination within TB accredited regions given a TB outbreak occurs. We use partial budgeting
methods to determine <strong>the</strong> net benefit <strong>of</strong> MAP vaccination within each TB accredited region in <strong>the</strong> U.S. by
comparing <strong>the</strong> benefit <strong>of</strong> MAP vaccination (ex ante costs) to <strong>the</strong> extra costs associated with <strong>the</strong> cross-reactivity
with TB test results (ex post costs). We also compare <strong>the</strong> net benefit <strong>of</strong> MAP vaccination to non-MAP vaccinated
herds within each TB accredited region. Tentatively we find that <strong>the</strong> benefit <strong>of</strong> MAP vaccination exceeds <strong>the</strong>
costs <strong>of</strong> cross-reactivity for a net gain <strong>of</strong> $16.33 per cow (range <strong>of</strong> $12.02 per cow to $27.49 per cow), lowering
<strong>the</strong> losses attributed to TB. Overall <strong>the</strong> losses attributed to TB for MAP vaccinated herds were less than non-
MAP vaccinated herds with an average net loss <strong>of</strong> $44.22 per cow (range $28.04 per cow to $54.19 per cow)
compared to $60.55 per cow (range $55.52 per cow to $67.04 per cow).
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