viral genomes were searched for, it is very likely that infectious
virus might be present in such vaccines, as most of them were
prepared with live microorganisms. This opens the possibility of
potentially infectious virus to be present in the end product. It has
been suggested that contamination of live vaccines with CAV may
have influenced the epidemiology of chicken anemia in Brazilian
and Argentinian poultry flocks [9]. In Brazil, a high prevalence of
antibodies to CAV (89%) was detected in all States with intensive
commercial broiler flock production [17]. Although this hypothesis
might give rise to debate, it is clear that the presence of unwanted
CAV might potentially introduce the virus and/or disease in flocks
vaccinated with contaminated immunogens. In addition, it may
lead to misleading attempts to trace the origin and evolution of the
infection in the contaminated flocks; moreover, if CAV is introduced,
it may lead to immune responses that may interfere with
immunization programs. Therefore, this type of contamination,
which involves a recognized pathogen, must be eliminated primarily
to avoid introduction of the contaminant and disease and,
secondarily, to avoid unnecessary complications in flock vaccination
and monitoring of the responses to vaccination.
viral genomes were searched for, it is very likely that infectiousvirus might be present in such vaccines, as most of them wereprepared with live microorganisms. This opens the possibility ofpotentially infectious virus to be present in the end product. It hasbeen suggested that contamination of live vaccines with CAV mayhave influenced the epidemiology of chicken anemia in Brazilianand Argentinian poultry flocks [9]. In Brazil, a high prevalence ofantibodies to CAV (89%) was detected in all States with intensivecommercial broiler flock production [17]. Although this hypothesismight give rise to debate, it is clear that the presence of unwantedCAV might potentially introduce the virus and/or disease in flocksvaccinated with contaminated immunogens. In addition, it maylead to misleading attempts to trace the origin and evolution of theinfection in the contaminated flocks; moreover, if CAV is introduced,it may lead to immune responses that may interfere withimmunization programs. Therefore, this type of contamination,which involves a recognized pathogen, must be eliminated primarilyto avoid introduction of the contaminant and disease and,secondarily, to avoid unnecessary complications in flock vaccinationand monitoring of the responses to vaccination.
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