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HEAL ▶▶▶TH Vaccine handling and administration


Live vaccines may be inactivated due to improper handling or adminis- tration. Points to consider include: • Do not vaccinate birds during stress periods, especially a few days before or after debeaking, transfer, and grading. These create stress conditions that may lower the immunity of birds.


• Do not vaccinate birds during extremely hot weather. As indicated above, heat stress may lower the birds’ immunity and impair the effi- cacy of the vaccine. Vaccination should be carried out during the cooler periods of the day (morning and evening).


• Avoid using metal drinkers and containers for mixing vaccines. Met- als may inactivate live vaccines presented in the drinking water. Alu- minum and brass containers are also known to have high inactiva- tion properties and are similarly not recommended. Plastic containers should be used instead.


• Use clean equipment, drinkers and sterile syringes. • Do not use chemical disinfectants to clean utensils before vaccina- tion because residues of these chemicals may inactivate the vaccines. The utensils should be rinsed only with fresh water.


• Always use sterile diluents preferably of the same company for the re- constitution of injectable vaccines. This is because some diluents may contain more than optimum levels of dye which act as a sterilizer for the diluent but which at the same time may inactivate the vaccine.


• Do not use chlorinated water for vaccine dilution because the chlo- rine will destroy the vaccine. Suspect municipal tap water should be allowed to stand in an open plastic container for at least two days to allow dissolved chlorine to evaporate.





In areas where a high salt concentration in water has been estab- lished, the preferred route of vaccination is either by injection or through eye, nose and mouth dropping.


• The addition of skimmed milk to the water used for oral vaccination aids with the optimum distribution and stabilisation of vaccines.


Vaccine preparation needs to be done with the right equipment and in accordance with the issued guidelines.


• The birds should be made to consume the reconstituted vaccine within one hour, bearing in mind the temperature of the pen and feeding time. Delays in ingesting the vaccine by the birds may lead to a reduction in vaccine efficacy.


• Do not expose reconstituted vaccines to heat, sunlight, high room temperature or brooding house temperature.


• Do not open the lid of the vaccine vial in the open because the vial is sealed under negative pressure and will suck in contaminated air.


• Use a sterile disposable syringe to reconstitute the vaccine or open the vial under water.


• Avoid reused or disinfected needles and syringes. Always use wide bore needles for vaccine suction or dilution as narrow bore needles may retain some cell culture vaccines, thus possibly making mixing nonuniform.


Diseases and parasites The health status of the flock should be checked 1 to 2 days before vaccinating, devoting particular attention to all chronic or sub-clinical pathologies which could either reduce the ef- fect of the vaccination or cause secondary infections spurred by a post-vaccination reaction (mycoplasma Pasteurella, E. coli, coccidiosis mycotoxins, etc.). These potential risks therefore need to be addressed by giving preventive treatment before and after vaccination. It is not advisable to vaccinate sick birds because the capacity of their immune systems is already diminished. Introducing a live virus vaccine into these birds often results in a reduced immune response and an adverse reaction because, in many cases, they are unable to develop a response even to the milder vaccine virus. A basic rule for vaccination is always to delay vaccination un- til the birds are healthy. It is better to skip a vaccine in a


10 ▶ POULTRY WORLD | No. 1, 2020


diseased flock than to vaccinate in the presence of a concur- rent disease. Parasite infection also affects chickens’ response to vaccina- tion. A study was conducted to investigate the influence of helminths on antibody response after vaccination against Newcastle disease of free-range chickens naturally infected with the parasite Ascaridia galli. The response was compared with vaccinated groups that had been dewormed with fen- bendazole and niclosamide. The results showed that the anti- body titers rose in the dewormed groups but not in the para- site-infected groups. Among the latter, the synthesis of immunoglobulins was reduced owing to an absolute loss of protein and this might have resulted in a reduced humoral antibody response. Anthelmintic treatment should therefore be done well before vaccination to allow the birds to recover from the helminth infections and hence improve their immune response.


PHOTO: RUUD PLOEG


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