The
main purpose of all vaccines and consequently vaccination is to
administer an optimum and safe amount of antigen to elicit immune response in
the bird.
Vaccination
does not give guarantee that birds are protected. There are a number of factors
which may furnish the success of a vaccine.
It
is a worth remembering that antigens or vaccine or vaccination itself does not
produce immunity rather it is the bird’s immune system in general and immune
cells in particular that provoke the immune response and present the antigen to
T lymphocytes and by macrophages and from there it is expressed to b lymphocyte
where the immune response initiated in items of antibodies.
These
antibodies are identical to the antigen of vaccine.
The
successful vaccination comes up in terms of higher and stronger immunity. On
most of the occasions we get proper protection with vaccination but immunity
breakdown is usually not known. The current topic highlighted the factors which
will come up in term of good immunity.
General
Principles of Vaccination
Vaccination
involves the administration of antigen to stimulate the immune system to
produce specific antibodies against viral, bacterial, and protozoal disease.
Vaccination program should be based on the following considerations.
•
Diseases prevalent in the urea of operation.
•
Risk of exposure.
•
Immune status of parent stocks.
•
Cost of acquisition and administration of vaccines
•
Flock placement programs.
•
Availability of specific vaccines.
•
Cost benefit ratio associated with vaccination taking into account
the risk of infection and financial losses from disease.
Precaution for
Use of Vaccines
1. Do not
vaccinate the birds during stress period particularly few days before or after
the debeaking,
transfer shifting and grading. In these conditions negative Immuno-modulation
occur which ended with low level of active immunity.
2. It is not wise
to vaccinate the birds during extreme weather, because heat stress on one end
affect the bird and on the other end effect the vaccine due to high environment
temperature.
3. Avoid using
metal drinkers and containers for mixing of vaccines, as the metal ions and
metals react with the vaccines to inactivate the live vaccines offered through
the drinking water. Aluminum and brass containers are not recommended due their
maximum inactivation properties. It is recommended to use the PVC or PET
containers (Plastic).
4. Use clean
equipment and drinkers and sterile syringes, so not use any chemical to
disinfect the vaccine utensils because the residues of these chemicals
inactivate the vaccines. Rinse the utensils with fresh water to avoid the
errors.
5. Always use
sterile diluents preferably of the same company for reconstitution of
injectable vaccines as the different sources are not synchronized with the
optimal requirements. Some diluents contains dyes more than optimum levels
which act as sterilizers for diluent and at the same time inactivate the vaccine.
6. Do not use water
for vaccine dilution containing disinfectants, particularly the Bleaching
Powder (Chlorine compounds) to avoid the possibility of these chemicals from
rendering the vaccine inactive. Either stop usage of these substances a day
earlier before the vaccine is offered or two days earlier before the vaccine is
offered, enteric forms of vaccines are more sensitive to these type of
chemicals.
7. Try to use the
vaccines as soon as possible the vaccines are reconstituted, delay to offer by
the farmers or consumption by the birds leads to temporal decrease in the
vaccine tillers.
8. In those areas
where the salt concentration is too high preferably vaccinate the birds through
injection or eye, nose or mouth dropping.
9. Addition of
skim milk is recommended, as the particles of vaccines are distributed well in
the water. In case milk with fat or fresh milk is used it make aggregates on or
near the surface of the container (due to light weight fat) where the vaccine
is mixed, leading to develop different concentration zones in the container.
10. Lower limit of
skim milk per litre is fixed but there is no upper limit, the higher the milk
concentration the best will be the suspension of vaccine in drinking water, the
drinkers should be empty in one hour maximum taking in consideration of
temperature of house and feed time, the off water time may be adjusted.
Route of
Administration
It
is emphasized that appropriate control over the reconstitution of live vaccines
is required to ensure potency. The actual administration of vaccines of should
be monitored by submission of serum samples to diagnostic laboratory for titter
assay using ELISA or acceptable technique. Various methods of administrating
vaccines are used commercially, including:
1. Intranasal: By
instillation or dipping the beak up to the naries. In birds nose, mouth and
lachrymal duct opened in mouth, therefore, each of the route ended up with the
same results with exception of the sensitivity and accommodation by the eyelid
epithelium otherwise routes are nearly same. In these route please do not dip
the beak for too long short time.
2. Intraocular: Eye dropping
is most popular route of vaccination. There some errors in the eye dropping
made during the vaccination. Eye drop and intranasal routes suitable for
hatchery administration and during brooding of chicks. In Pakistan the eye
droppers are 30ml for 1000 birds, the vaccinator make the vial and drop the
birds until and unless the whole of the vaccine is not spent. The too longer
time holding the vaccine. In these cases contaminated diluents or vaccines
leads to infection of eye and blocking of lachrymal duct and drooling of water from
the eye used for vaccination. This reaction may sometime normally occur after
vaccination of ILT.
3. In Drinking
Water:
This corresponds to oral and intra nasal administration. Drinking water
administration, can be implemented at low cost but it is of limited
effectiveness against some infections.
4. Injection: Subcutaneous,
intra muscular depending on the type of vaccine and the direction of the
manufacturer. Subcutaneous injection to administer either live or inactivated
emulsion vaccines to chicks rearing stocks and breeders.
5. In Ovo
Vaccination:
At 18 days of incubation using the patented Inovoject system. Most commonly
recommended in the case of Gumboro and Marek’s vaccines.
6. Post-hatch
Spray Vaccination: In cabinets for mass-administration of aerosol vaccines to day
old chicks. This is mostly employed for ND, IB vaccination on day one in
hatchery or farm.
7. Wing-web
Stab:
This method is used to administer fowl pox vaccine or other live vaccines
directly to each bird. Be careful that eye of the needle carries vaccine each
time or not.
8. Aerosol
Administration:
Using a knapsack or electric sprayer to deliver vaccines to flocks as a coarse
spray.
Failure of
Vaccine
Use of Expired
Vaccine:
Vaccines
are expired by many ways, among the most common, they are expired in storage
before sale, expired due to less shelf life (it must be year plus when reached
in Pakistan) expired supply by the manufacturer only with few months in hand.
Genetic
Resistance:
The
major histocompatibility complex varies from bird to bird and its structure
dictates if a bird will respond to an antigen at all. Due to some structural
lacks in MHC it is possibility that the birds are recognize the one of the
antigens. Therefore that strain of birds might be more susceptible to pathogen.
Improper Storage
of Vaccines:
This
is the most common cause of vaccine failure in routine uses of vaccines. This
might be due to transportation from market to farm or from manufacturer to
distributor to market, failure of electricity, failure of refrigerators,
storage in deep freezers, exposure of sunlight.
Ignoring
the use of ice box, coolers or thermos and using the translucent thin membrane
shoppers permitting the sunlight exposure.
•
Exposure of heat, sunrays, room temperature, brooding house
temperature to diluents mixed vaccines. To avoid the damages bottles either
packed in cold bucket or use chilled diluents.
•
Do not open the lid of vaccine in the open environment as the
vaccines are contained in negative pressured bottles. Use disposable syringe to
constitute the vaccine or open the bottle lid inside the water to avoid the
sudden change in pressure.
•
Avoid to use the improper disinfected syringes and needles. Always
use wide bore needles for vaccine suction or dilution, narrow bore needle may
retained the cell culture vaccines, which make the non-uniform mixing of
vaccine and lower the antigen amount.
•
Exposure to viricidal disinfectants (phenols, alcohol) may be
avoided as these chemicals inactivate the vaccinal virus.
Health Status of
the Flock:
The
infectious agents such as Chicken Anaemia Agent (Circo virus), Gumboro Disease
Virus (Birna virus), Marek’s Disease Virus (Herpes Virus ), REO Virus,
Salmonella and Mycoplasma etc. may cause varying degree negative
immunomodulation which consequently may lead to vaccinal failure or adverse
reaction in the face of these disease.
Immuno
Suppression Due to Drugs:
Continuous
administration of Immuno-suppressive drugs such as chloramphenicol,
furazolidone may cause poor immunity development.
Mycotoxins:
Presence
of mycotoxin in the feed affect the vaccinal response very badly. Mycotoxin
reduce host immunity directly by reducing the Macrophage engulfing tendency and
production of toxin, lymphocytes which give poor output in immunity
development. Mycotoxin indirectly affect the bird by producing steroids from
the adrenal glands which decrease the lymphocytes and increase the neutrophils
by the virtue of increased nutrophil the bird become Immune compromised.
Water
Deprivation and Heat Stress:
Due
to water deprivation the bird is exposed to heat stress. Due to heat stress lot
of steroid production do occur which decrease the lymphocytes produce the
antibodies. This is common observation that the dehydrated and heat exposed
birds commonly infected with coli septicaemia and other diseases.
Cold and High
Density Stress:
These
are social stress as well as stress like heat stress and decrease the immunity
by decreasing the number of lymphocyte, which is the factory of antibodies.
Poor Nutrition:
Hypoproteinaemia
especially protein hurt the immune response as antibodies are made up of amino
acids. Poor nutrition causes problem with metabolism, protein synthesis and
immunity.
Presence of
Ammonia in Houses:
On
the port of entry from where the pathogens are entered the body to produce
infection there are some host defence mechanism which prevent the entry of
pathogens. Hairs cilia moist membranes are among the preventive cushions. The
moist membranes of or the mucous membranes among the gut, trachea, nostrils and
bronchi produce Immunoglobulin through the lymphocytes present on the surface
of these organs. This is called secretory immune mechanism and it is watch dog
on the port of entry.
If
the ammonia levels are high in the house above 30 PPM it has bad effect on the
birds ability to produce local immunity as the cells on the surface of moist
membranes are affected badly with the ammonia because ammonia is water soluble
gas. In the absence of the local immunity the bird become susceptible to viral
diseases particularly those which proliferates in respiratory tract. Ammonia concentration
above 100 PPMm always associated with the respiratory disease. As the ammonia
is water soluble gas one can easily felt the ammonia as it dissolved in
lachyymal secretion of the eyes.
Administration
Errors
Quality of
Water:
Water
quality is poor in most of the areas of Pakistan, particularly in salinity
affected areas such as Faisalabad, Sheikhupura and Multan Division, where the
salt level is half of the sea water and EC even in Islamabad is 600 - 2000.
Poor water quality and high salt concentration produce ill effect on the
vaccine diluted in such kind of water.
Maternal
Antibodies:
High
maternal antibodies inhibit the chicken immune response. It has negative feedback
effect on B lymphocytes. Moreover high levels of maternal antibodies against infectious
agent such as Gumboro, also play a role in neutralizing the vaccinal antigen
thus making the vaccine less effective and designing the vaccine program more
difficult. Due to high maternal antibodies not only the vaccinal antigen is
destroyed but also the maternal antibodies are also destroyed leaving the bird
exposed to field challenge if earlier vaccination in high titter is done.
Presence of
Variant in Field:
It
has been observed that with the emergence of new variants the classical
vaccines are no more effective to control the disease. Classical vaccine of Gumboro
is missing the VP-2 protein therefore it is not effective against field variant
or strain. The hot intermediate and intermediate plus do have the VP-2 protein
and can penetrate up to the site of proliferation. In the same manner classical
IB is no more effective against IB variants.
Poor
Antigenicity of Vaccines:
Live
vaccines must be applied at a level at or above the minimum infective dose.
After the live virus has been applied the bird serves as a virus production
site. The bird is media in which the initial dose of vaccine can multiply to a
level which will stimulate a proper immune response. For potency testing of
vaccines, always contact well facilitated Lab. Inactivated vaccines should
contain sufficient amount of antigen to stimulate an immune response when
applied the bird as there is no multiplication of the virus of bacteria in the
bird.
Interference:
Do
not give live respiratory vaccines (IB, ND, ILT) within 3 to 4 days if not combined
by the manufacturer in licensed combination. Reaction may be too great or
response to the later vaccine may be compromised due to interference. This is
also true in case of ND and AI vaccine. Do ND vaccine earlier and then proceed
for AI vaccine.
Genetics:
Means
simply the geographical influence on the genetics of local poultry population.
The geographical influence may affect the ultimate response of birds to vaccine
under indigenous environments and may result in vaccine failure. The difference
pay more if they are present in MHC.
Vaccination
Reactions
Adverse
vaccine reaction, however do not serve a useful purpose and should be prevented
if at all possible. Several factors can affect the severity of the reaction
that occur. These include:
•
Chick quality.
•
Level of maternal antibodies.
•
Vaccine strain.
•
Doses of vaccine used.
•
Route of application.
•
Timing of vaccination.
•
Immuno suppression.
•
House sanitation.
•
Down time.
•
Water, litter and air quality.
A
normal respiratory vaccine reaction in broiler chicks begins about four days
post vaccination and lasts about five days. A build-up of dust and ammonia
often occurs, and will cause respiratory vaccine reactions to be more severe
which may never clear completely between vaccinations. A rolling vaccine
reaction is one of increased duration and/or intensity compared to what is
normally expected. The bacteria or fungus in haled during few hours of life or
present in the yolk sac, can complicate vaccination and result in airaculitis.
These birds will react to respiratory vaccines for several days some time
during the entire grown out.
- Dr. Tariq Javed, DVM, MSc. (Hons) Pathology, Ph. D (Microbiology), Post-Doctorate (Toxicology) USA. Mediexcel
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