- How effective has the use of vaccination been in controlling AI?
Vaccination against highly pathogenic avian influenza (HPAI) or low pathogenic avian
influenza (LPAI) viruses, along with other measures, was successful in eradicating AI in very few countries where the competence of national veterinary services or the geography and bird density have contributed favorably to the outcome especially Indonesia. A “game changer” vaccine targeting smallholders should be universal to protect against all field viral strains and reduce significantly, if not totally eliminate, the need for costly post-vaccination surveillance. The ease of administration of this vaccine (one single injection) would further contribute to its relevance in the field. These characteristics are considered essential for the product profile of an AI vaccine that can contribute in a meaningful way to the livelihoods of poultry smallholders. The main constraints to an effective AI vaccination are vaccine composition matching field strains, reliable cold chain and logistics to target all poultry smallholders like small farmers in the village or rural area in Indonesia, constraints related to the availability of sufficient financial and human resources. Luckily, Medion has many branches spread throughout Indonesia which are always ready to serve customers such as small farmers, even in rural parts of Indonesia. In addition, Medion also produces AI vaccines, both HPAI or LPAI, which are homologous to the field virus strains in Indonesia, and we always carry out routine surveillance to ensure which strains are dominant in the Indonesian field. Vaccines from Medion are also still very affordable in terms of price and quality so that small farmers can continue to use them without hesitation.
- Are vaccines causing more challenges or less? (eg: mutations, etc)
When not conducted properly, vaccination can also contribute to the emergence of new
field viral strains, through genetic drifts of HPAI or LPAI viruses. While new technologies
have improved the possibility to produce high quality vaccines matching field strains,
recurrent issues like post-vaccination field surveillance and vaccination coverage continue
to limit the relevance of AI vaccination in smallholder settings. Note that antigenic variation
also occurs when vaccination is not used for example H6 in China (Wang et al., 2014).
Antigenic change will occur slowly in places where vaccinated or immune birds are rarely
exposed to virus. In Vietnam and Indonesia, the bigger driver of vaccination failure was the
introduction of a novel strain of virus from outside the country. Antigenic drift was not a
factor for Clade 1 viruses and vaccines in southern Vietnam over a number of years.
Circulation of multiple strains of virus is also a constraint – matching becomes more
difficult when more than one antigenic variant is circulating. Would use of vaccine be
regarded as improper in places where infection is endemic and high-level population
immunity across areas is hard to achieve but good immunity at the individual farm level is
achievable? Much depends on the purpose of the vaccination programme and
homologous vaccines are needed.
- Can you explain about AI situation in Indonesia? Predictions for 2023?
Medion is always active and at the forefront of following the development of disease cases
in the field, especially for diseases whose causes are easy to change, such as ND and AI in
Indonesia. Based on data collected by the Technical Education and Consultation team from
samples of sick chicken organs suspected of being infected with AI, followed by PCR
(Polymerase Chain Reaction) and DNA sequencing tests to see the genetic composition of
the virus. From 2016 to 2022 the AI H5N1 virus was only found in clade 2.3.2. and there
was a change in the character of the clade (different in the amino acid composition) at the
end of 2019 which had a significant impact on the effectiveness of the AI vaccine. While
Low Pathogenic Avian Influenza (LPAI) is still found and causes a large decrease in egg
production with low mortality, but morbidity is still relatively high. LPAI can cause high
mortality if there is a combined infection with other diseases. The AI H9N2 virus found in
Indonesia during the 2019–2022 period has not changed. Below is the PCR positive of HPAI
and LPAI from some area in Indonesia:
Disease trends in 2023 are predicted not to be much different from previous years.
Bacterial diseases are still a major problem in broiler and laying hens, followed by viral and
parasitic diseases. Some bacterial diseases that may still be found are CRD, colibacillosis,
coryza, NE necrotic enteritis and cholera. CRD will still be the predominant respiratory tract
disease. However, there are other bacterial diseases that need to be watched out for
because the past few years have continued to increase. These diseases are colibacillosis
and NE.
1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 10
0
5
10
15
20
25
30
35
40
AI H5N1 & H9N2 by PCR Positive
Period 2020-2022 (Oct)
HPAI LPAI
2020 2021 2022
Sources: Medion Indonesia
In viral diseases, Gumboro, IBH, ND and AI are the most common diseases. Viral diseases
that cause immunosuppression such as Gumboro are a major problem because
immunosuppressive properties can cause attacks of other diseases. The case of IBH disease
also requires more attention because it greatly affects the performance of broiler chickens,
moreover, the incidence rate has continued to increase in the past few years. In addition,
non-infectious diseases such as mycotoxicosis are still prone to occur. This was marked by
an increase in the incidence of mycotoxicosis from the previous year. Another disease that
needs to be watched out for is a disease caused by protozoan parasites in the digestive
tract, namely coccidiosis. The incidence rate of this disease in the previous year was still
quite high and ranked fourth. Poor maintenance management factors such as poor hygiene
of liters and the existence of AGP prohibition policies cause the incidence of coccidiosis to
remain high.
In the case of AI disease itself, as long as there are no external viral agents from wild birds
and there is no change in mutation, deletion or insertion of the virus itself, both LPAI and
HPAI, it can be controlled with strict biosecurity and proper vaccination program.
- How to control AI?
Seeing some of the losses caused and the character of the AI virus that is easy to mutate
and from our monitoring these changes occur periodically for about 2-3 years. So it is
necessary to increase awareness of AI attacks. One of the efforts that we can do is a
synergistic combination between vaccination and the implementation of biosecurity which
is supported by good maintenance management. Here are some things to consider in its
implementation:
• Strict application of Biosecurity: The application of
Biosecurity aims to reduce the number of germs in the
Farms. Model 3 zones (clean, transition, dirty) can be
applied to secure farms from germs from outside. Strict
and disciplined disinfection program in the farm/house
environment. Traffic restrictions for transportation or
personnel who will enter the farm area are also important
to avoid the entry of infectious agents from other
vulnerable places. It is necessary to do regular cleaning of
feces to prevent feces from accumulating and becoming damp. This is because
dirt/feces is an ideal medium that can carry germs. Limit contact between
commercial poultry and free-range chickens, waterfowl or wild animals. Because as
we know AI in wild birds is usually subclinical, does not show symptoms but is
capable of infecting the birds that we keep in our farm. Next, house rest for at least
2 weeks calculated when the house is ready to be filled in order to break the chain
of disease. It is no less important to sanitize drinking water using Desinsep, because
the AI virus can be transmitted through drinking water and can last up to 35 days.
• Proper vaccination: In controlling viral diseases,
one of the efforts that can be done is prevention
by vaccination. This vaccination aims to bully the
formation of immunity in chickens, so that when
an AI infection enters, the body has chosen
defense. To support the success of vaccination, it
is necessary to pay attention to the quality of the
vaccine, the accuracy of determining the
vaccination schedule, the appropriate vaccination
technique and application, and the condition of
the poultry when vaccinated. Selection of the
right vaccine determines how optimal the
formation of antibody titers in the body of
chickens is. The use of a vaccine that is
homologous to the field virus is highly recommended because it will provide optimal
protection. In order to overcome AI attacks, AI vaccines can be given such as
Medivac AI H5N1 & H9N2 which are inactivated vaccines in the form of an emulsion
containing Avian Influenza (AI) virus subtypes H5N1 clade 2.3 and H9N2 which are
homologous to the latest field isolates to prevent AI in poultry. As an option, a single
Medivac AI subtype H5N1 2.3 vaccine or Medivac AI subtype H9N2 can also be used.
In addition to choosing the right vaccine, the timing of the vaccination is one of the
critical points that we must pay attention to. The AI vaccination program should be
structured based on the high or low AI virus challenge in the field and the baseline
titer in each farm. Based on field data, AI usually infects broilers aged >3 weeks.
Thus, it is sufficient to carry out AI vaccination for broilers once, namely at the age
of 4 days at the same time as the active ND vaccination, or at the age of 10 days.
While laying hens are recommended AI vaccination 3 times before entering the
production period and 2 times after peak production. Repetition of AI vaccination
during the production period can be done by looking at the results of antibody titer
monitoring.
• Antibody titer monitoring: The condition of the bird's immune status needs to be
monitored as an early warning through routine antibody titer monitoring at least
once a month. The results of this data can be used to determine the baseline titer
(standard titer) in a farm location. The baseline titer can be determined by collecting
data from previous serological tests which are checked regularly for at least 3
batches of rearing periods with the same vaccination program and taken from birds
house that healthy in condition. So that a titer image pattern will be formed on a
farm. In order for the results of the analysis carried out to be representative in
accordance with field conditions, sampling must be carried out randomly
representing all locations of birds in the house with a total of 15-20 samples/house
or 0.5-1% of the total population in the house.
In the production phase layer birds, antibody titer monitoring was carried out to
determine the appropriate revaccination schedule. In monitoring bird antibody
titers, the analysis carried out not only looked at the Geometric Mean Titer (GMT)
value with protective standards, but also looked at the percentage of immunity and
uniformity compared to the baseline titer. This baseline will differ from one farm to
another in different locations, due to vaccination programs and challenges as well as
different environmental conditions.
• Suppress immunosuppressants with supplementation: Basically creating
comfortable conditions for birds helps to prevent from getting sick easily. For this
reason, it is necessary to implement optimal management such as appropriate air
circulation (ventilation), temperature, and humidity. Poor ventilation management
can increase the occurrence of respiratory tract diseases. Moreover, on farms with
open house systems that are very dependent on external conditions, farmers must
adapt to the environment so that the birds remain in comfortable conditions and
could avoid disease. In addition, the need to suppress immunosuppressant
conditions such as mycotoxin contamination, stress and other immunosuppressant
diseases needs to be done because these conditions can affect the antibodies
formed in the body of birds to be not optimal, so that if the challenge of AI in the
field is high, birds will be susceptible to AI. Giving multivitamins (Solvit, Aminovit, or
Fortevit) and premix (Mix Plus) as feed supplements will increase the immune
system of birds. With vitamin supplementation, the condition of the mucous
membranes of poultry will optimal so that when the AI virus will enter the birds
body, trapped at mucous membranes and can be optimally dispelled. In addition to
vitamins, the addition of premix is also important to complete the nutritional needs
of the feed, so that the metabolic process of the poultry body's defenses can run
optimally.
With the implementation of the steps above, hopefully that farmers will get more information
about the latest AI, and its prevention efforts so that cases of AI incidents on farms could be
prevent.
Dr. Yonatan Dimascahyo Budianto, DVM., MSc., MM., MBA.
Technical Education and Consultation
Artha Vena International Pte. Ltd
