Poultry Viral Diseases and Intervention Measures: An Indian Perspective
Author:
Gautham Kolluri and Ashok Kumar Tiwari
ICAR-Central Avian Research Institute, Izatnagar- 243 122, Uttar Pradesh
Background:
Indian poultry industry has made a tremendous and remarkable growth ever since its inception and is presently emerging as a sunrise sector with a growth rate of 10-15% as against 1-2% from agricultural crops and provides employment opportunity to 4 million people. India has created its unique position in the world by occupying 3rd and 6thranks in egg and meat production respectively. In terms of poultry production, India ranks fifth internationally. The estimated egg (in shell) production is presently around 114.38 billion numbers, while that of broiler meat production is 4.34 million tons (3 billion live birds) with an annual growth rate of 34.3 and 65.3 % contribution respectively.The per capita consumption is 79 eggs and 4.5 kg meat. India has acquired majority of its self-sufficient mode in poultry production with 851.81 million bird population, 33.58 million ducks (native and commercial), 10.41 million turkeys and quails (BAHS, 2019). On other hand rural poultry also contributes to total poultry production with 317.07 million chickens across the land. With 8.2% rise in production, the value of Indian poultry industry is approximately 2 lakh crores from 45500 crores in 2011 and Indian animal health market worth around INR 67.83 billions.
Despite its vigorous growth and development, industry is facing challenges of emerging and new emerging diseases especially of viral origin with the periodical evolvement of more virulent strains. This continues to pose a serious threat to poultry production and the development of more effective control and coping strategies remains a significant challenge all the time. The present paper mainly aims towards understanding of occurrence pattern of important viral diseases at national and global level in the light of control. Pathogenic avian influenza and respiratory disease complex are challenging, due to the need for timely diagnosis and control.
Existing Scenario:
Viral diseases such as Avian Influenza (Highly Pathogenic and Low Pathogenic), Newcastle/Ranikhet Disease, Infectious Bursal Disease (IBD), Avian Infectious Bronchitis (IB), Infectious Laryngotracheitis (ILT), Turkey Rhinotracheitis and Duck Viral Hepatitis (DVH) are the notifiable diseases. Except for avian influenza, all disease outbreaks are going almost unnoticed. Chronic respiratory disease (CRD) caused by M. gallisepticum and complicated CRD due to Mycoplasma and avian pathogenic E. coli (APEC) are the most limiting factors for potential broiler production in the country. Respiratory disease complex is another troubling factor that disturbs the industry causing severe economic loss. ILT virus is currently circulating in Tamil Nadu, Haryana, Rajasthan and Uttar Pradesh states. The presence of ILT in the country seems to be phylogenetically more closely related to vaccine strains of Italy, China, Brazil and USA (Gowthamanet al., 2014) indicating extensive use of ILT vaccines in the country which might be responsible for field outbreaks referred to as vaccinallaryngotracheitis (Dufour, 2008). Infectious Bronchitis (IB) strains prevalent in India are 793B/NMK/72/IVRI/10; PDRC/Pune/9/99; 744-AD/04 (Jackwood, 2012). Mass/Massachusetts and 793B types are the most common IBV types reported in India since 1991 (Wang et al., 1996; Pradhanet al., 2013). Recently, India has experienced an emergence of new IB strains i.e., mass genotype that shares unique cluster group with THA280252 (Thailand) and 4/91 (793/B) that resembles European vaccine strain (Sumiet al., 2012).
Incidence of poultry diseases in India during 2018 (BAHS, 2019)
Disease |
Outbreaks |
Infected |
Coccidiosis |
121 |
91336 |
Ranikhet disease |
39 |
17414 |
Fowl pox |
48 |
14470 |
Fowl cholera |
7 |
8219 |
Marek’s disease |
3 |
10116 |
Gumboro disease |
17 |
16378 |
Infectious coryza |
9 |
218044 |
Chronic respiratory disease |
83 |
288103 |
Disease wise deaths in poultry during 2018 (BAHS, 2019)
Avian Infectious Laryngotracheitis:
ILT is an acute respiratory disease of fowl caused by Gallidherpesvirus 1, caused a considerable mortality worldwide with their tendency to occur during fall and winter months due to their inability to survive in heat. The presence of ILT in the country seems to be phylogenetically more closely related to vaccine strains of Italy, China, Brazil and USA (Gowthamanet al., 2014). This indicates extensive use of ILT vaccines in the country which might be responsible for field outbreaks referred to vaccinallaryngotracheitis (Dufour, 2008). Poultry population in Tamil Nadu, Haryana, Rajasthan and Uttar Pradesh states are confirmed to be positive for ILTV. Existence of ILT in Indian flocks dates back to 1964 (Singh et al., 1964) and other report in 2012 (Srinivasanet al., 2012), but is based on clinical pathological observations.
Infectious Bronchitis:
Infectious bronchitis virus (IBV) is ubiquitous in most parts of the world where poultry are reared and is highly contagious with ability to spread very rapidly in non-protected birds and pose a significant economic impact in the poultry industry. IB strains prevalent in India are 793B/NMK/72/IVRI/10; PDRC/Pune/9/99; 744-AD/04 (Jackwood, 2012). Mass and 793B types were the most common IBV types reported in India since 1991. In 2002, IB variant nephropathogenic strain with a unique sequence of S1 was identified in chicken flock showing visceral gout and nephritis complications which are thought to be different from other known IBVs (Baryret al., 2005). Recently, India has experienced an emergence of new IB strains i.e., mass genotype that shares unique cluster group with THA280252 (Thailand) and 4/91 (793/B) that resembles European vaccine strain (Sumiet al., 2012).
Marek’s Disease:
Marek’s disease, a lymphoproliferative disease of chickens is of great concern to the poultry industry. Estimated worldwide economic impact of Marek’s disease is 1-2 billion dollars annually. The present challenge of Marek’s disease, is occurrence in vaccinated flock with increased virulence. Even after successful employment of MD vaccination, outbreaks are occurring elsewhere in vaccinated flocks under the right conditions. There has been a drastic change in MD scenario over the past 110 years since it recognition in 1907 with a striking emergence from mild to very virulent and very virulent plus (vv+). This developed a new clinical picture characterized by more than 90% morbidity and mortality and absence of classical signs as lymphomas and peripheral neuritis but produces acute rashes (Osterrieder, 2006). In India reports of MD outbreaks from Orissa, Punjab, Assam, Uttar Pradesh, Andhra Pradesh, Arunachal Pradesh and Tripura, Gujarat appeared periodically and the annual loss accounts for Rs. 4 Crores. The incidence of disease is reported to be higher in dust prone and mining areas (Muniyellappaet al., 2013). Latest report indicates that, the Tamil Nadu (Namakkal) isolates of Mareks Disease is projecting towards a more virulent form (vv MDV) and this might be the most responsible factor for increased incidence of clinical signs of Marek’s disease (Balachandranet al., 2009).
Chicken Infectious Anaemia:
Chicken infectious anemia (CIA) has emerged as an economically important disease and is of global significance as it adversely affects the poultry health and production systems with high mortality, immune suppression, secondary infections and vaccination failures (Dhamaet al., 2008 and Schat, 2009). In India, recent reports indicate a very high sero‐prevalence (86%) with detection of maternal antibodies for CIAV infection in commercial poultry farms (Bhatt et al., 2011). Further, a recent molecular epidemiological report confirmed the wide distribution of CIAV with high prevalence rate of 73.3% (Waniet al., 2013). These Indian isolates are phylogenetically more closely related to USA, Brazil and China isolates which are the leading poultry producers of the world and origin might probably be linked with the contaminated vaccines or infected breeders.
Infectious Bursal Disease:
IBD viruses being found nearly in all commercial poultry producing regions around the world indicate its global scale evolution and continue to be an economic hardship for the poultry industry. Contagious nature of virus coupled with geographically limited antigenic drift is always challenging as it may not be an economic approach to produce vaccine for every antigenically new virus population that is found in relatively small geographical regions. The live-attenuated vaccines developed against classical strain fail to respond against the variant strains. Worldwide, about 60–76% of IBDV isolates are of vvIBDV genotype. Rampant vaccination without genotype matching resulted in genetic diversification of circulating viruses through reassortment that acquired segment A from very virulent IBDV and segment B from classical IBDV D78 strain in Poland. The economic impact of IBD on the poultry industry is difficult to assess due to the complex nature of losses associated with the disease. IBDV infection-induced immunodeficiency in chickens makes the flock susceptible to other viral, bacterial, and parasitic infections, thus resulting in indirect losses. Being resistant to most of the disinfectants and environmental factors, the poultry house remains contaminated with IBDV that persists on the premises and tends to reappear in subsequent flocks.The acute or chronic IBD in the flock reduces the efficiency of production and net profitability in terms of feed conversion ratio.
Avian Influenza:
India remained free from H5N1 infection until 2006 (DAHDF 2015). Ever since the inception of first outbreak in 2006 in the country, H5N1 emerged as an economically important disease with significant impact on marginal and rural backyard poultry farmers (DAHDF, 2015). The out breaks have occurred as epidemic waves during 2008-09 and thereafter established as sporadic occurrences (Dhingraet al., 2014). Frequent hitting of North East and eastern regions with H5N1 infections clearly indicates a massive border migration involvement and this must be controlled with stringent security measures. Eastern states share borders with Nepal, Bangladesh, Bhutan and Myanmar and it is increasingly being recognized that HPAI is now a regional cross-border problem with porous borders and illegal movement of poultry and poultry products contributing to the threat of potential endemic circulation within the region (Dhingraet al., 2014). Unlike other countries, India is continuously experiencing a frequent HPAI H5NI strain alone (DAHDF, 2014). Genome characterization and phylogenetic analysis reports from ICAR-NIHSAD, Bhopal of this strain from 2006-14 outbreaks in the country revealed a origin of three different clades attributing to different areas in different years i.e., clade 2.2 during 2006-2010 (Pattnaiket al., 2006 and Chakrabartiet al., 2009); clade 2.3.2.1-A during 2011 to early 2014 (Nagarajanet al., 2012). Recent H5N1 events in ducks and turkeys in Kerala and ducks in Chandigarh in 2015 are due to clade 2.3.2.1-C (DAHDF, 2015). In 2016, a new strain H5N8 has been reported in migratory/wild birds and poultry of Delhi, Madhya Pradesh, Kerala, Karnataka and Haryana and Punjab.
Details of avian influenza outbreaks and birds destroyed from 2006 to 2022
State (with no. of epicentres) |
District |
Date of start of event |
Species |
No. of birds destroyed |
Gujarat (1) |
Surat |
27/01/06 |
Poultry |
91886 |
Maharashtra (28) |
Nandarbur |
27/01/06 |
Commercial and backyard chicken |
323585 |
Maharashtra |
Jalgaon |
28/03/06 |
Birds |
240200 |
|
Jalgaon |
14/03/06 |
Birds |
93637 |
|
Jalgaon |
18/04/06 |
Birds |
31970 |
|
Jalgaon |
05/04/06 |
Birds |
251393 |
Manipur(1) |
Imphal East |
07/07/07 |
Backyard Poultry |
11 |
West Bengal(68) |
Birbhum |
04/01/08 |
Backyard Poultry |
0 |
|
DakshinDinajpur |
07/01/08 |
Birds |
0 |
|
Nadia |
15/01/08 |
Backyard Poultry |
113 |
|
Burdwan |
15/01/08 |
Backyard Poultry |
0 |
|
Murshidabad |
15/01/08 |
Backyard Poultry |
323 |
|
Murshidabad |
17/01/08 |
Backyard Poultry |
3181 |
|
Nadia |
17/01/08 |
Backyard Poultry |
856 |
|
Bankura |
17/01/08 |
Backyard Poultry |
0 |
|
Birbhum |
17/01/08 |
Backyard Poultry |
85657 |
|
Bankura |
19/01/08 |
Backyard Poultry |
800 |
|
Malda |
19/01/08 |
|
0 |
|
Burdwan |
19/01/08 |
|
90905 |
|
Birbhum |
19/01/08 |
|
95770 |
|
Nadia |
19/01/08 |
|
27884 |
|
Murshidabad |
21/01/08 |
|
297389 |
|
Birbhum |
22/01/08 |
|
325540 |
|
Howrah |
22/01/08 |
|
0 |
|
Purulia |
22/01/08 |
|
0 |
|
Coochbehar |
23/01/08 |
|
0 |
|
Hooghly |
23/01/08 |
|
0 |
|
Burdwan |
23/01/08 |
|
76707 |
|
Birbhum |
25/01/08 |
|
210183 |
|
Murshidabad |
25/01/08 |
|
209945 |
|
South 24 Parganas |
25/01/08 |
|
91969 |
|
Coochbehar |
25/01/08 |
|
27859 |
|
PaschimMednipur |
25/01/08 |
|
0 |
|
Murshidabad |
26/01/08 |
|
72873 |
|
Hooghly |
26/01/08 |
|
35848 |
|
Birbhum |
26/01/08 |
|
14913 |
|
Birbhum |
26/01/08 |
|
124402 |
|
Howrah |
26/01/08 |
|
126066 |
|
Nadia |
26/01/08 |
|
233116 |
|
Murshidabad |
04/03/08 |
|
28995 |
|
Malda |
18/03/08 |
|
23572 |
|
Jalpaigur |
22/03/08 |
|
0 |
|
Nadia |
27/03/08 |
|
7075 |
Tripura (3) |
Dhalai |
03/04/08 |
|
0 |
|
West Tripura |
14/04/08 |
|
30087 |
|
West Tripura |
15/04/08 |
|
9025 |
West Bengal |
Darjeeling |
01/05/08 |
|
33100 |
|
Darjeeling |
11/05/08 |
|
42411 |
Assam (18) |
Kamrup |
21/11/08 |
|
51761 |
|
Kamrup |
28/11/08 |
|
18292 |
|
Kamrup |
30/11/08 |
|
183584 |
|
Barpeta |
30/11/08 |
|
45690 |
|
Nalbari |
30/11/08 |
|
15964 |
|
Kamrup |
05/12/08 |
Chicken |
37657 |
|
Chirang |
05/12/08 |
Backyard poultry |
5480 |
|
Kamrup |
06/12/08 |
|
22673 |
|
Dibrugarh |
07/12/08 |
|
15508 |
West Bengal |
Malda |
13/12/08 |
Backyard poultry |
28695 |
Assam |
Barpeta |
15/12/08 |
|
3385 |
|
Bongaigaon |
15/12/08 |
|
23173 |
|
Kamrup(Metro) |
15/12/08 |
|
1684 |
|
Kamrup |
17/12/08 |
|
6955 |
|
Kamrup |
17/12/08 |
|
5743 |
|
Nagaon |
18/12/08 |
|
11731 |
|
Bongaigaon |
19/12/08 |
|
2620 |
|
Baksa |
19/12/08 |
|
0 |
|
Bongaigaon |
19/12/08 |
|
2620 |
West Bengal |
Darjeeling |
01/01/09 |
|
30898 |
|
Darjeeling |
02/01/09 |
|
9627 |
|
Darjeeling |
02/01/09 |
|
10441 |
|
|
|
|
|
West Bengal(11) |
Coochbehar |
29/01/09 |
|
0 |
|
Coochbehar |
29/01/09 |
|
10058 |
|
Coochbehar |
29/01/09 |
|
1385 |
|
Darjeeling |
13/02/09 |
|
1580 |
|
DakshinDinajpur |
14/02/09 |
|
39582 |
|
Darjeeling |
08/03/09 |
|
20337 |
|
Uttar Dinajpur |
17/03/09 |
|
0 |
|
Uttar Dinajpur |
20/05/09 |
|
0 |
|
Murshidabad |
12/01/10 |
|
0 |
|
Murshidabad |
14/01/10 |
|
25060 |
|
Murshidabad |
14/01/10 |
|
55918 |
|
Murshidabad |
18/01/10 |
|
3138 |
|
Murshidabad |
19/01/10 |
Backyard Poultry |
2088 |
|
Murshidabad |
19/01/10 |
|
3125 |
Tripura(1) |
Agartala |
03/02/11 |
Duck and Poultry |
5268 |
|
Agartala |
04/03/11 |
Poultry |
13936 |
|
|
|
|
|
Assam(1) |
Dhuburi |
29/08/11 |
Rural Backyard Poultry |
15409 |
West Bengal(2) |
Nadia |
14/09/11 |
Rural Backyard Poultry |
47732 |
Odhisa |
Khordha |
03/01/12 |
|
31912 |
Odhisa(1) |
Mayurbhanj |
06/01/12 |
|
11216 |
Tripura(3) |
West Tripura |
16/01/12 |
Poultry |
6204 |
Odhisa |
Khordha |
01/02/12 |
Poultry |
38000 |
Tripura |
West Tripura |
07/03/12 |
Poultry |
5000 |
|
Gomati |
18/04/12 |
Poultry |
2000 |
Karnataka(1) |
Bangalore Urban |
12/10/12 |
Turkey |
33006 |
Bihar (1) |
Purnea |
27/02/13 |
|
6662 |
|
Durg |
30/07/13 |
|
1685 |
Odhisa |
Keonjhar |
31/01/14 |
Crow |
0 |
Kerala (3) |
Alappuzha |
20/11/14 |
Ducks |
135999 |
|
Kottayam |
20/11/14 |
Ducks |
16384 |
|
Alappuzha |
20/11/14 |
|
406196 |
|
Kottayam |
20/11/14 |
|
10455 |
|
Alappuzha |
20/11/14 |
|
26746 |
|
Kottayam |
28/11/14 |
|
5474 |
Kerala |
Kollam |
18/01/15 |
Turkey |
6475 |
Uttar Pradesh (2) |
Amethi |
04/03/15 |
Chicken and Crows |
844 |
|
Sultanpur |
20/03/15 |
|
0 |
|
Amethi |
20/03/15 |
|
0 |
Manipur (1) |
Imphal |
06/04/15 |
|
20874 |
Tripura (1) |
Tripura West |
19/01/16 |
Chicken |
5263 |
Gujarat (2) |
Ahmedabad |
22/12/16 |
Birds |
157 |
Orissa (3) |
Khordha, Sundergarh and Ankur |
19/12/16 |
Birds |
4333 |
Karnataka (1) |
Bengaluru East |
26/12/17 |
Birds |
942 |
Odisha (2) |
Puri and Cuttack |
07/12/18 |
Birds |
13871 |
Odisha (1) |
Jagatsinghpur |
11/02/18 |
Birds |
1823 |
Odhisha (1) |
Puri and Cuttack |
20/01/20 |
Birds |
1024 |
Karnataka (2) |
Devanagere and Mysuru |
10/03/20 |
Chicken |
8448 |
India adopted stamping out protocol as the main strategy for the control of AI. The outbreak area is demarcated as culling/infected and surveillance zone for 3 km and 10 km radius respectively. All the poultry facilities and its associated materials like poultry droppings, feed and feed bags will be culled within 3 km of the foci of infection. Witnessing the global outbreaks of notifiable avian influenza, India has discussed its ever first draft on AI control in 2005. Following an outbreak in 2006, an action plan has been released for the State Governments. It describes strategic actions that can be undertaken to handle an outbreak and consists of four main frames. Part I advises states on pre-outbreak preparedness. Part II indicates the action to be taken in case of any suspicion of occurrence of Avian Influenza at any place. Part III describes the actions in the event of the outbreak of the disease being confirmed by laboratory tests. Part IV provides advice on bio-security measures and to persons who may be required to handle NAI infected poultry, etc. With the new experiences gained from the repeated outbreaks scientific contemporary, action plan has been revised thrice in 2012, 2015 and 2020. The latest plan involves minor modifications mainly in terms of simplification, sending a copy of test report to chief secretary of state, reduction of re-induction from three to one month, inclusion of sero-surveillance etc.(GOI notification, 2015).
Compensation paid from February 2006 to April 2015 in India due to avian influenza outbreaks associated forced culling of poultry, feed and eggs
State (with no. of epicentres) |
Compensation paid (rupees in Lakhs) |
Gujarat (1) |
32 |
Maharashtra (28) |
270 |
Madhya Pradesh (1) |
3 |
Manipur (1) |
94 |
West Bengal (68) |
1229 |
Tripura (3) |
71 |
Assam (18) |
170 |
Assam |
36 |
Sikkim(1) |
3 |
West Bengal(11) |
68.80 |
Tripura(1) |
2.40 |
Assam(1) |
6.52 |
West Bengal(2) |
19.29 |
Odhisa |
24.71 |
Meghalaya |
7.89 |
Odhisa(1) |
5.87 |
Tripura(3) |
1.20 |
Odhisa |
2.86 |
Tripura |
0.09 |
|
|
Bihar (1) |
2.06 |
Kerala (3) |
379.5 |
Kerala |
2.16 |
Emerging health issues that need to be addressed:
Diseases are progressing with their evolutionary trend towards greater virulence with new pathotypes (as a result of molecular evolution) and withstanding the protective efficacy of prevailing vaccines. This makes vaccine ineffective during disease outbreak. The major hitch with MDV is that vaccination could stop only the tumour formation but not the generation of infectious MD particles. Lack of induction of sterilizing immunity although reduces the infection, causes shedding of virus in vaccinated flocks.This continuous virus reservoir in vaccinated flock provides opportunity to selection and adoption to new field virus with increased virulence. HVT vaccine may be inefficient in providing protection against these virulent strains as a result of which outbreaks occur despite repeated vaccinations in layer flocks mainly in India.
Vaccines and Vaccination: Lower vaccine dose and low PFU levels (as in MD): The claiming quantity and actual content are reported to vary which needs to be addressed. Similarly, poor vaccine administration, missed vaccination and use of partial vaccine dose are posing detrimental effects due to reduced titer levels. Live IBDV vaccines are attenuated classical virulent strains with reduced pathogenicity while maintaining immunogenicity (Schijnset al., 2008). However they exhibit poor efficacy in presence of maternally derived antibodies(MAb). While intermediate and intermediate plus/ hot vaccines sustain the MAb interference but produce mild IBD lesions (Rautenschleinet al., 2005). Further safety and efficacy of these vaccine strains are questionable, as they may not show complete protection for vvIBDV strains and its corresponding antigenic variants.
Besides vaccines, vaccination protocols like revaccination and double vaccination also needs to be emphazised as it has been established that two vaccinations at day old decreases the risk of a chick not being injected, gives more uniform response and a higher peak of replication and increases the protection of birds in case of strong field challenge (Le Galludec, 2008). However this needs further evaluation to validate the expected outcome under field conditions. Currently, there is no vaccination policy for HPAI, LPAI, ILT and CIA (for commercial flocks) diseases in India. However, illegal import of specific vaccines against government policy resulting in vaccine induced infections that is not seen previously. Further, details of vaccine label sometimes vary from the actual content of it.
Disease reporting:
Lack of transparency in disease reporting
Under reporting of ND leads to endemicity in these areas. It is reported that the sero-prevalence of ND may be as high as 83% in India (Geethaet al., 2008). Stamping out programs require good disease reporting and majority of farmers or companies may not report disease to government despite appreciable compensations available.
Biosecurity shortfalls :
Poor clean out, increased number of farms with multi-aged birds ,increased density of poultry belts; (lesser inter farm distance). Intensification of poultry production (Van Boeckelet al., 2012) with high density populations and lack of structural biosecurity concept. Multi species rearing practices like Turkey, Guinea fowl, Japanese quail and native chicken with commercial chicken. Enriched water fowl (Ducks and Geese) production is in a complete free range mode and intensive to some extent. Road side opened unorganized poultry processing practices and transportation of commercial birds in completely open conditions from farm to fork.
Geographical scenario:
Complex production and marketing systems,close and frequent contact of humans, backyard poultry, commercial birds and crows,cock fighting (as in Andhra Pradesh), live poultry trading in shandies or household exchange of rural birds and back tracing of unsold birds from live and wet markets. Movement of humans and transportation of infected poultry to markets with improved road connectivity (Yupianaet al., 2010 and Gilbert and Pfeiffer, 2012). Land-cover, such as river networks, presence of inland water bodies (Biswaset al., 2009; Martin et al., 2011). Water presence may be considered a direct risk by supporting transmission through contaminated water because virus can remain infective for several days at ambient water temperature (Naziret al., 2010). Frequent encountering of migratory birds from different continents are posing significant threat. It has been observed that initial introduction of HPAI to a country is usually associated with long distance transmission from infected areas through migratory birds (Si et al., 2009 and Newman et al., 2012).
India is witnessing repeated occurrences of emerging and re-emerging diseases. Pathogenic and emerging diseases namely Avian Influenza often causes heavy losses both in domestic market and international trade. Respiratory disease complex and complicated chronic respiratory disease in poultry are major challenging issues to Indian poultry industry. Under reporting is the endemicity of Newcastle disease (ND) in these areas.India is the country where wide area culling is adopted, but often done late as several days after start of the event due to delay in disease reporting and diagnostic confirmation. This provides a chance of time transmission of virus and significant movement of birds to occur. Stamping out programs requires good disease reporting and majority of farmers or companies may not report disease to government despite appreciable compensations available. Passive surveillance for HPAI often results in under reporting, especially in areas where the culling of birds has been carried out as a control measure. Compensation paid is not matching with losses occuring due to culling of birds, feed disposal, ban on restocking etc
Survey report on poultry economics in West Bengal (as cited in Otte, 2008) indicated that economic impact through losses largely exceeds the monetary support provided by Govt. and therefore, there is little incentive for farmers to report infection, which compromises the efficiency of passive surveillance. It has been observed that initial introduction of HPAI to a country is usually associated with long distance transmission from infected areas through migratory birds (Si et al., 2009 and Newman et al., 2012). Frequent hitting of NE and eastern regions with H5N1 infections clearly indicates massive border migration involvement and this must be controlled with stringent security measures. Eastern states share borders with Nepal, Bangladesh, Bhutan and Myanmar and it is increasingly being recognized that HPAI is now a regional cross-border problem with porous borders and illegal movement of poultry and poultry products contributing to the threat of potential endemic circulation within the region (Dhingraet al., 2014). Level of commitment to deal vigorously with outbreaks is also another important factor to visualize.
Concurrent disease challenge with immunosuppressive diseases and interference of maternally derived antibodies with vaccine uptake is a major problem especially with live vaccines (Block et al., 2007) as in case of Infectious Bursal Disease.
Control strategies: A way forward
Visualizing suitable platform in the light of development of new generation vaccines that can control the evolutionary trend of various pathotypes. Focus on new technology vaccines may drive disease control strategies towards a safe line by halting pathogenic evolution. It is indicated that molecularly defined new generation/new technology vaccines may have better protection than most of the currently used vaccines. Vaccines for MD and IBD have been developed and introduced into the market. These include immune complex vaccines, vector HVT vaccines and vector FP vaccines. Most commonly they are vaccines of exclusively vector based HVT technology. New technology vaccines are becoming popular with global usage of 45% in the hatchery. Amongst the three targeted major diseases, new technology vaccines against IBD are the front runners, which were the first to be introduced (from 2002 to 2008) and have the largest usage share followed by ND new technology vaccines, whose percentage is rapidly expanding (Comte, 2013). Vaccine technology can be made efficient with the use of continuous cell lines.Chicken embryo fibroblasts minimize the number of aseptic handling during production and increase the possibility for production in bioreactors. Polyvalent vaccines could be imagined in places where bivalent or monovalent vaccines are ineffective. But the issue of efficacy at field challenges with highly dense poultry populations needs to be addressed.
Regular acidification of drinking water with new generation and natural sanitizers should become an integrated part of poultry management.Implementation of policy issues like strategies for testing the efficacy of commercial vaccines and their suitable combinations.Preference befor good vaccine brand, choice is important as some vaccines show lower replication rates leading to delayed and/or weak immunity and adoption of intelligent vaccine handling and vaccine administration practices. In the line of improving vaccine efficacy, stringent laws may be imposed on vaccine usages and their marketing patterns.Pathogen monitoring includes identification of new variants associated with disease in vaccinated birds and characterizing their pathogenicity in time; continuous monitoring of potential spread of unique genotypes by predicting global movement of poultry and poultry products.Studying genetic variation within populations of viruses that includes their geographic distribution (Phylogeography) allows tracking of spatial diffusion process for a virus as it occurs over time and mostly for highly contagious diseases like IBDV.
Focus on developing disease resistant chicken lines through immune genetics and transgenics mediated approaches by exploiting the hidden innate immune mechanisms of alternate poultry species like Ducks and Guinea fowl which showed stronger immune competence traits against most common poultry diseases. Similarly, revealing the mechanisms responsible for harboring the influenza virus in wild birds, water fowls, migratory birds and house crows should be given the utmost priority. The discoveries of IBV-like strains in alternate poultry (Cavanagh, 2005), might also play a role in the spread of IBV strains over the world. It would provide a great chance for spreading IBV across the globe in a very short time if specific IBV strains affect other poultry especially migratory birds. However, the role of these birds in spreading of IB is largely unknown at present and future studies in this line may be required.
Use of geographic information system (GIS) technology benefits many industries including agricultural systems. In poultry, GIS technology is an ideal tool for disease surveillance, outbreak control and emergency management (Johnson et al., 2000). It has solved many poultry related issues for the last ten years in many countries. GIS technology allows for accurate location of all premises, quick adjustments of any changes in the data and manipulation and analysis of the data for sound decision-making besides providing a base for design of vaccination zones and demarcation between vaccinated and non-vaccinated zones. Grid and road maps although pose minor constraints ,they provide information of affected farms and susceptible surrounding premises simultaneously when all the farms are mapped. Computer software is used to draw zones of biosecurity or vaccination during an outbreak (Dofour, 2008). However, this necessitates the digitization of all the poultry farms in the country.
Consideration of drones for health management in poultry:
Application of drones has been considered a better solution for free-range or yard farms where birds are allowed to roam freely by their owners. In this case the drones play the role similar to that of a sincere care taker. The drones can be used for constant monitoring of the chicks. Drones take pictures of the bird throughout the day at designated pace and send it instantly to the systems and build the database for analyzing the behavior of the flock.Cattle, sheep, chickens, pigs, and other free-range animals can be difficult to keep track of,especiallyon large ranches. But, farmers can fly drones over hundreds, if not thousands, of acres to regularly capture a snapshot of their herds. And Precision Analytics Agriculture can evaluate drone imagery to deliver an accurate count. By deploying a thermal camera on a drone, farmers can identify sick livestock by their signature elevated body temperature.
AI has a significant role to play in detecting bird diseases like the bird flu etc. The infected birds have symptoms like nasal and saliva secretions apart from high temperature. Pictures sent from drone are then fed to the machine, which can recognize the disease at an early stage. Since the infection is contagious, it leads to reduced production therefore early detection helps poultry farmers to check the disease spread by giving the necessary treatment to the birds or chicks. The computer models are designed for differentiating infected bird from a healthy bird by just noticing the nasal or oral secretion on the beak/mouth of a chicken. Similarly nutritional deficiencies can be detected in young chicks.
Machines can be utilised to detect the behavior of feather pecking in birds and its adverse affects. This also helps in identifying the injured birds. Building machines give timely alerts to the farmers about cannibalism thereby ensuring higher productivity of the poultry. Pecking behavior often leads to the plumage of laying hens which has a negative impact over health of the flock, and under this situation death can occur within 10 minutes of pecking. Therefore early detection becomes essential.
Farm management practices become less stressful with the use of AI. With the help of computers a large amount of information can be stored in cloud spaces which can be utilized by machine or robotics to control parameters like humidity, temperature, light etc. Through Machine Learning, robotics can be used to monitor large number of parameters which are essential for farm management. AI can also process the data and can be used for instant decision making thus improving efficiency of the farm.
Programming and robotics are also beneficial for improving genetic quality of a particular chicken breed. AI application can identify traits of a particular breed and aids in decision making while selecting the particular breed characteristics. These processes can significantly lower the trial cost and also provide accurate trial results. As per reports technologies like smart automation and machine vision can be used by nutrition companies, feed manufacturers, vaccine or drug producing companies, and improve accuracy and efficiency and also further enhance the quality control in their manufacturing facilities. The benefits are numerous which is beyond the scope of discussion in this article. In coming future AI is most likely to contribute significantly in development of poultry industry though enhancing efficiency and accuracy at every level. Artificial Intelligence has great potential in poultry industry since the numerous challenges which are very difficult or nearly impossible to be resolved manually, can be done through involvement of Machines and Robotics. In the last few years many companies have started evaluating use of AI at various levels of value chain and have successfully adopted them.
The opportunity for drones in chicken houses may seem a little farfetched. There is concern that the drone could make the flock nervous and cause undue stress. To this point, an experiment by Georgia Tech in 2015 showed the birds were not yet ready for this technology, compared to robots, which are probably better suited for indoor tasks anyway. Free-range or yard-kept chickens and turkeys that roam fields freely would be a better application for drone technology, which could herd, protect and monitor them. Adaptation of avian species to drones would probably require training but will most likely succeed outdoors. Newer diagnostic platforms like biosensors, gold nano particle based Lateral Flow Assay for timely on farm disease diagnosis. In addition, a new portable biosensor based H5N1 detection system in field has been developed. It was observed that, this unit could detect virus in poultry samples within an hour. Standardization of multiplex PCR for timely diagnosis of respiratory disease complex has also been developed. Development of predicting models for the future spread of avian influenza will provide valuable support for the control in India. Based on the poultry environment, previous outbreaks information, seasonal pattern, prevailing control strategies and influenza hot spots, the future outbreaks can be expected and control measures can be placed in more efficient way with less economic impact.
In conclusion, the constant evolution of various viral diseases has forced the development of new vaccines or vaccine strategies that control the more virulent emergent strains. However, this race between the introduction of new vaccines and the evolution of MDV represents a major threat for the poultry industry. Even though much advanced methods have been made to control viral diseases through advanced biosecurity, novel vaccination, improved diagnostic approaches and policies, facing the massive outbreaks is still questionable for deadly diseases like HPAI.
References: Available upon request