Biosecurity Measures – The First Line of Defence Against Bird Flu

Dr. Sagrika Bhat1, Dr. Sundus Gazal2, Dr. Sabahat Gazal3and Dr. Anvesha Bhan4
1Division of Veterinary Biochemistry, 2,3,4Division of Veterinary Microbiology
and Immunology, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu

Microscopic pathogens, including bacteria, viruses, fungi, and parasites, pose significant threats to poultry health, with avian influenza being a major concern due to its high mortality, economic impact, and zoonotic potential. The disease is caused by Influenza A virus belonging to the family Orthomyxoviridae. Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11, respectively). The highly pathogenic strains such as H5N1, H7N9, and H9N2 have been reported to cause severe disease. The virus spreads through direct contact with infected birds, contaminated feed, water, and fomites, while wild migratory birds serve as natural reservoirs, enabling global transmission. Highly pathogenic avian influenza can lead to near-total flock mortality, significantly disrupting poultry production and trade. Additionally, zoonotic strains such as H5N1 and H7N9 can cause severe respiratory illness, pneumonia, multi-organ failure, and high fatality rates in humans, necessitating global surveillance by organizations like the World Health Organization (WHO).

Poultry farms constantly face the risk of Avian influenza and other infectious diseases that persist in dust, droppings, and farm waste, making biosecurity a fundamental component of disease prevention. Biosecurity measures serve as the first line of defence, preventing pathogen entry and transmission through stringent hygiene, controlled farm access, and optimized housing conditions. Effective biosecurity minimizes outbreaks of avian influenza, Newcastle disease, duck plague, and bacterial infections such as fowl cholera and mycoplasmosis, which compromise poultry health, reduce productivity, and weaken consumer confidence.

Given the increasing incidence of avian influenza worldwide, including India, strengthening biosecurity is imperative to safeguard poultry health and public safety. Disease prevention strategies must integrate high-quality stock, proper housing, clean feed and water, regular disinfection, and restricted farm access. Additionally, modifying industry practices in poultry production, transport, and marketing is essential to curb disease spread. Veterinary authorities must continuously evaluate and refine biosecurity measures in high-risk areas while considering economic and social impacts. Several biosecurity measures have been implemented or require further revision in Asian countries, including India, to effectively control avian influenza and ensure sustainable poultry production. Above all, biosecurity must be a continuous effort rather than a reactive response to outbreaks.

A well-structured, proactive approach remains critical for preventing disease outbreaks, ensuring industry stability, and minimizing zoonotic risks.

Key Biosecurity Measures in the Poultry Industry
1. Marketing Systems: Live bird markets serve as critical points for avian influenza (AI) transmission due to continuous operation, overnight poultry retention, and the reintroduction of unsold birds to farms. These practices facilitate pathogen circulation. Implementing a mandatory market rest period of 24 hours in a week, accompanied by thorough cleaning and disinfection, is essential to mitigate viral persistence and spread.

2. Species Segregation: Domestic waterfowl and quail act as reservoirs for avian influenza viruses. Their cohabitation, transportation, and marketing alongside other poultry should be restricted to minimize interspecies transmission. Additionally, swine reared in proximity to infected poultry farms are found to be infected with HPAI (Highly Pathogenic Avian Influenza) therefore should undergo systematic veterinary surveillance. In cases of confirmed avian influenza infection, culling of affected herds is recommended to prevent viral reassortment and potential zoonotic spillover.

3. Farming Practices: Extensive poultry rearing systems, particularly in village settings, pose a heightened risk for avian influenza introduction due to their lack of biosecurity controls. Strategic vaccination programs targeting backyard poultry can enhance herd immunity. Commercial farms should adhere to an ‘all-in, all-out’ production model to reduce pathogen exposure and poultry workers must adhere to strict biosecurity protocols, including cleaning, disinfecting, or changing protective clothing, equipment, and footwear before entering and after leaving farms.

4. Transport Biosecurity: Transport cages and egg containers should be constructed from non-porous materials such as plastic or metal over wooden cages to facilitate effective disinfection. To prevent environmental contamination and disease spread, bio-secure transport protocols should be implemented. This includes minimizing faecal contamination during poultry unloading, ensuring transport cages are cleaned and disinfected before returning to farms, and using easily sanitized materials for transporting table eggs, fertile eggs, and day-old chicks.

5. Compartmentalization: In regions where avian influenza is endemic, creating compartmentalized poultry populations with distinct health statuses is essential for disease control and international trade compliance. This requires strict biosecurity measures, including traceability of fertilized eggs, certified hatchery and feed sources, vermin control, and regulated transport. Poultry operators must maintain detailed records of suppliers, egg crate circulation, employee responsibilities, and transport activities to ensure compliance and effective disease containment.

Mitigation of Stress through Managemental Interventions
While biosecurity is crucial for disease prevention, stress reduction is equally important in enhancing poultry resistance to infections, including avian influenza. Environmental factors such as high temperatures, ammonia build-up, overcrowding, feed deprivation, handling, and transportation induce physiological stress, compromising immunity. Strategies such as adjusting feeding schedules, providing cool drinking water, supplementing essential nutrients, and optimizing dietary energy and amino acid levels help mitigate heat stress. Maintaining appropriate temperature, ventilation, and humidity is vital for flock health, especially in regions with high heat and humidity. Since wet litter contributes significantly to ammonia production, proper litter management, ventilation, and dietary adjustments are necessary to reduce ammonia levels and support biosecurity measures.

Nutritional Biosecurity Measures
Poultry immunity depends on proper nutrition, as essential nutrients regulate immune cell activity and function. Balanced diets rich in proteins, vitamins, trace minerals, and energy sources are critical for disease resistance. Probiotics enhance immunocompetence by stimulating antibody production, while prebiotics selectively promote beneficial gut bacteria, improving immune function. Additionally, mycotoxins in poultry feed suppress immune responses, making birds more susceptible to infections. Strict feed quality control and mycotoxin mitigation strategies should be integral to biosecurity programs.

Hygienic Disposal of Poultry Waste
Poultry operations generate waste, including dead birds, broken eggs, manure, litter, and contaminated equipment, which serve as reservoirs for pathogens. Proper disposal methods include burial, incineration, rendering, and composting.
Burial is effective but requires a 90-day period for pathogen deactivation before use as fertilizer. Incineration is reliable but often limited by facility size. Open burning is costly and environmentally unfavourable. Rendering is viable if decontamination is ensured, though private facilities may be reluctant to handle infected material. Composting within farm premises minimizes the risk of disease transmission during transport. Additionally, high-risk practices like using contaminated water and recycling untreated poultry waste should be strictly prohibited.

Wild Bird and Vector Control for Disease Prevention
Wild birds, particularly waterfowl, act as reservoirs for avian influenza and other pathogens, and play an important role in introducing infections to poultry farms. Effective biosecurity includes wild bird-proofing quarantine facilities and preventing their access to contaminated areas. Rodent control is equally essential, as rats and mice serve as mechanical carriers of the pathogens. A structured eradication program should minimize their dispersal from infected sites. Flying insects also contribute to disease transmission; thus, integrated pest management strategies should be implemented to reduce their presence in poultry sheds.
Immunomodulation through Nutritional Supplementation and Genetic Strategies
Regular supplementation of vitamins, minerals, and proteins strengthen poultry immunity and should be a core component of modern biosecurity. Nutrient deficiencies compromise resistance, increasing vulnerability to avian influenza and other diseases. As the influenza virus rapidly mutates and can exist as various subtypes and pathotypes, it questions the efficacy of existing vaccines and antivirals, and hence, genetic interventions offer a promising alternative. Screening poultry populations for disease-resistant genes, particularly in native breeds, and incorporating these traits through selective breeding can enhance flock resilience against infections.

Vaccination Strategies for Avian Influenza
Vaccination integrated with biosecurity measures can act as a critical tool for influenza control. Vaccines should provide adequate protection and minimize virus shedding. Vaccination programs coupled with virological and serological surveillance can be used to effectively detect viral mutations and assess vaccine effectiveness. In past influenza outbreaks in Maharashtra, Gujarat, and Madhya Pradesh, India successfully controlled the disease through culling and biosecurity measures. Establishing vaccine banks and enhancing domestic vaccine production are essential for rapid response to outbreaks. Policymakers must decide on vaccination strategies based on epidemiological data and national disease trends.

Strengthening Quarantine and Flock Profiling
Strict quarantine protocols are crucial in preventing disease introduction through newly acquired birds. Newly introduced poultry should be isolated for at least 21 days, monitored for clinical symptoms, and tested (blood, faecal, and nasal swabs) before integration with existing flocks. Beyond farm-level quarantine, strict regulations should be enforced to control cross-border movement of live poultry and poultry products.

Conclusion:
Effective biosecurity is the cornerstone of bird flu prevention and control, serving as the primary defence against disease outbreaks in poultry. Raising awareness among poultry farmers, industry stakeholders, and policymakers is essential for strengthening biosecurity at all levels. Training programs for grassroots poultry managers should be prioritized to ensure the proper implementation of preventive measures. In addition to immunity-boosting strategies and advancements in disease control, continuous surveillance of avian influenza and other infectious diseases is crucial. A proactive and well-enforced biosecurity framework not only safeguards poultry health and industry stability but also minimizes public health risks associated with zoonotic disease transmission. By integrating stringent biosecurity protocols with modern disease prevention strategies, the poultry sector can achieve long-term sustainability and resilience against emerging threats like avian influenza.

Dr. Anvesha Bhan1, Dr. Sundus Gazal2 and Dr. Sabahat Gazal3
Division of Veterinary Microbiology and Immunology, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu

The poultry sector is among the fastest-growing industries, playing a crucial role in providing employment, income, and animal protein to both urban and rural populations, while also serving as manure for crops. Despite the global increase in meat supply, challenges such as bird handling, housing, rearing, and disease control still hinder the industry’s progress. During the monsoon season, continuous rainfall can lead to higher relative humidity and lower temperatures, affecting both the quality and quantity of feed. Additionally, wind speed can influence disease outbreaks. These weather changes impact poultry production, particularly for laying birds, as egg production declines in extremely cold or hot weather. Such conditions stress the birds, compromising their immune systems and reducing their disease resistance. Some of the common poultry diseases during the rainy season are:

Fowl Pox: Fowl pox is a highly contagious disease affecting poultry birds of all ages, caused by a poxvirus transmitted mainly by mosquitoes and other blood-sucking insects. The prevalence of fowl pox increases during the wet season due to the abundance of stagnant water, which provides breeding grounds for mosquitoes. Additionally, wet litter from poorly shielded poultry houses can lead to fly problems. Fowl pox exhibits round lesions with scabby centers on the birds’ skin, primarily on the wattle, face, comb, and occasionally on the legs. It can also affect the mouth and windpipe, causing lesions that may block the throat and lead to suffocation. Lesions on the face can spread to the eyes, potentially causing temporary or permanent blindness.

Fowl Cholera: Fowl cholera is a bacterial disease caused by Pasteurella multocida, affecting birds aged 6 weeks and above. It is highly contagious with high mortality in acute cases. The bacterium spreads readily during the rainy season as wet litter harbors numerous microorganisms.In acute cases, birds may die suddenly without prior signs, while chronic cases show symptoms similar to fowl typhoid, including yellow, green, or grey diarrhea; loss of appetite; labored breathing; drooped wings and tail feathers; ruffled feathers; swelling of leg joints, sinuses, wattles, and footpads.

Salmonellosis, Colibacillosis, Pullorum Disease (Bacillary White Diarrhea): These bacterial diseases affect birds of all ages and thrive in farms with poor sanitation, especially when wet litter is left unchecked. They impact the digestive system, presenting symptoms such as severe diarrhea, loss of appetite, depression and emaciation, chicks suffering from omphalitis, white pasty diarrhea in pullorum disease, huddling together and labored breathing.

Aspergillosis: Aspergillosis, caused by Aspergillus fumigatus, is prevalent during the rainy season due to high humidity, which dampens feed and litter, creating a conducive environment for fungal growth. Inhalation of Aspergillus spores lead to respiratory issues and lesions in the lungs. It is exhibited as Acute form which is common in young chicks and is characterized by rapid onset and high mortality with symptoms like lethargy, depression, loss of appetite, difficulty breathing, and cyanosis; or as Chronic form which develops subtly over weeks or months and affects older birds with symptoms like weight loss, reduced appetite, respiratory issues, and changes in vocalization.

Coccidiosis: Coccidiosis, a parasitic disease caused by the protozoan Eimeria spp. is an intestinal infection which causes extensive intestinal damage. It is widespread in poultry and game birds during the rainy season where wet litter and high pen temperatures favour the sporulation of oocysts of the parasite. Clinical signs include bloody faeces, ruffled feathers, anaemia, somnolence, severe diarrhoea, and high mortality. Decreased growth, feed and water consumption, weight loss, and decreased egg production are common. Infected survivors may suffer long-term performance loss.

Managemental Practices in Monsoons: Achieving Maximum Efficiency
The monsoon season brings challenges such as high relative humidity and temperature fluctuations. These extreme weather conditions create a favourable environment for the propagation of various pathogenic organisms, including bacteria, viruses, fungi, parasites, and vectors like flies and mosquitoes. This necessitates careful consideration and appropriate measures to optimize bird health and ensure efficient production.

Housing Management for Poultry During Monsoon:
A well-maintained shed is crucial for minimizing climatic stress and health challenges in poultry. Before the monsoon season, it is important to inspect the roof and walls for any holes or leaks and repair them promptly. Ensure the drainage ditch around the shed is clear to prevent waterlogging. The roof should have side overhangs of at least 3 to 4 feet to prevent rainwater from entering the shed. Cover the side walls of the empty shed with polythene curtains that are in good condition and can be adjusted based on ammonia concentration or rain intensity. Improper curtain management can lead to poor ventilation, resulting in ammonia buildup, which can cause issues such as improper digestion, abnormal respiration, and a high incidence of ascites. During the day, allow 1-2 feet opening at the top of the side curtains to ventilate ammonia and other undesirable gases. Atleast a 10-feet perimeter outside the shed should be kept clean and free of bushes and grasses. Waterlogging in the surrounding area can lead to propagation of insects like mosquitoes and flies inside the shed and since these act as vectors for many infectious diseases, proper cleanliness and pest control becomes crucial. To control the insect population regular spray of insecticides like bleaching powder and formalin (3-5%) should be done.

Litter Management in Poultry Housing During Monsoon:
A good litter material absorbs moisture when the surface is moist and the air is humid, and releases moisture when the air is dry. Ideally, the litter moisture content should be between 25% and 30%. If moisture falls to around 20%, the litter becomes too dusty, and if it rises to around 40%, the litter becomes wet and caked, which is undesirable. There are various issues that are faced with poor litter management viz., wet and caked litter promotes rapid microbial growth, which may cause infections leading to irritation, cracking, and infection of the foot. High moisture content in litter leads to ammonia buildup in the poultry house. Ammonia and other noxious gases can damage the respiratory tract lining, exposing birds to infections. Although the maximum permissible level of ammonia in the litter is 25 ppm, but adverse reactions including irritation of the eyes and respiratory tract start appearing at concentrations as low as 6 ppm, while reduced animal performance may be observed at 11 ppm. Thus, the level of ammonia in the shed must be kept at the minimum.

1. Moisture Control:
– Regularly check litter moisture. Compress the litter sample in hand; if it shows crevices and gently falls apart, moisture is optimal. If it forms a cohesive ball, it is too wet. If it crumbles easily, it is too dry.
– If litter moisture exceeds 40%, it indicates wet and caked litter which requires immediate disposal and replacement with fresh litter.
– Practice litter racking twice a day to prevent caking.
– To reduce litter moisture, add 1 kg of slaked lime and 150 gm of bleaching powder per 100 ft² of floor area.
– Operate ceiling fans at a ratio of one fan per 300 birds in deep litter broiler farms.

2. Overall Maintenance:
– To prevent mold growth, treat new litter with a 2% aqueous solution of copper sulphate spray.
– Regularly inspect and maintain the poultry house roof and walls to prevent leaks and ensure good drainage around the shed.
– Use polythene curtains to cover side walls and adjust them based on ammonia concentration and rain intensity, allowing for proper ventilation.
– Maintain cleanliness around the shed, keeping at least a 10-foot perimeter free from bushes and grasses to prevent waterlogging and insect breeding.
– Use insecticides, bleaching powder, and formalin spray (3-5%) outside the shed to control insect populations.

Feed and Water management to navigate through the Monsoon Season

Feed Management:
1. Adjust diet formulations to include all vital nutrients, considering the reduced feed intake of the birds due to high temperature and humidity.
2. Avoid long-term storage of feed as shelf life is shorter due to high humidity.
3. Prevent feed from heating up or forming lumps, which indicate decomposition and mold growth.
4. Ensure that vehicles for feed transport are leak-proof and maintain a 4-5 day extra feed stock to avoid frequent transportation during rainy days.
5. Use a Dunnage system to store feed bags. Stack bags on wooden or bamboo pallets at least 1 foot off the floor and away from side walls to avoid moisture contact and allow air circulation.
6. Implement a FIFO (First In, First Out) system for feed distribution.
7. Avoid wooden feed troughs to prevent mold growth and toxin production. Use plastic troughs for easier cleaning and disinfection.
8. Clean the feeders daily with a dry cloth.

Water Management:
1. Ensure clean, safe water supply as it significantly impacts flock performance.
2. Regularly sanitize water to prevent contamination, especially during the rainy season when E. coli and other coliform counts are higher.
3. Use water sanitizers with sufficient contact time and proper dosing.
4. Acidify drinking water to lower the pH, which reduces bacterial growth. Drinking water pH should preferably be around 5.0 to 5.5 to inhibit most pathogens. Poultry prefer water with a pH of 6 to 6.8.
5. Clean drinkers daily with detergents and bleaching powder to reduce water-borne diseases.
6. Clean pipelines at least once a week to reduce biofilm formation.
7. Monitor Oxidation-Reduction Potential (ORP) to evaluate the effectiveness of water sanitizers. An ORP value > 650 mV indicates good quality water, which can be effectively sanitized with 2-4 ppm free chlorine.