The Deadly Threat: Understanding Newcastle Disease in Poultry Flocks

1Jayant Kumar Kakwani, 1AkashWadal, 1Prasad Shinde

1MVSc Scholar, Department of Animal Nutrition

College of Veterinary Science and Animal Husbandry

Acharya Narendra Deva University of Agriculture and Technology

Kumarganj, Ayodhya-224229

Newcastle disease is a contagious bird disease affecting many domestic and wild avian species. It can spread to humans. Avian Paramyxovirus -1 is a single stranded non segmented negative sense RNA virus that causes virulent strains of Newcastle disease, a significant infectious illness of poultry. While there are occasional outbreaks of Newcastle disease in Europe, the disease’s epizootics in poultry still occur in Asia, Africa, Central America, and South America. Animal proteins make up a large portion of the diets of people living in developing nations, around 66% of the population. Newcastle disease is a serious threat to the chicken industry as well as a disease with significant economic impact. Variability in NDV strains can be attributed to variations in flock mortality and morbidity rates.

Etiology-

The current taxonomy places the viruses that cause Newcastle disease, Avian Paramyxovirus serotype 1 [APMV-1], in the genus Avula virus, sub-family Paramyxovirinae, family Paramyxoviridae. Avian paramyxoviruses have ten serotypes, numbered APMV-I to APMV-10, while ND virus (NDV) is known as APMV-1. Based on clinical symptoms in infected hens, the Newcastle disease virus has also been divided into five pathotypes, labeled

  • viscerotropic velogenic
  • neurotropic velogenic
  • mesogenic
  • lentogenic or respiratory
  • asymptomatic

The virus is extremely contagious and can spread via a number of ways such as-

  • Direct contact: Direct contact with infected birds or their secretions (such as feces, nasal, or ocular discharges) might result in the transmission of the virus.
  • Indirect contact: Infected people, vehicles, apparel, or equipment can serve as mechanical vectors to transfer the infection to vulnerable birds.
  • Airborne transmission: The virus can travel small distances in the form of aerosols or dust particles.
  • Vertical transmission: Breeder chickens who are infected with the virus may occasionally pass it on to their young through the egg.

Clinical signs-

After being naturally exposed to viruses, the incubation period lasts, on average, 5 to 6 days, although it can range up to 15 days. Infected individuals may experience sudden and significant fatalities of up to 100% in unprotected herds, depending on the strain that is present. All that is caused by lentogenic strains is a mild respiratory infection. Mesogenic strains cause low mortality and respiratory discomfort due of their intermediate virulence. Viscerotropic strains induce far more greenish-colored diarrhea and digestive diseases than neurotropic velogenic strains, which cause neurological (torticollis, paralysis of legs and wings) and respiratory (cough, rales) disorders. Infected chickens typically exhibit sadness, prostration, oedema around the eyes, diminished or stopped laying, cyanosis of the crest, and enlargement of the head in addition to the clinical indications already stated.

Diagnosis-

Newcastle disease is a highly contagious virus that primarily affects chickens and other birds. A mix of clinical symptoms, laboratory results, and epidemiological data are usually used to make a diagnosis. This is the typical method of diagnosis:

  • Clinical Indications-Veterinarians keep an eye out for obvious signs in the flock, including diarrhea, respiratory illness, paralysis, and nervous signs like tremors. Nevertheless, these symptoms may differ based on the virus strain and the type of bird affected.
  • Postmortem Examination-When birds pass away, an examination of their corpses may reveal lesions that are indicative of Newcastle disease, including lung congestion, swollen eyelid tissues, and digestive tract hemorrhages.
  • Laboratory testing: Laboratory testing are usually used to confirm Newcastle disease. This comprises:
    • virus isolation: The spleen, lung, or trachea are among the tissues from which the virus can be isolated. Usually, to accomplish this, suspected samples are injected into particular cell cultures or embryonated eggs.
    • The molecular method known as reverse transcription polymerase chain reaction, or RT-PCR, finds Newcastle disease virus (NDV) RNA in clinical samples. It is really particular and sensitive.
    • Serology: Antibodies against the Newcastle disease virus can be found in blood samples using serological assays including ELISA (enzyme-linked immunosorbent assay) and HI (hemagglutination inhibition). This aids in ascertaining the flock’s immunological condition.
  • Epidemiological Investigations: Knowledge of the flock’s past, especially any recent bird introductions, interactions with other flocks, and vaccination records, can be crucial in setting the diagnosis in perspective.

Nutritional intervention-

In poultry, nutritional intervention is helpful in treating Newcastle disease (ND). Although there isn’t a specific nutritional therapy for ND, giving the bird the best nutrition possible will strengthen its immune system and general health, speeding its recovery and lessening the severity of the illness. The following are some dietary tactics to think about:

  • A well-balanced diet that includes all the necessary nutrients like proteins, carbs, fats, vitamins, and minerals should be provided to birds. A healthy diet boosts the immune system and makes it easier for birds to handle the strain of illness.
  • High-quality protein-Protein is essential for tissue repair and immune system maintenance. High-quality protein sources that can enhance the immune response during ND infection include fish meal, soybean meal, and poultry by-products.
  • Vitamin Supplementation-The immune system depends heavily on vitamins. Make sure birds have access to sufficient amounts of B-complex vitamins, as well as vitamins A, D, E, and C. Among the antioxidants that can lessen the oxidative stress brought on by viral infections is vitamin E in particular.
  • Mineral Supplementation-Immune system function depends on minerals like zinc, selenium, and copper, which can also strengthen defenses against infections. Make sure the birds have access to feed that satisfies their needs or mineral supplements.
  • Electrolytes and Water-Diarrhea or a decrease in water consumption can cause dehydration in birds infected with ND. Electrolyte supplements added to drinking water can enhance general health by preserving electrolyte balance and hydration.
  • Probiotics and Prebiotics-Probiotics are beneficial bacteria that can help maintain gut health and support immune function. Prebiotics are non-digestible fibers that promote the growth of beneficial gut bacteria. Including probiotics and prebiotics in the diet can help improve gut health and immune response in birds with ND.
  • Stress Management-Minimize stressors in the environment, as stress can suppress immune function and make birds more susceptible to infections. Provide a comfortable housing environment with adequate space, ventilation, and lighting.

Prevention and control measures-

  • Vaccination-The most effective method of preventing ND is vaccination. Vaccination against ND is recommended for birds in order to avoid ND in chicks. There are several ways to get immunized: by drinking water, subcutaneous, intranasal (spray), and eye drop. When using the ND vaccine in drinking water, it is necessary to stop using drugs and sanitizing agents 24 hours before drinking and to start again 24 hours after the immunization. For immunization, non-chlorinated water should be utilized.
  • Avoiding vaccine failure-When vaccines fail, ND outbreaks happen. Despite intensive and frequent immunization, ND continues to cause havoc in chicken flocks, and outbreaks have occurred in flocks that have received vaccinations as well. Inadequate vaccination techniques, vaccinations given during the ND concurrent incubation period, exposure to harsh winter or summer weather, vaccinations given to birds after they have been vaccinated, etc. are all causes of vaccine failure. Another issue that might lead to vaccine failure is low vaccine quality.
  • Biosecurity-The spread of ND is aided by insufficient biosecurity. Strict biosecurity and limiting the movement of sick birds can help prevent ND.
  • Minimizing bird stress-Factors that contribute to bird stress include transportation over extended periods of time, damp litter, ammonia buildup in winter sheds, overstocking, heat, cold, and concurrent diseases. Poultry flocks experiencing respiratory and digestive distress because of Mycoplasma gallisepticum and salmonella infections stress the birds and may accelerate the spread of ND.

Economic impact-

Poultry farmers suffer significant financial losses due to diseases. High rates of mortality and morbidity, decreased egg production from layer flocks, and low-quality egg production from breeder flocks are the main causes of the economic losses resulting from ND. The expense of therapy and additional flock management during the disease’s course increases the financial losses brought on by ND.

ND is the cause of increased bird morbidity and death across all age groups. A highly virulent strain of the ND virus may be the reason. Increased production losses in layer and breeder flocks are caused by ND, which has a disastrous impact on chicken productivity. Egg production is significantly reduced by velogenic strains of ND, whereas it is moderately reduced by mesogenic strains of NDV.

Economic losses are increased by the treatment costs incurred by the flocks affected by ND. The eggs from the afflicted flock lighten in color, their shells thin, and become harsh and the egg’s quality drops the albumin may be squishy and the egg white’s thickness is reduced, and breeder egg fertility is declining, which lowers hatchability. There could be long-term damage to the reproductive system, and egg production Peak production is not reached by performance. Antibiotic residues in meat and eggs are another reason why the use of antibiotics to prevent subsequent infections throughout the course of the disease lowers the quality of the eggs produced by ND affected flocks. Because meat and eggs have high quantities of drug residues, they are no longer suitable for human consumption.

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