Source: REUTERS

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Context

• Brazil has declared an animal health emergency in the state of Rio Grande do Sul due to the detection of Newcastle disease on a poultry farm.
• This led the Brazilian agriculture ministry to halt poultry exports to certain countries as a preventive measure.
• The emergency declaration aims to contain and manage the outbreak effectively​

Details

Newcastle Disease

• Newcastle disease (ND) is a highly contagious viral disease affecting birds, especially poultry.
• It is caused by avian paramyxovirus serotype 1 (APMV-1), which has multiple strains varying in virulence.
• The disease is found worldwide and can lead to significant economic losses in the poultry industry.
• Newcastle disease is a minor zoonosis and can cause conjunctivitis in humans who are in close contact with infected birds. However, it is not considered a significant public health threat​.

Types of Newcastle Disease Virus (NDV)

• Lentogenic (Mild) Strains: These strains cause mild respiratory symptoms and are often used in live vaccines.
• Mesogenic (Moderate) Strains: These cause moderate respiratory and neurological symptoms but typically result in low mortality.
• Velogenic (Virulent) Strains: These are further classified into viscerotropic (affecting the intestines) and neurotropic (affecting the nervous system). They cause severe disease with high mortality rates​​.

Transmission 

• NDV is primarily transmitted through direct contact with infected birds, their droppings, and respiratory secretions.
• The virus can spread via contaminated feed, water, equipment, and human clothing.
• Wild birds and pigeons can act as reservoirs, maintaining the virus in the environment and posing a risk to domestic poultry​​.

Clinical Signs 

Symptoms of ND vary depending on the strain and can include:

• Respiratory distress: gasping, coughing, sneezing.
• Nervous signs: tremors, twisted necks, paralysis.
• Digestive issues: greenish diarrhea.
• Sudden death without prior symptoms.
• Decreased egg production and quality in laying hens​

Prevention and Control 

• Biosecurity: Implementing strict biosecurity measures to prevent the introduction and spread of the virus. This includes disinfecting equipment, restricting access to poultry farms, and isolating new or returning birds for at least 30 days​​.
• Vaccination: Prophylactic vaccination is widely practiced, especially in regions with a high incidence of ND. Live attenuated and inactivated vaccines are commonly used.
• Surveillance and Reporting: Continuous monitoring and immediate reporting of outbreaks to veterinary authorities are crucial for controlling the disease spread​​.

Geographical Distribution 

• ND is present worldwide, with varying levels of control in different regions.
• It is endemic in parts of Africa, Asia, and South America, while countries like the United States, Canada, and some European nations have achieved better control over the disease​​.

Various Types Of Diseases Related To Birds And Poultry

Disease	Causative Agent	Key Clinical Signs
Newcastle Disease	Avian Paramyxovirus Serotype 1	Respiratory distress, nervous signs, greenish diarrhea, sudden death
Avian Influenza (Bird Flu)	Influenza A Virus	Coughing, sneezing, lethargy, decreased egg production, mortality
Marek's Disease	Marek's Disease Virus (Herpesvirus)	Paralysis, weight loss, tumors, irregular pupils
Infectious Bronchitis	Coronavirus	Respiratory distress, nasal discharge, decreased egg production
Fowl Cholera	Pasteurella multocida	Swelling of the face, diarrhea, respiratory distress, sudden death
Infectious Bursal Disease	Birnavirus	Diarrhea, ruffled feathers, dehydration, immunosuppression
Avian Pox	Avipoxvirus	Lesions on comb, wattles, and beak, respiratory distress
Coccidiosis	Eimeria spp. (Protozoa)	Bloody diarrhea, weight loss, lethargy
Aspergillosis	Aspergillus spp. (Fungus)	Respiratory distress, weight loss, lethargy
Mycoplasmosis	Mycoplasma gallisepticum	Chronic respiratory disease, nasal discharge, conjunctivitis
Salmonellosis	Salmonella spp.	Diarrhea, lethargy, reduced growth, mortality
Infectious Laryngotracheitis	Gallid Herpesvirus 1	Coughing, nasal discharge, bloody mucus, mortality
Egg Drop Syndrome	Adenovirus	Soft-shelled or shell-less eggs, decreased egg production
Psittacosis (Parrot Fever)	Chlamydia psittaci	Respiratory distress, diarrhea, lethargy, conjunctivitis
Avian Tuberculosis	Mycobacterium avium	Weight loss, lethargy, diarrhea, nodules in organs

Sources:

REUTERS

PRACTICE QUESTION Q: With reference to Newcastle disease, consider the following statements: 1.Newcastle disease is caused by an RNA virus belonging to the family Paramyxoviridae. 2.The disease primarily affects poultry but can also infect wild birds. 3.Human infection with Newcastle disease virus can lead to severe respiratory illness. Which of the statements given above is/are correct? (a) 1 and 2 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2, and 3 Answer: (a)