Ranikhet disease, commonly known as Newcastle disease virus (NDV) is an endemic virus that causes ND and remains a significant threat to the poultry industry in Bangladesh.

Current Situation Overview

• Endemic Status:NDV is widely considered endemic in Bangladesh’s commercial poultry sector, with regular outbreaks reported across various regions.
• Prevalence:Annually ND causes 30% of the birds’ death. Research indicates varying rates of seroprevalence, around 21% in domestic poultry and significantly higher in commercial layers (ranging from 37% to over 90% in some studies). Clinical prevalence in sick or dead birds has been documented at over 25% in specific district studies.
• Economic Impact:The disease is a major constraint on food security and industry productivity, costing the country millions of dollars annually due to high mortality and reduced production.

NDV genotypes in Bangladesh:

Newcastle disease Virus (NDV) genotypes in Bangladesh causing outbreaks in poultry are primarily Genotype VII (specifically VII.2) which is highly virulent & responsible for affecting commercial chicken farms and Genotype XIII (specifically XIII.2), which is also highly virulent (velogenic). Moreover, Genotype XXI.1.2 are found in pigeons of Bangladesh. All these genotypes cause significant mortality in commercial farms.

Etiology: Newcastle disease virus (NDV), also designated as avian avulavirus 1 or avian paramyxovirus-1 (APMV-1)

• Characteristics:single-stranded RNA virus belonging to the family Paramyxoviridae
• Pathotypes based on its virulency:
• Velogenic strains (neurotropic, viscerotropic, and pantropic),
• Mesogenic strains (moderately pathogenic),
• Lentogenic strains (not harmful at all)

• Transmission:Spreads rapidly through direct contact with infected birds, contaminated feed, water, and equipment or via airborne transmission in crowded conditions.

Diagnosis

• Clinical signs: Gasping, greenish diarrhea, nervous system impairment (such as a twisted head or paralysis) and sudden death.
• Common Post-Mortem Lesions

Haemorrhages and necrotic plaques in the proventriculus, intestines, and caecal tonsils, airsacculitis and tracheitis, haemorrhages in the heart, internal tissues and on the inner surface of the chest wall. Affected birds often show signs of emaciation, dehydration, and inappetence.

Differential Diagnosis:

Avian Influenza, Infectious bronchitis,Infectious laryngotracheitis, Avian metapneumovirus, Infectious coryza, Mycoplasmosis, Fowl cholera, Aspergillosis

Laboratory confirmation:

RT-PCR, virus isolation in embryonated chicken eggs, or serological testing like the Hemagglutination Inhibition (HI) assay.

Management and Control

• Vaccination
• Strict vaccination schedule (e.g., using F-strain or LaSota strain vaccines).
• Biosecurity

Strict biosecurity eg. Isolation of new birds, and prompt disposal of infected birds to prevent further spread.

Prepared by-

Dr. Nurey Ferdousi Muna,

DVM, MS in Theriogenology,

Bangladesh Agricultural University,

Bangladesh.