Newcastle Disease (ND) is a highly contagious viral disease that affects birds, especially poultry. It is caused by the Newcastle Disease Virus (NDV), a strain of Avian Paramyxovirus Type 1. This disease can lead to severe economic losses in the poultry industry due to high mortality, decreased egg production, and trade restrictions.
Affected Species
- Primarily chickens
- Also affects turkeys, ducks, pigeons, wild birds, and other avian species
Transmission
ND spreads through:
- Direct contact with infected birds (droppings, respiratory secretions)
- Contaminated equipment, feed, water, clothing, and vehicles
- Airborne particles in confined spaces
Types (Pathotypes)
NDV has different pathogenic strains classified by severity:
| Pathotype | Severity | Effects |
|---|---|---|
| Velogenic | Highly virulent | Severe respiratory, nervous, or digestive signs; high mortality |
| Mesogenic | Moderately virulent | Moderate symptoms; lower mortality |
| Lentogenic | Low virulence | Mild or inapparent signs |
Symptoms (Clinical Signs)
Respiratory Signs
- Coughing, gasping, nasal discharge, sneezing
Digestive Signs
- Greenish diarrhea, decreased appetite
Nervous Signs
- Twisting of neck, tremors, paralysis, drooping wings
Reproductive Signs
- Drop in egg production
- Abnormal eggs (soft shells, misshapen)
Mortality: Up to 100% in unvaccinated flocks infected with velogenic strains
Diagnosis
- Clinical signs and history
- Virus isolation in embryonated eggs
- PCR and serological tests (e.g., ELISA, HI test)
Public Health Concern
- Zoonotic Potential: Can cause mild conjunctivitis and flu-like symptoms in humans (especially poultry workers), but not considered a serious human disease.
