Ranikhet (Newcastle) disease

Ranikhet disease, internationally known as Newcastle disease, is a highly contagious acute viral infection of poultry caused by Newcastle disease virus (NDV), an Avian paramyxovirus serotype 1. The disease was first identified in 1927 at Ranikhet in Uttarakhand, giving rise to the Indian name that persists in veterinary and trade usage. India remains endemic with seasonal outbreaks in both commercial and backyard flocks.

Identification and symptoms

Clinical signs depend on the virus pathotype and host immune status. Velogenic forms cause sudden onset of high mortality (often above 50% in unvaccinated flocks), respiratory distress with gasping and rales, greenish watery diarrhoea, drop in egg production, soft-shelled or shell-less eggs, twisted necks and other neurological signs. Mesogenic forms produce milder respiratory disease with patchy mortality. Lentogenic forms are largely subclinical and are exploited as vaccine strains.

Host species and life cycle

All domestic and many wild birds are susceptible; chickens are most clinically affected, while ducks and geese can shed virus with little or no clinical sign — a critical epidemiological feature in mixed village systems and migratory duck routes (Duck Farming Migratory, Country Chicken Nattu Kodi). Transmission is by direct contact, aerosol, contaminated feed, water, equipment and personnel. The virus survives weeks in cool damp environments, so inter-batch sanitation matters.

Damage and economic impact

Newcastle disease is the most economically important viral disease of Indian poultry. Outbreaks in commercial broiler (Broiler Chicken) and layer (Layer Chicken Bv 380) flocks cause flock-level mortality losses and prolonged egg-production depressions; outbreaks in backyard country chicken, Kadaknath (Kadaknath) and Sonali (Sonali Breed) flocks regularly wipe out village poultry. The disease is notifiable to the WOAH (formerly OIE) under the Terrestrial Animal Health Code.

Management

There is no antiviral therapy; control rests on vaccination plus biosecurity. The standard Indian vaccination schedule combines a lentogenic LaSota strain at day-old to 7 days, administered through drinking water, intra-ocular instillation or coarse spray, conferring immunity for about six weeks. A mesogenic R2B (Mukteshwar) booster is given at 8-10 weeks of age via subcutaneous injection. Breeder flocks receive annual boosters with inactivated oil-adjuvant vaccines. Vaccination is paired with cold-chain integrity, correct chick-handling at brooding (Brooding Chicks) and strict inter-batch sanitation (Biosecurity Cleaning Between Batches) of houses and equipment. Effective mortality management (Poultry Mortality Management) on commercial farms therefore begins with reliable Newcastle vaccination.

References

Live R2B Vaccine. Hester Biosciences.
Newcastle Disease in Backyard Poultry in North-East India. PMC.