Ranikhet Disease (Newcastle): Symptoms, Prevention and Control
Ranikhet remains the single most damaging viral disease in Indian poultry. How to recognise it early, why vaccination fails when it fails, and what to do once a flock breaks.
Ranikhet disease — Newcastle disease elsewhere in the world — is caused by a paramyxovirus and remains the most economically damaging viral disease in Indian poultry. A velogenic outbreak in an unvaccinated flock can approach total mortality within a week.
Recognising it
Signs vary with the strain, which is part of what makes the disease hard to catch early. Three systems are affected, in roughly this order of visibility:
- Respiratory — gasping, open-mouth breathing, rattling, coughing, nasal discharge. Usually the first thing a farmer notices, often at night when the shed is quiet.
- Digestive — greenish watery diarrhoea, sharply reduced feed intake.
- Nervous — twisted neck (torticollis), paralysis of wings or legs, circling, tremors. These appear later and are close to diagnostic when combined with the above.
In layers, an early and easily missed sign is a sudden drop in production together with soft-shelled, misshapen or depigmented eggs — sometimes days before obvious illness.
Why vaccination fails
Most Indian outbreaks happen in flocks that were vaccinated. The vaccine is not usually the problem — handling and timing are:
- Broken cold chain. Live vaccines lose potency quickly above 8°C. A vaccine that spent an afternoon on a motorcycle in June may be worthless.
- Chlorinated water. Chlorine and metal ions inactivate live vaccine given through drinking water. Use clean unchlorinated water and add skimmed milk powder (about 2 g per litre) as a stabiliser.
- Maternal antibody interference. Vaccinating chicks too early means maternal antibodies neutralise the vaccine before immunity develops.
- Partial coverage. Birds that refuse water in the vaccination window are unprotected and become the reservoir for the next outbreak.
- No booster. A single dose does not carry a layer flock through a full cycle.
A working vaccination schedule
| Age | Vaccine | Route |
|---|---|---|
| Day 5–7 | Lasota or F strain | Eye drop or intranasal |
| Day 24–28 | Lasota booster | Drinking water |
| Week 6–8 | R2B (Mukteswar) | Subcutaneous |
| Week 16–18 (layers) | Killed vaccine | Intramuscular |
| Every 8–10 weeks in lay | Lasota | Drinking water |
Eye-drop delivery is more reliable than water for the first dose because you can confirm every bird received it. It takes longer, and it is worth the time.
If a flock breaks
There is no treatment for the virus itself. What you can do is limit spread and support the survivors:
- Stop all movement of birds, staff, feed bags and equipment on and off the farm immediately.
- Isolate affected sheds; work healthy sheds first and infected sheds last, never the reverse.
- Remove and dispose of dead birds by deep burial or incineration, well away from the sheds and any water source.
- Give supportive care — clean water, electrolytes, vitamins A, D and E. Broad-spectrum antibiotics only on veterinary advice, and only to control secondary bacterial infection, not the virus.
- Disinfect thoroughly. The virus is susceptible to formaldehyde, phenolics and sodium hypochlorite, but organic matter blocks disinfectants — clean before you disinfect.
- Report to your local veterinary authority. Ranikhet is notifiable.
Keeping it out
- Control visitors and vehicles. Most introductions arrive on wheels, boots or crates.
- Keep new birds in quarantine for at least two weeks before mixing.
- Exclude wild birds. Net the sheds and store feed covered.
- Never return unsold birds from market to the farm.
- Follow all-in, all-out batching with a proper cleaning and rest period between flocks.