Ranikhet disease, also known as Newcastle disease, is a highly contagious viral disease that primarily affects poultry. It is caused by the avian paramyxovirus type 1 (APMV-1), which is a single-stranded RNA virus. The virus can infect chickens, turkeys, pigeons, and other birds, causing severe respiratory, nervous, and digestive system symptoms.

Statement A: Ranikhet disease is the disease of poultry.
This statement is correct. Ranikhet disease is indeed a disease that affects poultry, particularly chickens and turkeys. It can cause significant economic losses in the poultry industry due to high mortality rates and decreased egg production.

Statement B: It is caused by a virus.
This statement is also correct. Ranikhet disease is caused by the avian paramyxovirus type 1 (APMV-1). This virus belongs to the Paramyxoviridae family and is known for its ability to cause respiratory and neurological symptoms in infected birds.

The avian paramyxovirus type 1 (APMV-1) can be classified into different strains or subtypes based on their genetic and antigenic characteristics. Some strains of APMV-1 are highly virulent and can cause severe disease outbreaks in poultry, while others are low pathogenic and may only cause mild symptoms or no symptoms at all.

Ranikhet disease is primarily transmitted through direct contact with infected birds, their bodily fluids, or contaminated materials. The virus can also be spread indirectly through contaminated feed, water, equipment, or by humans and other animals that have come into contact with infected birds.

In poultry, the virus primarily targets the respiratory and gastrointestinal systems, leading to symptoms such as respiratory distress, coughing, sneezing, nasal discharge, diarrhea, and decreased egg production. In severe cases, the disease can progress to neurological symptoms, including paralysis and death.

Control and prevention of Ranikhet disease in poultry mainly involve implementing strict biosecurity measures, vaccination programs, and proper hygiene practices. Vaccination can help reduce the severity of the disease and limit its spread within poultry flocks.

In conclusion, both statements A and B are correct. Ranikhet disease is a viral disease that primarily affects poultry, and it is caused by the avian paramyxovirus type 1 (APMV-1).