River Region North Livestock Director Mamut Njie said his department will
embark on a mass chicken vaccination campaign against the New Castle Disease
(NCD) starting today.
The thirty-day vaccination campaign will be conducted in Lower and Upper Saloum, Nianija, Niani and Sami districts.
Mr. Njie commended cattle owners for their support and cooperation during the recent vaccination campaign against Contagious Bovine Pleuropneumonia (CBPP) that was conducted in the region.
He also acknowledged the support of district chiefs, Alkalolu, National Livestock Owners Association (NaLOA), security and the office of the governor of the region.
Newcastle disease, he said, is a viral disease of birds caused by avian paramyxovirus 1 (APMV-1). “For official control purposes, this disease is currently defined as the most severe form of the illness, which is caused only by certain viral strains. Many less virulent strains of APMV-1 also circulate among domesticated and wild birds,” he said.
He indicated that the disease usually cause much milder clinical signs or infect birds asymptomatically. “However, they can sometimes evolve to become the highly virulent strains that cause Newcastle disease,” he stated.
Mr. Njie thus maintained that the disease is considered to be one of the most important poultry diseases in the world, saying chickens are particularly susceptible and may experience morbidity and mortality rates of up to 100%.
“Outbreaks can have a tremendous impact on backyard chickens in developing countries where these birds are a significant source of protein.”
He said APMV-1 can be transmitted by inhalation or ingestion and birds shed these viruses in both feaces and respiratory secretions. He said gallinaceous birds are thought to excrete APMV-1 for 1-2 weeks, but psittacine birds often shed these viruses for several months, and sometimes for more than a year.
Commenting on the incubation period of the disease, Mr. Njie said APMV-1 infections in poultry ranges from 2 to 15 days and is commonly 2-6 days in chickens infected with Velogenic isolates. “Incubation periods up to 25 days have been reported in some other avian species. In pigeons, PPMV-1 causes clinical signs after 4 to 14 days with some authors reporting incubation periods as long as 3-4 weeks,” he said.
On the clinical signs, Mr. Njie said APMV-1 viruses can cause varying clinical signs, depending on the pathogenicity of the isolate and the species of bird. He explained that Lentogenic strains usually infect chickens sub clinically or cause mild respiratory disease with signs such as coughing, gasping, sneezing and rales. “Illnesses caused by mesogenic strains can be more severe in these species.”
He said there may be respiratory signs, decreased egg production and in some cases, neurological signs but the mortality rate is usually low. With both Lentogenic and mesogenic viruses, Mr. Njie said the illness can be more severe if the flock is co-infected with other pathogens.
Velogenic strains cause severe, often fatal illnesses in chickens but the clinical signs can be highly variable. Early signs may include lethargy, in appetence, ruffled feathers, and conjunctival reddening and edema. Some birds develop watery, greenish or white diarrhea, respiratory signs (including cyanosis) or swelling of the tissues of the head and neck.
Egg laying often declines dramatically, and eggs may be misshapen, abnormally colored, and rough or thin-shelled, with watery albumen. Sudden death, with few or no preceding clinical signs, is also seen frequently.
Mr. Njie said the vaccination will be conducted free of charge and called on all poultry owners to ensure that their birds are vaccinated, saying it will be conducted both in the morning and evening and inoculators will move from compound to compound.