Description of Disease:
Newcastle disease is a member of the paramyxo- virus group which includes other known viruses such as distemper virus in dogs, rinderpest in cattle as well as measles and mumps in man. This is a highly contagious viral disease of poultry and various other types of birds. All birds are susceptible, but chickens and turkeys show the most severe signs. The disease is less severe in ducks and geese. Pigeons show mild clinical signs depending on the breed. Man can also be infected with the virus and develop an inflammation of the mucous membrane of the eyes. Newcastle disease manifests as 3 different forms which vary in severity, namely the velogenic, mesogenic and lentogenic forms. 

In the case of the velogenic form the respiratory system, nervous system and the alimentary system are affected with clinical signs such as lethargy, laboured breathing, cyanotic (blue) comb, paralysis and green diarrhoea. There is a decrease in egg production. Sudden mortalities occur which increase every hour. The mortality rate can be up to 100 %. The mesogenic form gives the same clinical signs as the velogenic form but to a lesser degree. There is a lower mortality rate of between 15 and 20 %. 

Almost no clinical signs are noted if birds are infected with the lentogenic form of Newcastle disease. Some birds may have slight difficulty in breathing. There are no mortalities with this form of the disease. The lentogenic virus is used by some vaccine producers to produce vaccine. The virus is fairly stable when exposed to environmental con- ditions. Chicken houses and poultry products can remain infectious for 6 to 8 weeks or even longer. In refrigerated poultry carcasses the virus can remain viable for several months. 

Newcastle disease is transmitted by contact and the virus enters through the mucous membranes of the eyes, the respiratory system or of the intestinal tract. The virus is present in secretions or excretions of infected poultry and consequently the virus is easily disseminated under intensive housing conditions and when poultry and their products are transported. The disease is not transmitted by insects and airborne infection over long distances rarely occurs. It is not transmitted through the egg. 

The disease has a world-wide distribution and is at present endemic in South Africa. Wild birds, particularly parrots, are frequently infected, but are apparently only temporary carriers. International trade in parrots and other wild birds has been responsible for several outbreaks of the disease in countries that were free of infection.

Back to list

Description of Disease
Pox occurs in various poultry and bird species and is caused by a pox virus. Wild birds such as crows and cranes are also susceptible to pox. The disease occurs throughout the year in South Africa with a peak season from December to April. The virus is transmitted mechanically by biting insects such as mosquitoes and to a lesser degree by bite wounds as a result of discord concerning the pecking order.

The pox virus of poultry, pigeons and canaries are specific for each species, although there is some relationship between fowl pox and pigeon pox. The viruses that affect chickens and turkeys however, are apparently identical.

The incubation period is between 1 and 2 weeks and is characterized by fever, listlessness, reduced egg production and wart-like growths on the featherless parts of the skin. The lesions observed are red lumps, especially on the eyelids. The condition may worsen and more lesions also appear on the cere areas of the beak and on the legs and toes.

The lesions change from yellow to a dark brown colour and later slough off causing scarring. An atypical form of pox occurs in pigeons characterized by a single bloody lesion between the feathers which is first observed when it starts bleeding. This type (skin form) of lesion heals spontaneously after 3 to 4 weeks and has a low mortality rate. The diphtheroid form of pox (wet pox) is more severe. Viscous yellow-grey plague-like lesions develop on the tongue in the oral cavity, and in the throat accompanied by difficult breathing. High mortalities usually occur. In such cases a laboratory investigation is necessary to make a definite diagnosis.

In the acute septicaemic form the birds are sleepy, cyanotic, loose their appetite and the feathers are ruffled. Lesions typical of the skin and diphtheroid forms may also be seen during the septicaemic form. Birds die between 3 hours and 3 days after infection. The disease can also manifest itself as a nasal cold (coryza) with a watery nasal discharge. In severe cases the eyelids may also be affected. Pox virus may turn cancerous. Such cancerous lesions may dry up and slough off, otherwise it may be necessary for a veterinarian to excise them.
Back to list

Description of Disease
This is an acute, contagious disease of chickens and turkeys over 8 weeks of age and is characterized by depression, diarrhoea, weakness and a high mortality rate. It is caused by the bacterium Salmonella gallinarum. The disease is transmitted by contact and the ingestion of feed contaminated with the excreta of diseased poultry. It can also be spread mechanically eg on the hands, clothes and shoes of workers. Recovered fowls serve as carriers. Heavier breeds of chickens are more susceptible than lighter breeds such as the White Leghorn. 
Back to list

Name of disease	Haemophilus Coryza  (Haemophilus paragallinarum)
Name of vaccine	Onderstepoort Haemophilus Coryza Vaccine
	Product code: 1153

Description of Disease
Coryza is an acute infectious disease of adult fowl but may sometimes affect chickens as young as 2 weeks of age. It is caused by the bacterium Haemophilus paragallinarum and is spread by means of direct contact, infected water and aerosol ovei short distances. It can also be transmitted mechanically eg by means of mopping rags. Recovered birds remain carriers of the disease. 

The disease is characterized by the sudden onset of upper respiratory symptoms such as a serous nasal discharge, lachrymation, swelling of the face and eyes, sinusitis, laboured breathing and moist rales. In laying birds there is a sudden and dramatic drop in egg production, which can be of great economic significance. 
Back to list