Smallholders who keep a small flock of chickens very often do not bother to vaccinate their birds against diseases. They reason that if they feed them well, do not overcrowd and maintain good hygiene, the chickens will be able to withstand disease. However, when one considers how easy it is for diseases to spread, it might be worth rethinking this policy.
A healthy chicken will remain healthy as long as there is no direct contact between the chicken and viruses, bacteria, protozoa or mycotoxins. The chickens can be exposed to diseases through contact with wild birds, rodents or their faeces, insects such as flies and litter beetles, wind, dust and feathers from passing vehicles ~ even their water might be carrying disease. People who work on the plot or even visitors may carry disease-carrying organisms on their clothing or shoes.
Stress may arise in the flock due to a variety of factors and can also render the poultry vulnerable to passing diseases.
Vaccination is the process by which a vaccine is given to the birds: in the drinking water, sprayed or by injection. It must penetrate the body.
The smallholder needs to understand that a vaccine is not a medicine, but is rather a preventative measure against disease. It contains the disease-causing organism in a weakened state. In an overdose it can kill the birds. Correct dosage stimulates the formation of antibodies, which is the body’s way of fighting the disease.
There are vaccines available against Newcastle Disease, Infectious Bronchitis, Marek’s Disease, Salmonella gallinarum, Salmonella enterica and typhimurium, Infectious coryza, Mycoplasma gallisepticum, Fowl cholera and Fowl pox. There are different strains of Newcastle disease, so different vaccines are administered at different times.
Note though that vaccination against Avian Influenza is prohibited by law in South Africa.
There are different ways of vaccinating chickens: by spray, drinking water, injection and the eye-drop method.
Some vaccines must be given using a specific route, for example, pox vaccination is only given via a wing-web-stab method, not in drinking water or in the eye.
Only healthy chickens should be vaccinated.
Most vaccines are available at veterinary chemists, co-ops, veterinarians and sometimes at feed stores.
Vaccines are fragile in many respects and require very careful handling to ensure they retain their potency. Poor handling procedures will, in most cases, result in a rapid decline of potency.
The important handling requirements are:
Q On receipt of the vaccine, check and record that the vaccine has been transported in the recommended manner, which is usually in the chilled or frozen state. Prolonged exposure to atmospheric temperature will result in rapid loss of potency.
Q Check the expiry date of the vaccine – vaccines have a date by when there is a significant risk that they will no longer retain their potency and will not produce the immunity required. The expiry date is based on the vaccine being handled and stored in the recommended manner.
Q As soon as possible place the vaccine into recommended storage conditions. Read the instructions to find out what these are.
Q If you have to mix the vaccine with water, ensure that the water does not contain chlorine (ie is not municipal water). Some smallholders add skimmed milk powder to the water, as it is believed that that can act as a stabiliser and it eliminates the negative effects of chlorine. Add one teaspoon for every litre of water. Alternatively, buy a bottle of distilled water when you purchase the vaccine if you don’t have clean untreated water available.
Q Remove the vaccines from storage immediately prior to use. Only remove and re-constitute enough for immediate needs and repeat this through the day if more is required. Do not mix what is required for an entire day at the start of the day and leave it stand until required, as the vaccine will rapidly lose it efficacy.
Q Protect the vaccines after mixing by holding them in an ice bath. Some vaccines have a very short life once mixed.
Q Use the recommended administration techniques and do not vary these without veterinary advice.
Q Always clean and sterilise the vaccinating equipment thoroughly after use and destroy unused mixed vaccines after the task has been completed. Some vaccines have the potential to cause harm if not destroyed properly.
South Africa has a list of controlled and notifiable diseases that are listed within the regulations of the Animal Diseases Act (No 35 of 1984). Listed poultry diseases are Newcastle Disease, Salmonella gallinarum, Salmonella enterica and Avian Influenza and outbreaks of these must be reported to the State Veterinarian, which maintains Gauteng offices in Pretoria, Germiston, Randfontein, Vanderbijlpark, Hammanskraal and Johannesburg.