Challenges facing immunity monitoring

The poultry industry constitutes a significant sector of Egypt agriculture. In Egypt, millions of birds are produced yearly with a value exceeding LE 60 billion. Broiler chickens are the largest segment of the industry. Birds raised under commercial conditions are vulnerable to environmental exposure to a number of diseases. Therefore, disease prevention by vaccination is an important part of flock health management protocols. Active immunization using live vaccines is the current industry standard. Routinely used vaccines in chickens include NDV, IBV, and IBDV, H5N1, H9N2.

Vaccination programme monitoring:

Evaluation of the efficacy of a vaccination programme involves the overall assessment of the health conditions of the flocks. The results of the evaluation should indicate when changes in the programme must be made. An effective vaccination plan should result in a general improvement of the health status and the productive performance of the vaccinated flocks. Useful measurable and comparable indicators to judge the overall health status of a flock are the morbidity and mortality rates, and other performance parameters, such as feed conversion, egg production and egg quality. The efficacy of vaccine administration and the level of immunological response in vaccinated birds can be serologically monitored. If vaccination is routinely applied, data on the antibody response elicited in vaccinated birds should be collected and analyzed in order to define the baseline of the antibody titre in different bird species and types of production. This serological monitoring can provide useful information whenever adequate samples have been analyzed over time for each vaccination programme. The serological baseline obtained should be used only to compare similar species and production types. Deviation above or below the established baseline permits the identification of flocks with possible field exposure or poor protection, respectively. 

Although the immune surveillance of poultry flocks is an important operation, more than 80% of poultry producers do not care about it for the following reasons:

- Reducing expenses because poultry producers consider immunity measurement is ineffective, they seek to market the herd safely.

- The ignorance of the poultry producer about the importance of measurement of immunity levels.

- The poultry producer is not aware of the age at which immunization should be measured.

- The poultry producer is not trusted in laboratory results.

- Poultry producers are not aware of diseases whose immunity level should be measured.

- The poultry producers are not aware of how to take and save the samples sent to the laboratory.

- Poultry producers are convinced that the laboratories will not provide suitable solutions to the problems they face.  On the other hand, we find that laboratories do not provide adequate solutions to the health problems faced by poultry producers.

- The inability of most poultry producers to read and evaluate the results of the laboratory.

In any case, despite all the above, it is necessary to follow up and monitoring the immune system of the poultry flocks. Without this follow-up, we will not be able to overcome the health problems of poultry flocks.

Newcastle disease virus (NDV) is an important pathogen in poultry. Waterfowl and a number of other avian species serve as the host for NDV. The severity of the disease is variable and infected animals mainly develop respiratory and neurological symptoms. Outbreaks of NDV in poultry are recorded regularly in Egypt despite the widespread use of vaccines. Therefore, continuous follow-up of this disease should be carried out in all flocks and in different ages.

The importance of the immunological follow-up to IBD is due to the role of this follow-up in determining the appropriate time to begin vaccination against the disease. The immunological monitoring of IBD has an important role to determine the extent to which the flocks of broiler breeders and layer breeders need to be revaccinated at the age of 40-45 weeks with IBD dead vaccine.

Due to the indiscriminate use of vaccines for the infectious bronchitis disease, this causes the disease to persist in all poultry flocks. It is therefore important to follow up the disease in a laboratory to determine the type of strains to be used.

What applies to ND-IB-IBD applies to other diseases that can infect poultry so the immune follow-up of the herds is of great importance.