What should we ask of a vaccine against Eimeria?

The need for prevention against this disease is as old as coccidiosis itself in poultry farming. It has been some time since the first vaccines were developed and fortunately innovations have been incorporated into the production process which have meant that prevention against Eimeria is now safer, more effective and longer-lasting.

 

The first vaccine against coccidiosis in poultry farming was developed in 1952.

At that time, the product contained only a single, non-attenuated species of Eimeria (Eimeria tenella). In 1974, Dr. Jeffers and his colleagues published their discovery of the precocious lines, thereby revealing the method of attenuation by precociousness.

However, for various reasons, the first vaccine containing Eimeria species attenuated by precociousness was not marketed until 1989 (Williams, 2002).

During this period, other innovations appeared in Eimeria prevention, such as vaccines for turkeys and attenuation by means of adaptation of strains to chicken embryos that generated attenuated strains and that in combination with strains derived from attenuation by precociousness, form part of some of the vaccines that are on the market.

Attempts have been made to produce inactivated vaccines with antigens derived from parasite fractions (specifically the macrogamete), the basis of which was an increase in the humoral response in breeders and the transfer of this to the progeny.

However, as has already been shown, humoral immunity plays a secondary role and the efficacy of these vaccines has been shown to be inadequate.

Innovation has therefore been a constant in the development of these biologicals against coccidiosis in poultry farming.

Today, there is a wide range of Eimeria vaccines available to the producer and unquestionably the advantages brought by the different innovations that have been developed over the years need to be clearly set out.

So what can we ask of a product for the prevention of coccidiosis in poultry farming?

  1. The composition of the product in terms of Eimeria species contained in the vaccine.

The composition of the vaccine selected depends on the category of birds (broilers or long life-cycle birds).

It is not necessary to replicate more oocysts in the intestine than are required and it is very important that vaccines that are targeted at the broiler segment take account of Eimeria species that are involved in subclinical coccidiosis (e.g.: Eimeria praecox).

  1. The type of attenuation

The strains of Eimeria attenuated by precociousness have been shown to have a much lower impact on the birds’ intestines, together with an immunogenic capacity similar to that of non-attenuated strains.

This fact ensures that zootechnical results are obtained which are not affected by the replication of the vaccinal parasite, as well as a uniform pattern in long life-cycle birds (especially in breeders) which is higher during rearing periods.

Of course, this type of vaccine does not require the use of coccidiostatic or coccidiocidal products to soften the impact of replication.

  1. The degree of sterility of the vaccines.

Given the method by which they are obtained, these vaccines have a major drawback in terms of achievement of sterility.

It should be mentioned that not all Eimeria vaccines on the market have the assured sterility required for this type of product.

  1. The use of technological supports to encourage ingestion of the vaccine

On the basis that the best and most practical method of application is “coarse spray”, the incorporation into our product of colourings and aromas that promote ingestion of the vaccine is the best option for ensuring the success of vaccination.

Accordingly, HIPRACOX® was the first Eimeria vaccine to incorporate, in addition to a specific colouring, an aroma to improve ingestion under conditions of low light intensity.

  1. The incorporation of specific adjuvants to stimulate the immune response

Considering the importance of cellular immunity in the protection against coccidiosis in poultry farming, the addition of adjuvants that generate a stimulus of this type of immunity unquestionably means improved efficacy and duration of immunity of an Eimeria vaccine.

HIPRA is the pioneer in the use of this type of adjuvant, with EVALON® – with HIPRAMUNE® T- being the reference for this innovation.

Today, now that we have arrived in the 21st century, more than ever poultry producers have different options for prevention against coccidiosis in poultry farming.

It is important to be aware of these different options and of the innovations that there have been over the last 50 years which have allowed a substantial improvement in Eimeria vaccines.

References

Williams R.B., 2002. Fifty years of anticoccidial vaccines for poultry (1952-2002). Avian Dis. 46(4): 775-802.