Eimeria species in long-life cycle birds: breeders, layers and special long life broilers. The importance of Eimeria tenella. 

Avian coccidiosis is a common protozoal gastrointestinal parasitosis caused by the Eimeria species resulting in considerable economic losses in the poultry industry, especially in long life-cycle birds such as layers and breeders. In these high value birds, Eimeria species infection results in clinical or subclinical coccidiosis associated with increased mortality, decreased flock uniformity and a general rise in secondary pathologies subsequent to intestinal damage. Without any doubt, the best known and most widely diagnosed species is Eimeria tenella.


Microscopic picture of the five Eimeria species included in EVALON®: Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria necatrix and Eimeria tenella.

Chickens are susceptible to seven Eimeria species, the most common species affecting long-life birds being Eimeria tenella, Eimeria necatrix, Eimeria brunetti, Eimeria acervulina and Eimeria maxima. The above-mentioned Eimeria species can lead to clinical coccidiosis in which the affected birds show typical symptoms of the disease, such as bloody droppings and increased mortality. The other two Eimeria species which can affect chickens, Eimeria praecox and E. mitis, are known to cause subclinical coccidiosis, as the affected birds show no clear symptoms of the disease; however this subclinical form may lead to uncontrollable bodyweight and uniformity (out of standard) with a major impact on broilers.
Generally in layers and breeders we distinguish between caecal and intestinal coccidiosis. Caecal coccidiosis is due to Eimeria tenella that is confined to the caecum and consists of the presence of hemorrhages on the outside or inside of the wall of the caecum. This acute infection occurs most commonly in young chick and is by far the most diagnosed in the field due to its typical lesions and localization.

E. Tenella lesion degree 3: large quantities of blood or caecal moulds; the caecal wall is greatly thickened and very little or no faecal content in the caeca (according to Johnson and Reid, 1970).

Most serious cases of intestinal coccidiosis are caused by Eimeria necatrix (and fewer by Eimeria brunetti). They develop within deeper tissues of the small intestine and besides Eimeria tenella are major pathogens of poultry. Eimeria necatrix and Eimeria brunetti mainly affect birds of more than 8-9 weeks or age.
Eimeria acervulina and Eimeria maxima develop in epithelial cells within the small intestine and generally cause chronic intestinal coccidiosis associated with marked weight loss and heterogeneity.
Eimeria mitis and Eimeria praecox have a limited impact on long-life birds as they have very rapid biological life cycles within the host and this is closely related to their effect in the first weeks of production cycles. In long-life birds, the growth rate and weight development is quite irrelevant and even later on (from 3-4 weeks) weight is monitored and the feed administered is restricted.
The approach to prevention of coccidiosis is very specific in long-life birds (layers and breeders) and totally different to that in standard broilers, the aim being to build a rapid and long-lasting immunity against the main Eimeria species that can infect this kind of bird. The ability to build a good immunity relies on the choice of a balanced and comprehensive vaccine solution: EVALON®.

The importance of the length of immunity in the prevention of coccidiosis in chickens raised for a long cycle

When we think about the prevention of coccidiosis in chickens raised for a long cycle (breeders and layers) we cannot imagine any treatment other than vaccines. Apart from cost considerations, the use of coccidiostats has been always a handicap in birds that usually have restrictions on feed consumption. This is the reason why the protection conferred by a vaccine applied in the first days of life should be high enough to give a level of immunity that is able to protect them throughout the cycle.
Lesion scores of mid-intestine at 6 days post-challenge with E. necatrix. Lesion scoring grading 0-4 according to Johnson and Reid, 1970. Control vs EVALON® + HIPRAMUNE®T.

Layers and breeders have a production cycle of not less than 60 weeks in most cases. One of the main characteristics of these birds is that the rearing period in a normal poultry house is different to that in a production house. During this rearing period, the broiler breeders in particular have restrictions on their feed consumption and the birds are caught several times in order to apply different vaccines and to carry out other procedures. Coccidiosis in chickens is a parasitic disease caused by Eimeria species and the biological cycle of the parasite (external and internal) is essential for this parasite to survive. Vaccines manufactured for the prevention of coccidiosis in chickens works in the same way so that the conditions for replication should be good enough to ensure that the attenuated strains are able to induce good and long-lasting immunity.
Apart from the necessary management at vaccination and selection, there are other major stress factors on the birds. These include the transfer from rearing houses to production houses with the normal equipment for egg-laying. This means extra stress that could cause interference with the establishment of immunity. Onset of lay is another source of stress that again means interference with immunity against coccidiosis in chickens.
So, how can a vaccine applied in the first days of life provide protection throughout the cycle? In a normal situation, if the birds have constant contact with the parasite in the litter, the adaptive immunity mechanism allows the birds to maintain a level of protection. However, the situation is not always so normal and the occurrence of other diseases, weather conditions, extremely dry litters that do not favour the replication of oocysts and other problems can reduce or even minimize protection.
Obviously, in the composition of the vaccines, we must ensure that we include those species of Eimeria affecting birds at more than 8-9 weeks or age (E. necatrix, E. brunetti).
Generally, live attenuated vaccines have been proved to provide protection until 37 weeks. However, in the case of EVALON®, a live attenuated vaccine from HIPRA, its efficacy is boosted by co-administration with a special adjuvant, HIPRAMUNE®T.
For the registration of EVALON®, Pre-clinical and Clinical studies were performed to assess the safety and efficacy of the vaccine (Study of the efficacy of a new live coccidiosis vaccine, EVALON® for breeders and layers under field conditions in farms with a history of clinical coccidiosis. Proceedings of the XIXth World Veterinary Poultry Association Congress). The duration of immunity was assessed for EVALON® + HIPRAMUNE®T under laboratory conditions. Under these conditions, the introduction of external Eimeria oocysts that could produce trickle infections throughout the rearing and laying period was impaired. Birds were not moved from rearing to laying – on the contrary they were maintained in the same room. It is well-known that at farm level and after vaccination, trickle infections occur, and are important to maintain and enhance long-term immunity against Eimeria parasites (Williams 2002). In the study we tried to prove that protection was extended in the absence of trickle infections.
To study the efficacy of this vaccine against coccidiosis in chickens, birds were randomly selected at different time points (14, 28, 40 and 60 weeks) and individual challenge tests for each Eimeria species included in the vaccine were performed using highly pathogenic heterologous challenge strains. The groups of vaccinated and non-vaccinated birds were compared using macroscopic intestinal lesions as the main parameter (according to the Johnson and Reid score) after the challenge. Other parameters were also evaluated such as individual body weight, post-challenge oocyst excretion, clinical signs and mortality.
The results obtained in these trials showed an extended duration of immunity with EVALON® when the vaccine is administered together with the adjuvanted solvent HIPRAMUNE®T under conditions that do not favour the presence of oocysts in the litter. The duration of immunity was confirmed as 60 weeks post-vaccination.

INTRADERMAL VACCINATION (HIPRADERMIC®) WITH UNISTRAIN® PRRS IN A MASS VACCINATION IN SOWS

javier sanz animal health

Busquet*, M.; Blanch, M.; Torrents, D.; Verdaguer, J.; Sánchez-Matamoros, A. *Corresponding author (marta.busquet@hipra.com)
HIPRA, Amer (Girona), Spain


OBJECTIVE
Hipradermic®, a needle-free injection device, has been designed as a new option for the intradermal (ID) vaccination of the MLV UNISTRAIN® PRRS on swine farms. Intradermal and needle-free vaccination in pigs has been reported to improve animal welfare, to generate an effective immune response and to be easy to administer, amongst other benefits (Chase et al., 2008). The aim of this study was to demonstrate that UNISTRAIN® PRRS administered using Hipradermic® was as safe and efficacious as when administered via the conventional intramuscular (IM) and intradermal (ID) route in a mass vaccination in sows.

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INTRADERMAL VACCINATION (HIPRADERMIC®) WITH UNISTRAIN® PRRS IN A MASS VACCINATION IN SOWS

Busquet*, M.; Blanch, M.; Torrents, D.; Verdaguer, J.; Sánchez-Matamoros, A. *Corresponding author (marta.busquet@hipra.com)
HIPRA, Amer (Girona), Spain


OBJECTIVE
Hipradermic®, a needle-free injection device, has been designed as a new option for the intradermal (ID) vaccination of the MLV UNISTRAIN® PRRS on swine farms. Intradermal and needle-free vaccination in pigs has been reported to improve animal welfare, to generate an effective immune response and to be easy to administer, amongst other benefits (Chase et al., 2008). The aim of this study was to demonstrate that UNISTRAIN® PRRS administered using Hipradermic® was as safe and efficacious as when administered via the conventional intramuscular (IM) and intradermal (ID) route in a mass vaccination in sows.

Click here to read the article.

“HETEROLOGOUS CELL-MEDIATED IMMUNE RESPONSES AGAINST PRRS VIRUS IN BREEDERS VACCINATED INTRAMUSCULARLY AND INTRADERMALLY WITH UNISTRAIN® PRRS”

Miranda*1, J.; Torrents1, D.; Busquet1, M.; Fenech1, M.; Mateu2, E.; Díaz2, I. *Corresponding author (joel.miranda@hipra.com)
1HIPRA, Amer (Girona), Spain. / 2CReSA (Centre de Recerca en Sanitat Animal), Barcelona, Spain.
Current knowledge on PRRS virus immunology is still limited but it seems clear that modi ed live vaccines (MLV) are a reasonable choice for the immunisation of pigs (1). Cell-mediated responses after MLV vaccination could be responsible for limiting the duration of viraemia, and consequently the spread of the virus (2). Recently, interest in intradermal vaccination has increased due to research on the skin and subcutaneous tissues immunology. Although the intradermal PRRSV vaccination has been investigated (3), the high variability between different virus isolates makes it advisable to assess the intradermal response for each vaccine strain. The aim of this study was to compare the cell-mediated immune response developed in gilts vaccinated intramuscularly and intradermally with UNISTRAIN® PRRS.

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Coccidiosis in poultry: Innovation in vaccination with maximum traceability

In the world of livestock farming and animal protein production, the poultry industry has always been the sector with the greatest focus on achieving maximum control and information when it comes to the management of the production process and of the system for monitoring the medicinal products used in this process. HIPRA is going one step further along this path by offering a new vaccination concept, Smart vaccination, designed to provide improved vaccination monitoring and traceability for the prevention of coccidiosis in poultry.
From the early days of animal production, poultry farming has been in the vanguard of technology, feeding systems, farm automation, etc. Poultry production is one of the most advanced and streamlined of all the animal production sectors, guaranteeing all the quality standards demanded by the consumer in each market. A paradox exists, however: the processes associated with vaccination, unlike other parameters such as feeding, environmental conditions, etc., are beyond control.

Finally, HIPRA has come up with a system that enables poultry producers and veterinarians to manage the vaccination process. HIPRA is ahead of the game in leading the way and offering maximum information in the processes associated with vaccination to ensure the efficacy and correct administration of its products, with the specific benefit to the poultry farmer of improving the control and prevention of coccidiosis in poultry.
A new concept in vaccination is thus born: “Smart vaccination” by HIPRA. This concept is defined as follows:

Vaccines with an RFID chip containing all the information relating to the vaccine lot.

HIPRA vaccination devices that ensure that the vaccines are administered correctly and incorporate data logging and full connectivity. Hipraspray® is the name of the veterinary device used to administer the EVALON® vaccine. Hipraspray® is a single dedicated spray machine for hatchery administration.

A platform for tracing, managing and analysing all these data from the vaccination process: HIPRAlink®.

What kind of traceability does HIPRA offer with the “Smart vaccination” concept in the prevention of coccidiosis in poultry?

With this new concept, HIPRA offers the possibility of monitoring something as simple as it is valuable: access to all the data relating to the vaccination process, which are logged automatically, and the ability to make them available to both hatcheries and their clients.
With HIPRAlink®, it is possible to trace information such as the doses administered, details of the vaccine lots used, process dates, details regarding the operation and use of the Hipraspray® device and to add information about the batch of chicks vaccinated.
What does the system offer the hatchery?
With the EVALON®, Hipraspray® and HIPRAlink® pack, the hatchery has a platform that offers better management of the vaccination process, while at the same time having access to an optimum precision device for administering the EVALON® vaccine for the prevention of coccidiosis in poultry.
What’s in it for the end producer?
The end producer and recipient of the chicks gets a certificate to show that the vaccine has been administered correctly, together with the reassurance that the batch of chicks received has been vaccinated in the best way possible.
What does the poultry production industry get out of this system?
The poultry production industry gets a highly innovative system designed to provide maximum control and information when it comes to the management of the production process and of the system for monitoring the medicinal products used in this process.
Where does this put HIPRA?
By taking this step, HIPRA is positioning itself as a leader in the traceability of vaccination processes, with the ability to provide its clients with services focused on monitoring the administration of its products.
EVALON®, Hipraspray® and HIPRAlink® give veterinarians and producers the possibility of access to a new concept, Smart vaccination, with vaccination certificates, improved management of process-related information, HIPRA vaccination devices that ensure optimum administration of the vaccine and complete traceability in the prevention of coccidiosis in poultry.

In order to follow up the PRRS situation in the farm, what type of serology test would you recommend besides ELISA and/or PCR? Is it realistic and accurate to test IFN gamma or IL-10 to show whether the management/ treatment is implemented properly?

Answered by: Enric Marco
Published on: June 9, 2016
Cytokines determination has been used to study PRRS infection under experimental conditions but it’s not a test routinely used, may be because of different reasons:
These products are not induced specifically byPRRS virus, but also byother infectious agents: SIV, M. Hyo, etc.

Abnormal levels in a PRRS infection are not yet well established. We do not know if there are differences between different strains, probably this is the case as some of these products (IL-12) have been related to persistence of the virus in the lung.

Some of these inflammatory products have a short life which is the case of IL-10 (in some experimental studies levels are reduced at 42 dpi).

This test is probably too expensive to be used routinely.

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In a PRRS-free farm, we vaccinated 10% of the sows with a live vaccine against PRRS by mistake. What are the possible consequences?

Answered by: Enric Marco
Published on: June 6, 2016

The application of a live vaccine may lead to a certain spread of the virus among the animals in the farm, so the virus might be temporarily circulating in the herd. However, because the vaccine virus is an attenuated virus, it is not going to give clinical problems that threaten the productivity of the farm.
The persistence of vaccine viruses in a population has not been sufficiently studied, but it should be lower than that of the wild virus.
Should the virus come to spread in the herd, then negative herd status should be recovered after a certain period of time without intervention.

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