Is it possible to administer a live PRRS vaccine to animals already infected to stop the piglet’s infection?


Vaccinating the infected sows with a PRRS live vaccine does not seem to help to reduce the clinical signs. It normally reduces the clinical signs in sows when the vaccination is administered before the infection with the field virus. The non-immunised gilts are animals that can help in the replication of the virus on unstable positive farms, and because of this, the vaccination and adaptation before their introduction on the farm is recommended to reduce the clinical signs in these animals and to lower the circulation of the virus on the farm.

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A PRRS outbreak is causing 40% of stillborn piglets. Is it possible to administer a live vaccine to animals already infected to stop the piglet’s infection? Could a vaccine of this kind reduce the number of dead piglets and stop the transmission to new litters?

In this case, an outbreak of stillborn piglets (around 40%) is described, and it is suspected that the cause is PRRS. When we ask for more information on the case, we are told:

Most of the affected litters belong to first parity sows.

No PCR diagnosis of PRSSV on deadborn piglets has been carried out.

Gilts come from another farm, their health status regarding PRRS is unknown, and they are not vaccinated.

The semen used for AI has an external origin.

Vaccinating a newly infected animal with the PRRS field virus does not have practical advantages for the animal, because the immune system already has a strong antigen to process the answer needed. The difficulty does not lie in the individual animal, but on an animal population, because not all the animals become infected at the same time. The PRRS virus is not very contagious, and because of this, the contamination of all the sows on the farm with the field virus will take a long time if we leave the virus to circulate naturally. In these cases, the clinical symptomatology will go on until the last sow becomes immunocompetent against the virus. This can take several months or even years, when negative subpopulations appear on positive farms.

PRRSV-naive gilts are another source of active virus replication when they enter an unstable farm with an active virus circulation. In this case, a situation like the one described can appear. Nevertheless, to be sure, we must diagnose if the PRRSV is the agent responsible for the mortality of the piglets.

If the PRRSV diagnosis is confirmed in the piglets and the gilts that come from an external source, the next step is to reduce the virus circulation on the farm, mainly in the gilts, that may be where the virus proliferates. In cases like this, we recommend vaccinating all the sows to induce some kind of immunisation against the PRRSV and to reduce the clinical symptoms in the sows NOT infected at the time of vaccination. We are not going to avoid the infection of new litters with the field virus, but we can reduce its negative impact and the clinical signs if there is an immunisation previous to the infection.

There is the risk of not achieving enough immunological protection against the field virus with some vaccines, but as of today there is not a technology that allows us to say, with confidence, which is the most effective vaccine for a certain farm. Even after sequencing the virus and choosing the vaccine with the highest homology degree, nothing guarantees us that it will be the most effective one on the farm.

The strategy that we use in clinical outbreaks like this (with a confirmed PRRS diagnosis) is:

The vaccination of all the sows and boars on the farm with a live vaccine on the same day (we will vaccinate the most immunodepressed sows the following week: on the insemination/mating week and the farrowing week). The goal is to obtain a quick immune response against the PRRSV in all the sows in the group, and we expect a certain degree of cross-protection between the vaccine and the field strains. Revaccinate 4 weeks later with the same protocol. 

The gilts that enter the pregnancy stage must be well immunised and non-viraemic (PCR-negative to PRRS and IgG-positive). The vaccination and adaptation of viraemic animals on the farm and allowing enough time in quarantine until they do not excrete the virus (12 weeks is normally enough) are recommended. This is very important for the future control of PRRS on the farm. 

Buying PRRS-negative semen to inseminate the sows. 

Knowing if the virus is circulating in the nurseries. If there is circulation, implement biosecurity rules to reduce the transmission of the virus to the sow herd. 

After the second vaccination of the sows, evaluate if there are still viraemic piglets at birth. If this improves, we can keep the vaccination and adaptation programme only in the gilts in quarantine. 


Is it possible to rear broilers without antibiotics? First step to achieve the goal: vaccination against coccidiosis in chickens

Prevention of coccidiosis in chickens with live vaccines means suspending the use of anticoccidials, but a reduction in other antibiotics has also been observed. Reduction in antibiotic use in animal production is currently one of the aims of the poultry industry. Antimicrobial resistance has become a global public health problem in humans and livestock and plans to reduce the use of antibiotics are being implemented by the authorities in most countries.

Obviously, chemicals and ionophores used to control coccidiosis should be considered as antibiotics because the parasites that are intended to be controlled with these products can develop resistance with prolonged use of these substances.

Vaccination against coccidiosis in chickens has an indirect effect on gut-related diseases (dysbacteriosis, necrotic enteritis, septicaemia after gut leakage) and the consumption of antibiotics could therefore be altered.
It has already been seen that the implementation of a coccidiosis vaccine (HIPRACOX®) in a rotation programme yields a significant improvement in zootechnical results (Ronsmans et al. 2015a). Hipra, in collaboration with the poultry practice Galluvet in Belgium (Ronsmans et al. 2015b), has conducted a study to determine whether vaccination with HIPRACOX® affected the use of antibiotics in broilers. The hypothesis was that if intestinal health was enhanced, the overall health of broiler farms would improve.
In the trial, the effect of the administration of HIPRACOX® on the use of antibiotics on 21 farms in Belgian field conditions was studied. The trial was conducted on the premise of the benefits of rotational programmes but we realised that the use of the vaccine could have a positive effect on reduced antibiotic use during the rearing period.
Some of the farms had a background of coccidiosis problems. Under these circumstances, the use of a coccidiosis vaccine offered adequate protection and there was a clear and significant reduction of treatments against coccidiosis in chickens. As we can see in Graphs 1 and 2, the number of days of treatment fell by 79.56% during the vaccination and by 51.38% after the vaccination cycles (see image above).
However, more significant still is the fall in the administration of gastrointestinal treatments during the period of use of HIPRACOX®. We evaluated the consumption of molecules used to improve intestinal pathologies (Tylvalosin, Linco-Spectin, Tylosin, Penicillin and Amoxicillin).
The graphs below show the evolution of their use on the farms before the administration of HIPRACOX®, during administration of the vaccine and after. The days of treatment per cycle fell by 16.4% during vaccination and by 45.24% after vaccination. Moreover, the amount of active molecule per kg of average weight decreased by 17.39% during and 30.4% after vaccination.

Popular belief tells us that more cases of necrotic enteritis and dysbacteriosis appear in vaccinated flocks due to the lack of the anticlostridial effect of the ionophores. However, no cases of necrotic enteritis were seen during the trial. Furthermore, the quantity of antibiotics used for enteric diseases fell in the period in which the vaccine was used. These observations are consistent with the review conducted by Williams (2005).

Once again, prevention in broiler production is key. A good vaccination programme including vaccines against coccidiosis in chickens could be the best option for those producers that are considering reducing or even phasing out the use of antibiotics on rearing broilers.
In conclusion, the first aim of a coccidiosis vaccine is to prevent coccidiosis in chickens but an indirect effect of coccidiosis vaccine on other diseases can be expected, probably due to an improvement in intestinal integrity.

HIPRA digitalise the animal vaccination process with Watson IoT technology in the cloud of IBM

The service is already available for veterinarians and farmers worldwide.

Madrid – 29 sep 2016: IBM and HIPRA have announced an agreement to integrate the Internet of Things (IoT) solutions that are available in the IBM cloud with animal vaccination   This Technology allows HIPRA to be in the forefront of the Animal Health market. HIPRA name this new world as “the Smart Vaccination” concept, and they are the pioneers in developing this new concept in Animal Health.  

The Smart Vaccination concept is a turning point and there will be a new era after the IoT arrival to animal farming. The Smart Vaccination is a new world where HIPRA vaccines are connected to HIPRA’s Medical Devices and HIPRAlink (HIPRA’s software) to offer vets and farmers a new world of services and benefits for the Prevention of diseases.

Can Eimeria vaccines replace anticoccidials for the prevention of coccidiosis in poultry farming?

Coccidiosis – due to parasites of the genus Eimeria – is one of the most devastating diseases in poultry: a disease which has always being present in every poultry flock since the first chick appeared on the earth; in fact, Eimeria is an ever-present parasite that it is impossible to eradicate. For this reason, a coccidiosis prevention strategy needs to be put in place for each batch of chickens that arrives on a farm. Worldwide losses due to coccidiosis in poultry are estimated to be around US$1.5 billion/year.

From the 1950s the use of some chemical molecules has been implemented to prevent the effects of the several Eimeria species that cause the disease. Whereas the use of vaccines is quite commune in breeders, only between 5 and 6% of broilers in the world are actually vaccinated instead of being treated with anticoccidials.

The prevention of coccidiosis in poultry with some Eimeria vaccines is absolutely safe and efficacious as also demonstrated recently by Alameda et al. 2015 and Ronsmans et al. 2015. So the question is, why is the prevention of coccidiosis with the vaccines available not more widely used around the world? In this post I will try to answer this question from several perspectives.
The first important question to answer is whether or not it is possible. The answer is clearly yes it is. The entire production of breeders, free-range or organic chickens and a percentage of the industrial production of broilers are produced today without the use of anticoccidials. So, the first thing to take into account is the willingness of broiler producers to do it.
The second question is the cost. Some people think that vaccines are more expensive than anticoccidials, but this is not always true. It depends on the duration of fattening of the broiler, the anticoccidial programme used and, of course, on the quality of the final broiler produced, whether or not it is free of anticoccidials.
The third question is management. Some producers think that the use of anticoccidials in the feed is much simpler than vaccination. But it is not well known that the use of anticoccidials in the feed could potentially lead to cross-contamination in the feed mill, especially when the plant produces feed for more than one animal species. This could be the case with salinomycin in turkeys: salinomycin is one ionophore widely used in broiler feed as an anticoccidial, whereas it is well known that it is very toxic for turkeys, even at levels lower than therapeutic ones (Potter et al. 1986). Moreover, it has to be recalled that nowadays the administration of Eimeria vaccines is becoming more and more practical and standardised as most of the applications – especially for broilers – are performed in the hatchery with spraying devices that have been designed for this specific use, like Hipraspray®.
Finally, there is another important question to answer which is whether the availability of vaccines would be sufficient to replace anticoccidials completely. The answer to this question is not easy. Of course companies producing Eimeria vaccines do not produce sufficient quantities at present, because there is no need for it. However, if broiler production in the world started to demand Eimeria vaccines, there’s no reason to think that given time, the companies would not have a sufficient amount of vaccines available.
Eimeria vaccines have a short shelf-life, so they have to be manufactured in response to demand because they cannot be stored for more than a few months. But, again, this is not a very important problem due to the fact that the modern poultry production system is so industrialized that vaccinations can be planned easily and with a long notice period. For this reason, the production of vaccines can be easily planned and in the most accurate way.

Coccidiosis in chickens: the role of subclinical species of Eimeria

The fight against coccidiosis in chickens means the adoption of different strategies depending of the type of bird. If we are managing long life cycle birds, we have to pay special attention to clinical Eimeria species that are able to generate a real coccidiosis process with macroscopic lesions and symptoms that will reduce the healthy status of the birds and will compromise the development of immunity against other diseases or cause the death of the birds.

However, when we are rearing standard, certified or even free-range broilers, the focus needs to be a different one. In these cases it will be difficult to find real clinical coccidiosis. Otherwise, the “silent” species – such as Eimeria praecox among others – will affect the intestinal mucosa and will reduce the capacity of a broiler for nutrient absorption. Dealing with subclinical species is essential in coccidiosis in chickens with a high growth rate.

For a long time, there was a trend to classify coccidiosis in chickens according to the age of the birds. It was considered that E. acervulina, E. maxima and E. tenella were species affecting all the birds. In the case of long life cycle birds such as breeders and layers, it was necessary to include E. necatrix and E. brunetti in the composition of vaccines against coccidiosis. Indeed, this is true for long life cycle birds because feed conversion and growth is important, but not the key point. In fact, these birds are reared under feed restriction.

The chicken intestine has a very important part that plays a main role in digestion and absorption of nutrients. This is the duodenum.
The duodenum is a part of the small intestine where the main digestive processes occur. The pancreas will provide digestive juices into the duodenum for protein digestion in particular and the liver (via the gall bladder) will produce the bile, a gastric juice involved in the digestion of lipids and absorption of vitamins A, D, E and K. When we are treating coccidiosis in chickens –and more specifically in fattening broilers- it is essential to identify the species of Eimeria located in this part of the intestine.
E. acervulina, one of the most prevalent species in broilers, prefers this part of the intestine even if the level of infection is moderate. It is quite typical to find the white ladder-like spot lesions scattered and confined to the duodenum:

E. praecox is also located in the duodenum. For a long time, E. praecox was considered to be a non-pathogenic strain. After the studies by Williams et al. (2009), the pathogenicity of E. praecox was demonstrated. There are two facts to consider with regard to the damage caused by E. praecox in coccidiosis in chickens:

On the one hand, praecox causes microscopic damage in the cells of the duodenum. In infections with E. praecox oocysts (106) it is possible to see villus atrophy, crypt hyperplasia and increased leukocyte infiltration.
On the other hand, praecox modifies the viscosity of the liquids in the duodenum. In infections with E. praecox an increase in whitish mucus and non-digested feed is observed.

Finally, in other studies carried out by Répétant et al. 2011, the impact of the infection caused by E. praecox was related to the infective dose but its impact on performance was present from the lowest dose of 5,000 oocysts/bird when it was co-administered with E. acervulina.

After all these arguments it seems of great importance to include Eimeria praecox as a target in the fight against coccidiosis in chickens in fattening birds where the integrity of the duodenum is a must. This is the reason why in the design of the composition of HIPRACOX® it was decided to include E. praecox together with E. mitis to protect against the effects of subclinical coccidiosis in chickens.

The Eimeria species responsible for coccidiosis in broiler chickens

The Eimeria species responsible for coccidiosis in the species Gallus gallus are: E. acervulina, E. maxima, E. mitis, E. praecox and E. tenella, which are responsible for the disease in short life-cycle poultry (broilers), and E. necatrix and E. brunetti, which, together with the above 5 species, are responsible for the occurrence of outbreaks in long life-cycle poultry (breeders and layers). They are all ubiquitous in their behaviour and vary in their pathogenicity.

There are seven Eimeria species that are responsible for avian coccidiosis, 5 of which cause the disease in broilers: E. acervulina, E. mitis, E. tenella, E. maxima and E. praecox.

There are two more strains of Eimeria that are not recognised as causing the disease. These are: E. hagani, the only description of which was by Levine P.P. in 1938; and E. mivati, a species found in a vaccine in the USA which appears to be a mixture of other Eimeria, E. mitis and E. acervulina (M. W. Shirley et al. 1983).
Focussing on the species that are really important in the generation of the disease in broilers, we need to know exactly which species cause most damage and how they interact by generating synergies between one another, thereby causing greater damage within the host. E. acervulina, E. maxima, E. tenella, E. mitis and E. praecox are the main species that cause avian coccidiosis in broilers. They can all be found along the intestine of poultry, affecting different areas and causing different lesions depending on the species concerned.
Focussing on E. acervulina, E. maxima, E. tenella, E. mitis and E. praecox, the species that are responsible for avian coccidiosis in broilers, we need to know the lesions they cause and their behaviour and distribution within the gastrointestinal tract of chickens. Below is a video giving details of the different species of Eimeria that affect the gastrointestinal tract of poultry.
For the development of vaccine strains, the Eimeria species have to be attenuated. There are three methods of doing this: passage through embryonated eggs, gamma irradiation and selection for precociousness. When they are selected by passage through embryonated eggs and by gamma irradiation, this is generally associated with a loss of immunity by the line and therefore stable attenuation is not maintained (Shirley M.W et al. 1984). The best method shown so far is selection for precociousness developed by Jeffers (1975). during the nineteen seventies. The method is based primarily on the reduction of the reproductive potential of the strain, resulting in attenuation of the virulence, maintenance of the immunogenicity and genetically controlled stability.
When the appropriate method of attenuating the Eimeria species has been identified, we need to know which species will be necessary for development of the vaccine. E. acervulina, E. maxima and E. tenella are well known as the pathogens responsible for the disease and are included in the great majority of existing commercial vaccines, but this is not the case with E. mitis and E. praecox, which have been regarded as species of “less importance” in the field.
In his study on the pathogenesis of Eimeria praecox in broilers, R.B. Williams et al. (2009) demonstrated the importance of E. praecox as a pathogenic strain in itself. In this study, it was compared with E. acervulina and it was observed that the lesions caused by E. acervulina were macroscopic and severe, but did not last for more than 14 days post-infection. In contrast, in the case of E. praecox, the lesions were microscopic and caused a reduction in the viscosity of the intestinal content. In other studies such as those carried out by J.M. Répérant et al. 2011, the impact of the infection caused by E. praecox was related to the infective dose but its impact in performances was present from the lowest dose of 5000 oocysts/bird. When it was co-administered with E. acervulina, it caused a greater impact on production indices.
Furthermore, the selection of strains within an Eimeria species is essential in order to obtain good protection, thus conferring cross-protection within each species, as is the case with the vaccine strain E. maxima 013, which is able to provide protection against 6 different pathogenic strains of E. maxima obtained from different geographic locations.
It is essential to find out about the epidemiological behaviour of the Eimeria oocysts in order to understand how the vaccine strains will behave and what vaccine load will be necessary in order to produce an appropriate vaccine response. Generally, the oocysts that are found in the bedding can persist for up to 3 weeks (Williams R.B. 1995), with sporulation being better with a moisture content of the litter from 31 to 62.1%. Whether or not they are sporulated, 20% are ingested by the chickens and pass through their intestines. As immunity is generated within the flock, the percentage of oocysts eliminated is reduced with each life cycle of the parasite. Hence the necessity of determining accurately the volume of oocysts necessary for each vaccine strain, in order to ensure an appropriate response to the vaccine.
In order to confer immunity against all the Eimeria species that are present in the environment, all the Eimeria vaccine strains need to be included as there is no cross-protection between the different species, hence the necessity of formulating a vaccine with the 5 Eimeria species when the target category is represented by broilers.
With all this tested knowledge, HIPRA, a specialist in avian coccidiosis, has developed the HIPRACOX® vaccine, the only vaccine specially developed for short life-cycle poultry, containing in its formulation all the Eimeria species responsible for avian coccidiosis in broiler chickens.

Eimeria tenella is probably the most diagnosed Eimeria on the planet, but what is the prevalence of the other Eimeria species that cause coccidiosis in poultry?

Eimeria tenella is by far the most widely detected species on farms when routine lesion scoring is performed. However, it is well known that Eimeria infections very seldom occur with one single species of Eimeria, most of the time they are multiple. Let’s investigate what are the most prevalent species and how multiple infections usually occur.

As Eimeria tenella is probably the easiest species to detect by lesion scoring, a common belief is that this species is the most prevalent all over the globe. In fact, macroscopic lesions are amongst the most pathognomonic with blood or typical moulds in the caecum and common finding of bloody droppings in the litter.

There are seven species of Eimeria recognized as parasitizing chickens (Gallus gallus), which vary in their ability to induce diarrhoea, morbidity and mortality (Williams 1998). They are Eimeria tenella, Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix and Eimeria praecox. They occur throughout the world wherever commercial broilers are reared. All seven species of Eimeria infecting chickens were detected in surveys of commercial poultry farms in many countries, for example, the Czech Republic (Kučera 1990), France (Williams et al. 1996), Sweden (Thebo et al. 1998), the UK (Eckert et al. 1995), Argentina (Mcdougald et al. 1997; Mattiello et al. 2000), Australia (Jorgensen et al. 1997; Morris et al. 2007), China (Sun et al. 2009), India (Aarthi et al. 2010), South Korea (Lee et al. 2010) and Brazil (Moraes et al. 2015).
Like Eimeria tenella that is localized in the caecum, the different Eimeria species tend to develop in different parts of the chicken gut and may be identified by the nature and location of the lesions they cause during multiplication (Long et al. 1976, Long et al. 1982). However, a definitive diagnosis requires additional laboratory investigations. Nowadays, polymerase chain reaction (PCR) and morphometric identification of the Eimeria species are frequently used together as a means of differentiation in the field samples of faeces and litter.
In Europe, few field surveys of Eimeria species are available and even fewer have been conducted using samples from broiler farms. In a study conducted by HIPRA (Pagès et al. 2015), litter samples obtained from broiler farms between 2003 and 2008 in Spain, Belgium, Italy and France were evaluated for the presence of Eimeria species. Samples of litter faeces from each farm were pooled from 10 different random locations within a single broiler house on each farm. In fact, the species composition of coccidial populations is highly repeatable among different broiler houses on the same farm (Jeffers 1974). The evaluation was performed using a polymerase chain reaction (PCR) developed at the Institute for Animal Health (Compton, UK) to specifically detect E. tenella, E. acervulina, E. maxima, E. mitis and E. praecox. Together with this molecular tool for detecting Eimeria species in litter samples, oocyst counts and the evaluation of the percentage of species by using a morphometry test were also performed to further evaluate the samples.
We decided only to look for the five species of Eimeria that usually affect commercial broiler farms -Eimeria tenella, Eimeria acervulina, Eimeria maxima, Eimeria mitis, and Eimeria praecox- due to the fact that E. necatrix has been reported to cause disease in long-lived birds -up to 12 weeks or more- (Williams et al. 1996, Williams 1998) and similarly E. brunetti is often reported to be rare in broilers (Long et al. 1982, Williams et al. 1996, Graat et al. 1998).
Analyzing the 3 species of Eimeria of known and high pathogenic potential (Eimeria tenella, E. acervulina and E. maxima), Eimeria acervulina has been shown to be the most widespread in the four European countries studied, whereas between the two species causing subclinical problems and affecting productivity: E. mitis seems to be quite uncommon, whereas E. praecox was shown to be present in all countries. Combinations of 3 species together were the most common especially: E. tenella, E. acervulina, and E. praecox. E. praecox was found to be highly associated with E. acervulina.

Similar to the study conducted in Europe and using the same techniques of evaluation of the samples, in 2012 HIPRA also performed the first Eimeria spp. prevalence study in South Africa (Pagès et al. 2015)

Analyzing the 3 species of Eimeria of known and highly pathogenic potential (Eimeria tenella E. acervulina and E. maxima) Eimeria acervulina was shown to be the most widespread in South Africa (40.5%), whereas regarding the 2 species that cause subclinical problems and affect flock productivity: E. mitis was less prevalent (7.1%) then E. praecox (9.5%). Combinations of 2 species together were the most common especially: E. acervulina + E. tenella and E. acervulina + E. maxima.
Once again these studies showed the widespread presence of Eimeria praecox and thus of subclinical coccidiosis that “remains one of the most important infections causing decline in production performances” (Haug et al. 2008).
Finally, these results confirmed that the most prevalent species of Eimeria by far is E. acervulina, in contrast with the field perception that most of the time coccidiosis is only caused by E. tenella.

What is a correct way to choose a PRRS sow vaccination program? When PRRS vaccination of piglets is needed?

Answered by: Enric Marco

Piglet vaccination is usually done when we would like to reduce PRRS virus circulation on the growing phase. Vaccine will reduce the amount of PRRS virus shed by viremic animals and also will reduce duration of shedding. Those reductions are not spectacular but can help to control the PRRS virus circulation.
Sow PRRS vaccination is used in two ways. The first one is to bring back to normality the farm after an outbreak; the second one is to help the farm to maintain stability by avoiding PRRS virus recirculation among sows which will produce viremic piglets.
By vaccinating sows, immunity will be higher and more stable helping to reduce subpopulations of sows which we know are the responsible for on farm virus recirculation.

Eimeria praecox: a brief story of the big unknown of coccidiosis in poultry

Seven species of Eimeria (E. acervulina, E. brunetti, E. maxima, E. mitis, E. necatrix, E. praecox and E. tenella) are recognized to be causative agents of coccidiosis in chickens of the genus Gallus gallus. Until recently, Eimeria praecox was considered to be a non-pathogenic species unable to cause adverse effects in the host. Read more

In fact, in 1970, when Johnson & Reid wrote the milestone article that for the first time standardized and described the scoring scale for lesions caused by all Eimeria spp., Eimeria praecox was not included. It was, and still is, well know that E. praecox is not able to provoke pathognomonic lesions like E. acervulina, E. brunetti, E. maxima, E. necatrix and E. tenella, however even then some researchers were investigating whether this species of Eimeria was truly non-pathogenic.

Peter L. Long in 1968, attempted to demonstrate the adverse effects of Eimeria praecox on the host and for this purpose he compared its effects with those of Eimeria acervulina. His conclusions were that even if E. praecox was less pathogenic than E. acervulina, high doses of oocysts of E. praecox depressed the rate of weight gain and food and water consumption.
Some years later, in 1982, Gore and Long reported that mortality and morbidity are not characteristics associated with Eimeria praecox, however in their studies it was shown to interfere with digestion and consequently cause significantly retarded weight gain. It was the first time that E. praecox was recognized to be economically significant and thus could no longer be considered non-pathogenic.
At the same time, the first prevalence studies were performed and the general outcomes for Eimeria praecox prevalence were quite surprising: this species was shown to be present in many countries all over the globe and with percentages that were far from what was considered to be negligible. See table here. 

From 2003 to 2008 HIPRA also performed several prevalence studies in Europe -namely in Spain, Belgium, Italy and France- and the widespread presence of Eimeria praecox was also confirmed by these (Pagès et al. 2015). 

In 2012 HIPRA performed the first study of Eimeria spp. prevalence in South Africa (Pagès et al. 2015) and there, too, E. praecox was found to be present on 9.5% of farms.
Further confirmation that Eimeria praecox can exhibit a wider range of virulence than previously thought, came in 2009 from a study conducted by Willians et al. where it was observed for the first time that E. praecox was able to cause actual body weight loss and market increases in FCR, as did E. acervulina. Also for the first time, it was observed that the virulence of E. praecox may not only be equal to but may exceed that of E. acervulina.

In the field, single Eimeria species infections are quite rare and most of the time infections involve multiple species. Since Eimeria praecox replicates in the same tract of the gut as E. acervulina -the duodenum- and both impact early in the production cycle, one of the aspects to be investigated was whether during a co-infection with these two species either a competitive exclusion or a synergic effect took place. In 2012, Répérant et al. found that when E. praecox -even with a low infective dose- is inoculated together with E. acervulina, its negative effect on growth was added to the latter and significantly increased compared to a single E. acervulina infection.
Nowadays it is quite clear that Eimeria praecox constitutes one of the major causes of subclinical coccidiosis with repercussions on the productive performances and due to its early impact in the cycle, it is especially important in broiler meat productions where the first weeks are crucial for the overall performance of the birds. It is therefore worth taking into account this species of Eimeria in prophylactic approach to fully protect poultry.
HIPRACOX® was the first attenuated vaccine for coccidiosis in broilers that took this aspect into consideration by also including E. praecox in its composition.

Coccidiosis in poultry: an objective assessment of the incorporation of a rotation programme using precocious attenuated vaccines

Within the scope of assessing new strategies for the control of coccidiosis in poultry, the first factors to consider are always immunological and physiological but also include less objective factors such as the management. However, when these new strategies come to be assessed, the exercise has to be carried out in perspective by evaluating those indicators that are the most critical in order to decide whether maintaining such strategies or to replacing them with others. In the production of broiler chickens, these indicators are solely productive.

Live precocious attenuated vaccines for coccidiosis in poultry like HIPRACOX® have been used in numerous countries and situations, and these experiences serve to support the implementation of vaccine rotation programmes for the control of coccidiosis in poultry.

Over the past 10 years, experiences in the field have provided data regarding this cost/benefit ratio, derived from the use of rotation programmes with precocious attenuated vaccines, such as HIPRACOX®. Having vaccinated several million birds in different circumstances throughout the world, these experiences have enabled us to draw various conclusions.
Minor intestinal injuries
Reduction of the total mean lesion score (TMLS), according to the Johnson and Reid method (1970) for coccidiosis in poultry, in vaccinated and post-vaccination cycles compared to pre-vaccination cycles (Dardi et al. 2015, see image above).
Improvements in production indicators
Production results improved during the vaccination phases and in subsequent cycles where the use of anticoccidial drugs was reincorporated, both in winter vaccine cycles in Spain (Alameda et al. 2015) and in central European farms during the summer (Ronsmans et al. 2015):

Cost-benefit assessment

Production costs per 1,000 kg were reduced, as a result of the birds’ improved performance.

(Alameda et al. 2015) showed that production cost (euros/1,000 kg live weight) was always below average (€923) in the months with vaccination cycles (CDV) compare with previous cycles with anticoccidial drugs (CAV). From the first cycle, there was a positive trend that persisted in all subsequent cycles (CPV). The cost included the value of the vaccine given on the first day of life by coarse spray.

Using precocious attenuated vaccines such as HIPRACOX® against coccidiosis in poultry provides several advantages over traditional programmes based solely on control through the use of anticoccidial drugs. Aimed at broiler chickens in particular, this control strategy is being used in several companies across different countries with optimum results. Ultimately, it has proven a simple tool for reducing the use of antibiotics, as indicated by the major producing countries.