The fourth session of the 32nd International Biovet Symposium , held on May 27-28 at the Chamber of Commerce of Tarragona, focused on common pathologies in the fields of poultry and aquaculture.

The first conference reviewed the 14 most prevalent diseases in poultry production , followed by a conference focused on the most frequent diseases in salmon farming . The session was complemented by another conference dedicated to the most important zoonoses in poultry production , and then it closed up with an informative conference on European legislation related to the management of poultry farms from the perspective of the regional government of Catalonia.

The top 14 worldwide avian pathology

Dr. Júlia Pié from Biovet SA began her conference with a theoretical introduction on the basic principles of forensic veterinary medicine, and then went on to listing some pathologies that currently have the greatest impact on the poultry industry worldwide.

Of all the pathologies discussed during the conference, Dr. Pie went particularly in depth onto coccidiosis , necrotic enteritis , infectious toxic hepatoenteritis and infections caused by Shigella :

Coccidiosis and necrotic enteritis

The clinical coccidiosis in poultry is caused by a protozoa of the Eimeria type and the main consequences are stunting, poor feed conversion and mortality, amongst others . Lesions caused by this digestive parasitosis, if not controlled in time, can trigger other infectious processes such as necrotic enteritis , caused by toxins produced by Clostridium perfringens .

Avian Toxic Hepatoenteritis

The avian toxic hepatoenteritis affects chicks and chickens and can cause injuries to a large number of vital organs. It is usually related to vitellum contamination by SH2 enterobacteria, especially Salmonella , Pseudomona and Proteus . The toxins produced by this infection can poison the liver, also affecting other limbs such as the intestine, the gizzard and the cornea layer due to the regurgitation of fluids coming from the vitellum.

Some of the most common physical symptoms related to toxic avian hepatoenteritis are usually weight loss, unilateral lameness in chicks or crest involution in adult chickens, among others.

Shigella infection

Shigella sp . is an enterobacteria usually transmitted by oral infection due to faecal contamination, mainly through drinking water. Shigella infection may develop into hepatitis involving multiple focal necrosis. Shigella infection is vertically transmitted through the vitellum. Like Salmonella, Shigella has a tendency to form thoracic nodules. However, unlike Salmonella, Shigella nodules tend to appear on the chest wall.

This infection is considered emergent in America and Asia, and can trigger episodes of enteritis and in the bile ducts – white dots. It is important to establish prevention methods from an early age with the use of intestinal biocides. Treatment in adult breeders and layers must be carried out by the use of antibiotics that perform an enterohepatic cycle, such as beta-lactams and quinolones.

Predisposing factors

Dr. Pié concluded her talk by stating that most infectious agents require  the presence of some predisposing factors to cause a disease, since they tend not to be pathogens originally by themselves. Most frequent predisposing factors can be grouped into 5 groups : the presence of mycotoxins; poor hygiene in feed; biotin deficiency; enzymatic deficiency; and lack of pronutrients .

Review on pathologies affecting Atlantic salmon farming

Fiona Groves, coordinator of regulatory compliance at Pontus Research Ltd. in the UK , led the second conference of the session with a summary of diseases of high importance in aquaculture . Specifically, Groves delved into a total of 18 frequent and emerging viral, bacterial and parasitic pathologies in the Atlantic salmon production around the world.

By introducing the attendees into the topic, Groves stated that world production of farmed Atlantic salmon will reach 2.5 million tons in 2019. However, the overall impact of pathologies in this species is causing losses of nearly USD 6,000 million per year to this sector, being the main restricting factor for further industry expansion.

Viral pathologies

Amongst the main viral diseases with available treatment exposed by Groves, there was Pancreas Disease (PD) with high presence in Norway affects salmon growth, increases feed conversion rate and can cause high mortality . Although vaccines are available for its treatment, their effectiveness has been questioned. Another of the diseases highlighted was Infectious Pancreatic Necrosis (IPN) , for which the vaccines developed have shown a greater degree of effectiveness.  Also Infectious Salmon Anaemia (ISA)  for which there is a vaccine available in Chile, where it has caused significant losses but it is not available to farmed fish producers in the European Union.

Amongst the viral diseases for which vaccines have not yet been developed, Groves highlighted Infectious Hematopoietic Necrosis (IHN). There is no available treatment beyond biosecurity prevention methods such as broodstock eggs’ disinfection. Another of the diseases that have no vaccine is the Heart and Skeletal Muscle Inflammation (HSMI), which is often related to stress periods. Its prevalence is currently on the rise within fish farms around the world and accounts for the third most common viral disease Norway.

Bacterial pathologies

Bacterial diseases found in Atlantic salmon that currently have some form of treatment, either antibiotic or via vaccination, are vibriosis , cold water vibriosis and furunculosis. There are vaccines available generally delivering positive outcomes . Cases of  Enteric Redmouth (ERM)  have proved to be particularly serious in the past in countries such as Australia. There are vaccines and antibiotic treatments on the market, although the latter has shown cases of resistance.

The Salmon Rickettsial Disease (SRD) , with high prevalence in producing countries such as Chile and causing up to 90% of mortality within infected specimens, have inactivated and adjuvanted injectable vaccines on the market, although attenuated vaccines  are still not available.  Winter Ulcer Disease is another of the pathologies with a high degree of incidence, especially due to its difficult detection and the limited effect of its vaccination and antibiotic treatments.  It is one of the pathologies that generate higher economic losses in fish farms around the world .

Bacterial Kidney Disease (BKD) was highlighted by Groves as it currently has no effective treatment compared to the aforementioned bacterial diseases . It can be transmitted both vertically and horizontally and its systemic infection causes a chronic disease on the infected specimens.

Parasitic pathologies

Regarding parasitic pathologies Groves highlighted Amoebic Gill Disease (AGD), which is more prevalent within fingerlings and young individuals. The causative parasite (Neoparamoeba perurans protozoa) can survive in dead fish, sediments and cages. Serious outbreaks have been reported in fish farms in Ireland, Scotland and Norway between 2011 and 2013, although there are treatments available in the market.

Another of the disease with great prevalence and generating important economic losses worldwide is caused by sea ​​lice . In Norway alone, losses in 2011 were around of USD 436 million. The two main parasite species of this type specific to salmonids are Lepeophtheirus salmonis and Caligus elongatus. The infection occurs in seawater stages and  there is no vaccine against this pathology, although there are numerous feed treatments and pharmaceutical baths.

The Proliferative Kidney Disease (PKD) has no specific treatment nowadays. However, predictions of potential future vaccines have been made given the resistance developed by the surviving specimens. Research is also underway for future vaccines to combat White Spot Disease in Salmon (ICH) , which usually occurs in freshwater stages and is significantly important because of its incidence worldwide.

Finally, Groves explained how the Gyrodatylus parasite adheres to Atlantic salmon and rainbow trout specimens and feeds on its skin, blood and mucus. The digestive solution that it secretes causes damage to the epidermis, thus being a potential source for other infections. Cases have been reported with up to 95% mortality. A specific treatment is not yet available, although it has this parasite has shown limited sensitivity to formalin.

Most important zoonoses in poultry: regulatory mechanisms in Argentina

Dr. Roberto Minetti , representative of the National Health and Food Quality Service of Argentina (SENASA), gave a talk focused on the most common diseases in poultry production. He firstly introduced his presentation with a theoretical approach to emerging and re-emerging diseases, and their causative agents: viruses, bacteria, parasites and fungi. A few examples were given when introducing direct transmission viral diseases, such as avian influenza; diseases vector-transmitted viral diseases , such as West Nile encephalitis; bacterial-transmitted diseases , such as salmonellosis and campilobacteriosis , among others.

Subsequently, viruses’ mechanism of adaptation was introduced with an example of mutation, rearrangement and re – emergence processes experienced by the Spanish Flu strain. It was subsequently followed by an approach to the  mechanisms of bacterial resistance to antibiotics. Finally, the SENASA’s regulatory mechanisms concerning the avian health were introduced.

Management of poultry farms: regulatory framework in the European Union

The closing conference of the fourth and final session of the International Biovet Symposium 2019 came from the hand of Mrs. Montse Álamos , head of the Livestock Management Service of the Department of Agriculture, Livestock, Fishing and Food of the regional government of Catalonia. In an introductory way, the talk introduced the regulatory framework of the European Union applied to both Spanish and Catalonia. In parallel, data and graphics about European state members’ poultry meat and egg were shown.

Next, Mrs. Álamos introduced the regulatory framework in force in Europe in relation to the specifications of production holdings for self-consumption and industrial production. Moreover, , legislative specifications on different poultry breeding methods – caged, on floor, free range and organic production – and current regulations on biosecurity, animal health and welfare, environmental pollution and marketing regulations.

Subsequently , the content of the talk began to focus on conventional and alternative meat and egg production systems , from which the general requirements and standards were introduced in aspects such as the types of feed to be used, drinking water accessibility, bed, room availability, noise and lighting standards, cleaning and disinfection measures, as well as monitoring and data recording.

Finally, with regard to alternative production systems , Mrs. Álamos provided relevant data on regulatory and labelling standards in the extensive free range breeding methods.