European perspectives on the control and Eradication of some poultry diseases

Infectious diseases of poultry are mostly associated with severe economic losses. Many of these diseases once re-emerging or introduced into a geographic area can explode into an epidemic and may have a significant negative effect on international trade. Beside general control approaches like biosecurity, improvement of rearing management, monitoring, and vaccination several governmental measures on control of poultry diseases were adopted in European countries.

Eradication policy and killing of animals for disease control purposes are commonly applied in cases of suspicion or confirmed outbreaks of emergency diseases, outbreaks of diseases with a considerable public health and/or economic impact and in case of possible irregularities during the intra-community trade of live animals and their products.

The List A of the Office of International Epizooties (OIE) including diseases of signifying rapidly spreading diseases of major economic importance, such as highly pathogenic Avian Influenza (AI) and Newcastle Disease (ND). The EU legislation to control avian influenza is laid down in Council Directive 2005/94/EC (EC, 2005a). For the Newcastle disease the Council Directive 92/66/EEC (EEC, 1992) introducing Community measures for the control of Newcastle disease is laid down. In addition, the European Union adopted a Council Regulation 2160/2003/EC (EC, 2003) on the control of salmonella and other specified food-borne zoonotic agents. There are also a number of Council Directives covering the control of diseases such as: Directive 82/894/EEC on the notification of animal diseases within the Community (EEC, 1982); Directive 90/425/EEC concerning veterinary and zootechnical checks applicable to intra-Community trade in certain live animals and products with a view to the completion of the internal market (EEC, 1990)

The aim of this paper is to describe the regulations related to control of the above mentioned diseases and /or infections.

Avian influenza

Avian influenza (AI) caused by influenza A viruses is a disease of many kinds of poultry, wild and cage birds characterised by marked variation in morbidity, mortality, signs and lesions. In addition, the infection causes periodically epidemics in humans, horses, pigs, seals, whales, and variety of birds (Swayne et al., 2013).

According to the European Union legislation “Council Directive 2005/94/EC Avian influenza means an infection of poultry caused by any influenza A virus which has an intravenous pathogenicity index in six-week-old chickens greater than 1.2 or any infection with influenza A viruses of H5 or H7 subtype for which nucleotide sequencing has demonstrated the presence of multiple basic amino acids at the cleavage site of the haemagglutinin.

All suspected cases of AI in domestic poultry and captive birds must be investigated and appropriate measures taken in case of confirmation of both Low and High Pathogenic Avian Influenza. To limit the spread, infected poultry must be killed in a humane way and disposed of safely. The poultry which have died or been killed and all eggs shall be destroyed. Any substance such as animal feed, litter or manures liable to be contaminated, shall be destroyed or treated to render the virus inactive. In addition, the competent authority should establish a protection zone based on a minimum radius of three kilometres around the infected holding, itself contained in a surveillance zone based on a minimum radius of 10 kilometres. The establishment of the zones must take in account the geographical, administrative, ecological and epizootiological factors relating to avian influenza, and of monitoring facilities.

The Council Directive 2005/94/EC on control of Avian Influenza allows emergency vaccination as a short term measure to respond to a disease outbreak. As a new tool the revised Directive now also gives the possibility to use preventive vaccination. This long term measure can be used by Member States that based on a risk assessment identify certain areas, poultry categories or their husbandry systems (e.g. free range) as being at a particular risk for virus introduction. Vaccinated birds may still become infected by the virus. They must therefore be monitored closely to detect virus infection. Vaccination plans must follow a DIVA strategy which allows Differentiating between Infected and Vaccinated Animals. The DIVA strategy is important to keep the virus from spreading from vaccinated birds to other animals. It also ensures safe trade of products from vaccinated birds. Vaccination plans must be formally approved by a Decision.

Newcastle disease

Newcastle disease (ND) is a viral disease of many species of poultry characterised by marked variation in morbidity, mortality, signs and lesions. Newcastle disease of poultry is ranked as the major virus disease of poultry in many countries worldwide and it is extremely difficult to assess the prevalence of ND in the world. In developed countries with established poultry industries, outbreaks with very virulent ND are not only extremely costly, but also other control measures, including vaccination are additional costs (Alexander, 2003).

According to Council Directive 92/66/EEC „Newcastle disease“ means infection of poultry caused by any avian strain of paramyxovirus 1 with an intra-cerebral pathogenicity index (ICPI) in day - old chicks, greater than 0.7. According to the above mentioned directive infected poultry means any poultry in which the presence of Newcastle disease has been officially confirmed following an examination by an approved laboratory, or in the case of second and subsequent outbreaks in which clinical symptoms or post-mortem lesions consistent with Newcastle disease are present. Once the presence of Newcastle disease in poultry has been officially confirmed on a holding, the Member States shall ensure that all poultry on the holding shall without delay be killed on the spot. The poultry which have died or been killed and all eggs shall be destroyed. These operations shall be carried out in a way which minimizes the risk of spreading disease; any substance or waste, such as animal feed, litter or manures liable to be contaminated, shall be destroyed or treated appropriately. This treatment, carried out in accordance with the instructions of the official veterinarian, shall ensure the destruction of any Newcastle-disease virus present.

Further measures are similar to that for avian influenza. After the confirmation of Newcastle disease, the competent authority shall establish a protection zone (based on a minimum radius of three kilometres around the infected holding) and a surveillance zone (based on a minimum radius of 10 kilometers around the infected holding), in which specific measures apply. These measures include, amongst others, the identification of all holdings keeping poultry, periodic visits, clinical examinations and isolating animals.

In addition, Member States shall ensure that (a) vaccination against Newcastle disease with vaccines authorized by the competent authority may be used for a prophylactic purpose or to supplement the control measures carried out when the disease appears; (b) the only vaccines allowed are those which have received a marketing authorization from the competent authority of the Member State in which the vaccine is used.

Salmonella

Salmonellosis and salmonella infections in poultry are distributed world-wide and result in severe economic losses when no effort is made to control them. The large economic losses are caused by high mortality during the first four weeks of age, high medication costs, reductions in egg production in breeder flocks, poor chick’s quality and high costs for eradication and control measures. The most important aspect, however, is the continuing effect of salmonella contaminated eggs, poultry meat and meat-products on public health (Hafez, 1999).

In November 2003, the European Parliament Council Regulation 2160/2003/EC (EC, 2003) on the control of salmonella and other specified food-borne zoonotic agents was passed. This regulation covers the adoption of targets for the reduction of the prevalence of specified zoonoses in animal populations at the level of primary production, including meat turkey. After the relevant control programme has been approved, food business operators must have samples taken and analysed for the zoonoses and zoonotic agents. The flocks should be sampled also by the competent authority.

In June 2005 Commission Regulation No 1003/2005/EC (EC, 2005b) implementing Regulation (EC) No 2160/2003 as regards a Community target for the reduction of the prevalence of certain salmonella serotypes in breeding flocks of Gallus gallus and amending Regulation (EC) No 2160/2003 was put into force. The Community target is the reduction of the maximum percentage of adult breeding flocks comprising at least 250 birds remaining positive for S. Enteritidis, S. Hadar, S. Infantis, S. Typhimurium and S. Virchow in breeding flocks of Gallus gallus to 1 % or less by 31 December 2009. The testing scheme to verify the achievement of the Community target is set out in the Annex. This includes Monitoring by sampling at the initiative of the operator and official control sampling (EC, 2005b).

If results of examined samples indicate the presence of S. Enteritidis or S. Typhimurium in a breeding flock of Gallus gallus, non-incubated eggs from the flock must be destroyed. However, such eggs may be used for human consumption, if they are treated in a manner that guarantees the elimination of S. Enteritidis and S. Typhimurium in accordance with Community legislation on food hygiene. All birds, including day-old chicks, in the flock must be destroyed or slaughtered. Slaughtering must be carried out in accordance with Community legislation on food hygiene. If not destined for human consumption, such products must be used or disposed of in accordance with Regulation No 1774/2002 of the European Parliament and of the Council of 3 October 2002 laying down health rules concerning animal by-products not intended for human consumption. Where eggs for hatching from flocks in which Salmonella Enteritidis or Salmonella Typhimurium is present are still present in a hatchery, they must be destroyed or treated in accordance with Regulation No 1774/2002 (EC, 2002).

From 2010 fresh poultry meat may not be placed on the market for human consumption when Salmonella was detected. The criterion laid down does not apply to fresh poultry meat destined for industrial heat treatment or another treatment to eliminate salmonella in accordance with Community legislation on food hygiene (EC, 2003).

Conclusions

In general the major strategy to control infectious diseases include cleaning the production chain from the top in case of vertically transmitted diseases, hygienic measures throughout the production chain, vaccination, therapy, education programs, and eradication. The reason for using killing instead of slaughtering is to avoid the spread of the infectious agents in the live animals and their products and must be carried out as soon as and as safely as possible.

In all cases agent surveillance and monitoring programmes must be adapted and followed strictly in aim to allow early intervention. In addition, since the success of any disease control program depends on the farm and personal sanitation, it is essential to incorporate education programs about microorganisms, modes of transmission as well as awareness of the reasons behind such control programs by people involved in poultry production. Finally, research must continue to find additional control and preventive means (Hafez, 2005).

References

ALEXANDER D.J. (2003) Newcastle disease, other avian paramyxoviruses, and Pneumovirus Infections. In: Diseases of Poultry,11th Ed. Saif, Y.M., H.J. Barnes, J.R. Glisson, A.M. Fadly, L.R., McDougald, D.E. Swayne, (Eds.). Ames, Iowa State Press a Blackwell Publishing company. pp. 63-87.

EC (2002) Regulation (EC) No 1774/2002 of the European Parliament and of the Council of 3 October 2002 laying down health rules concerning animal by-products not intended for human consumption. Official Journal of the European Commission L 273: 1-95.

EC (2003) Regulation (EC) No 2160/2003 of the European Parliament and of the Council of 17 November 2003 on the control of salmonella and other specified foodborne pathogenes. Official Journal of the European Commission. L 325: 1-15.

EC (2005a) Council Directive 2005/94/EC of 20 December 2005on Community measures for the control of avian influenza and repealing Directive 92/40/EEC. Official Journal of the European Commission. L 10: 16-62.

EC (2005b) Regulation (EC) No 1003/2005 of 30 June 2005 implementing Regulation (EC) No 2160/2003 as regards a Community target for the reduction of the prevalence of certain salmonella serotypes in breeding flocks of Gallus gallus and amending Regulation (EC) No 2160/2003. Official Journal of the European Commission L 170:12-17.

EEC (1982) Directive 82/894/EEC of 21 December 1982 on the notification of animal diseases within the Community. Official Journal of the European Commission. L 378: 58 - 62.

EEC (1990) Council Directive 90/425/EEC of 26 June 1990 concerning veterinary and zootechnical checks applicable in intra-Community trade in certain live animals and products with a view to the completion of the internal market. Official Journal of the European Commission. L 224: 29-41.

EEC (1992) Council Directive 92/40/EEC of 14 July 1992 introducing Community measures for the control of Newcastle disease. Official Journal of the European Commission. L 260: 1-20.

HAFEZ, H.M. (1999) Poultry meat and food safety: pre- and post-harvest approaches to reduce food borne pathogens. World’s Poultry Science Journal 55: 269-280.

HAFEZ, H.M. (2005) Governmental regulations and concept behind eradication and control of some important poultry diseases. World’s Poultry Science Journal 61: 569-582.

SWAYNE, D.E. Suarez, D.L. and Sims, L.D. (2013) Influenza.In: Diseases of Poultry, 13th Ed. Swayne, D.E., J.R. Glisson, L.R., McDougald, L.K. Nolan, D.L. Suarez and V. Nair (Eds.). Wiley- Blackwell -AAAP. pp. 181-218.