Whereas early organic farming was mainly focused on plant production, in the last decade, the number of organically-managed poultry farms within the European Union has increased significantly. Similar to organic crop production, organic animal farming is based on the same principles: welfare-friendly, sustainable production and resource utilisation without or with very little addition of synthetic substances, such as antibiotics and antiparasitic treatments. These practices, as well as the access to wild animals, make the free-range poultry production systems predisposed to different viral diseases and, thus, associated with potentially higher public health risks or reduction in production quality. On the other hand, intensive farming amplifies the impact of viral diseases due to high density, low genetic diversity and elevated immunodeficiency. The aim of this analytical study is to compare free-range with intensive poultry systems and the occurrence of different viral diseases in these types of farms in the EU over the past decade. The research is based on official data from the statistical office of the European Union, as well as official data from the Member countries. The results were similar in each country and demonstrate that free-range production has a higher incidence of viral diseases with high zoonotical potential. This makes year-round surveillance absolutely necessary, as well as the need for implementation of additional criteria and requirements towards free-range systems.

European Union, farming systems, free-range poultry, intensive farming, meat production

In recent years, we have observed the characteristics, defined by Armelagos et al., of the Third transitional period in infectious diseases (Armelagos et al. 1991). This transitional period is characterised by the re-emergence of pathogens already considered eradicated or under control, as well as new pathogens (for example: HIV, SARS, MERS, SARS-CoV-2) and increasing antibiotic resistance. In addition to the recurrence of these viral diseases, some of them have significantly increased virulence (Barrett et al. 1998). According to other studies, human intervention and, in particular, the effects on the environment as a result of modern agricultural practices, are crucial for the emergence of these phenomena (Lebarbenchon et al. 2008).

The present study aims to trace the situation in the European Union with regard to the various poultry farming systems – both traditional and organic. Wild birds as a vector of viral diseases are also considered as a factor.

Demand for products produced by organic farmers has grown significantly over the last decade. The Council of the European Union defines organic farming as a system of food management and production that combines best practices in terms of environmental protection, high degree of biodiversity, protection of natural resources, application of high standards of animal welfare and a production method tailored to the preferences of some consumers for products produced using natural substances and processes (EC 2007).

On the other hand, intensive poultry farming, with a high density of animals in confined spaces, is a system with conditions significantly different from those of organic farming and wild birds. At the same time, the use of a number of drugs and modern vaccines in intensive care systems aims to protect animals from a number of pathogenic factors. In organic systems, significantly limited drug use would be a factor for allowing the easy spread of pathogens amongst herds, which, on the other hand, would be limited by significantly lower stocking densities compared to intensive systems. The introduction of specific requirements for organic production in terms of cultivation methods - regular control of certain infectious diseases, the requirement for indoor feeding etc. – is successful in terms of protection against a number of bacterial and parasitic diseases (Wierup et al. 2017) (Thapa et al. 2014). Despite these results, the presence of an outdoor area where birds spend most of the day poses a high health risk for some viral diseases (such as bird flu) compared to intensive care systems (Koch and Elbers 2006; Gonzales et al. 2013).

Based on these studies, it is difficult to determine whether organic systems pose a lower health risk to the population or a higher risk. At the same time, there is a significant increase in interest in organic farming in the European Union: doubling the size of organic farms compared to those with intensive production, more than 70% increase in the size of organic farming land within 10 years (EC 2019).

To date, analytical studies, based on data from Member States, have focused on an annual period and are published annually on the European Food Safety Authority (EFSA) website. Therefore, the aim of our study is to use and analyse data from a period of time longer than 5 years. The advantage of using the results of the EU Member States is the collection and processing of data collected on the basis of unified criteria and through the use of uniform formats. In other words, EU Member States can present themselves as a country consisting of 27 districts. This, in contrast to previous studies, eliminates the problem of the lack of heterogeneity of input information - criteria and mechanisms of collection, all giving maximum statistical reliability of the processed data.

This study will examine the levels of infectious risk in traditional and organic systems in order to further clarify the presence of zoonotic risk in different systems, referring to the data recorded by individual Member States in the period 2012–2020.

When selecting indicators in the design of this study, we focused on the following parameters: viral disease of zoonotic nature or having the potential for such, developed reliable methods of diagnosis, diseases subject to mandatory control and reporting by Member States and prevalence or establishment giving statistically significant results. West Nile Virus and Avian Influenza, considered as the two viral diseases in birds requiring mandatory reporting, were taken into account Council Directive of 30 November 2009 (EC 2009). The data for the registered cases are given in Table 1. For Avian Influenza, the count for registered cases is consolidated between High Pathogenic Avian Influenza (HPAI) and Low Pathogenic Avian Influenza (LPAI).

Referring to the indicated data and the p-values, both determining the use of data for Avian Influenza (AI) as a statistical indicator, give a better expression of the purpose of the present study.

The number of consumers of organic products is constantly growing and is based on various motives, such as the belief in better taste, welfare of farm animals, low levels of unnecessary use of antibiotics and growth stimulants etc. This leads to a constant increase in the number of producers of organic products (EC 2019). The regulatory framework for organic production in the European Union is defined in Council Regulation (EC) No 834/2007 (EC 2007). One of the questions from consumers of organic products is related to whether the risks to human health from zoonotic diseases transmitted by farm animals are higher than in conventional agricultural production. Despite the limited use of anti-infectious drugs, previous studies have shown no significant differences in the level of infectivity with potential human infections between the two types of agricultural production (Miranda et al. 2008; Young et al. 2009; Smith-Spangler et al. 2012).

Data from Member States for the period 2012 to 2020 show minimal differences between intensive and organic production in terms of HPAI or LPAI infectivity. These minima are probably due to the increased requirements for organic production, with the better health of animals on organic farms (Anderson 2011).

Wild birds continue to be a major source and reservoir of HPAI and LPAI. The annually increasing number of positive results in passive control in wild birds raises the requirement and need for the development of active control methods. Access to free-range and backyard open areas for most of the day creates an increased likelihood of farm animals coming into contact with wild birds. The lack of a high percentage of positive tests in Conv relative to FrBy may be the result of the insufficient number of tests in organic and backyard birds. The graphics in Figs 4, 5 show significant similarities between the levels of positive tests in free-range and backyard birds on the one hand and wild birds on the other. This determines the expected increase in the difference between organic and intensive cultivation methods with a future increase in the number of tests in the organic sector.

As a first of its kind analytical study, the observed trend in annual gradual increases in positive results in wild birds and the symmetry of related results in FrBy, necessitate the expansion of the present study by adding data from subsequent years and analysing trends, based on aggregated data.

The results were similar in each country and demonstrate that free-range production has an annually increasing number of incidences of viral diseases with high zoonotic potential. This makes year-round surveillance absolutely necessary, as well the need for implementation of additional criteria and requirements for free-range systems. Data collection and analysis need to continue in the future. The current study could be a starting point for similar studies in the coming years.