Enzootic Bovine Leucosis (EBL) is a lymphatic neoplasm sustained by a virus (BLV - Genus Deltaretrovirus in the Retroviridae family) (Hunter et al., 2000).

The target of disease is represented by cattle herds, but many other farm animals are susceptible to BLV infection; either naturally (eg. in water buffalo or experimentally induced (eg. in sheep) (Burny et al., 1988).

We remember that European Union declared "Eradication of EBL as mandatory" (Council Directive EEC n 432, 1964).

The Italian normative references for the National Plan for the Eradication of the EBL are: Health Ministry Decree 358 (2 May 1996) and the Legislative Decree n. 196 (22 May 1999).

On September 18, 2017, the "Standing Committee for plants, animals, food and feed" recognized Italy as officially free of Enzootic Bovine Leucosis Country.

In brief a farm can qualify to be disease free, if all animals over age of 12 months have reacted negatively to two diagnostic checks (performed with an interval of, at least, four months during the last 12 months of life).

Tests required by the law (regulations for the diagnosis of EBL) are serological such as AGID and ELISA, the latter being the option of choice, offering the possibility of using serum pools.

A territory is accredited as EBL free, if all the cattle and buffalo farms have been checked (on an annual basis) and if the prevalence of infected farms does not exceed 0.02% of controllable farms; in Italy the minimum territorial base, that can qualified as a "free area", corresponds to the administrative district, qualified as a Province.

A regional district is defined as undamaged when all its Provinces are recognized as such.

The documentation for recognition of disease free area is realized by the Region of competence and then submitted by the Ministry of Health to the European Commission; if the assessment is positive, the Commission shall amend Chapter 2 of Annex III to Decision 2003/467 / EC containing the list of regions officially EBL free; the list of States whose entire territory is EBL free is indicated in Chapter 1.

In any case, the finding of infected animals, entails the suspension or loss of disease free area status, and therefore may have repercussions on the entire territory of reference.

Considering the European norms foresee that the indemnity of a territory can be demonstrated also on a statistical basis (Legislative Decree n. 196 (1999) annex D chapter 1, point E, C paragraph “... a method shows, with a confidence rate of 99%, that the infected farms are less than 0.2%”), the prevalence of infection in Italy, has been estimated; to this purpose the target population was considered as: "total of the farms subject to the eradication plan".

In order to estimate the prevalence, the total number of farms found infected has been placed in the numerator, while the total number of serologically controlled herds was taken as denominator.

Data were extracted from the national veterinary information systems VET-INFO.

In Figure 1 the epidemiological situation of the EBL is reported (as shown in Annex III, Chapter 2 of Decision 467 EC (2003; updated to 11/10/2016).

In red: non officially free territories, in green: officially free territories.

Regions and Provinces free from EBL are listed in the table.

Figure 2 shows the outbreaks of EBL infection recorded in the 2013 - 2016 years

Figure 3 highlights the outbreaks of infection (for periods here considered), in some specific areas; epidemiological links have been highlighted for at least four infection clusters in Lazio, Campania, Puglia and Sicily Regions.

Data on activities related to the EBL eradication plan for the years 2013-2016, have been reported

Table 1. Data about activities carried out by the Italian Veterinary Services in the EBL eradication plan (2013-2016)

The Figure 4 shows the prevalence of infected farms.

Activities carried out in Italy. The prevalence of infection (period 2013-2016), is summarized in table 2.

Eradication of EBL has been achieved with great efficiency in the northern Regions of Italy. The implementation of the "Zootechnical Registry", contributed to achieving the programmed objectives.

The Southern Regions, in spite of the presence of modern livestock breeding farms characterized by an adequate entrepreneurial spirit, are penalized by the presence of outdated animal husbandry structures, located in marginal areas, in which breeders (for social, cultural and economic limits), often don't act collaboratively with the veterinary services.

Besides, recently these faced various health emergencies (Blue tongue, Avian influenza) and endemic diseases (Brucellosis, Tuberculosis) that have had the precedence over Leucosis.

In addition to this, the three remaining infection clusters (in Lazio, Puglia and Sicily Regions) are characterized by extensive cattle bred, with indocile or even feral like animals, that made the surveillance on Enzootic Bovine Leukosis even more difficult.

Basically a lack of controls may encourage animal exchange and illegal trade activities.

This results in positive tests that occur even after a prolonged period of negative findings on the controlled population.

Not officially considered EBL free Regions (eg. Abruzzo, Molise, Basilicata, Calabria), where there have been no outbreaks for years; can't take advantage of government reimbursement, because of the lack of control of some farms. The Ministry of Health has tackled these problems by promoting extraordinary measures in order to advantage unscathed Regions. EBL, Brucellosis and Tuberculosis have been the subject of some regulations, starting from the Ministerial Ordinance (28 May 2015).

Thanks to these initiatives, and a renewed commitment by the competent Regions, BLV infection is now reduced in Italy to a few well-identified areas that do not represent a real risk of infection. The surveillance system, which is guaranteed by the Veterinary Service, has allowed to exclude the presence of viral circulation in uninjured herds: so, no new "outbreaks" have been recorded. Given the epidemiological situation, it was decided to ask for the recognition of EBL free status for the entire Country. Looking ahead, work is being done to save resources by making the minimum surveillance level in Leukosis free territories, to ensure the maintenance of the health status, while more stringent measures will be adopted in the affected territory. In these areas, where the eradication plan activities have not been sufficient to vanquish the infection, it's necessary to adopt specific plans to re-qualify the breeding system itself.

The experience allowed to develop concrete proposals:

create livestock control facilities in extensive farms, adopt electronic animal identification tools and rehabilitate animal populations that are not attributable to any owner, create sustainable and (bio) safe commercial flows that allow infected livestock to be moved for the finishing phase of breeding.

The ultimate objective is to find solutions to the problem of controlling infectious diseases avoiding to destroy the extensive system of breeding, which allows the social, cultural and economic survival of marginal areas of the Country.

Therefore, it is necessary to protect the business interests of the intensive food supply chains and maintain biodiversity and food quality that made Italy famous all over the world.

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