Enzootic bovine leukosis

Article 11.8.1.

General provisions

For the purpose of this chapter, susceptible animals include cattle (Bos indicus and B. taurus).

Standards for diagnostic tests are described in the Terrestrial Manual.

Article 11.8.2.

EBL free country or zone

1. Qualification

   To qualify as free from enzootic bovine leukosis (EBL), a country or zone should satisfy the following requirements for at least three years:

   1. all tumours, suspected to be lymphosarcoma, are reported to the Veterinary Authority, and are examined at a laboratory by appropriate diagnostic techniques;

   2. all cattle with tumours in which EBL has been confirmed or cannot be ruled out are traced back to the herds in which they have been kept since birth; all cattle over 24 months of age in these herds are subjected to an individual diagnostic test for EBL;

   3. at least 99.8 % of the herds are qualified as EBL free.

2. Maintenance of free status

   For a country or zone to maintain its EBL free status:

   1. a serological survey should be carried out annually on a random sample of the cattle population of the country or zone sufficient to provide a 99 % level of confidence of detecting EBL if it is present at a prevalence rate exceeding 0.2 % of the herds;

   2. all imported cattle (except for slaughter) comply with Article 11.8.5.;

   3. all imported bovine semen and embryos/ova fulfil the requirements referred to in Article  11.8.6. and in Article 11.8.7., respectively.

Article 11.8.3.

EBL free compartment

1. Qualification

   To qualify as free from EBL, a compartment should satisfy the following requirements.

   All herds in the compartment have satisfied the requirements of Article 11.8.4., and:

   1. all cattle introduced into the compartment come from a free herd;

   2. all bovine semen and embryos/ova introduced into the compartment after the first test have fulfilled the conditions referred to in Article 11.8.6. and in Article 11.8.7., respectively;

   3. the compartment is managed under a common biosecurity plan complying with Article 4.3.3. and Article 4.4.3., which protects the cattle from contact with EBL virus, which might occur from introduction of infected cattle, cattle products or material and through practices such as vaccinations and other injections, collection of blood and other biological samples, dehorning, ear-tagging, pregnancy diagnosis, etc.;

   4. the compartment has been approved by the Veterinary Authority in accordance with Chapters 4.3. and 4.4.

2. Maintenance of free status

   For a compartment to maintain its EBL free status, all herds in the compartment should remain free in accordance with Article 11.8.4. and specific surveillance implemented in accordance with Article 4.4.5. has not detected the agent.

3. Revocation and re-approval of free status

   If in an EBL free compartment any cattle react positively to a diagnostic test for EBL as described in the Terrestrial Manual, the status of the compartment shall be revoked until all herds have recovered their free status in accordance with Article 11.8.4. and the compartment has been re-approved in accordance with Chapters 4.3. and 4.4.

Article 11.8.4.

EBL free herd

1. Qualification

   To qualify as free from EBL, a herd should satisfy the following requirements:

   1. there has been no evidence of EBL either clinical, post-mortem, or as a result of a diagnostic test for EBL within the previous two years;

   2. all cattle over 24 months of age have been subjected to a diagnostic test for EBL on two occasions with negative results, at an interval of not less than 4 months during the preceding 12 months;

   3. cattle introduced into the herd after the first test have fulfilled the conditions of Article 11.8.5.;

   4. all bovine semen and embryos/ova introduced into the herd after the first test have fulfilled the conditions referred to in Article 11.8.6. and in Article 11.8.7., respectively.

2. Maintenance of free status

   For a herd to maintain its EBL free status, the cattle in the herd over 24 months of age on the day of sampling should be subjected to a diagnostic test for EBL with negative results at intervals of no more than 36 months and the conditions referred to in points 1a), 1c) and 1d) above continue to be fulfilled.

3. Suspension and restoration of free status

   If in an EBL free herd any cattle react positively to a diagnostic test for EBL as described in the Terrestrial Manual, the status of the herd shall be suspended until the following measures have been taken:

   1. the cattle which have reacted positively, and their progeny since the last negative test, should be removed from the herd immediately; however, any cattle within the progeny which has been subjected to a PCR test with negative results (under study) may be retained in the herd;

   2. the remaining cattle should have been subjected to a diagnostic test for EBL carried out as described in point 1b) above with negative results at least four months after removal of the positive cattle and their progeny.

Article 11.8.5.

Recommendations for the importation of cattle for breeding or rearing

Veterinary Authorities of importing countries should require the presentation of an international veterinary certificate attesting that the cattle:

1. come from a country, zone or compartment free from EBL; or

2. come from an EBL free herd; or

3. meet the following three conditions:

   1. the cattle were kept in a herd in which:

      1. there has been no evidence of EBL either clinical, post-mortem, or as a result of a diagnostic test for EBL within the previous two years;

      2. all cattle over 24 months of age have been subjected to a diagnostic test for EBL on a blood sample on two occasions with negative results during the preceding 12 months, at an interval of at least 4 months, or were tested on two occasions while segregated from the herd in an isolation unit approved by the Veterinary Authority at an interval of at least 4 months;

   2. the cattle were subjected to a diagnostic test for EBL within 30 days prior to shipment with negative results;

   3. if less than two years of age, the cattle come from 'uterine' dams which have been subjected to a diagnostic test for EBL on a blood sample on two occasions at intervals of at least 4 months within the preceding 12 months, with negative results.

Article 11.8.6.

Recommendations for the importation of bovine semen

Veterinary Authorities of importing countries should require the presentation of an international veterinary certificate attesting that:

1. the donor bull was resident at the time of semen collection in an EBL free herd; and

2. if less than two years of age, the bull came from a serologically negative ‘uterine’ dam; or

3. the bull was subjected to diagnostic tests for EBL on blood samples on two occasions with negative results, the first test being carried out at least 30 days before and the second test at least 90 days after collection of the semen;

4. the semen was collected, processed and stored in accordance with Chapters 4.5. and  4.6.

Article 11.8.7.

Recommendations for the importation of bovine embryos/ova

Veterinary Authorities of importing countries should require the presentation of an international veterinary certificate attesting that the embryos/ova have been collected, processed and stored in accordance with Chapters 4.7., 4.8. and 4.9., as relevant.