Enzootic bovine leucosis p. 89 -

Question 1

Officially enzootic bovine leukosis free herd

Answer 1

• There is no evidence, either clinical or as a result of a laboratory test, of any case of
enzootic bovine leukosis in the herd and no such case has been confirmed in the previous
two years and
• All animals over 24 months of age have reacted negatively during the preceding 12 months to
two tests carried out at an interval of at least four months; or is situated in an officially enzootic
bovine-leukosis-free Member State or region.
• A herd shall retain officially enzootic-bovine leukosis-free status provided:
o Any animals introduced into the herd come from an officially enzootic bovine-leukosisfree
herd;
o All animals over 24 months of age continue to react negatively to a test carried out at
intervals of three years;
o Breeding animals introduced into a herd and originating from a third country have
been imported in accordance with EU rules.
• The officially leukosis-free status of a herd is to be suspended if;
o the conditions are not fulfilled,
o where as a result of laboratory tests,
o on clinical grounds one or more bovine animals are suspected of having enzootic bovine
leukosis and the suspect animal(s) are immediately slaughtered

Question 2

What to do if a single animal is positive with Enzootic bovine leukosis?

Answer 2

If a single animal in an officially enzootic-bovine leukosis-free herd has reacted positively,
or where infection is otherwise suspected in one animal in a herd:
o The animal which has reacted positively, and, in the case of a cow, any calf it may have
produced, must have left the herd for slaughter under the supervision of the veterinary
authorities;
o All animals in the herd more than 12 months old have reacted negatively to two
serological tests (at least 4 months and less than 12 months apart) carried out at least
three months after removal of the positive animal and any possible progeny thereof;
o An epidemiological inquiry has been conducted with negative results and the
herds linked epidemiologically to the infected herd have been tested.
o However, the competent authority may grant a derogation from the obligation to
slaughter the calf of an infected cow where it was separated from its mother
immediately after calving. In this case, the calf must be tested at the age of 24
months.

Question 3

A member state or part of a member state may be considered officially enzootic-bovine-leukosis-free if

Answer 3

• At least 99.8 % of the bovine herds are officially enzootic bovine-leukosis-free; or
• No case of enzootic bovine leukosis has been confirmed in the Member State or the part of the
Member State for the past three years, and the presence of tumours suspected of being due to EBL
is compulsorily notifiable, with investigations of cause being carried out, and in the case of a
Member State, all animals aged over 24 months in at least 10 % of the herds, selected randomly,
have been tested with negative results in the previous 24 months, or
• In the case of a part of a Member State, all animals aged over 24 months have undergone
a test with negative results in the previous 24 months; or
• Any other method which demonstrates to a confidence rating of 99 % that less than 0.2 % of
herds were infected.