2002/106/EC: Commission DecisionShow full title

CHAPTER III U.K. Guidelines on main criteria to be considered for the recognition of a holding as a classical swine fever suspected holding

The decision to recognise a holding as a suspected holding will be taken on the basis of the following findings, criteria and grounds:

(a)

clinical and pathological findings in pigs. The main clinical and pathological findings to be considered are:

• fever with increased morbidity and mortality;

• fever with haemorrhagic syndrome;

• fever with neurological symptoms;

• fever of unknown origin where treatment with antibiotics failed to improve the health state;

• abortions and increased fertility problems during the last three months;

• congenital tremor of piglets;

• chronically diseased animals;

• growth retarded (runted) young animals;

• petechial and ecchymotic haemorrhages, especially in lymph nodes, kidneys, spleen, bladder and larynx;

• infarction or haematomas, notably in the spleen;

• button ulcers in the large intestine of chronic cases, particularly near the ileo-caecal junction.

(b)

epidemiological findings. The main epidemiological findings to be considered are:

• where pigs had direct or indirect contact to a pig holding proven to have been infected with classical swine fever;

• where a holding has supplied pigs that were subsequently shown to be infected with classical swine fever;

• where sows have been artificially inseminated with semen originating from a suspect source;

• where there has been indirect or direct contact with feral pigs of a population where classical swine fever occurs;

• where pigs are kept outdoors in a region where feral pigs are infected with classical swine fever;

• where pigs have been fed with swill and there is the suspicion that this swill has not been treated in such a way as to inactivate classical swine fever virus;

• where possible exposure might have occurred, e.g. due to persons entering the holding, transports, etc.

(c)

findings related to results of serological tests. The main laboratory findings to be considered are:

• serological reaction caused by an unnoticed classical swine fever virus infection or by vaccination(1);

• cross-reaction between antibodies to classical swine fever and to other pestiviruses(2);

• detection of singleton reactors(3).

(1)

If pigs have been vaccinated against classical swine fever with a conventional vaccine they can be found seropositive due to the vaccination alone, or due to a silent infection in vaccinated animals.

(2)

Under certain circumstances up to 10 % of the pigs within a herd may have antibodies against ruminant pestiviruses causing bovine viral diarrhoea and border disease. For example, when pigs have direct contact with cattle or sheep infected with BVD virus or BD virus, or when pigs have contact with materials contaminated with ruminant pestiviruses.

(3)

In all of the current serological tests for classical swine fever a small proportion of sera give false/positive results either due to the lack of specificity of the test-system or due to sera from the singleton reactors.