2002/106/EC: Commission Decision of 1 February 2002 approving a Diagnostic Manual establishing diagnostic procedures, sampling methods and criteria for evaluation of the laboratory tests for the confirmation of classical swine fever (Text with EEA relevance) (notified under document number C(2002) 381) (c. 106)

ANNEX U.K. CLASSICAL SWINE FEVER DIAGNOSTIC MANUAL

CHAPTER II U.K. Description of classical swine fever with emphasis on differential diagnosis

C. Chronic form U.K.

1. The chronic course of infection occurs when pigs are not able to develop an effective immune response against classical swine fever virus. Initial signs of a chronic infection are similar to the acute infection. Later, predominately non-specific signs are present, i.e. intermittent fever, chronic enteritis and wasting. The typical haemorrhages of the skin are missing. U.K.

These pigs may show clinical signs of disease for 2 to 3 months before death. Classical swine fever virus is constantly shed from the onset of clinical signs until death. Antibodies may be temporarily detected in serum samples.

2. Pathological changes are less typical, especially haemorrhages in organs and serosa may not be observed. In animals showing chronic diarrhoea, necrotic lesions are common on the ileum, the ileocaecal valve and the rectum. U.K.

3. As clinical signs of chronic classical swine fever are rather non-specific, many other diseases must be considered for differential diagnosis. The increased body temperature is not necessarily present in every animal, but in an infected holding fever can be detected at least in some pigs. U.K.