See also: 14 May 2004, 26 March 2004

Emergency report

Information received on 23 July 2004 from Dr Masako Kurimoto, Director of Animal Health and Animal Products Safety Division, Ministry of Agriculture, Forestry and Fisheries, Tokyo:

Date of the report: 22 July 2004.

A new event was reported in relation with the vaccine cases of classical swine fever (CSF) detected in March 2004 (see Disease Information, 17 [13], 94, and 17 [20], 138).

According to the results of a series of epidemiological investigations conducted to date, this new event should not be considered as an outbreak of CSF caused by a wild-type virus strain. Investigations into the source and route of the infection are continuing.

Geographical location of the affected premises: Kanoya city, Kagoshima prefecture. The affected farm is located at a distance of 800 m from the farm in which the application of unapproved CSF vaccine was detected in March.

Total number of animals on the affected premises: approximately 500 pigs.

Diagnosis: the test results and the signs below indicate that the event does not constitute a CSF outbreak.

A. Main clinical signs:

- The breeding sows showed signs of anorexia and slight fever.

- The piglets had diarrhoea.

- There were no major clinical signs in the fattening pigs.

B. Test results:

- On 20 July 2004, ELISA⁽¹⁾ gave positive results for 9 of the 10 breeding sows.

- On 20 July, the fluorescent antibody test gave positive results for 4 piglets.

- On 22 July, RT-PCR⁽²⁾ gave positive results which indicated that the isolated virus is highly likely to be of vaccinal origin.

Source of agent / origin of infection: at present, it is considered that this event should be attributed to either the application of unapproved vaccine — the same one as in the previous event in March — or to a vaccine virus derived from the unapproved vaccine used in the previous event. Epidemiological investigations are to be conducted to determine whether or not the new event was caused by the application of unapproved vaccine.

Control measures:

- Movement control for all farms within a 3-km radius of the affected premises. Investigations (on-site inspection and serological testing) are to be carried out in all farms located within the movement control area. Movement control is to be lifted when the results of the investigations indicate that each farm is free from infection.

- All pigs kept on the affected premises are to be killed and destroyed.

(1) ELISA: enzyme-linked immunosorbent assay

(2) RT-PCR: reverse transcriptase - polymerase chain reaction

Source: Office International Des Epizooties - 30th July 2004