Disease Information

8 December 2000
Vol. 13 - No. 48

FOOT AND MOUTH DISEASE IN SOUTH AFRICA
Outside the FMD control zone

See also: 27 October 2000, 13 October 2000, 6 October 2000, 29 September 2000, 22 September 2000, 15 September 2000

Emergency report

Text of an e-mail received on 2 December 2000 from Dr Emily Mmamakgaba Mogajane, Chief Director, Agricultural Production, National Department of Agriculture, Pretoria:

Report date: 30 November 2000.

Nature of diagnosis: clinical and laboratory.

Date of initial detection of animal health incident: 29 November 2000.

Estimated date of first infection: 20 November 2000.

Background:

Cattle from Arendsfontein farm were sent to the abattoir in Matsapha, Swaziland, on 23 November, and suspicious lesions were found on ante-mortem inspection on 24 November. Samples taken by the Swaziland authorities and dispatched to the Onderstepoort Veterinary Institute (OVI, South Africa) on 28 November were found to be positive for foot and mouth disease (FMD) virus SAT1 on 29 November (see Disease Information, 13 [47], 217, dated 1 December 2000).

Outbreaks:

Location	No. of outbreaks
Arendsfontein farm (25º 53' 41'' S - 29º 34' 02'' E), Middelburg district, Mpumalanga province	1

Total number of animals in the outbreak:

species	susceptible	cases	deaths	destroyed	slaughtered
bov	12,500	30	0	0	0
sui	52,000	0	0	0	0

Arendsfontein farm is a dedicated feedlot system for cattle and pigs housing 12,500 cattle in the feedlot and 52,000 pigs - both groupings in separate isolated facilities. There is no immediate physical or human contact between the two units.

Diagnosis:

An investigation was immediately made on Arendsfontein farm, on 29 November and clinical lesions were detected in 30 bovines. No clinical disease has been detected in the pig unit.

Samples were dispatched to the OVI and, late during the night of 29 November, were confirmed positive for SAT1 FMD virus. Subsequent samples, submitted on 30 November, also yielded positive results for SAT1 FMD virus. Serological samples taken from the pig unit are thus far all negative.

A. Laboratory where diagnosis was made: Onderstepoort Veterinary Institute (OVI), Exotic Diseases Section.

B. Diagnostic tests used: liquid phase blocking ELISA⁽¹⁾; 3ABC ELISA; virus neutralisation tests; PCR⁽²⁾; virus isolation on primary porcine kidney cells.

C. Causal agent: FMD virus type SAT1. Virus sequencing is being conducted by the OVI; the results should become available on 3 or 4 December 2000.

Epidemiology:

A. Source of agent / origin of infection: the origin of the infection is being investigated.

B. Mode of spread: suspected contact with infected animal(s) introduced into the feedlot.

C. Other epidemiological details: this is the first occurrence of FMD virus type SAT1 in South Africa outside the FMD control zone since 1957.

Control measures:

- The immediate aim is to minimise virus excretion from the cattle in the feedlot and it was thus decided to commence with vaccination of all the cattle in the feedlot with SAT1 vaccine supplied by the OVI. Vaccination will commence on 1 December and should be completed on 2 December. All the cattle will be re-vaccinated 14 days after the initial vaccination. The vaccination of the cattle is an emergency vaccination in accordance with the guidelines of the International Animal Health Code. Slaughtering of the vaccinated cattle will commence 14 days after the revaccination provided no further virus activity is detected.

- The pig unit will be intensively inspected twice daily and also subjected to sero-surveillance until 14 days post vaccination of the feedlot cattle. Strict sanitary control to prevent cross-contamination between the cattle feedlot and pig unit is being maintained.

- A sanitary cordon has been placed on farms within a 3- to 5-km radius around the outbreak, with movement control of animals and animal products backed up by intensive sero-surveillance and daily physical inspections.

- Intensive tracing of all movements to and from the farm Arendsfontein during the past 4-6 weeks is already being conducted.

- Exports of meat from export abattoirs were suspended with immediate effect on 29 November until the trace-back of animal movements has been completed.

- Imports of live cattle from neighbouring countries have been suspended pending the outcome of the investigation into the source of the infection.

The outbreak can be regarded as an isolated incident and currently confined to one farm only.

(1) ELISA: enzyme-linked immunosorbent assay.

(2) PCR: polymerase chain reaction.

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