Foot-and-mouth disease in a flock of sheep in southern Brazil
Hancock, R.D.; Prado, J.A.
Veterinary Record 132(11): 278-279
1993
ISSN/ISBN: 0042-4900 PMID: 8385377 Document Number: 411920
In 1990 an outbreak of foot-and-month disease (FMD) affected 4 farms in Rio Grande do Sul, Brazil causing significant sheep losses. A detailed study was carried out on one of the farms where oropharyngeal scrapings and blood samples were taken on 5 visits: day 0 (approximately 4 weeks after the initial outbreak) and days 59, 102, 152 and 194. Clinically, the disease was characterized by severe lameness, loss of body condition and abortion in ewes; no oral lesions were seen. By day 59 approximately 40% of the sheep flock had either died or become so debilitated that they had been killed by dogs. No signs of disease were seen on subsequent visits. The diagnosis of FMD had been confirmed following culture of virus type O subtype 1 from a vesicular lesion on a bovine tongue on the farm. The presence of antibodies to FMD virus infection associated antigen at the start of the investigation and the presence of high virus neutralizing antibody titres which declined over the investigation period indicated that the infection was recent. Virus cultures yielded FMD virus type O and demonstrated that some of the sheep continued to carry virus throughout the investigation. It is suggested that the risk posed by carrier sheep to unvaccinated stock in the area should be assessed before the area is declared 'FMD free' as part of the River Plate FMD eradication scheme.