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VLA: Influenza Outbreaks Press On in December

by 5m Editor
8 February 2010, at 10:15am

UK - One further outbreak of swine influenza caused by H1N1 (2009) is among the cases reported in the VLA Monthly Scanning Surveillance Report for December 2009.

Respiratory Diseases

Swine Influenza

Influenza outbreaks continued this month and a second outbreak of pandemic (H1N1) 2009 influenza infection was diagnosed by Bury as the cause of widespread coughing in at least 50 per cent of a group of indoor growing pigs.

Swine influenza due to an endemic strain was also diagnosed as the cause of respiratory disease on a 720 pig indoor finisher unit. The unit had experienced chronic respiratory disease over approximately two weeks which had responded to medication. Pigs were submitted after a resurgence of respiratory disease over a period of a week with seven pigs dying the day prior to submission and six on the day of submission. Three good pigs were submitted and extensive pulmonary consolidation was present in all three, this was distributed cranioventral and also in dorsal parts of all lung lobes and affected 40 to 70 per cent of the lung tissue. Pasteurella multocida was isolated and is likely to have been the cause of death, however all three pigs also tested positive for an endemic strain of swine influenza which is being typed. It is likely that the swine influenza precipitated the resurgence of respiratory disease.

Enzootic pneumonia

A seventeen-week-old Gloucester Old Spot pig was submitted to Winchester for post mortem examination, to investigate a problem with pneumonia on this small unit. The pig had been recently purchased. Approximately 50 per cent of the total lung area showed pinkish collapse/consolidation; this involved mainly the cranioventral lung lobes, but was also present in patchy areas in the caudal lung lobes. The pattern and appearance of lesions was thought to be typical of enzootic pneumonia and Mycoplasma hyopneumoniae DNA was confirmed by PCR examination. Co-incidentally, Yersinia pseudotuberculosis was also isolated in septicaemic distribution.

Other diseases

Streptococcal endocarditis

The carcases of three, 22 week old, finishing pigs were submitted for post-mortem examination with a history of increased death rate in fattening pigs over the previous two weeks with some pigs having lost weight and others showing signs of increased respiratory rate prior to death. Post-mortem examination revealed severe endocarditis with involvement of the left and right atrio-ventricular valves and thickening of the pericardium. Streptococcus dysgalactiae s.s. equisimilis was isolated from lung and cardiac tissues of two of the carcases.

Erysipelas

A 15-week-old Saddleback was submitted to Starcross for post mortem examination from an outdoor small holding where 3 out of 15 pigs had suddenly died over a two week period. Post mortem findings suggested a septicaemia including serosanguinous fluid in the abdomen, fibrin on serosal surfaces of viscera, pulmonary haemorrhages and congested lymph nodes. Erysipelothrix rhusiopathiae was isolated in septicaemic distribution. This organism has traditionally been associated with outdoor pigs. A heavy Ascaris suum infection with milk spot liver lesions and lungworms (Metastrongylus apri) were also noted, another consequence of outdoor pig farming.

Further Reading

- Find out more information on the diseases mentioned in this article by clicking here.