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There has been a further outbreak of disease in chickens caused by infectious bronchitis virus QX strain. This isolation follows the previous trend of disease being diagnosed in small flocks. The contact networks involved in backyard flocks need to be studied in order to understand how newly introduced infectious agents can be spread and what risk this poses to large poultry units and to public health should any future agent be a zoonosis.

Commercial Layers and Layer Breeders

Intestinal Spirochaetosis

Avian intestinal spirochaetosis was diagnosed in two flocks of 24- and 28-week-old free-range layers, which were experiencing a drop in egg production. Brachyspira pilosicoli was cultured from caecal contents in the flock experiencing a slight drop in egg production whereas a more pathogenic strain – Brachyspira intermedia – was present in the pasty yellow caecal content of the flock undergoing a 20 per cent drop in egg production.

Infectious bronchitis

A QX-like infectious bronchitis virus was isolated from pooled tracheal and lung tissue submitted from a group of 12- to 16-week-old pullets, six of which had died out of a group of 200. The unit was a small rearing enterprise which bought in day-old chicks rearing to point of lay. Mild respiratory signs of sneezing and loss of weight were described in the group.

Broilers and Broiler Breeders

Rickets

Rickets was suspected in a flock of 29 day-old broilers submitted with a history of inactivity, depressed growth and deterioration of litter conditions. Findings at post mortem examination were of pododermatitis poor bone strength affecting leg bones in particular, and slight enlargement of parathyroid glands.

Pseudomonas

Pseudomonas aeruginosa septicaemia was diagnosed in two successive submissions of one- and six-day-old broiler breeder chicks. Routine cultures of liver, spleen and heart produced good virtually pure growth of Pseudomonas aeruginosa. Histological examination of skin and tissues at the back of the neck revealed mild focal necrosis with congestion and oedema associated with dense clusters of bacterial rods suggesting the possibility that bacteria might have been introduced during vaccination.

Backyard Flocks

The visceral form of Marek's disease and concurrent 'scaly-leg' was diagnosed in an 18-month-old Light Sussex hen. Post mortem examination findings included multiple creamy nodules in the heart and thickening of the scales of the legs. Histological examination confirmed the presence of a pleomorphic infiltrative lymphosarcoma in myocardium muscle and peripheral nerve with a pattern of perivascular distribution. Examination of skin from the leg and within the thickened scales there were numerous burrowing mites consistent with Knemidocoptes mutans.

Turkeys

Blackhead

Malaise and occasional deaths were reported in a batch of 28 five- to eight-week-old turkeys. Ten birds in total had died, including five on one day. The livers of all five birds examined showed multiple necrotic lesions consisting of slightly sunken coalescing foci with pale centres surrounded by reddening. Each bird also had caeca, which were enlarged and had a necrotic, sometimes caseous, core with extensive mucosal necrosis and some associated serosal inflammation. The lesions were typical of histomoniasis, or blackhead, caused by Histomonas meleagridis. Chickens were also present on the premises and the turkeys had been housed in a shed previously used by chickens.

Gamebirds

Staphylococcal septicaemia

Five live birds were submitted to Thirsk for examination. The post mortem findings were unremarkable apart from marked, irregular pale-coloured lesions in a trabecular pattern in the livers in two of the birds. The crop and proventriculus of all the birds were devoid of any food. Routine cultures on liver and spleen revealed moderate to heavy, mostly pure growths of beta-haemolytic Staphylococcus aureus. The clinical signs, post mortem findings and culture results were consistent with a diagnosis of Staphylococcus aureus septicaemia. It has been suggested that removal of hard plastic anti-pecking bits from pheasant poults by twisting them without cutting them first, with resulting damage to the nasal mucosa, may sometimes be responsible for introducing staphylococcal infections such as septic arthritis and tenosynovitis and this may have been the pre-disposing factor in this case.

Further Reading

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Further Reading

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