Brachyspira Intermedia Infection in Free Range Laying Hens

UK - Brachyspira intermedia infection was implicated as cause of diarrhoea in free range laying hens.
calendar icon 24 January 2012
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Commercial Layers

Brachyspira intermedia

Avian intestinal spirochaetosis was tentatively diagnosed in a group of 1,000 free-range layer hens aged 24-weeks, part of a much larger multi-age flock. The birds presented with declining egg production and weight loss. Loose droppings with a "skimmed milk" appearance were described. Initially mortality was not a feature, but it increased as dehydration predisposed to visceral gout, affecting those birds most severely debilitated. Brachyspira intermedia was isolated following anaerobic cultures of pooled caeca.

Broilers & Broiler Breeders

Infectious Bronchitis

Evidence of Infectious Bronchitis Virus (IBV) infection was detected by real time RT-PCR testing of pooled tracheal swabs in several broiler flocks aged between 22 and 50 days. Partial S1 gene sequencing identified European QX-like IBV infection in a number of these flocks with associated problems respectively including poor performance, E. coli septicaemia, wet droppings and increased rejections at processing due to airsac lesions. Furthermore, in one 32-day-old broiler flock there was a rising mortality to 0.8% per day with a history of birds being found dead.



Familiar seasonal diagnoses were recorded in flocks of turkeys over 10-weeks of age being reared for the Christmas market. Commonly, sporadic sudden deaths were reported in affected flocks over a period of 1-2 weeks prompting laboratory investigations. At necropsy, lesions consistent with bacterial septicaemia were evident in birds from some of these flocks and Erysipelothrix rhusiopathiae was frequently isolated from tissues confirming a diagnosis of Erysipelas. Interestingly, in one flock incomplete (single dose) Erysipelas vaccination had been administered one month prior to the onset of losses and historically pigs had been kept on the unit.


Eight of a group of 50 turkeys aged 14-weeks had died and some were showing unusual yellow droppings and dullness for 2-3 days before death. At post-mortem examination, characteristic gross changes of Blackhead (Histomonosis) were seen including multiple circular yellow necrotic hepatic 'target' lesions with distension, thickening and necrosis of the caeca. Histopathology confirmed chronic lymphohistiocytic hepatitis and typhlitis with protozoal infection. The disease was diagnosed in several other Christmas-market rearing flocks where intermittent mortality over a 1-2 week periods was often reported.

Backyard flocks

Marek's disease

Marek's disease was diagnosed in backyard hens of varying ages from different flocks. Histories of illthrift and clinical signs of Classical Marek's disease were reported, including unilateral wing droop. In some cases failure to respond to antimicrobial, anticoccidial and anthelmintic treatment were also reported prior to submission. Consistent necropsy findings included marked splenomegaly and multifocal 2-5mm whitish nodular infiltrative visceral lesions. Histopathological examination confirmed the presence of pleomorphic lymphocytic infiltrates in affected viscera, typical of Marek's disease.

Game birds

Heterakis isolonche

One dead pheasant from a group of 18 was submitted to investigate the cause of loose faeces following the introduction of three pheasants ten days previously. The birds had been wormed shortly before the addition of the new poults in September. At necropsy of the casualty poult the caeca were markedly distended with khaki-coloured contents and there were slightly raised, firm, 2mm nodular lesions over the caecal mucosa. Histopathological examination identified the changes as chronic proliferative typhlitis and the presence of nematode parasites confirmed this typhlitis as being consistent with Heterakis isolonche infection. This species is pathogenic in pheasants causing diarrhoea, weight loss and death and the condition has been rarely seen by AHVLA in recent years. However, suspected Heterakis isolonche typhlitis was also reported by AHVLA earlier in the 2011 rearing season affecting 8-week-old pheasant poults on a different site.

Further Reading

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

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