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Between November 1984 and February 1985, a serious outbreak of pyrexia, diarrhoea, agalactia, metritis and severe weight loss affected most of the recently calved cows in a 183-cow dairy herd in Norfolk. Fifteen cows died and 20 were culled. Forty cows aborted during or after the outbreak, and many of them produced mummified fetuses; 18 calves were stillborn and three others died soon after birth. Necropsy of three affected cows revealed ulceration of the gastrointestinal tract similar to that seen in cases of mucosal disease. Bovine virus diarrhoea virus was isolated from the intestines of one cow that died soon after the onset of illness. The virus was also isolated from the blood of four acutely ill cows and seroconversion was demonstrated in three of those that survived. The virus was isolated from three aborted fetuses, a stillborn calf and a live neonatal calf. Body fluids from two aborted fetuses were seropositive for the virus as were sera from all the aborting cows tested. In addition to widespread seroconversion to bovine virus diarrhoea virus during the outbreak, there was serological evidence of recent infection with Leptospira interrogans serovar hardjo and Coxiella burnetii in a high proportion of cows. It was concluded that this was primarily an acute outbreak of bovine virus diarrhoea but its unprecedented clinical severity was probably associated with the concurrent introduction of L hardjo and C burnetii into an immunologically naive herd during the main calving period. Epidemiological analysis suggested that the source of the virus and L hardjo was down-calving heifers returning from communal marsh grazing.

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Investigation of a disease causing up to 50% mortality in 6 to 14-day-old ducks and up to 25% in 4 to 6-week-old ducks, resulted in the detection and isolation of an astrovirus-like agent. The virus was detected by electron microscopy in the livers of infected ducks and isolated in the amniotic-sac of embryonating specific pathogen free chicken eggs. The clinical, postmortem and histopathological findings resembled duck hepatitis type I. However, the results of laboratory investigations suggested that the disease was due to duck hepatitis type II. Inoculation of ducks with a duck hepatitis type II vaccine resulted in protection against experimental challenge with the astrovirus-like isolate.

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Investigation of respiratory disease and high mortality which occurred on a commercial duck fattening farm between August 1979 and March 1980 resulted in the isolation of 10 influenza A viruses. The viruses were characterised as Hav6 N2 (three isolates), Hav4 Navl (four isolates), Hav4 Nl (two isolates) and Hav7 Neq2 (one isolate) subtypes by haemagglutination-inhibition and neuraminidase-inhibition tests. A Newcastle disease virus isolate was also obtained from the ducks. All isolates had low intravenous pathogenicity indices in 6-week-old chickens.

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Urolithiasis and kidney disease as causes of significant mortality in fowls were investigated in two flocks of commercial laying birds on farms where outbreaks had occurred previously. The investigation, covering the first 10-11 months of egg production, included macroscopic and histological examination of individual cases of the disease, biochemical studies on blood samples collected at regular intervals from marked birds and the analysis of feed samples taken at the same time. The aetiology and pathogenesis of the condition was not established and the various investigations carried out did not reveal any consistent features. The possibility of an association between infectious bronchitis virus and the pathological entity described in the paper is discussed.

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A survey of routine mortality was carried out on six different broiler sites. A total of 535 individual post mortem examinations was carried out. The chief cause of mortality on all six sites was colisepticaemia. Fatty liver and kidney syndrome caused significant loss on three of the six sites and on three of them a low incidence of an oedema syndrome was of interest. Salmonella senftenberg was isolated during the first four weeks from the intestines of chickens from five of the six sites but on none of them was this occurrence associated with any manifestations of disease. The vaccination procedures against Newcastle disease and infectious bronchitis were not producing adequate immunity against a possible challenge by a virulent virus of either although the administration of the vaccines appeared to be causing stress sufficiently severe to be one of the factors predisposing to a high incidence of colisepticaemia.

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Thirty seven piglets with transmissible gastroenteritis (TGE) and 41 with other enteric diseases were examined for evidence of villous atrophy and reduced lactase activity. Widespread villous atrophy appeared indicative of TGE whereas normal lactase activity tended to exclude this possibility. However, both tests are far from specific and neither is recommended to practitioners as an aid to clinical diagnosis.

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A survey of the causes of mortality in four pheasant rearing units in Norfolk showed that although specific pathogens were found in some birds they were not associated with a significant number of losses.

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An account is given of a severe outbreak of type C botulism in waterfowl that occurred on the Norfolk Broads during the exceptionally warm summer of 1975. Forty-five mud samples were collected from 22 well distributed aquatic sites representing a considerable proportion of the total number of Broads. All samples except one (ie, 97-8 per cent) were shown to contain Clostridium botulinum and 58 per cent contained more than one type of the organism. Types B, C and E were demonstrated in 62-2 per cent, 51-1 per cent and 60 per cent of samples respectively. Recent surveys, made by identical methods, of aquatic environments in the London area and the Camargue (France) showed prevalences of Cl botulinum of 72-5 per cent and 4-5 per cent respectively. It seems likely that the Norfolk Broads will continue to present a risk to waterfowl from botulism in future hot summers.

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A survey of mortality was carried out in 51 caged laying flocks between point of lay and slaughter and lasted from March 1971 to June 1973. Flocks were composed of 26 white egg strains and 25 brown egg strains. Total flock population sampled was 281,000 laying fowl. Types of holding that were sampled or sub-sampled were representative of units on which 80% of the laying fowl are maintained in England and Wales. Sampling was performed at four Veterinary Investigation Centres of the Ministry of Agriculture, Fisheries and Food (M.A.F.F.) by obtaining a single day's mortality per fortnight and at a fifth Centre by collecting a specified day's mortality at weekly intervals. In 42 of the 49 flocks for which overall mortality figures were available, mortality did not exceed 16% (mean +/- SEM = 9.12 +/- 0.53) and the monthly mortality rate did not rise above 2.5%. The total number of specimens examined was 2,615. Primary and secondary diagnoses were recorded and of the former, kidney lesions (20%), disorders of the reproductive tract (15.1%), cannibalism and other injury (11.0%), Marek's disease (10.6%), staphylococcal infection (7.1%) and obesity, fatty liver and ruptured liver (7.7%) were the principal conditions encountered. Excluding those specimens for which the cause of death was unestablished, this group of conditions comprised 78.9% of all primary diagnoses. Significant variation in mortality during successive periods of lay was recorded in reproductive disorders, cannibalism, Marek's disease, staphylococcal infection and associated diagnoses of ruptured liver and obesity. No relation was found between flock size and mortality.

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Poutry may require a wide range of salmonella serotypes from various sources including feedingstuffs, breeding flocks, rodents, wild birds and other vectors. Clinical disease is uncommon, but all infections are of importance as potential sources of food poisoning in man.

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