Fowl adenoviruses were isolated and characterized from severe cases of hydropericardium syndrome in Ecuador and Pakistan. All were neutralized by antibodies against serotypes 4 and 11. Cross-neutralization tests and restriction enzyme analysis strengthen the classification as serotype 4 strains. The restriction endonucleases used allowed the differentiation among field isolates and reference strains. All field isolates tested induced high embryo mortality. One-day-old specific pathogen free (SPF) chicks were infected with 10 5 plaque-forming units by natural routes to reproduce the disease with plaque purified virus. Whereas no mortality was seen with the reference strain, the mortality with the field isolates was 100%. A reduced mortality occurred with a lower infectious dose. Field isolate K1013 from Ecuador was also highly pathogenic for 1-to 3-week-old SPF chicks after intramuscular inoculation. The main pathological signs were swollen livers, severe hydropericardium and nephritis, reflecting the field situation and underlining the role of FAV4 strains in the aetiology of infectious hydropericardium.

Erysipelas was diagnosed in 1998 from 34-wk-old laying hens in a free range flock in Germany. Erysipelothrix rhusiopathiae of serotype 1 was cultured from internal organs of the affected birds. This article describes the pathogenicity of the field isolate of E. rhusiopathiae in experimentally infected specific pathogen-free (SPF) laying hens. Three experiments were performed with SPF chickens inoculated at 17, 27, and 37 wk of age by either intramuscular (IM) or oral route. Inoculated birds were observed for 14 days. The highest mortality rates occurred in older birds, with 100% mortality observed in the 37-wk-old birds inoculated IM, 60% mortality reported in the younger 27-wk-old birds, and no mortality in the 17-wk-old age group. In the orally infected 27-wk-old birds, 40% mortality was detected, whereas no mortality was observed in the oldest birds by the same route. The results of the experiments support the contention that older birds are more sensitive to infection than younger birds and that mortality in laying hens is age related and dependent on the route of infection.

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Erysipelas was diagnosed in a layer breeder flock in Sweden in 2002. Although vertical transmission of Erysipelothrix rhusiopathiae has not been previously described in chickens, the potential of erysipelas infection to adversely affect hatching eggs was of concern. To clarify the possible impact of erysipelas on hatching eggs and their progeny, an experiment was done using 200 hatching eggs collected from the infected flock. The eggs were incubated for 21 days, and the egg shells, infertile eggs, dead-in-shell embryos, and a sample of day-old hatched chicks and blood samples from 5-day-old chicks were cultured for E. rhusiopathiae. In addition, after 28 days of grow-out, the male chickens were euthanatized and cultured for the bacterium, and the remaining female chickens were placed as a backyard flock and observed over a 4-mo period. Bacteriological test results of the above-mentioned samples were negative for E. rhusiopathiae. Mortality rates were not excessive, and no clinical symptoms of erysipelas were observed during the period of observation. The result of the investigation suggests that in layer breeder chickens, E. rhusiopathiae is not vertically or egg transmitted and that the disease outbreak in the parent stock had no adverse impact on the quality of hatching eggs in terms of increased embryo mortality.

Primary Audience: Broiler Producers, Veterinarians, Field Supervisors SUMMARYThe initial purpose of this investigation was to document nonuniformity and poor performance that had reportedly occurred in several successive grow-out flocks on a commercial broiler ranch in California. Previous sporadic necropsy submissions of birds to the diagnostic laboratory resulted in reports of Escherichia coli septicemia, reovirus isolations from joints, and adenovirus isolations from livers. Intranuclear virus inclusion bodies had been detected in the liver of 1 bird from 1 submission. Therefore, an in-depth diagnostic investigation of the birds sampled weekly from each house on the ranch was undertaken to establish the role of these and other potential pathogens in the forthcoming flocks. Partway through the investigation, histopathology indicated the flock had a bursal disease problem. Polymerase chain reaction analysis of bursal tissues was performed on selected samples. An infectious bursal disease virus (IBDV) strain different from that used in the vaccine was detected in the bursas by reverse transcription-polymerase chain reaction-restriction fragment length polymorphism. This IBDV strain had sequences across the hypervariable VP2 region, which is identical to the T1 strain except for 1 position. The weight gains, recorded and averaged at wk 5 and 6 according to the producer's management plan, were within the producer's standard expectations. Although reovirus and adenovirus were isolated and rotavirus-like particles were noted in pooled intestinal samples on examination by electron microscopy, little significance was attributed to these agents because the agents were detected from healthy birds. Identification and documentation of involvement of this T1 strain of IBDV was facilitated by weekly diagnostic submissions from all the houses on the ranch.