The isolation of avian influenza virus from chickens is reported for the first time in the United States since the fowl plague outbreak of 1929. The type-A virus was isolated from commercial Leghorn laying hens between 54 and 55 weeks old and involved three different farms in north-central Alabama. These flocks experienced up to 69% mortality and a severe decrease in egg production within a 14-day period.
The epidemiology of the first reported non-fowl-plague avian influenza (AI) virus, A/Chicken/Alabama/75 (Hav4Neq2), isolated from chickens in the United States is discussed. The signs and pathologic changes have been described. The environment, nutrition, and stress factors are discussed as possible contributors to the disease syndrome observed in 3 commercial egg-laying flocks. Avian influenza antibody was demonstrated by agargel precipitation in convalescent chickens through 83 days postinfection. A serological survey of 321 additional poultry flocks was negative for antibodies against avian influenza. A survey was made by serology and virus isolation techniques on 387 wild free-flying birds that fed and roosted in the area. Wild waterfowl are discussed as a possible source of the AI virus.
An integrated broiler company experienced a major outbreak of pullorum disease during 1990. The outbreak resulted in the distribution of Salmonella pullorum-infected birds to more than 150 roaster flocks in five states. Twenty-two parent (multiplier) breeder flocks became infected. An epizootiological investigation uncovered a grandparent male line breeder flock as the index flock supplying males to the affected parent flocks. Transmission apparently occurred vertically through the egg and horizontally by contact in the hatcheries and by placement of chicks on contaminated litter.
As part of a USDA/APHIS study on the prevalence of Salmonella enteritidis in spent laying hens, 3700 pooled cecal samples were cultured for Salmonella. Samples were received from a single processing plant and represented 81 commercial egg-type layer flocks from nine southern states. Salmonella were isolated from 2418 of the 3700 (65.4%) cecal pools, but only six isolates were serotype enteritidis. S. enteritidis was isolated from three flocks from two states but was detected in only six of 140 samples from those flocks. Various Salmonella isolation media and procedures were compared. Xylose-lysine-tergitol-4 plates detected 64% of the total Salmonella-positive cecal samples. Brilliant green agar with novobiocin detected 72% of the total Salmonella-positive samples. When used in combination, 82% of the positive samples were detected with these two plates. The remaining 425 Salmonella-positive samples were detected after delayed secondary enrichment.
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