Prevalence was estimated for Salmonella enterica serotype eneritidis (SE) in layer house environments (n = 200 layer houses) and house mice (n = 129 layer houses) in 15 states throughout the United States. Environmental swabs were collected from manure, egg belts, elevators, and walkways. Live-catch rodent traps were placed for 4-7 days. Swabs and house mice were submitted to the laboratory for bacterial culture. Overall, 7.1% of layer houses and 3.7% of mice were culture positive for SE. The highest prevalence was in the Great Lakes region of the United States, and no SE was recovered from houses or mice in the southeast region. Presence of SE in layer houses was associated with age/molting, floor reared pullets, and number of rodents trapped. Cleaning and disinfecting houses between flocks was associated with a reduced risk. The prevalence of SE in mice from environmentally positive houses was nearly four times that of mice from environmentally negative houses.
In order to better characterize spontaneous respiratory cryptosporidiosis in chickens, a retrospective examination of histopathology reports from the Georgia Poultry Laboratories for an 18-mo period (4/1/86 to 9/30/87) was made; 12 cases were found. Collected data were analyzed and certain epidemiologic and histologic features were identified. Eleven of the 12 cases involved broiler type chickens. The ages of chickens with respiratory cryptosporidiosis were evenly distributed between 17 and 52 days of age. The infected birds were always clinically ill. Viruses or bacteria or both often accompanied respiratory Cryptosporidium sp. infections. Histologic lesions (including those of ciliary-adherent bacteria) are described. As the inflammatory response in infected organs became progressively nonpurulent (lymphocytes and plasma cells predominate), numbers of Cryptosporidium diminished. Cytologic preparations were useful for making diagnoses of respiratory cryptosporidiosis in chickens. Identification of epidemiologic features of respiratory cryptosporidiosis, and improved ability to make accurate and prompt diagnoses of Cryptosporidium sp. infection, are vital for a more complete understanding of the impact of this disease on poultry health.
Histopathology and direct immunofluorescent antibody (DIFA) tests were compared for diagnoses of infectious laryngotracheitis (ILT) in 144 cases of spontaneous respiratory disease in chickens presented to the Georgia Poultry Laboratory during 1988. For the 48 cases in which ILT was diagnosed, correct histologic diagnoses were made 100% (48/48) of the time and correct DIFA diagnoses were made 96% (46/48) of the time. For the 96 cases in which ILT was not diagnosed, correct histologic and DIFA diagnoses were made in every case. A Kappa test showed that DIFA was as effective as histopathology for the diagnosis of ILT in chickens (P = 0.0). It was concluded that increased use of DIFA could be instrumental in the abatement of ILT in chickens.
A prospective study to survey for the presence of parvovirus-like virus (PVLV; so-called chick anemia agent) antibody in broiler breeder pullets in Georgia, North Carolina, and Florida was conducted by collecting serum samples from 52 breeder flocks that ranged in age from 1 day to 55 weeks old. Results indicated that PVLV infection was widespread. Ninety-eight percent (51/52) of chicken flocks and 62% (530/861) of chickens had PVLV antibody. Rates of antibody-positive chickens among flocks ranged from 0% to 100% and averaged 76%. Upon initial examination, the percentages of chickens positive for PVLV appeared evenly distributed with respect to several convenient age groups and geographic locations. However, compared with young chickens (less than or equal to 19 weeks old), markedly significantly lower proportions of positives were present among chickens more than 19 weeks old (P = 0.00001) or chickens 30 weeks old or more (P = 0.000004). Also, there were significant (F = 7.7, df = 3/827, P less than 0.001) differences among the rates of PVLV antibody in chickens among various companies. The relatively high rate of PVLV antibody among broiler breeder chickens helps explain the low incidence of clinical disease among their offspring.
Chicken anemia agent (CAA)-antibody-positive and -negative broiler chicks and specific-pathogen-free chicks were confined in six broiler houses. Data on seroconversion to common avian pathogens and production performance were collected. No significant differences were seen between CAA-antibody-positive and -negative chickens in geometric mean antibody titers against common avian pathogens or in production performance.
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