Biomedical subjects

D H Read

Publications and source records attributed to D H Read.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Tracheal aspergillosis in 6 1/2-week-old chickens caused by Aspergillus flavus.

A case of localized tracheal aspergillosis in 6 1/2-week-old single-comb white leghorn pullets caused by Aspergillus flavus is documented. Yellow caseous plaques adherent to the mucosal surface of the tracheas were observed grossly. In several tracheas, the plaques occluded the lumina, and the surrounding tracheal walls were reddened. Histologically, the mucosa was necrotic and infiltrated with macrophages, and fibroplasia was evident in the subadjacent tracheal wall. The lumen of the trachea was almost completely occluded by a combination of fungal mycelia and pyogranulomatous exudate. Portions of tracheal cartilage were elevated into the lumen of the trachea. Other than a sudden increase in mortality to 0.5% per day, there was no evidence of disease in the flock. Depletion of bursal lymphocytes, with concomitant cryptosporidiosis, was evident on histological examination. Acute infectious bursal disease was diagnosed in the succeeding flock at this ranch based upon serology and typical histology.

Animals↗

PubMedDate not supplied

Salmonella enteritidis, phase type 4 infection in a commercial layer flock in southern California: bacteriologic and epidemiologic findings.

Salmonella enteritidis, phage type 4 (SE PT4), was isolated from five of six 27-wk-old layer chickens submitted for necropsy from a flock of 43,000. Bacteriologic and epidemiologic investigations on the ranch revealed that five of the eight flocks (n = 176,000) were infected. The prevalence of SE PT4 in randomly selected healthy birds ranged from 1.7% (in caged birds) to 50% (in free-range birds) and prevalence in culled birds (kept on dirt floor houses) ranged from 14% to 42%. The estimated overall prevalence of group D Salmonella in eggs contaminated with group D Salmonella was 2.28 per 10,000. The estimated prevalence of group D Salmonella in eggs from caged birds in three infected houses ranged from 1.5 to 4.1 per 10,000, whereas in two houses of free-range birds, prevalence was 14.9 to 19.1 per 10,000. Three of the eight flocks on the ranch remained negative for Salmonella between May 1994 and December 1995 or until removed from the ranch. Salmonella enteritidis PT4 was also isolated from 12.5% (6 of 48) of mice; 57% (four of seven) of cats; and two of two skunks tested. Environmental drag swabs and well water samples yielded multiple serotypes of Salmonella (23/180 and 5/14, respectively) but not S. enteritidis.

Animals↗

PubMedDate not supplied

Sewage effluent: likely source of Salmonella enteritidis, phage type 4 infection in a commercial chicken layer flock in southern California.

Following the diagnosis of Salmonella enteritidis, phage type 4, infection in a commercial layer flock in southern California, effluent from a nearby sewer treatment plant was investigated as a potential source of infection. Between July 1994 and March 1995, 68 Salmonella isolations, comprising 27 serotypes, were made from the inflow (raw sewage) and effluent (treated sewage). Thirty-nine of 68 (57%) isolations yielded six serotypes, which consisted of S. enteritidis 12% (8/68), S. cerro 10% (7/68), S. typhimurium 7.4% (5/68), S. tennessee 7.4% (5/68), S. give 7.4% (5/68), S. mbandaka 7.4% (5/68), and S. panama 6% (4/68). The remaining 43% (29/68) isolations were represented by 21 serotypes. Seventeen S. enteritidis isolates originating from the effluent (creek water), resident feral animals (rodents, stray cats, skunks), and chickens (organs, eggs) of the affected flock were subjected to plasmid profile and restriction endonuclease analysis. Twelve of the 17 isolates had identical plasmid profile and restriction digestion patterns. Two of 17 isolates showed similar patterns but both differed from the rest; and 1 of 17 did not yield plasmids. Two other isolates were found to be different from each other and from the rest of the group.

Animals↗

PubMedDate not supplied

Prevalence of Salmonella in municipal sewage treatment plant effluents in southern California.

Effluents from 12 sewage treatment plants in southern California were examined for Salmonella using a Moore swab technique. Eight of the 12 plants were positive for Salmonella when sampled at the chlorination/dechlorination site (inside the plant). Effluents from 11 of 12 sewage treatment plants were positive for Salmonella when samples were analyzed downstream of the chlorination/dechlorination site, before effluents merge with the receiving stream (outside the plant). Two of the three control sites, an urban runoff, a raw potable water reservoir, and two other sites were also positive for Salmonella. A total of 683 Salmonella isolations were represented by 11 serogroups and 54 serotypes from 26 of 32 sampling sites. Effluents from three treatment plants and one control site (raw potable water resevior) yielded Salmonella enteritidis phage type 4, in addition to other serotypes.

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