A. A. Bickford

Salmonella enteritidis, phage 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.

Preliminary Characterization of a Pleomorphic Gram-Negative Rod Associated with Avian Respiratory Disease

An unidentified, pleomorphic, gram-negative rod (PGNR) bacterium has been isolated from domestic fowl with respiratory disease. The PGNR was isolated in 5% of turkey accessions and 3% of chicken accessions, primarily from the respiratory tract. Preliminary characterization of this organism included reviewing accession records, conducting cultural and biochemical tests, and analyzing cellular fatty acids. The PGNR was also compared with other bacteria capable of inhabiting the avian respiratory system. Biochemical and cellular fatty acid analysis failed to identify the organism, however all 14 isolates were similar.

Investigation of problems associated with intramuscular breast injection of oil-adjuvanted killed vaccines in chickens.

Case submissions and a field investigation indicated that oil-adjuvanted killed vaccines may produce long-lived residual lesions in chickens. The lesions typically are yellow opaque cysts along the fascial planes separating the superficial and deep pectoral muscles. Microscopic evaluation shows that most lesions are cysts with thin fibrous capsules, sometimes associated with lymphocytic aggregates and, more rarely, a granulomatous reaction.

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.

Pathogenicity of Campylobacter jejuni for Turkeys and Chickens

A Campylobacter jejuni isolate obtained from a turkey liver, designated C101, and a C. jejuni isolate obtained from the feces of a chicken, designated C111, were used to inoculate their respective hosts. Isolate C101 depressed weight gain by 20% when inoculated into newly hatched poults or 4-day-old poults. It also caused death, hepatic necrosis, and generalized hemorrhages in turkey embryos. The chicken-derived isolate, C111, did not reduce weight gain in newly hatched chicks, but it did induce mortality in chicken embryos. The supernatant of the cultures of both C. jejuni isolates also caused mortality in embryos.

Complementary Randomly Amplified Polymorphic DNA (RAPD) Analysis Patterns and Primer Sets to Differentiate Mycoplasma Gallisepticum Strains

Randomly amplified polymorphic DNA (RAPD) analysis was used to differentiate 7 strains of Mycoplasma gallisepticum. Six commercially available primers or primer combinations were screened for their ability to differentiate vaccine and type strains. Although major and minor bands were produced with each primer, many of the primers were unsuitable for strain differentiation. The use of primer 6 and combined primers 3 and 4 resulted in complementary RAPD banding patterns for each M. gallisepticum strain. Eleven different isolates representing 7 different strains were segregated into 7 different patterns, corresponding to the 7 strains.

Periodic recurrence of gangrenous dermatitis associated with Clostridium septicum in a broiler chicken operation

The association of gangrenous dermatitis (GD) of chickens with Clostridium septicum infection was well documented in the United States during the 1960s (Bickford AA: 1971, Proc 20th Western Poult Dis Conf, pp. 6, 7). At about the same time, GD was recognized as a source of considerable economic loss to broiler production operations in the United Kingdom and Australia. 1,3 Subsequently, the potentiating role of immunosuppression induced by infectious bursal disease virus (IBDV) and other viral agents was recognized. Reduction of losses caused by GD requires control procedures for IBDV and other immunosuppressive agents. Recent reports have suggested that there may be an increased incidence of the clostridial diseases of chickens in the United States. Among these diseases, GD associated with C. septicum is a major concern. At the California Veterinary Diagnostic Laboratory System (CVDLS), Turlock Branch, the diagnosis of this disease was once as frequent as 5% of all diagnostic cases (Bristow DL: 1971, Proc 20th Western Poult Dis Conf, p. 11). After producers implemented procedures to limit the effects of IBDV, the diagnosis of GD became a rare event in California. This report documents an unusual annual recurrence of C. septicum-associated GD over 3 consecutive years in a single house of a multiple-house broiler facility. The ranch involved in this report is situated on flat delta valley terrain and consists of 8 broiler houses. The houses are similar in design but differ in size. Three houses are 10,000 sq ft, 3 are 15,000 sq ft, and 2 are 17,500 sq ft. Feed sources, feed delivery systems, ventilation systems, and litter management procedures are uniform on the ranch. A single well serves as the water source for all houses, and hot-water brooding is practiced in all houses. The ranch is operated on a year-round all-in, all-out basis. On February 3, 1993, 7 dead 43-day-old broiler chickens were submitted from house 5 (15,000 sq ft) to CVDLS, Turlock Branch, for necropsy. Mortality in the house had increased suddenly to about 1% per day. Stocking density in all three 15,000-sq-ft buildings had been 19,000 chicks at placement. This density is approximately 8.5% higher than normal for these houses. Climatic conditions were normal for winter with characteristically high humidities and cool temperatures. Litter conditions in the house were described as old and wet. On January 18, 1994, a similar group of 6 dead broiler chickens was submitted from house 5. A sudden increase in mortality had occurred in this house only. The birds were

The Diagnosis of Very Virulent Infectious Bursal Disease in California Pullets

Abstract This report documents the occurrence of a very virulent infectious bursal disease virus (vvIBDV) in Northern California commercial brown pullets. Diagnosis was made from multiple accessions from two neighboring and epidemiologically related ranches submitted to the California Animal Health and Food Safety (CAHFS) laboratory. Pullets, 11 and 14 wk of age from ranch A (rA) and ranch B (rB) respectively, were submitted from infectious bursal disease virus vaccinated flocks experiencing a drastic increase in mortality. The December 2008 outbreak resulted in 26% and 34% mortality on rA and rB respectively. Gross and histologic lesions characteristic of acute vvIBDV were observed. Gross lesions included edematous bursas, hemorrhages at the junction of the proventriculus and gizzard as well as hemorrhages on skeletal muscles. Microscopic lesions included severe lymphoid necrosis and inflammation in edematous bursas, lymphoid necrosis in thymus, spleen, Peyers patches and cecal tonsils. Diagnosis of vvIBDV was confirmed by molecular characterization of the IBDV from bursas as well as viral pathogenicity in specific-pathogen-free birds. RT- PCR and nucleotide sequencing of the hypervariable region of the VP2 (vVP2) gene segment of the IBDV genome was performed on rA, rB and embryo passaged rA virions.The amino acids compatible with vvIBDV isolates: 222(Ala), 242(Ile), 256(Ile), 294(Ile) and 299(Ser) were reported from both ranches. In addition, nucleotide sequencing of a fragment of the VP1 gene demonstrated the viruses have the segment B genotype associated with highly pathogenic vvIBDV. Inocula of 105.5 50% egg infective dose of vvIBDV virus from rA and rB were introduced orally into two groups (g1 and g2 respectively) of 4 wk 2-day-old SPF leghorns. At 4 days postinoculation, there was 100% (22/22) morbidity in g1 and g2; 91% (20/22) mortality in g1; 100% (22/22) mortality for g2; 0% (0/20) morbidity and 0% (0/20) mortality was reported in the control group. This is the first occurrence of vvIBDV reported from birds in the United States.

Infectious coryza in meat chickens in the San Joaquin Valley of California.

Two cases of infectious coryza in meat chickens are reported. The first case involved 6-week-old broiler chickens in which only Haemophilus paragallinarum was isolated. The second case involved 11-week-old roaster chickens in which H. paragallinarum and Mycoplasma synoviae were isolated. Both farms were in close proximity to layer-chicken farms where infectious coryza had been previously diagnosed. In both cases, only certain houses on the farm were affected, and mortality in these houses increased slightly. At processing, the condemnation rates for affected houses were considerably higher than rates for unaffected houses. Condemnations for affected houses were mostly due to airsacculitis. A dissecting fibronopurulent cellulitis was a prominent lesion in the second case. This lesion could lead to confusion with chronic fowl cholera and swollen-head syndrome.

Avian Paramyxovirus Type 1 Infections in Racing Pigeons in California. I. Clinical Signs, Pathology, and Serology

An outbreak of diarrhea and neurological disease in California racing pigeons caused by avian paramyxovirus type 1 (PMV-1) is documented. Predominant clinical signs were polydipsia, ataxia, poor balance, torticollis, head tremors, inability to fly, and diarrhea that was unresponsive to therapy. Gross pathologic findings were often unremarkable or non-specific. The predominant histologic lesions were interstitial nephritis, chronic tubular necrosis, lymphoplasmacytic infiltration within the kidney, liver, and pancreas, and focal non-suppurative encephalitis. Pigeons from 20 submissions demonstrated characteristic clinical signs of PMV-1 infection. Pigeons from 17 submissions exhibited typical histopathology. Serologic evidence of PMV-1 infection was present in pigeons from 13 submissions, and PMV-1 was isolated from pigeons received in six submissions. None of these pigeons had been vaccinated against PMV-1.