Estimating within-flock transmission rate parameter for H5N2 highly pathogenic avian influenza virus in Minnesota turkey flocks during the 2015 epizootic.

Better control of highly pathogenic avian influenza (HPAI) outbreaks requires deeper understanding of within-flock virus transmission dynamics. For such fatal diseases, daily mortality provides a proxy for disease incidence. We used the daily mortality data collected during the 2015 H5N2 HPAI outbreak in Minnesota turkey flocks to estimate the within-flock transmission rate parameter (ß). The number of birds in Susceptible, Exposed, Infectious and Recovered compartments was inferred from the data and used in a generalised linear mixed model (GLMM) to estimate the parameters. Novel here was the correction of these data for normal mortality before use in the fitting process. We also used mortality threshold to determine HPAI-like mortality to improve the accuracy of estimates from the back-calculation approach. The estimated ß was 3.2 (95% confidence interval (CI) 2.3-4.3) per day with a basic reproduction number of 12.8 (95% CI 9.2-17.2). Although flock-level estimates varied, the overall estimate was comparable to those from other studies. Sensitivity analyses demonstrated that the estimated ß was highly sensitive to the bird-level latent period, emphasizing the need for its precise estimation. In all, for fatal poultry diseases, the back-calculation approach provides a computationally efficient means to obtain reasonable transmission parameter estimates from mortality data.

Culicoides bottimeri as a vector of Haemoproteus lophortyx to quail in California, USA.

Arthropod sampling via periodic direct bird examination and regular light trapping was conducted between June 2000 and October 2002 to survey for potential vectors of Haemoproteus lophortyx to nonnative, captive-raised bobwhite quail (Colinus virginianus) in northern California, USA. Examination of individual bobwhite quail (from 5 weeks of age through adult, total n=76) was conducted on several dates during the transmission period (June-October). No ectoparasites, including hippoboscid flies (reported as Haemoproteus vectors to wild quail in early literature), were collected from the birds. Trapping with ultraviolet light suction traps near the quail revealed nine species of biting midges (Culicoides spp.). Of these, 94% were C. bottimeri, which was abundant near the birds, and 65% of collected C. bottimeri were engorged with blood. C. bottimeri adult activity began in late-April, slightly before the onset of disease in the quail. Activity peaked between July and late-September, coincident with maximum reported transmission, and adult activity ceased by early-November. Nonengorged C. bottimeri had a parity rate of 43.6% overall, suggesting excellent survival for biological transmission of a pathogen like H. lophortyx. A controlled study was done injecting a macerated slurry of pooled, nonengorged, wild-caught C. bottimeri into the peritoneum of 1-day-old bobwhite quail hatchlings held in insect-proof containers. Blood smears 13-19 days later confirmed H. lophortyx infection in zero controls but all insect-injected quail. Biting midges, especially C. bottimeri, transmit H. lophortyx to captive quail and probably are the dominant vector to native California quail (Callipepla californica) as well.

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.

Wry necks associated with Mycoplasma meleagridis infection in a backyard flock of turkeys.

Two 5-week-old bronze turkeys were submitted with crooked necks that could not be straightened. Both birds were serologically and culturally positive for Mycoplasma meleagridis (MM). Histologically, there were lymphoid follicles in the cranial thoracic and cervicoclavicular air sacs, and inflammatory changes in the cartilage of some cervical vertebrae. This appeared to be a case of MM-associated wry necks.

True hermaphrodites in a flock of Cochin bantams.

Three birds from a flock of 125 Cochin bantam chickens were true hermaphrodites, having both ovarian and testicular tissues. These birds were recognizable by their intermediate comb size, intermediate plumage, and spur development. At necropsy, the left gonad of all three birds was an ovotestis and the right gonad was a testis. Microscopically, both ovarian follicles and seminiferous tubules were present within the ovotestes. Chromosomal analysis of lymphocytes from the whole blood of the third bird revealed triploid ZZW sex chromosomes. This high incidence (2.4%) of hermaphrodism suggests that there may be a hereditary predisposition for genetic intersex.

Squamous-cell carcinoma on the legs of an Aracauna chicken.

Squamous-cell carcinoma was diagnosed on both legs of a 6-year-old pet Aracauna chicken. Grossly, the tumors were raised and horny with superficial ulceration. Histologically, the tumors were highly invasive, extending deep into the dermis, tendon sheaths, and periosteal tissues. There was no evidence of vascular invasion or metastasis to other organs.

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.

A syndrome in commercial turkeys in California and Oregon characterized by a rear-limb necrotizing skeletal myopathy.

A necrotizing skeletal myopathy of rear limbs was diagnosed in 17 flocks of commercial turkeys. The mean mortality attributed to the myopathy was 2.29% (range = 0.13-9.7%) over a mean period of 9.6 days (range = 6-14 days). The mean age of the birds at the time of onset was 7.4 weeks (range = 4-10.5 weeks). Clinically, birds experienced an episode of watery droppings and high-pitched crying, followed by rear-limb paresis or paralysis. Creatine kinase and aspartate aminotransferase were markedly elevated in birds with the myopathy. Grossly, a few birds had pale streaking in the muscles of the thighs and legs. Histologically, acute and subacute degeneration was present in myofibers of the legs, abdomen, thighs, back, and tail. The subacute lesion was characterized by marked sarcolemmal cell proliferation. Feed analyses ruled out selenium deficiency and the presence of mycotoxins as etiologies. Monensin was present in approved usage or only slightly elevated levels. A known potentiating antibiotic was being used concurrently with monensin in only one flock.

Intranuclear inclusions of unknown pathogenic significance from diagnostic cases in three avian species.

Intranuclear inclusions were observed with light microscopy in tissues from necropsy cases from three different species of birds. Because of the nature of these inclusions, the species affected, or their distribution, the inclusions were considered of unknown pathogenic significance. The inclusions were examined ultrastructurally. Parvovirus-like particles were observed in the intranuclear inclusions of pigeon hepatocytes and duodenal stromal cells from a quail. Finely granular eosinophilic intranuclear inclusion bodies from two unrelated pigeon cases were found to be composed of loosely organized filaments. One liver sample from a 16-week-old laying chicken had prominent eosinophilic hepatocellular intranuclear inclusions composed of electron-dense coarsely granular amorphous material.

Skeletal myopathy produced with experimental dosing of turkeys with monensin.

Monensin was given via gavage to 5- and 6-week-old broad-breasted white turkeys. The birds were allotted into four groups--three groups given monensin and one group of controls--in two experimental trials. Treated turkeys in Trial 1 received one dose of monensin per day for 4 days at 4.7 mg monensin/kg body weight, 8.8 mg/kg, or 17.6 mg/kg. Treated turkeys in Trial 2 received one dose of monensin per day for 5 days at 1.93 mg/kg, 4.7 mg/kg, or 8.8 mg/kg. Turkeys receiving the lowest dose showed no clinical signs of myopathy. Birds receiving 4.7 mg monensin/kg developed ataxia after the third dose and rear limb paresis and paralysis after the fifth dose. Turkeys receiving 8.8 mg/kg were ataxic after the second dose and paretic or paralyzed after the fourth dose. Turkeys receiving 17.6 mg/kg were ataxic 3 hours after the first dose and paretic or paralyzed 8 hours after the first dose. Histologically, a necrotizing skeletal myopathy was present in the muscles of the rear limbs. A dose-related response was observed in the percentage of myofibers damaged in birds that survived until the end of the trials. Intrafiber edema and vacuolation were observed in histologic sections from myocardium of turkeys from the two highest dose groups.

Enterococcus durans infection in young chickens associated with bacteremia and encephalomalacia.

Two unrelated flocks of chicks experienced elevated mortality from 4 to 10 days of age. Clinical signs in affected birds included a full range of neurological disorders. Livers and spleens were grossly enlarged at necropsy. Enterococcus durans was isolated from multiple organs, including brains. Histologically, there were multifocal coagulative necrosis in the liver, areas of malacia in brain stem, and cerebellar white matter. Inoculation of 1-day-old chicks with a suspension of E. durans resulted in bacteremia but did not produce the lesions observed in field cases.

Facial cellulitis associated with fowl cholera in commercial turkeys.

Severe cephalic swelling and facial cellulitis in turkeys associated with fowl cholera were present in seven accessions submitted to two laboratories in a 2-year period. Flocks ranged in age from 6 to 18 weeks and included both toms and hens. Interestingly, turkeys with facial cellulitis had no gross internal lesions of fowl cholera, whereas birds with gross lung, liver, and air-sac lesions did not have swollen heads. Histologically, the facial cellulitis was characterized by extensive fibrinonecrotic inflammation of the deep dermis with heterophilic perivasculitis and thrombosis. Additional characterization of Pasteurella multocida isolates from these cases was conducted retrospectively from lyophilized cultures. Serogrouping, serotyping, and an enzyme-linked immunosorbent assay (ELISA) for dermonecrotic factor were performed. All isolates were serogroup A or unencapsulated. Serotype 1 was the most prevalent serotype isolated in association with facial cellulitis. ELISA results for dermonecrotic toxin were inconclusive.

Protection of turkeys from hemorrhagic enteritis with a recombinant fowl poxvirus expressing the native hexon of hemorrhagic enteritis virus.

Hemorrhagic enteritis (HE) is an economically important disease of turkeys caused by a type II aviadenovirus, hemorrhagic enteritis virus (HEV). The vaccines currently available to the commercial poultry producer are highly effective in preventing disease outbreaks; however, they are immunosuppressive. A recombinant fowl poxvirus (rFPV) expressing the native hexon of HEV has been shown to induce an anti-HEV humoral immune response in turkeys. In this study, the rFPV expressing the native hexon of HEV was compared with a commercial HEV vaccine (vxHEV) for its ability to protect turkeys from virulent HEV challenge. Complete protection from the enteritis of HE was achieved in experimental groups vaccinated with either the rFPV or the vxHEV. Lymphocyte stimulation was measured in turkeys inoculated with rFPV, vxHEV, or a sublethal dose of HEV or not inoculated. No statistically significant immunodepression was observed in turkeys receiving the rFPV.

Effect of orally administered epidermal growth factor on the jejunal mucosa of weaned pigs.

The effect of ingested epidermal growth factor (EGF) on the small intestinal mucosa of conventionally weaned pigs was determined. At 21 days of age, 39 pigs were randomly distributed into suckling and weaned treatment groups that were administered 124 micrograms of EGF, 372 micrograms of EGF, or the dosing compound daily. Fecal water content was determined daily. On postweaning days 0, 3, 6, and 9, representative pigs from each group were euthanatized, and jejunal mucosa samples were collected for determination of villus-to-crypt ratio, total protein content, disaccharidase activities, and microbiological populations. At postweaning day 3, the 372-micrograms dose of EGF significantly (P less than or equal to 0.05) increased jejunal lactase and sucrase activities in the weaned pigs. Increased lactase activity was not greater than that of the suckling pig controls, whereas sucrase activity was significantly (P less than or equal to 0.05) higher than that of the suckling pig controls. Significant changes were not observed in villus-to-crypt ratio, mucosal protein content, or disaccharidase activities on other collection days.

Characterization of a recombinant fowlpox virus expressing the native hexon of hemorrhagic enteritis virus.

The structure of the icosahedral adenovirus capsid is highly conserved among Adenoviridae. In its native form, the hexon is the major capsid protein. The nascent hexon requires the 100 kDa folding protein to fold into its native, trimeric form. The hexon and 100 kDa folding protein were co-expressed in a fowlpox virus (FPV) vector and in the recombinant FPVs (rFPVs) in which the hexon and 100 kDa folding protein genes are cloned head to tail, the native hexon could be detected with indirect immunofluorescence and immunoprecipitation using a native hexon monoclonal antibody. The FPV-@X100 construct, in which the 100kDa folding protein gene follows the hexon gene in a head to tail fashion, elicited the best humoral response in chickens. An attenuated HEV commercial vaccine elicited higher and longer lasting anti-HEV titers than FPV-@X100. Humoral immunity was also compared in turkeys inoculated with rFPVs expressing the hexon alone, the 100 kDa folding protein alone, or expressing both genes in different configurations. No anti-HEV humoral immune response was detected in turkeys inoculated with the rFPVs expressing the hexon alone or the 100 kDa folding protein alone.