Potential of low pathogenicity avian influenza viruses of wild bird origin to establish experimental infections in turkeys and chickens

The potential of low pathogenicity (LP) avian influenza virus (AIV) isolates of wild bird origin to establish infection in commercial turkeys and broiler chickens was studied. Isolates, representing subtypes H5N1, H7N3, H6N2, and H3N6, were recovered in 2005 and 2006 from waterfowl and shorebirds in the Delmarva Peninsula region of the east coast of the United States. The LP AIV isolates were not pathogenic for 2-wk-old meat-type turkeys and broiler chickens. No mortality, clinical signs, or gross lesions were observed following intratracheal and conjunctival sac routes of exposures with 10(6.0) EID50 (embryo infectious dose) per bird. Isolates resulting in an established infection based on virus isolation were: A/mallard/Maryland/1159/ 2006 (H5N1) in the upper respiratory tract of turkeys; A/mallard/Delaware/418/2005 (H7N3) in the upper respiratory and intestinal tracts of turkeys and chickens; and A/shorebird-environment/Delaware/251/2005 (H3N6) in the upper respiratory and intestinal tracts of chickens. Infections were also confirmed by production of AIV-specific serum antibodies detected by hemagglutination inhibition.     

RESULTS OF COMPUTED TOMOGRAPHY IN DOGS WITH SUSPECTED WOODEN FOREIGN BODIES

Detection of wooden foreign bodies in dogs can be challenging. A retrospective, cross‐sectional study was done to describe computed tomographic (CT) signs associated with wooden foreign bodies, and to estimate the accuracy of CT for detection of wooden foreign bodies. Patient records and CT images were reviewed for 72 dogs that had a history of suspected stick injury and CT of the affected body part, or possible wooden foreign object reported on CT, and had surgical exploration during the same period of hospitalization. Duration of clinical signs was acute in 48 (67%) dogs and chronic in 24 (33%). Wood was removed from 55 dogs, including a piece of a tree or shrub in 33 (60%) instances, kebab stick in 8 (15%), piece of bamboo garden cane in 2 (4%), cocktail stick in 2 (4%), thorn in 1 (2%), and unidentified wood in the remaining nine instances. Based on review of CT images with knowledge of the surgical findings, sensitivity of CT for wooden foreign bodies was 79% (95% CI 65%–89%), specificity 93% (78%–98%), positive likelihood ratio 11.5 (2.9–44.1), and negative likelihood ratio 0.23 (0.13–0.41). Wooden foreign bodies were predominantly rectangular or linear, with median length 48 mm (range 2–270 mm), median thickness 3 mm (range 1–22 mm), and median attenuation 111 HU (range ?344 to +640 HU). A CT finding of gas in soft tissues was significantly associated with acute cases, whereas suspected foreign material, cavitary lesions, fat stranding, and periosteal reaction on adjacent bones were associated with chronic cases.     

Improved detection of Mycobacterium avium subsp. paratuberculosis In milk by immunomagnetic PCR

The potential use of a novel immunomagnetic PCR (IMS-PCR) technique as a rapid method to screen milk samples for the presence of Mycobacterium avium subsp. paratuberculosis (M. ptb) was assessed. Immunomagnetic separation (IMS) for M. ptb, developed at Queen's University, Belfast, was applied to milk samples prior to IS900 PCR in order to selectively concentrate any M. ptb cells present and, at the same time, separate the cells from constituents of milk likely to inhibit subsequent PCR. This increased the sensitivity of IS900 PCR. IMS-PCR sensitivity could be further increased by initial centrifugation (2500 g for 20 min) of larger volumes of milk (10 and 50 ml), and resuspension of the sediment into a 1 ml volume appropriate for IMS treatment. Following IMS, template DNA for IS900 PCR was obtained by heating the bead-cell suspension in a thermal cycler at 100 degrees C for 15 min. It was estimated that the IMS-PCR assay could detect approximately 10(3)CFU of M. ptb per 50 ml of milk (equivalent to 20 CFU/ml), whereas the minimum detection limit of direct IS900 PCR was estimated at 10(5)CFU of M. ptb per 50 ml (equivalent to 2000 CFU/ml). A blind trial was carried out in which a total of 40 spiked (10(6)CFU M. ptb) and unspiked, raw and laboratory-pasteurised milk samples were independently tested by IMS-PCR and conventional IS900 PCR. IMS-PCR correctly identified 97. 5% of milk samples (sensitivity 100%, specificity 95%), including spiked milk samples before and after laboratory-pasteurisation. One false positive result was obtained which may have resulted from carryover between samples during the IMS procedure. Conventional IS900 PCR correctly identified only 72.5% of the same 40 milk samples (sensitivity 23%, specificity 100%). IMS-PCR was also shown to be capable of detecting natural M. ptb infection in raw sheep's milk, and raw and commercially pasteurised cows' milk.     

Genetic variation in susceptibility to Marek's disease in a commercial broiler population.

Two commercial broiler pure lines that were previously identified to differ in their susceptibility to Marek's disease (MD) were line-crossed to generate an F1 population. Eight F1 males were randomly mated to four or five F1 females to produce an F2 test population that would be segregating for genes affecting MD. All F2 progeny (four hatches) were pedigreed at hatch and placed in colony houses as nonvaccinated. At 5 days of age, they were challenged intraabdominally with MD virus RB1B. Clinical signs, mortality, and gross and microscopic lesions were recorded during the MD challenge. At 8 wk postchallenge, all remaining birds were euthanatized and necropsied. During the MD challenge of the first two hatches, we observed that several severely stunted broilers originated from certain families and the differences in body weight among birds appeared as early as 3 wk postchallenge. To confirm this observation, body weight at 6 wk postchallenge was determined for all surviving birds in hatches 3 and 4 (n = 242). Genetic variation in body weight among broiler sire families was apparent; the average body weight for males at this time was 2.07 kg, whereas with females, it was 1.87 kg. At least 12.2% of the broilers, including both sexes, weighed less than 1 kg ("severely stunted") at this time. The incidence of these growth-stunted birds within each broiler sire family ranged from 0 to 26% and for dam families, 0 to 60%. Correlation analyses between stunting and other MD-associated traits revealed that the incidence of stunting had a significant and positive association with paralysis (r = 0.50). Therefore, the data suggest that there may be a genetic component affecting body weight loss during MD infection. The genetic component is speculated to affect susceptibility to MD paralysis with an indirect effect on the body weight of birds. The significance of this finding is best exemplified by the identification of a broiler sire family with over 26% of its progeny affected by this MD-associated trait.     

Environmental characteristics of black crappie (Pomoxis nigromaculatus) nesting sites in two South Dakota waters

Abstract— A biotelemetry study was undertaken during spring 1995 to identify black crappie ( Pomoxis nigromaculatus ) nesting sites in two South Dakota water bodies. Individually coded ultrasonic transmitters were implanted into the body cavity of 15 adult male black crappie in each water body prior to spawning. Available habitat characteristics were recorded at 75 randomly selected sites within each water body, and habitat characteristics at nesting sites were recorded for each male black crappie believed to be nesting. Of the habitat characteristics analyzed, only substrate firmness did not differ ( P =0.79) between water bodies. In Richmond Lake, black crappie selected nesting sites with live cattails ( Typha spp.) that were protected from prevailing south winds. In Brant Lake, black crappie selected nest sites with vegetation (usually woody debris) and silty substrate that had warmer water and were protected from wind and waves. It appeared that black crappie nested in the most protected areas available.