High mortality of domestic turkeys associated with Ascaridia dissimilis.

Third- and fourth-stage Ascaridia dissimilis larvae were isolated from commercial white turkey intestinal scrapings from two farms that were experiencing high mortality. Lesions consisted of a necrotic-like enteritis that was most severe in the jejunum. Subsequent bacteriological isolation yielded heavy growth of Escherichia coli and Clostridium perfringens. The rate of mortality declined rapidly when the turkeys were administered 18 ppm fenbendazole for 7 days.     

Studies on the effect of concurrent infections of Ascaridia dissimilis and Eimeria meleagrimitis in turkeys.

The effects of concurrent infections of Ascaridia dissimilis and Eimeria meleagrimitis in turkeys were studied in two separate trials. In the first trial, newly larvated ova were used to inoculate poults 7 or 3 days before, on the same day as, or 3 days after the poults received E. meleagrimitis. Poults receiving the A. dissimilis 3 days before, on the same day as, or 3 days after receiving E. meleagrimitis had significantly lower total oocyst production than the E. meleagrimitis-positive control. In the second trial, larvated ova that were approximately 100 days old were used in the same regimen. In this trial, poults that were inoculated with A. dissimilis 3 days before or 3 days after receiving the E. meleagrimitis produced significantly fewer oocysts than poults inoculated simultaneously with both parasites. Poults inoculated with A. dissimilis 3 days before receiving E. meleagrimitis also had significantly fewer third-stage nematodes than the A. dissimilis-positive controls. There were no significant differences in weight gain between treatments in either trial.     

Efficacies of fenbendazole and levamisole in the treatment of commercial turkeys for Ascaridia dissimilis infections

A field trial was conducted on a farm in Michigan with commercial turkeys naturally infected with Ascaridia dissimilis. The birds were treated at approximately 8 and 14 wk of age on a per-barn basis with fenbendazole (Safeguard) in the feed at 16 ppm for 6 d (1 barn), or with levamisole (Prohibit) in the water at 16 mg/kg of BW (2 barns). Six birds were obtained at random and sacrificed in each barn for worm burden determinations before treatments and again soon after treatments. Nematicidal efficacies for fenbendazole and levamisole were shown to be 99.3 to 99.9% and 54.6 to 85.8%, respectively. Despite the far greater reductions in worm burdens by fenbendazole as compared with levamisole, the burdens at the time of retreatment had equalized in all barns, illustrating the role of premunition regarding turkey ascaridiasis, and highlighting the overriding importance of reducing the challenge to provide long-term control of this parasitism.     

Comparative efficacy of flubendazole and a commercially available herbal wormer against natural infections of Ascaridia galli, Heterakis gallinarum and intestinal Capillaria spp. in chickens

The efficacy of a commercially available flubendazole-based product and a commercially available herbal product were compared against three species of helminth parasites of chickens: Ascaridia galli, Heterakis gallinarum and Capillaria spp. A total of 48 naturally infected chickens were used in the study with 16 birds in each of three treatment groups (untreated control; flubendazole; and a herbal product). One bird from each treatment group was necropsied on Day 0 prior to first treatment to confirm the parasite species present in the birds. Treatments were administered as labelled and the 45 remaining birds were necropsied on Day 12 and worm counts performed. Average worm counts in the two treated groups were compared to the untreated controls to calculate efficacy. Flubendazole (Group A) achieved an overall efficacy of 99.4% for the three parasite species. The herbal product (Group B) achieved efficacies ranging from less than zero to 11.6% for the three parasites, with worm counts not significantly different to the untreated controls. At present, commercially available herbal products claiming anthelmintic properties do not require licencing as veterinary medicinal products (Directive 2004/28/EC: see Article 17 and 33-38) and thus are not required to meet specific efficacy thresholds. Products which do not appear to deliver acceptable anthelmintic efficacy, are obviously a concern from many aspects but specifically from an animal welfare perspective.     

Precision, repeatability and representative ability of faecal egg counts in Heterakis gallinarum infected chickens

This study investigated whether a precise and repeatable quantification of Heterakis gallinarum egg excretion, which considerably reflects the actual worm burdens, can be achieved based on collection of the daily total amount of faeces from chickens. Three-week-old birds (N=64) were infected with 200 embryonated eggs of H. gallinarum, and placed into individual cages 3 wk after infection for 5 wk to collect daily faeces (N=2240). The total daily faeces was mixed and a randomly taken sample per bird was analyzed to estimate the numbers of eggs per gram of faeces (EPG) and total number of eggs excreted within 24h (EPD). A total of 235 daily faecal collections were randomly selected and further examined to determine between and within sample variations of EPG counts as a measure of precision. For this, two random faecal samples were taken from the daily produced faeces by a bird, and the EPG was determined for each of the samples (EPG1 and EPG2). The second faecal sample was analyzed once more to determine a parallel EPG2 count (EPG2a) of the suspended sample. Precision of an EPG count was defined as its relative closeness to the average of two EPG counts using a relative asymmetry index (Index(EPG)). At an age of 11 wk, i.e. 8 wk p.i. the birds were slaughtered and their worm burdens were determined. There were no significant differences between EPG1 and EPG2 (P=0.764) nor between EPG2 and EPG2a (P=0.700), suggesting that the differences between or within the samples were not different from zero. Correlations between EPG counts, as between and within sample coherences, were r=0.85 and r=0.86, respectively. Precision of EPG counts, as measured by Index(EPG), was not influenced by consistency (P=0.870) and total amount of faeces (P=0.088). However, concentration of eggs in faeces (mean EPG) had a significant effect on the precision of the EPG counts (P<0.001). Similar results were also observed for the within sample precision (Index(EPG2)). A segmented regression analysis indicated an abrupt change in the precision of EPG counts as the response to changing egg concentration in the examined faecal samples. The precision of analyses remarkably heightened up to a breakpoint with an EPG count of ≤ 617. A similar breakpoint was also determined for within sample precision (EPG2 ≤ 621). Moderate repeatabilities (R=0.49) for EPG and EPD were estimated in the first week of egg excretion, whereas the estimates were higher (R=0.67-0.84) in the following weeks. Correlations between number of female worms with daily measured EPG and EPD increased to an almost constant level (r ≥ 0.70; P<0.05) in a few days after the nematode excreted eggs and predominantly remained so for the rest of the sampling period. It is concluded that mixing daily total faeces provides samples with random homogenous distribution of H. gallinarum eggs. Precision of the EPG counts increases as the egg concentration in faecal sample increases. Egg excretion of H. gallinarum, quantified either as EPG or EPD, is highly repeatable and closely correlated with the actual worm burden of birds starting as early as in 5 th wk of infection.     

An outbreak of avian encephalomyelitis in turkeys in Canada.

An outbreak of avian encephalomyelitis in two week old turkey poults is described. The disease was diagnosed by the fluorescent antibody technique and was confirmed by neutralization tests conducted in chicks.     

An outbreak of monensin poisoning in adult turkeys

Monensin, fed in excess of 200 ppm caused mortality in Triple 5 and Triple 6 turkeys aged 25 weeks old and over. Mortality commenced three to four days after administering feed containing monensin and ceased three to five days after it was removed. This concentration of drug did not have any detectable adverse effects on Triple 5 turkeys fed from day old, four weeks old, or 11 weeks old for periods of two weeks.     

Molecular characterization of Ascaridia galli from Bangladesh and development of a PCR method for distinguishing A. galli from Heterakis spp.

We analyzed the nuclear ribosomal internal transcribed spacer (ITS) 1 and ITS2 sequences for Bangladesh isolates of Ascaridia galli, and we determined that the sequences were unreliable as molecular markers for distinguishing A. galli from other Ascaridia species, because the sequences showed high identity with that of A. columbae. However, the ITS1 sequences were available for designing PCR primers distinguishable between Ascaridia galli and Heterakis spp. Bangladesh isolates of A. galli constituted a monophyletic clade along with other geographical isolates in the cytochrome c oxidase subunit I (COI) phylogenetic tree, however, we could not clarify the phylogenetic relationships between A. galli and other Ascaridia spp., because their available sequences in GenBank were very few. The developed PCR method using DNA from A. galli and Heterakis spp. eggs would enable differential diagnosis of the individual infections in the future.     

An outbreak of sarcocystosis in a cattle herd.

In a cattle herd, 3 steers had anorexia and variable emaciation; 1 showed additional muscle stiffness, pyrexia, became recumbent and was killed in extremis. Gross changes in tissue specimens from this steer included grey-white foci in the skeletal muscle and a thickened, fibrous pleura. By histology interstitial pneumonia, myocarditis and necrotizing myositis were seen. There were wide-spread vascular lesions with endothelial damage, thrombosis and periarterial infiltrations. Sarcocystis-like schizonts were found in several organs, and different stages of thin-walled sarcocysts were seen in the myocardium. Examination of organs of 6 other steers in the same herd slaughtered 2 months later showed myocarditis, myositis, interstitial pneumonia and occasional vascular occlusions. There were a few schizonts in the spleen and lungs, and thin-walled sarcocysts were seen in the myocardium and skeletal muscle. It is concluded that development of vascular lesions probably represents an important step in the pathogenesis of sarcocystosis.     

In vitro evaluation of B-lymphocyte function in turkeys infected with hemorrhagic enteritis virus

Studies were conducted on B-lymphocyte function in turkeys infected with hemorrhagic enteritis (HE) virus. Hemolytic plaque-forming technique was used to detect antibody-forming cells in turkeys. The plaque-forming cell responses in HE virus-infected and noninfected controls were compared. Results of this study indicated a decreased capability of HE virus-infected turkeys to produce antibodies to sheep RBC. The greatest inhibition of antibody-forming cell production was seen in the turkeys 19 days after exposure to the virus. However, after this period, the turkeys gradually recovered their immunocompetence to sheep RBC.