Characterisation of novel <Emphasis Type="Italic">Fusarium graminearum</Emphasis> microsatellite markers in different <Emphasis Type="Italic">Fusarium</Emphasis> species from various countries

Fifteen novel microsatellite markers were isolated from Fusarium graminearum. The level of polymorphism at these novel and 13 previously published microsatellite markers was analysed in 33 F. graminearum strains from Europe, North America, and Nepal. The number of alleles for each of the novel markers ranged from 4 to 20 and gene diversity from 0.417 to 0.962. In comparison with the previously published markers, the resolution for distinguishing among different strains was slightly increased. Twenty-seven markers were also detectable in three F. culmorum strains and one F. crookwellense strain. None of the markers was detected in three F. avenaceum and four F. poae strains, underlining the potential use of these microsatellite markers for species differentiation.     

Epidemiological investigation of Leptospira spp. in a dairy farming enterprise after the occurrence of three human leptospirosis cases

An epidemiological investigation was conducted in an unvaccinated dairy farming enterprise in which three workers on one of the milking herds (Herd 1) were diagnosed with leptospirosis due to serovars Hardjo (H) (n = 2) and Pomona (P) (n = 1) between January and March 2015. Blood and urine samples were collected from milking cows in Herd 1 (N = 230) and Herd 2 (N = 400), rising one‐ (R1, N = 125) and rising two‐year‐old (R2, N = 130) replacement heifers, and four pigs associated with Herd 1, in March 2015. Sera were tested using the MAT for serovars H, P, Copenhageni (C), Ballum (B) and Tarassovi (T), and urine samples were tested by qPCR. Seventy‐five per cent of 109 cows in Herd 1 and 36% of 121 in Herd 2 were seropositive (≥48), predominantly to H and P, and 23% of 74 cows in Herd 1 and 1% of 90 cows in Herd 2 were qPCR positive. Fifty‐five per cent of 42 R2 heifers were seropositive to T. No R1 and 17% of 42 R2 heifers were qPCR positive. Subsequently, all cattle were vaccinated for H and P, and Herds 1 and 2 were given amoxicillin. After the booster vaccination, 7% of 91 in Herd 1, 2% of 82 in Herd 2 and 11% of 38 R1 heifers (sampled as R2) were PCR positive. After the amoxicillin treatment, no cows in Herd 1 and 5% of 62 cows in Herd 2 were urine PCR positive. Calves and pigs were seropositive to H, P, C and B. Vaccination and antibiotic treatment appeared effective in reducing the risk of exposure of workers to vaccine serovars. However, evidence of non‐vaccine serovars indicated that workers likely remain at risk of exposure to Leptospira.     

A class capture enzyme immunoassay for immunoglobulin level determinations in bovine sera.

An enzyme immunoassay for determination of individual isotype concentrations in bovine serum was developed. Polystyrene tubes were coated with affinity purified goat antibovine IgA, IgG1, IgG2 or IgM, washed and then incubated with purified isotypes to ascertain crossreactivity and sensitivity limits. Bound isotype was detected using the homologous affinity purified antibody conjugated to horseradish peroxidase and hydrogen peroxide-2,2-azino-di-(3-ethylbenzthiazoline sulfonic acid), as the substrate/chromogen. A standardized serum was diluted and used as a control for comparison. Several dilutions were used initially, however, determinations may be made with a single dilution, 1:200, for all isotypes. Results for 100 sera were compared to data obtained with the same samples using a radial immunodiffusion technique. A low correlation coefficient was noted between results from the two assays. Day to day variation and within test repeatability were determined for both assays using ten samples. For the enzyme immunoassay method, day to day variation for IgA, IgM, IgG1 and IgG2 determinations was 17.5, 19.3, 7.6 and 7.3% while variation in repeatability (within a test) was 6.2, 5.9, 3.3 and 4.5%, respectively. Day to day variation for the single radial immunodiffusion test for IgA, IgM, IgG1 and IgG2 was 15.4, 26.0, 11.5 and 18.3% and variation repeatability (within a test) was 11.6, 13.9, 5.9 and 8.3%, respectively. The procedures consistently detected 0.1 micrograms of immunoglobulin whereas the radial diffusion sensitivity limit was approximately 500 micrograms.     

An outbreak of type C botulism in 12 horses and a mule

A USDA Early Response Team investigated deaths of several horses and a mule in northern Arizona at the request of local animal health officials. Thirteen animals (12 horses and 1 mule) housed at 5 facilities in a 7.4 square mile area died between August 1998 and January 1999. Clinical signs consisted of muscular weakness that rapidly progressed to lateral recumbency. Ten animals had paresis of the tongue, throat, or lips. Affected animals appeared alert and were interested in eating and drinking, even while recumbent. All 13 animals were euthanatized. Clostridium botulinum type C was isolated from feces or intestinal contents from 3 affected horses. Preformed toxin was detected in samples of soil and bird droppings collected from a nearby horse burial site. It was hypothesized that the outbreak was a result of birds, presumably ravens, feeding at the burial site and at horse facilities in the area that transferred toxin to the affected animals.     

Immunohistochemical diagnosis of chronic wasting disease in preclinically affected elk from a captive herd.

An immunohistochemical (IHC) method was used to test brain tissues from 17 elk in a captive herd in which chronic wasting disease (CWD) had previously occurred. The IHC technique detects the protease-resistant prion protein (PrP-res), which is considered a disease-specific marker for transmissible spongiform encephalopathies (TSE), regardless of the species affected. Of the 17 elk tested, 10 were positive by IHC. Only 2 of these 10 animals had shown clinical signs and histologic lesions of CWD, and an additional animal had histologic lesions only. The most consistently IHC-positive tissue was medulla oblongata, especially the obex. These results show that the PrP-res IHC test on brain tissue, specifically medulla oblongata at the obex, should be considered an essential component of any surveillance study intended to determine the incidence of CWD in captive or free-ranging cervids.     

The effects of kaolin particle film on Plutella xylostella behaviour and development

Studies were conducted to evaluate the effect of a kaolin-based particle film against the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). The effect of the particle film on development, survival and host plant selection was tested on calabrese seedlings, Brassica oleracea italica Plenck cv. Fiesta F(1), under controlled environmental conditions in the laboratory. Survival to adulthood was significantly reduced and development time increased on kaolin-treated compared with water-treated host plants. The hatch rate of neonate P. xylostella larvae from eggs laid on an artificial substrate was unaffected by the particle film applied after oviposition. Experiments showed that, when given the choice, significantly fewer larvae first made contact with the kaolin-treated compared with the water-treated plant material and that after 24 h there were still significantly fewer larvae present on kaolin-treated leaves. Adult females, however, deposited more eggs on host plants coated with the kaolin particle film. As part of this series of experiments the water control treatment was compared with plant material which had been sprayed with kaolin on the upper surface only and on both leaf surfaces. In general, any observed treatment effect was enhanced with an increase in the particle film coverage. The results warrant the extension of investigations of kaolin-based particle films to field-based P. xylostella management strategies.