Consistency in pest risk analysis – how can it be achieved and what are the benefits?*

This paper describes the efforts in the PRATIQUE EU project to increase consistency that were integrated into the revised EPPO Decision‐support scheme (DSS) for Pest Risk Analysis (PRA). The establishment section is used here to illustrate the changes and improvements of the DSS, as it has undergone the most comprehensive changes with reformulation and restructuring of many questions and detailed rating guidance. When revising the establishment section of the EPPO DSS for PRA, there were three principal objectives that influenced the revision: (i) to focus the assessment on the most relevant factors influencing establishment; (ii) to identify the area where establishment is possible before assessing the suitability of that area, and (iii) to enhance the consistency of the establishment section by providing rating guidance with sub‐questions and examples. To simplify the process, some questions were rephrased as closed questions (answer is either yes or no). Clearer notes were provided to explain what information is needed to answer the questions. Furthermore, consistency has been enhanced by developing tools to help assessors when deciding on an appropriate overall risk rating and uncertainty score by providing a visual summary of the risk ratings and uncertainty scores (‘Visualizer’) and a method for integrating all the responses to the questions to provide a summary score for each major section and an overall assessment of risk (‘Rule based matrix model’).     

Characterization of swimming motility and identification of flagellar proteins in Salmonella pullorum isolates

OBJECTIVE: To identify swimming motility in Salmonella pullorum isolates and to characterize the flagellar proteins produced by motile isolates. SAMPLE POPULATION: 30 S pullorum isolates and isolates of 7 other Salmonella sp. PROCEDURE: Salmonella pullorum isolates were inoculated into high motility medium to evaluate swimming motility. Putative flagellar proteins were purified from the organisms and analyzed by means of gel electrophoresis and western blotting procedures, using various antisera specific for flagellar proteins. Antisera shown to be reactive with putative flagellar proteins were incorporated into the growth medium to examine their effects on motility of the isolates. RESULTS: All S pullorum isolates had evidence of swimming motility. Two putative flagellar proteins were purified from 2 of the S pullorum isolates: a 60 to 62 kd protein shown to react with antiserum specific for type y flagellar protein, and a 58 to 59 kd protein shown to react with antiserum specific for type d flagellar protein and with antibody reactive to a highly conserved flagellar epitope found on various Enterobacteriaceae. Antiserum specific for type d flagellar protein inhibited swimming motility of S pullorum isolates, but antiserum specific for type y flagellar protein did not. CONCLUSIONS: Results suggest that S pullorum isolates can be induced to manifest swimming motility when grown on medium with a low agar concentration and possess a 58 to 59 kd protein of d serotype and a second protein of 60 to 62 kd that also may be a flagellar protein.     

Experimental horizontal transmission of Salmonella enteritidis strains (phage types 4, 8, and 13a) in chicks

The recent isolation of phage type 4 Salmonella enteritidis strains from poultry and humans in the United States has generated considerable concern because this phage type is predominant in both animals and humans in many other nations. Understanding whether the presence of these strains in poultry flocks poses an elevated threat to public health is a critical issue for developing effective disease control programs. The present study evaluated whether S. enteritidis strains of various phage types found in poultry in the United States (phage types 4, 8, and 13a) differed in their potential for horizontal transmission from experimentally infected chicks to uninoculated chicks housed in the same isolator units. Five days after two seeder chicks in each group of 12 were inoculated with oral doses of approximately 10(3) S. enteritidis cells at 8 days of age, ceca and livers were sampled from seeder chicks and from their contact-exposed penmates. On the basis of the detection of S. enteritidis in cecal samples, phage type 4 strains were transmitted horizontally at a significantly lower frequency than were strains of other phage types. Nevertheless, two of three phage type 4 strains evaluated were very highly invasive.     

Caudal vena cava obstruction and ascites in a cat treated by balloon dilation and endovascular stent placement

OBJECTIVE: To present details of an unusual case of caudal vena caval obstruction and its management in a cat. STUDY DESIGN: Clinical case report. STUDY POPULATION: A 15 month old male castrated domestic shorthaired cat. RESULTS: The diagnostic evaluation included the use of digital subtraction angiography and ultrasonography to locate the caudal vena caval obstruction. Treatment initially involved puncture and balloon dilation of the obstructed area of the cava. After reobstruction, the stenotic area was redilated and stented. The cat was euthanatized 4 weeks later because of vomiting, anorexia, and abnormal behavior, presumed to be associated with liver disease. CONCLUSION AND CLINICAL RELEVANCE: Interventional radiography provided a minimally invasive way to manage this unusual vascular anomaly.     

Antagonistic control of disease resistance protein stability in the plant immune system

Pathogen recognition by the plant immune system is governed by structurally related, polymorphic products of disease resistance (R) genes. RAR1 and/or SGT1b mediate the function of many R proteins. RAR1 controls preactivation R protein accumulation by an unknown mechanism. We demonstrate that Arabidopsis SGT1b has two distinct, genetically separable functions in the plant immune system: SGT1b antagonizes RAR1 to negatively regulate R protein accumulation before infection, and SGT1b has a RAR1-independent function that regulates programmed cell death during infection. The balanced activities of RAR1 and SGT1, in concert with cytosolic HSP90, modulate preactivation R protein accumulation and signaling competence.     

Presence of Campylobacter jejuni in various organs one hour, one day, and one week following oral or intracloacal inoculations of broiler chicks

Day-old broiler chicks (n=30) were obtained from a commercial hatchery and inoculated, either orally or intracloacally, with a characterized strain of Campylobacter jejuni. At 1 hr, 1 day, and 1 wk after inoculation, broilers (n = 5) from the orally and intracloacally inoculated groups along with control birds (n=4) were humanely killed by cervical dislocation. The broilers from the control and treatment groups were aseptically opened, and the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca were aseptically removed and individually analyzed for C. jejuni. Overall, C. jejuni was isolated after oral inoculation from 13% (10/ 75), 17% (13/75), and 28% (14/50) of the 1-hr, 1-day, and 1-wk samples, respectively. Campylobacter jejuni was isolated from 10% (4/ 40), 8% (3/40), 10% (4/40), 25% (10/40), and 40% (16/40) of the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca samples, respectively. Following the intracloacal route of inoculation, C. jejuni was recovered from 32% (24/75), 8% (6/75), and 16% (8/50) of the 1-hr, 1-day, and 1-wk samples, respectively. Campylobacter jejuni was isolated from 5% (2/40), 5% (2/40), 5% (2/40), 45% (18/40), and 40% (16/40) of the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca samples, respectively, for all sampling periods. Campylobacter spp. were not recovered from sample sites examined from the control broilers from trial one, trial two, or trial three samples examined after 1 hr and 1 day. However, one control sample was positive from the 1-wk sampling from repetition three; therefore, those data were omitted. The rapid movement of Campylobacter to internal organs following both oral and intracloacal inoculation may be significant, particularly if it persists in these organs as reservoirs throughout the 65-wk life cycle of breeding birds.     

Colonization of reproductive organs and internal contamination of eggs after experimental infection of laying hens with Salmonella heidelberg and Salmonella enteritidis

Internal contamination of eggs laid by hens infected with Salmonella enteritidis has been a prominent international public health issue since the mid-1980s. Considerable resources have been committed to detecting and controlling S. enteritidis infections in commercial laying flocks. Recently, the Centers for Disease Control and Prevention also reported a significant association between eggs or egg-containing foods and S. heidelberg infections in humans. The present study sought to determine whether several S. heidelberg isolates obtained from egg-associated human disease outbreaks were able to colonize reproductive tissues and be deposited inside eggs laid by experimentally infected hens in a manner similar to the previously documented behavior of S. enteritidis. In two trials, groups of laying hens were orally inoculated with large doses of four S. heidelberg strains and an S. enteritidis strain that consistently caused egg contamination in previous studies. All five Salmonella strains (of both serotypes) colonized the intestinal tracts and invaded the livers, spleens, ovaries, and oviducts of inoculated hens, with no significant differences observed between the strains for any of these parameters. All four S. heidelberg strains were recovered from the interior liquid contents of eggs laid by infected hens, although at lower frequencies (between 1.1% and 4.5%) than the S. enteritidis strain (7.0%).     

Ovarian cysts in guinea pigs: influence of age and reproductive status on prevalence and size

Forty-three guinea pigs presented as part of a screening programme were divided into six categories on the basis of age and reproductive history. Three age groupings were used: less than one year, one to two years, and over two years. Each age group was further divided into two categories: animals which had had single or multiple pregnancies, and animals which had never bred. Each animal received a clinical examination and was scanned using B-mode ultrasound for the presence of ovarian cysts. Possible relationships between reproductive history and the prevalence of cysts were investigated using Mantel-Haenzel analysis, and between prevalence, cyst size and age using linear regression analysis. Two out of the 43 animals (4.7 per cent) showed symmetrical alopecia. No statistically significant correlation between reproductive history and the prevalence of cysts was detected at the 95 per cent confidence level. A statistically significant relationship was found, however, between cyst size and age (P<0.01) and between cyst prevalence and age (P<0.02).