Herd-level risk factors for subclinical Salmonella infection in European finishing-pig herds

Our objective was to find herd factors associated with pigs testing seropositive for Salmonella. Data were collected from 359 finishing-pig herds in Germany, Denmark, Greece, The Netherlands and Sweden, between 1996 and 1998. Pigs fed non-pelleted feed (dry or wet) had 2- and 2.5-times lower odds of seropositivity, compared to pigs fed pelleted feed. The protective effect of non-pelleted feed over pelleted feed may be ascribed to the structure and composition. Also, pigs that were given whey (to drink or as the liquid part of the diet) had 2.6-times lower odds to test seropositive than pigs not getting whey. Pigs produced in batches in herds with hygienic-lock facilities had >3-times lower odds for testing seropositive compared to pigs in herds where only one or neither factor was present. In herds where the caretaker(s) washed hands consistently before tending to the animals, pigs had 1.5-times lower odds of seropositivity than pigs in herds where the caretaker did not. Pigs which were able to have snout contact with pigs in neighbouring pens (because pen separations were either open or too low) had 1.7-times higher odds to test seropositive compared to pigs for which such contact was prevented. Pigs in herds recruiting from more than three supplier herds had three-times higher odds to test seropositive than pigs in herds which breed their own replacement stock or recruit from a maximum of three supplier herds.     

The rate of Salmonella spp. infection in zoo animals at Seoul Grand Park, Korea

Salmonellosis is an important zoonotic disease that affects both people and animals. The incidence of reptile-associated salmonellosis has increased in Western countries due to the increasing popularity of reptiles as pets. In Korea, where reptiles are not popular as pets, many zoos offer programs in which people have contact with animals, including reptiles. So, we determined the rate of Salmonella spp. infection in animals by taking anal swabs from 294 animals at Seoul Grand Park. Salmonella spp. were isolated from 14 of 46 reptiles (30.4%), 1 of 15 birds (6.7%) and 2 of 233 mammals (0.9%). These findings indicate that vigilance is required for determining the presence of zoonotic pathogen infections in zoo animals and contamination of animal facilities to prevent human infection with zoonotic diseases from zoo facilities and animal exhibitions. In addition, prevention of human infection requires proper education about personal hygiene.     

Effects of porcine reproductive and respiratory syndrome vaccination in breeding-age animals

Little is known about the safety and efficacy of extra-label use of the modified live porcine reproductive-and-respiratory syndrome (PRRS) virus vaccine in gestating sows. Our purpose was to determine the impact of vaccination on reproductive performance in 54 herds in Ontario, Manitoba (Canada) and the mid-western United States that were PRRS-positive, PRRS-negative, or concurrently affected by an outbreak of PRRS when initially vaccinated. Majority-vaccinated herds vaccinated ≥50% but <100% of sows at one time, and limit-vaccinated herds vaccinated <50% of sows at one time. Most majority-vaccinated herds did not vaccinate sows in late gestation, and none vaccinated during the initial PRRS outbreak. Numbers of pigs born alive and weaned decreased when pregnant sows were vaccinated. The effect of vaccination on productivity in the gestation following vaccination depended on the vaccination protocol.     

Sample size calculations for Bayesian prediction of bovine viral-diarrhoea-virus infection in beef herds

We used a Bayesian classification approach to predict the bovine viral-diarrhoea-virus infection status of a herd when the prevalence of persistently infected animals in such herds is very small (e.g. <1%). An example of the approach is presented using data on beef herds in Wyoming, USA. The approach uses past covariate information (serum-neutralization titres collected on animals in 16 herds) within a predictive model for classification of a future observable herd. Simulations to estimate misclassification probabilities for different misclassification costs and prevalences of infected herds can be used as a guide to the sample size needed for classification of a future herd.     

Capability of the nematode-trapping fungus Duddingtonia flagrans to reduce infective larvae of gastrointestinal nematodes in goat feces in the southeastern United States: dose titration and dose time interval studies

Infection with gastrointestinal nematodes, particularly Haemonchus contortus, is a major constraint to goat production in the southeastern United States. Non-anthelmintic control alternatives are needed due to increasing resistance of these nematodes to available anthelmintics. Two studies were completed in Central Georgia in August 1999, and April–May 2000, using Spanish does naturally infected with Haemonchus contortus, Trichostongylus colubriformis, and Cooperia spp. to evaluate effectiveness of nematode-trapping fungi as a biological control agent. In the first experiment, five levels of Duddingtonia flagrans spores were mixed with a complete diet and fed once daily to the does (three per treatment) in metabolism crates. The treatment concentrations were (1) 5×10⁵, (2) 2.5×10⁵, (3) 10⁵, and (4) 5×10⁴ spores per kilogram body weight (BW), and (5) no spores. Fungal spores were fed for the first 7 days of the 14-day trial, and fecal samples were collected daily from individual animals for analysis of fecal egg count and establishment of fecal cultures. Efficacy of the fungus at reducing development of infective larvae (L3) in the fecal cultures was evaluated. The mean reduction in L3 from day 2 of the treatment period until the day after treatment stopped (days 2–8) was 93.6, 80.2, 84.1, and 60.8% for animals given the highest to lowest spore doses, respectively. Within 3–6 days after termination of fungal spore feedings, reduction in L3 development was no longer apparent in any of the treated animals. In a second experiment, effectiveness of 2.5×10⁵ spores of D. flagrans per kilogram BW fed to does every day, every second day, and every third day was evaluated. Reduction in L3 development by daily feeding was less in the second experiment than in the first experiment. Daily fungal spore feeding provided more consistent larval reduction than intermittant feeding (every second or third day). When fed daily under controlled conditions, D. flagrans was effective in significantly reducing development of L3 and appears to be an effective tool for biocontrol of parasitic nematodes in goats.     

Use of pre-partum urine pH to predict the risk of milk fever in dairy cows

The objective of this study was to evaluate the correlation between serum calcium (Ca) and inorganic phosphorus (IP) values and urine pH of cows fed common rations without the addition of anionic salts in late pregnancy. One hundred and seven Holstein cows, having completed two or more lactations and with an expected calving date within the next seven days were selected from two herds. In order to determine levels of serum Ca and IP and urine pH, blood and urine samples were collected seven to one days before parturition. Of the 107 sampled cows, 17 developed recumbency after calving and were considered to be affected by milk fever. There were significant ( p<0.01 ) negative correlations between urine pH and serum Ca, IP and the ratio of Ca to IP, The urine pH, and levels of serum Ca and IP measured within 48 h prior to parturition differed significantly ( p<0.001 ) between recumbent and non-recumbent cows. The sensitivity, specificity, positive and negative predictive values of urine pH test 48 h prior to parturition, using a cut off level of above pH 8.25, were 100%, 81%, 55%, and 100%, respectively. These signify that monitoring urine pH within 48 h prior to parturition is a sensitive method to assess the risk of parturient paresis. The results of this study emphasize the importance of acid-base status of the animal in the pathophysiology of milk fever.     

Effect of constant-release melatonin implants and prolonged exposure to a long day photoperiod on prolactin secretion and hair growth in mouflon (Ovis gmelini musimon)

The aims of this study were to examine whether mouflons exposed to constant long and short day photoperiods are able to exhibit an annual cycle of hair growth and moult, and prolactin (PRL) secretion. Mouflon ewes were assigned to three groups of treatment. Ewes were maintained, either under natural photoperiod (control, n=9), or received a series of subcutaneous melatonin implants from December to April (n=8), or were exposed to a constant long day photoperiod (16-h light:8-h dark; 16L:8D) during 18 months (n=7). Blood was collected weekly to determine PRL concentrations, and hair samples were clipped weekly from the base of the neck to measure the length of predominant hair. Under constant long days and with melatonin implants, mouflons expressed an annual rhythm of PRL secretion, even though these treatments modified the times of rise or falling of PRL concentrations throughout the year. Hair growth initiation was almost coincident with the summer solstice in both control and melatonin-implanted mouflons but occurred two months earlier in long day hold mouflons (P<0.001). Long day hold mouflons had a lower hair growth rate than control and melatonin-implanted mouflons (P<0.001), and at the end of the experiment, a shorter hair length (3.4±0.24 cm; P<0.01) than control (4.3±0.17 cm), and melatonin-implanted mouflons (4.2±0.12 cm). Our data support the conclusion that in mouflon, an endogenous circannual rhythm of PRL secretion exists, and that the seasonal cycle of hair growth and moult appears to depend, at least in part, on circulating levels of PRL.     

Influence of sodium diethyldithiocarbamate (Imuthiol) on lymphocyte function and growth in weanling pigs

Mitogen-stimulated lymphocyte proliferation, delayed-type hypersensitivity (DTH) reactions, interleukin-2 (IL-2) production, and growth performance were evaluated in 3-week-old pigs treated with imuthiol. Lymphocyte proliferative responses to Con A and PWM were reduced (P < 0.05) in pigs treated with imuthiol at 25 mg/kg; PHA proliferative responses were not influenced by imuthiol treatment. Imuthiol at 2.5 mg/kg and 25 mg/kg lowered IL-2 production when compared to saline-treated controls. Delayed-type hypersensitivity responses to PHA were higher in 25 mg/kg imuthiol-treated pigs; however, 2.5 mg/kg imuthiol-treated pigs had lower DHT reactions. Imuthiol at 2.5 mg/kg and 25 mg/kg reduced (P < 0.05) average daily feed intake. These data suggest that in vivo imuthiol treatment in pigs lowers lymphocyte proliferative responses, IL-2 production, and growth performance.     

A serologic survey of bovine rotavirus infection in Italy

Serum neutralization tests conducted by microtiter procedure on 2970 serum samples from calves, heifers and adult cows from representative regions of Italy indicate that rotaviruses, and the infection which they cause, existed in Italy long before the virus was isolated. At the present time the infection is distributed fairly uniformly throughout the cattle population with both sexes and all age groups being equally susceptible.     

Control of Salmonella enteritidis phage type 4 experimental infection by fosfomycin in newly hatched chicks

One hundred and twenty 1-day-old broiler chickens were divided into four groups: group I unmedicated and orally challenged with 1.5×10⁸ cfu of Salmonella enteritidis phage type 4; group F infected and treated with 300 ppm of fosfomycin in their drinking water; group CF uninfected and treated, and group C maintained as a control group. Their performance, clinical signs, S. enteritidis PT4 reisolation and biochemistry variables were compared. Group F showed fewer symptoms and gross lesions than those from group I. Fosfomycin treatment at 300 ppm improved body weight at 7 days of age by 42.3%. S. enteritidis PT4 reisolation in group I was higher than in the treated group, but total decontamination of challenged birds was not achieved. There was an increase in the levels of total protein and globulins in group I but not in the treated group. Fosfomycin caused no adverse effects on chickens from group CF, assessed by performance and biochemical variables. The results indicate that fosfomycin could be used in the treatment of S. enteritidis PT4 experimental infection.     

Epithelial response to experimentally introduced intraluminal bacteria in the avian epididymal ducts

The response of the epithelial cells of the various ducts of the avian epididymis, whose function is poorly understood, to intraluminal bacteria was evaluated by the injection of an avirulent strain of Salmonella gallinarium into the RT for 24 h. Ultrastructurally, bacteria and invading mononuclear cells were present in the lumina of the RT, proximal efferent ducts (PED) and distal efferent ducts. However, only the non-ciliated (Type I) cells of the PED epithelium ingested bacteria from the lumen. Fragments of bacteria also occurred in several intercellular spaces in the epithelium of the PED. Some mononuclear cells also contained fragments of bacteria. Neither cell death in the various epithelia nor mononuclear infiltration of the periductal tissue occurred. Therefore, in addition to the established function of absorbing most of the testicular fluid entering the epididymis, the Type I cells also appear capable of recognising and removing foreign particulate matter from the epididymal through-flow in the proximal part of the epididymis.     

Reactions of sera from laboratory, domestic and wild animals in Africa with Protein a and a recombinant chimeric Protein AG

An ELISA was developed to determine the reactivity of peroxidase labelled Protein A and a recombinant Protein A + Protein G construct, to sera from a variety of laboratory, domestic and wild animals from Africa. There was variability in the binding capacity of sera from individuals of the same species, but four groups could be recognized. Sera from birds and crocodiles were at most weakly reactive with either Protein A or the chimeric construct. Sera from some domestic animals such as horse, goat and cat, and sera from some wild ungulates including buffalo, wildebeest, waterbuck and impala were reactive with Protein A, but reacted to a much greater degree with the chimeric construct. Sera from larger wild animals such as elephant, rhinoceros and giraffe were strongly reactive with the chimeric protein and moderately reactive with Protein A. Sera from primates and dog, pig, guinea pig and rabbit reacted strongly with both proteins. Chimeric proteins that combine the IgG binding capacities of Protein A and Protein G can be used to detect immunoglobulin from a wide variety of African wild animal species. They may thus be of great value in seroepidemiological investigations of these animal populations.     

Immune response to avian leukosis virus infection in chickens: Sequential expression of serum immunoglobulins and viral antibodies

Chickens of a 15I₅ × 7₂ cross that produces endogenous Rous associated virus (RAV-0) were infected with subgroup A lymphoid leukosis virus (RAV-1). Within 3 weeks, before RAV-1 neutralizing antibodies were detected, significantly higher levels of serum immunoglobulin G (IgG) were found in infected birds than in uninoculated hatchmates. Immunoglobulin M was significantly elevated only during the late leukotic state. Although most of the inoculated birds tested had RAV-1 neutralizing antibodies, no correlation was found between IgG levels and antibody titers. Tolerance to endogenous virus (RAV-0) and viral group-specific antigen was apparently abrogated by RAV-1 inoculation because significantly higher percentages of iodinated envelope glycoprotein (gpE) of RAV-0 and a viral structural antigen of mol. wt 19,000 daltons (p 19) were precipitated by sera from inoculated birds than from control birds.     

Antibody levels to Brucella abortus, toxoplasma gondii, and Leptospira serogroups, in sera collected from healthy people in Fiji

A collection of 300 sera from a predominantly rural community on the island of Viti Levu in Fiji were studied for the presence of antibodies to B. abortus, T. gondii and Leptospira serogroups. Significant levels of immunity were found to B. abortus and T. gondii and over half the population had diagnostic leptospiral antibody levels.     

Genetic selection for resistance to mycoplasmal pneumonia of swine (MPS) in the Landrace line influences the expression of soluble factors in blood after MPS vaccine sensitization

We recently developed a Landrace line that is resistant to mycoplasmal pneumonia of swine (MPS) infection by genetic selection for five generations, and we reported that the immunophenotype of this line is different from that of the non‐selected line in terms of changes in peripheral blood leukocyte population after MPS vaccination. This study followed up previous findings demonstrating changes in soluble factors in blood, namely, hormones, Mycoplasma hyopneumoniae‐specific immunoglobulin G (IgG), and cytokines. These two lines were injected with MPS vaccine on days ?7 and 0 after blood sampling on those days, and blood samples were collected on days ?14, ?7, 0, 2, 7 and 14. We found changes in the levels of many hormones and cytokines in both lines. However, we found that only growth hormone (GH) and interferon (IFN)‐γ levels were statistically different between these two lines. GH concentration was reduced (day 0) and IFN‐γ concentration was increased (day 14) in the MPS‐selected line compared with the non‐selected line, despite unchanged IFN‐γ messenger RNA expression in blood cells. Although detailed mechanisms underlying these phenotypes remain unsolved, these traits would be useful to improve MPS resistance in pig production and provide an insight into MPS infection.     

In vitro susceptibility of field isolates of Francisella tularensis subsp. holarctica recovered in Spain to several antimicrobial agents

Forty-two recent (1997-1999) Spanish isolates of Francisella tularensis subsp.holarctica were tested in a broth microdilution method for their susceptibilities to 29 antimicrobial agents, including penicillins, cephalosporins, cephamicins, monobactams, penems, aminoglycosides, tetracyclines, macrolides, quinolones, chloramphenicol and fosfomycin. The isolates were resistant to beta-lactam antibiotics and susceptible to chloramphenicol, ciprofloxacin, levofloxacin and norfloxacin.     

Variations in the immune response to herpesvirus saimiri in squirrel and rhesus monkeys

Humoral and cell-mediated immunity (CMI) to herpesvirus saimiri (HVS), an oncogenic lymphotropic herpesvirus, was studied in squirrel and rhesus monkeys. Natural antibody to HVS was found in five of six squirrel monkeys but there was no evidence of specific CMI directed against HVS. Rhesus monkeys did not show natural antibody or CMI against HVS antigens. Immunization with HVS, however, produced both antibody and specific CMI in the rhesus monkeys, but no CMI developed in the squirrel monkeys. These findings are important in the development of animal models for the treatment of tumors associated with lymphotropic herpesviruses.     

Cell-mediated immune responses in man to Epstein-Barr (EB) virus infection

Cell-mediated immune response are now known to be important components of the host response to the Epstein-Barr (EB) herpesvirus. They are also likely to be essential in the control of EB-virus infection. Failure to mount any immune response to EB virus results in loss of control over the multiplication of cells transformed by the virus and gives rise to polyclonal neoplasia. A number of studies, using different preparations of antigen and a variety of assays, have demonstrated specific cell-mediated immune responses to the virus in normal individuals, most of whom by adulthood harbour the virus, and in patients with infectious mononucleosis (IM), where a consistent pattern of response is beginning to be established. However, in patients with Burkitt's lymphoma or nasopharyngeal carcinoma, specific cell-mediated immune responses to the virus have been less easy to detect and difficult to relate in any consistent way to the course of the disease. In this communication we review some of the recent results obtained on cell-mediated immune responses to EB-virus infection, with particular emphasis on the pathogenesis and control of EB-virus-associated diseases. It is clear that EB-virus, though an ubiquitous, almost universal human virus, has a demonstrated potential to produce malignant neoplasia. The oncogenicity of the virus is normally held in check, at least in part through cell-mediated immune mechanisms, so that the usual mode of infection is inapparent or, in some cases, a self-limiting lymphoproliferative disease (IM). Under particular circumstances, Burkitt's lymphoma or nasopharyngeal carcinoma may result, but the role of EB-virus in the pathogenesis of these diseases and especially the part played by cell-mediated immune responses to the virus have by no means yet been elucidated.