The purposes of this study were to describe the clinical signs observed in PRRS positive herds during a porcine reproductive and respiratory syndrome (PRRS) outbreak in Ontario and to determine associations between these clinical signs and herd demographics and PRRS control strategies. All PRRS polymerase chain reaction-(PCR)-positive submissions to a diagnostic laboratory between September 1, 2004 and August 31, 2007 were identified (n = 1864). After meeting eligibility requirements and agreeing to voluntary study participation, producers from 455 of these submissions were surveyed for information on clinical signs observed in their herds, herd demographics, and PRRS control strategies used in their herds at the time that the PCR-positive samples were taken. Larger herd size was associated with an increased risk of reporting abortion, weakborn piglets, off-feed sows, and sow mortality in sow herds, and with an increased risk of reporting mortality in finishing herds. When disease control strategies were examined, use of a commercial PRRS vaccine in sows and gilts was associated with a decreased risk of reporting weakborn pigs and high pre-weaning mortality, while the use of serum inoculation in breeding animals was associated with an increased risk of reporting off-feed sows and sow mortality. Providing biofeedback of stillborn/mummified piglets, placenta or feces to gilts was associated with an increased risk of reporting respiratory disease and mortality in finishing pigs while all-in/all-out flow in farrowing rooms was associated with an increased risk of reporting sow mortality and weakborn piglets.

A clinical field trial was performed to determine the effectiveness of an autogenous Salmonella Typhimurium bacterin compared with a commercial live S. Choleraesuis vaccine in pigs. The association between Salmonella shedding and weight gain was also investigated. Nine cohorts of weaned pigs, (330 to 350 pigs per cohort), were randomly assigned to 1 of 3 treatment groups (injection with S. Typhimurium bacterin, vaccination via water with S. Choleraesuis vaccine, or a control group receiving no vaccine). In each cohort, the average daily gain was calculated for a selected pen throughout the production stage. Pen (pooled) fecal samples were collected bi-weekly and cultured. The odds of Salmonella shedding in both vaccinated groups was higher than in the control group (P < 0.05). The prevalence of Salmonella shedding declined overall as pigs aged (P = 0.04). However, the control pigs showed the smallest decrease in Salmonella shedding over the entire production stage, while prevalence of Salmonella shedding in the vaccinated groups decreased twice as much as the control group over the entire production stage. Salmonella Typhimurium var. Copenhagen DT104, S. Cerro, and S. Agona, which had been isolated on the study farm previously, were recovered from pigs in this study. Shedding of S. Typhimurium var. Copenhagen decreased over time in both vaccine treatment groups. On the other hand, S. Cerro shedding rate was lower in the control pigs compared with vaccinated pigs and S. Agona could be recovered only from the samples collected from S. Choleraesuis vaccinated pigs. The pigs from pens with a higher Salmonella recovery rate experienced slower growth compared with pigs from pens where Salmonella was not isolated. This latter finding indicates that there might be an economic incentive for producers to try to control endemic salmonellosis if effective programs could be developed.

Canine distemper virus (CDV)-specific immune response was measured in different dog populations. Three groups of vaccinated or wild-type virus exposed dogs were tested: dogs with a known vaccination history, dogs without a known vaccination history (shelter dogs), and dogs with potential exposure to wild-type CDV. The use of a T-cell proliferation assay demonstrated a detectable CDV-specific T-cell response from both spleen and blood lymphocytes of dogs. Qualitatively, antibody assays [enzyme-linked immunosorbent assay (ELISA) and neutralization assay] predicted the presence of a T-cell response well, although quantitatively neither antibody assays nor the T-cell assay correlated well with each other. An interesting finding from our study was that half of the dogs in shelters were not vaccinated (potentially posing a public veterinary health problem) and that antibody levels in dogs living in an environment with endemic CDV were lower than in vaccinated animals.

Verotoxigenic Escherichia coli (VTEC) are important foodborne pathogens in Canada. VTEC of the O157:H7 serogroup have been the focus of regulatory action and surveillance in both Canada and the USA, due to their role in a number of high profile outbreaks. However, there is increasing evidence that other VTEC serogroups cause a substantial proportion of human illness. This issue is of particular importance to the cattle industry due to the role of beef as a vehicle for VTEC transmission. In this review, the evidence for non-O157 VTEC as cause of human illness in Canada and the potential for Canadian beef and cattle to serve as a source of VTEC are presented. In addition, the available strategies for the control of VTEC in cattle and beef are discussed.

This report describes the genetics of the prion protein gene (PRNP) at codons 136, 154, and 171 for sheep diagnosed with naturally acquired classical scrapie in Canada between 1998 and 2008. Genotyping analysis was performed on 249 sheep with confirmed classical scrapie infection representing 98 flocks from 6 provinces. A further case-control analysis of 3 of these flocks compared the genotypes between infected sheep (n = 72) and those of their healthy flockmates (n = 1990). The incidence of classical scrapie in the Canadian sheep population was highly associated with the ARQ haplotype (91.8%) and the ARQ/ARQ genotype (91.6%). In addition, the ARQ haplotype was found at significantly higher frequency in scrapie-infected sheep when compared with their healthy flockmates. Comparison with other published data suggests that the scrapie risk of PRNP genotypes differs between Canada and countries where the VRQ allele is associated with the highest susceptibility to infection.

The objective of this project was to develop and implement an active surveillance program for the early and rapid detection of equine influenza viruses in Ontario. For this purpose, from October 2003 to October 2005, nasopharyngeal swabs and acute and convalescent serum samples were collected from 115 client-owned horses in 23 outbreaks of respiratory disease in Ontario. Sera were paired and tested for antibody to equine influenza 1 (AE1-H7N7), equine influenza 2 (AE2-H3N8), equine herpesvirus 1 and 4 (EHV1 and EHV4), and equine rhinitis A and B (ERAV and ERBV). Overall, the cause-specific morbidity rate of equine influenza virus in the respiratory outbreaks was 56.5% as determined by the single radial hemolysis (SRH) test. The AE2-H3N8 was isolated from 15 horses in 5 outbreaks. A 4-fold increase in antibody levels or the presence of a high titer against ERAV or ERBV was observed in 10 out of 13 outbreaks in which AE2-H3N8 was diagnosed as the primary cause of disease. In conclusion, AE2-H3N8 was found to be an important contributor to equine respiratory viral disease. Equine rhinitis A and B (ERAV and ERBV) represented an important component in the equine respiratory disease of performing horses.

The objective of this study was to determine the capsular serotypes and potential virulence factors of Streptococcus suis isolated from pigs with polyserositis. Among the 24 isolates evaluated, serotype 3 [7 (29%) of the isolates] and serotype 4 [5 (21%)] were the most common. The isolates were also studied for the presence of the genes mrp, epf, and sly, which encode muramidase-released protein (MRP), extracellular factor (EF), and suilysin (SLY), respectively. Of the 24 isolates, 8 carried mrp: 4 of serotype 3, 2 of serotype 2, and 2 of serotype 4. One mrp+ isolate (serotype 2) also carried the epf gene. All 24 isolates carried the sly gene. The serotype and genotype distribution greatly differed from that reported for isolates from pigs with other clinical manifestations of S. suis infection in other countries.

Ticks collected from domestic cats (Felis catus), cheetahs (Acinonyx jubatus),caracals (Caracal caracal), African wild cats (Felis lybica), black-footed cats (Felis nigripes), a serval (Leptailurus serval), lions(Panthera leo), and leopards (Panthera pardus) were identified and counted. Thirteen species of ixodid ticks and one argasid tick were identified from domestic cats and 17 species of ixodid ticks from wild felids. The domestic cats and wild felids harboured 11 ixodid species in common. The adults of Haemaphysalis elliptica, the most abundant tick species infesting cats and wild felids, were most numerous on a domestic cat in late winter and in mid-summer, during 2 consecutive years. The recorded geographic distribution of the recently described Haemaphysalis colesbergensis, a parasite of cats and caracals, was extended by 2 new locality records in the Northern Cape Province,South Africa.

In a trial for comparison between the efficiency of single fowl pox (FP) vaccination and the efficiency of each combined FP and Avian encephalomyelitis (AE) vaccination and simultaneous vaccination with FP and Reo and with FP and Chicken anemia virus (CAV) vaccines our conclusion was that there is no antagonistic reaction between FP virus strain and each AE, Reo and CA viruses strains. In addition, humoral immune response against AE virus strain in case of combined AE+FP vaccination is markedly potent than that in case of single AE vaccination, more over the value of average EID50 of AE virus strain in several batches of combined AE+FP vaccines is significantly higher at P > 0.05 than that in several batches of single AE vaccines. On the other hand, immune response against FP virus strain and Reo virus strain in case of simultaneous vaccination with FP and Reo vaccines is higher than that in case of single FP vaccination and single Reo vaccination. Consequently, it is advisable to use combined live attenuated AE+FP vaccine instead of vaccination with single FP and AE separately. Also, application of simultaneous vaccination with FP and Reo vaccines is advisable as it is proved to be more beneficial than vaccination with each vaccine separately specially in case of that FP vaccine of low potency.

The present study concerned with Listeria monocytogenes which were isolated from apparently healthy buffaloes, buffaloes suffered from abortion, bedding and silage, which were collected from different localities. From the total examined samples (375), (300 samples from apparently healthy buffaloes, bedding and silage, also 75 samples from buffaloes suffered from abortion , bedding and silage) the prevalence of L. monocytogenes was 11(14.7%), isolates from buffaloes suffered from abortion, bedding and silage. All isolates were motile at room temperature, also exhibited positive CAMP test and exhibited narrow zone of β-hemolysis. Serological identification of isolates revealed 6(54.5%) were serotype 4 while 5(45.5%) were untyped. There were differences in isolates susceptibilities to different anti-microbial agents. L. monocytogenes had 100% sensitivity to Ampicillin, chloramphenicol, erythromycin, tetracycline and ceftiofur sodium. Virulence of isolates was assayed by I/P inoculation of 109 CFU in mice, all inoculated mice died within 1-5 days. PCR assay for L. monocytogenes isolates revealed positive amplification of 827 bp fragment of act A gene.