Surveillance programme for important equine infectious respiratory pathogens in the USA

Abstract

The prevalence and epidemiology of important viral (equine influenza virus [EIV], equine herpesvirus type 1 [EHV-1] and EHV-4) and bacterial (Streptococcus equi subspecies equi) respiratory pathogens shed by horses presented to equine veterinarians with upper respiratory tract signs and/or acute febrile neurological disease were studied. Veterinarians from throughout the USA were enrolled in a surveillance programme and were asked to collect blood and nasal secretions from equine cases with acute infectious upper respiratory tract disease and/or acute onset of neurological disease. A questionnaire was used to collect information pertaining to each case and its clinical signs. Samples were tested by real-time PCR for the presence of EHV-1, EHV-4, EIV and S equi subspecies equi. A total of 761 horses, mules and donkeys were enrolled in the surveillance programme over a 24-month study period. In total, 201 (26.4 per cent) index cases tested PCR-positive for one or more of the four pathogens. The highest detection rate was for EHV-4 (82 cases), followed by EIV (60 cases), S equi subspecies equi (49 cases) and EHV-1 (23 cases). There were 15 horses with double infections and one horse with a triple infection. The detection rate by PCR for the different pathogens varied with season and with the age, breed, sex and use of the animal.

New Real-Time PCR Assay Using Allelic Discrimination for Detection and Differentiation of Equine Herpesvirus-1 Strains with A 2254 and G 2254 Polymorphisms

“…Furthermore, it produced fewer false dual positives, regardless of the DNA extraction procedure employed, and is therefore better suited than E 2 for use in a routine diagnostic setting. In such an environment, an allelic-discrimination rPCR assay directed against ORF30 has the advantage over rPCR assays targeting other EHV-1 genes (e.g., gB and gD genes [3,16,18,27,32]) because it can both detect and discriminate between the A 2254 and G 2254 genotypes present in clinical samples. Although recent studies have suggested that possession of G 2254 is not always associated with a neuropathogenic phenotype (31), additional data from field cases of EHM are required before this issue can be fully clarified.…”

“…Alternatively, the E 1 assay is significantly more sensitive (88%), although it too was unable to detect EHV-1 in 15 whole blood samples shown to contain EHV-1 DNA by a magnetic-bead-based sequence capture nested PCR described by Allen et al (2). This technique was specifically designed to detect EHV-1 DNA that is in low abundance in lymph nodes and buffy coat cells during clinically quiescent periods and relies upon oligonucleotide hy- (32). While the ability to identify multiple genotypes within clinical samples represents a significant step in our understanding of the dynamics associated with in vivo EHV-1 replication events, false dual positive results are very detrimental in any diagnostic situation.…”

“…When a disease outbreak occurs, confirmation of a provisional clinical diagnosis with a rapid, sensitive, and specific laboratory diagnostic test(s) is vital to ensure that appropriate biosecurity and quarantine measures are implemented without unnecessary delay. Several reports have documented the use of PCR-based assays, both standard and real-time, for the detection of EHV-1 in clinical specimens (2,8,9,13,18,21,32). However, the allelic-discrimination rPCR assay described by Allen (1) has a distinct advantage because it can simultaneously detect and genotype EHV-1 strains.…”

Influence of the month of the year in the hematological profile in carthusian broodmares

“…Secondly, increased WBC and subsets is a moderately good marker of inflammation -infection in horses, with significant correlations with acute phase proteins [36]. There is seasonal variation in the prevalence of different doi: 10.7243/2052-434X-1-6 infectious diseases, mainly those affecting the respiratory tract, both in humans [37] and horses [38]. In horses, there are two peaks of incidence: during the training-competing season (spring-summer-early autumn) and during winter [38].…”

“…There is seasonal variation in the prevalence of different doi: 10.7243/2052-434X-1-6 infectious diseases, mainly those affecting the respiratory tract, both in humans [37] and horses [38]. In horses, there are two peaks of incidence: during the training-competing season (spring-summer-early autumn) and during winter [38]. Thirdly, the reproductive season starts in late January or February, with more activity and cortisol release [28].…”