Infectious Upper Respiratory Disease Research Articles

Prophylactic and therapeutic effects of twice-daily famciclovir administration on infectious upper respiratory disease in shelter-housed cats.

Prophylactic and therapeutic effects of twice-daily famciclovir administration on infectious upper respiratory disease in shelter-housed cats.

Comparison of nasopharyngeal and guttural pouch specimens to determine the optimal sampling site to detect Streptococcus equi subsp equi carriers by DNA amplification

BackgroundStreptococcus equi subsp equi (S. equi) is the cause of “equine strangles” which is a highly infectious upper respiratory disease. Detection of S. equi is influenced by site of specimen collection, method of sampling, and type of diagnostic test that is performed. We hypothesized i) that a loop-mediated isothermal amplification (LAMP) assay that targets the S. equi-specific eqbE gene would be more sensitive than a realtime PCR assay that targets the S. equi-specific seeI gene and ii) that LAMP of specimens obtained by guttural pouch lavage (GPL) would be more sensitive than LAMP of nasopharyngeal specimens to identify S. equi carriers.MethodsA nasopharyngeal flocked swab, nasopharyngeal wash, and GPL specimen was collected from 44 convalescent horses and the eqbE LAMP assay was performed. The seeI realtime PCR assay and aerobic culture were also performed on the GPL specimen. Logistic regression was performed to compare sampling sites and test methods (P-values ≤0.05 were considered significant).ResultsOne of 41 nasopharyngeal flocked swabs, 6/38 nasopharyngeal wash and 24/44 GPL specimens were positive by eqbE LAMP. 18/44 GPL specimens were positive by seeI PCR and S. equi was isolated from 4/44 of these specimens. Detection of S. equi DNA was 51 times more likely from the GPL samples than nasopharyngeal samples (OR 51.0, P < 0.0001). When eqbE LAMP GPL samples were positive, it was eight times more likely that the guttural pouch had any abnormality on endoscopy (OR 8.2, P ≤ 0.005), almost 20 times more likely that mild empyema was found (OR 19.7, P ≤ 0.002), and eight times more likely that the SeeI PCR was positive for S. equi DNA (OR 8.1, P ≤ 0.006).ConclusionThis study demonstrates that guttural pouch lavage specimens should be used to detect S. equi and that the eqbE LAMP assay was comparable to the seeI PCR.

Etiologic and epidemiologic analysis of bacterial infectious upper respiratory disease in Thoroughbred horses at the Seoul Race Park

Infectious upper respiratory disease (IURD) of Thoroughbred racehorses has been a frequent problem (29.6% of incidence) at the Seoul Race Park (Korea). Risk factors for IURD include the season with a high transfer rate (summer and fall), the stabling period (≤ 3 months), and age (2 to 3 years old), suggesting that the movement and new environment may have depressed the immune system of the horses and decreased their ability to respond properly to pathogens. The bacterial strains (n = 98) isolated from IURD horses included Pseudomonas spp., Escherichia coli, Staphylococcus spp., Streptococcus equi subsp. equi and zooepidemicus.

Is Dietary L-Lysine Effective for Treatment of Feline Ocular Disease Caused by Feline Herpesvirus-1?

Since the early 2000s, oral supplementation of L-lysine has been used to treat ocular disease in cats that was attributable to feline herpesvirus (FHV). Local (ocular) signs of disease that included conjunctivitis, blepharospasm, and ocular discharge were felt to improve when oral supplementation with a 250 or 500 mg bolus was administered once to twice daily. FHV-1 is considered the most common pathogen among other infectious agents, i.e., feline calicivirus and Chlamydophila felis, to cause ocular disease as well as infectious upper respiratory disease. It is felt that FHV-1 may establish a lifelong neural latency in 80% of infected cats. Early studies proposed that oral bolus administration of L-lysine reduced replication of FHV-1 by approximately 80% via antagonism of arginine, an essential amino acid for FHV-1 replication. Arginine is an essential dietary need for normal cat immune function. Studies evaluating serum arginine levels following oral L-lysine dose trials have found no adverse diminished levels of arginine. L-lysine is commercially available over the counter for treatment of the common cold sore in people that is caused by herpes simplex virus type 1. This formulation may be used for treatment of feline ocular disease by administering pills orally or by adding the contents of capsules to the diet. The generally recommended dose is a bolus of 500 mg, per os, twice per day in adult or average sized cats. Younger or smaller cats are typically fed 250 mg, twice per day. It has been shown that diets fortified with L-lysine that are consumed gradually throughout the day may not provide the immunologic effect necessary to reduce ocular disease and, specifically, infectious upper respiratory disease. Since the emergence of L-lysine as an effective and safe, long-term therapeutic for FHV-1 treatment, a number of commercially available products have become available on the veterinary market. By using palatable gels and treat products, administering a consistent and effective dosage regimen has become less problematic.

Etiologic and Immunologic Characteristics of Thoroughbred Horses with Bacterial Infectious Upper Respiratory Disease at the Seoul Race Park

Equine respiratory disease is a common cause of poor performance and training interruptions. The higher incidence rate of infectious upper respiratory disease (IURD) in thoroughbred racehorses at the Seoul Race Park coincided with the frequent stabling season, shorter stabling periods, and younger ages in this study. Incidence rates were also correlated with significantly lower proportions of cells expressing MHC class II-, CD2 antigen-, CD4+- or CD8+-T lymphocyte-, and B lymphocyte in IURD patients compared with healthy control groups in the summer and fall and in 2-and-3-year-old groups. The data suggested that movement and new environments may have resulted in immunosuppression and inappropriate responses to respiratory pathogens in IURD patients. The IURD incidence decreased with age, perhaps by the acquisition of immunity, and study results suggested that immunologic protection was associated with IURD, particularly in young thoroughbred racehorses. Streptococci isolates were identified in 11 of 72 IURD horses, and 3 of these isolates were identified as Streptococcus. equi subsp. equi. S. equi subsp. zooepidemicus was isolated from 2 of 23 IURD horses in the spring (8.7%), 5 of 23 in the summer (21.7%), and 1 of 6 in winter (16.7%). S. equi subsp. zooepidemicus (5%) was also identified in 3 of 61 isolates from clinically normal horses. Racetracks should implement anti-IURD protective measures by assessing the capacity of equine immunologic protection at the Park and by limiting the introduction of specific respiratory pathogens (such as S. equi subsp. equi) by preventing the access of infected horses with a respiratory pathogen-free certification system prior to Park entry.

Pulmonary Ultrasonographic Abnormalities Associated with Naturally Occurring Equine Influenza Virus Infection in Standardbred Racehorses

The purpose of this investigation was to determine if naturally occurring acute infectious upper respiratory disease (IRD) caused by equine influenza virus is associated with ultrasonographically detectable pleural and pulmonary abnormalities in horses. Standardbred racehorses were evaluated for signs of IRD, defined as acute coughing or mucopurulent nasal discharge. For every horse with IRD (n = 16), 1 or 2 horses with no signs of IRD and the same owner or trainer (n = 30) were included. Thoracic ultrasonography was performed within 5–10 days of the onset of clinical disease in horses with IRD. Horses without IRD were examined at the same time as the horses with IRD with which they were enrolled. The rank of the ultrasound scores of horses with IRD was compared to that of horses without IRD. Equine influenza virus was identified as the primary etiologic agent associated with IRD in this study. Mild lung consolidation and peripheral pulmonary irregularities were found in 11 (69%) of 16 of the horses with IRD and 11 (37%) of 30 of control horses. Lung consolidation (median score = 1) and peripheral irregularities scores (median score = 1) were greater in horses with IRD compared to horses without IRD (median score = 0; P &lt; .05). Pleural effusion was not observed. Equine influenza virus infection can result in abnormalities of the equine lower respiratory tract. Despite the mild nature of IRD observed in this study, lung consolidation and peripheral pulmonary irregularities were more commonly observed in horses with clinical signs of IRD. Further work is needed to determine the clinical significance of these ultrasonographic abnormalities.

Pulmonary Ultrasonographic Abnormalities Associated with Naturally Occurring Equine Influenza Virus Infection in Standardbred Racehorses

The purpose of this investigation was to determine if naturally occurring acute infectious upper respiratory disease (IRD) caused by equine influenza virus is associated with ultrasonographically detectable pleural and pulmonary abnormalities in horses. Standardbred racehorses were evaluated for signs of IRD, defined as acute coughing or mucopurulent nasal discharge. For every horse with IRD (n = 16), 1 or 2 horses with no signs of IRD and the same owner or trainer (n = 30) were included. Thoracic ultrasonography was performed within 5-10 days of the onset of clinical disease in horses with IRD. Horses without IRD were examined at the same time as the horses with IRD with which they were enrolled. The rank of the ultrasound scores of horses with IRD was compared to that of horses without IRD. Equine influenza virus was identified as the primary etiologic agent associated with IRD in this study. Mild lung consolidation and peripheral pulmonary irregularities were found in 11 (69%) of 16 of the horses with IRD and 11 (37%) of 30 of control horses. Lung consolidation (median score = 1) and peripheral irregularities scores (median score = 1) were greater in horses with IRD compared to horses without IRD (median score = 0; P < .05). Pleural effusion was not observed. Equine influenza virus infection can result in abnormalities of the equine lower respiratory tract. Despite the mild nature of IRD observed in this study, lung consolidation and peripheral pulmonary irregularities were more commonly observed in horses with clinical signs of IRD. Further work is needed to determine the clinical significance of these ultrasonographic abnormalities.

Occurrence of infectious upper respiratory tract disease and response to vaccination in horses on six sentinel premises in northern Colorado.

Horses vaccinated against common agents of infectious upper respiratory disease (IURD) may not have detectable serum antibody and may not be protected from clinical disease. The objectives of this study were to 1) investigate the serological response of horses to vaccination against influenza virus (H3N8 and H7N7) and equine herpesviruses (EHV) in a field setting and 2) evaluate associations among vaccination status, serum antibody concentrations, and occurrences of IURD in monitored horses. In this study, horses on 6 Colorado premises were vaccinated parenterally against influenza virus and EHV, and serological response evaluated. Horses were monitored, and biological samples collected from individuals with clinical IURD and control horses. Of 173 horses, 61 (35.3%), 21 (12.1%) and 4 (2.3%) seroconverted in response to vaccination against EHV, influenza virus H7N7 and influenza virus H3N8, respectively. Outbreaks of IURD in study horses were associated with influenza virus H3N8 and Streptococcus equi infection, and serological response to vaccination with conventional products was poor. These results confirm that horses may not respond with detectable serological responses to conventional vaccination against common respiratory viruses and, therefore, suggest that alternate methods of protecting horses against common respiratory viruses should be sought.

Evaluation of ELISA Titers to Infectious Laryngotracheitis

Infectious laryngotracheitis (ILT), a highly infectious upper respiratory disease of chickens, can cause serious economic loss in areas where the poultry industry is concentrated. To determine the antibody levels associated with vaccine administration, field challenge, and protection, six groups of 20 specific-pathogen-free leghorn chickens were housed in biosecured isolation units. Individual groups served as either negative controls, vaccinated (one full dose per bird of chicken embryo origin [CEO] administered by the eyedrop method) and challenged (intratracheal administration with USDA strain ILT virus at 10(4.1) 50% embryo infective dose [EID50]), or unvaccinated and challenged with USDA strain ILT virus at various dose levels (10(2.1), 10(5.1), or 10(4.1) EID50). Chickens in each group were bled weekly, and their sera were tested for antibody using a commercially available enzyme-linked immunosorbent assay test kit. The antibody response using CEO vaccine resulted in a 400-600 geometric mean titer that appeared to be protective against severe field challenge. Negative controls had no titers, whereas vaccinated and/or challenged chickens had detectable titers within 2 wk of exposure, and these titers remained high for the next 4-7 wk. Mortality in nonvaccinated controls began at 3 days post-challenge and continued for up to 10 days.

Feline infectious upper respiratory disease

INFECTIOUS upper respiratory disease in cats remains a common problem, despite widespread use of vaccination against the feline respiratory viruses over the past 20 years. This is partly due to the fact that, while vaccination reduces the severity of disease, it will not protect against viral infection, and does not eliminate or prevent the development of carrier states. The involvement of other pathogens, such as [i]Bordetella bronchiseptica[/i] and [i]Chiamydia psittaci[/i], in the syndrome may also be significant.