Inflammatory airway disease, nasal discharge and respiratory infections in young British racehorses

REASONS FOR PERFORMING STUDY

Respiratory disease is important in young Thoroughbred racehorses, but the variation in the rates of occurrence between different ages and training groups has not been characterised.

OBJECTIVES

To determine the rates of respiratory disease, particularly inflammatory airway disease (IAD), as well as evidence of infection, and their variation between age and group.

METHODS

Horses were examined monthly in 7 British flat training yards over a 3 year period. IAD was defined as increased mucus in the trachea with increased proportions of neutrophils in tracheal wash samples. Frequencies of disease outcomes were estimated from the data.

RESULTS

The prevalence of IAD was 13.8% and the incidence was 8.9 cases/100 horses/month. Rates varied with training and age groups, decreasing in older animals. The prevalence of nasal discharge (ND) was 4.1%. Rates of bacterial isolation were more common than viral infections. The incidence and prevalence of several bacterial species decreased with age.

CONCLUSIONS

IAD and ND were common in young racehorses, varying significantly between training groups and decreasing with age, consistent with infection playing a role in aetiology.

POTENTIAL RELEVANCE

The high prevalence of IAD in 2-year-old horses in Britain suggests that routine endoscopic examination may be helpful in providing early diagnosis and appropriate therapy. The transmission of bacteria and viruses within and between groups of young animals and the role of infection, stable environment and factors inherent to each horse, including their genetic make-up, in the multifactorial aetiology of the disease all merit further study.

Sepsis predisposition in children with human immunodeficiency virus

OBJECTIVE

To review predisposition to sepsis in children infected with human immunodeficiency virus (HIV) in the era of highly active antiretroviral therapy (HAART).

DESIGN

Summary of the literature with review by experts in the field.

RESULTS

In industrialized regions, new diagnoses of vertically acquired HIV infection are falling due to perinatal interventions. Provision of HAART has resulted in an enlarging cohort of clinically stable HIV-infected children, with low viral loads and normal CD4 T-lymphocyte counts. Access to HAART in "developed" countries has markedly decreased the rate of progression to acquired immunodeficiency syndrome, the prevalence of organ-specific complications of HIV, the risk of recurrent sepsis, and the high early childhood mortality from HIV infection. There are currently no data on whether initiation of HAART during acute sepsis reduces short-term morbidity or mortality. Undiagnosed, antiretroviral-naive, HIV-infected infants still present sporadically with opportunistic infections such as Pneumocystis jiroveci and cytomegalovirus pneumonia. HIV-infected children have a greater burden of disease due to viral, bacterial, and fungal sepsis, and the case fatality rate for nonopportunistic infections may be greater than in non-HIV-infected children. In "developing" countries, with limited access to HAART, the natural history of HIV infection has altered very little, with the majority of infected children dying from either opportunistic or nonopportunistic disease before 3 yrs of age.

CONCLUSION

Pediatric HIV infection is not a homogeneous condition in the era of HAART. Susceptibility to sepsis, morbidity, and mortality differ according to stage of disease, access to HAART, and virologic and immunologic response to treatment. These issues should be considered if HIV-infected children are to be enrolled and stratified in clinical trials.

Viral and bacterial pathogens in bovine respiratory disease in Finland

Pathogens causing bovine respiratory tract disease in Finland were investigated. Eighteen cattle herds with bovine respiratory disease were included. Five diseased calves from each farm were chosen for closer examination and tracheobronchial lavage. Blood samples were taken from the calves at the time of the investigation and from 86 calves 3–4 weeks later. In addition, 6–10 blood samples from animals of different ages were collected from each herd, resulting in 169 samples. Serum samples were tested for antibodies to bovine parainfluenza virus-3 (PIV-3), bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCV), bovine adenovirus-3 (BAV-3) and bovine adenovirus-7 (BAV-7). About one third of the samples were also tested for antibodies to bovine virus diarrhoea virus (BVDV) with negative results. Bacteria were cultured from lavage fluid and in vitro susceptibility to selected antimicrobials was tested. According to serological findings, PIV-3, BAV-7, BAV-3, BCV and BRSV are common pathogens in Finnish cattle with respiratory problems. A titre rise especially for BAV-7 and BAV-3, the dual growth of Mycoplasma dispar and Pasteurella multocida, were typical findings in diseased calves. Pasteurella sp. strains showed no resistance to tested antimicrobials. Mycoplasma bovis and Mannheimia haemolytica were not found.

Marked induction of IL-6, haptoglobin and IFNγ following experimental BRSV infection in young calves

Bovine respiratory syncytial virus (BRSV) has been identified worldwide as an important pathogen associated with acute respiratory disease in calves. An infection model has been developed reflecting accurately the clinical course and the development of pathological signs during a natural BRSV-infection. In the experiments described in the present study, calves were infected at 13-21 weeks of age and reinfected 14 weeks later. Blood samples from the entire infection period were analysed for acute phase protein (haptoglobin) by ELISA and for expression (mRNA level in peripheral blood mononuclear cells) of the cytokines interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-6 (IL-6) and interferon-gamma (IFNgamma) by quantitative real-time reverse transcribed polymerase chain reaction (RT-PCR). IFNgamma, interleukin-6 and haptoglobin were markedly induced together with development of clinical signs in response to the first infection with BRSV. The IFNgamma response was biphasic, with an early peak at day 1-3 post infection (p.i.) and a later increase between day 5 and 8 p.i. Reinfection also resulted in an induction of IFNgamma, but without induction of clinical signs, IL-6 and haptoglobin. These results indicate that early mediators connected with the innate responses are induced on a first encounter with the pathogen, but not on a second encounter (reinfection) where the adaptive immune system may act as the first line defence.

Longitudinal study of viruses associated with canine infectious respiratory disease

In this investigation a population of dogs at a rehoming center was monitored over a period of 2 years. Despite regular vaccination of incoming dogs against distemper, canine adenovirus type 2 (CAV-2), and canine parainfluenza virus (CPIV), respiratory disease was endemic. Tissue samples from the respiratory tract as well as paired serum samples were collected for analysis. The development of PCR assays for the detection of CPIV, canine adenovirus types 1 and 2, and canine herpesvirus (CHV) is described. Surprisingly, canine adenovirus was not detected in samples from this population, whereas 19.4% of tracheal and 10.4% of lung samples were positive for CPIV and 12.8% of tracheal and 9.6% of lung samples were positive for CHV. As reported previously, a novel canine respiratory coronavirus (CRCoV) was detected in this population (K. Erles, C. Toomey, H. W. Brooks, and J. Brownlie, Virology 310:216-223, 2003). Infections with CRCoV occurred mostly during the first week of a dog's stay at the kennel, whereas CPIV and CHV were detected at later time points. Furthermore, the evaluation of an enzyme-linked immunosorbent assay for detection of antibodies to CPIV and an immunofluorescence assay for detection of antibodies to CHV is described. This study shows that CPIV is present at kennels despite vaccination. In addition, other agents such as CHV and CRCoV may play a role in the pathogenesis of canine respiratory disease, whereas CAV-2 and canine distemper virus were not present in this population, indicating that their prevalence in the United Kingdom is low due to widespread vaccination of dogs.

Detection of Brazilian bovine respiratory syncytial virus strain by a reverse transcriptase-nested-polymerase chain reaction in experimentally infected calves

A reverse transcriptase (RT)-nested-polymerase chain reaction (PCR) was standardised to detect bovine respiratory syncytial virus (BRSV), using a Brazilian isolate, in three experimentally infected calves. This followed initial tests in infected chicken embryo related (CER) cells. One animal had lesions, characterized by interstitial multifocal pneumonia, severe interstitial and subpleural emphysema, and lung consolidated areas. Lung and tracheal tissues collected 6 days after infection were analysed by RT-nested-PCR. Primers, specific for the BRSV G and F glycoproteins genes, yielded amplification fragments of 371 and 481 bp, respectively, from the RNA of the cell-propagated virus. Using RNA extracted from organs of infected calves, RT-nested-PCR amplified the fragment of the G gene in all tracheal samples, but in only two of three lung samples analysed. These results suggest that RT-nested-PCR could be a promising assay for diagnosis and epidemiological analysis of BRSV in Brazil.

Respiratory viruses seasonality in children under five years of age in Buenos Aires, Argentina: a five-year analysis

OBJECTIVES

During the winter months there is a remarkable increase in paediatric hospitalisations due to viral acute lower respiratory infections (ALRI). We aimed to perform a five-year retrospective analysis (1998-2002) of ALRI viral aetiology in children under 5 years of age admitted to public hospitals in Buenos Aires city to evaluate its seasonality.

MATERIALS AND METHODS

Nasopharyngeal aspirates (NPA) were analysed by indirect immunofluorescence to determine viral aetiology. A Spearman's rank correlation test between meteorological parameters and viral frequencies was performed.

RESULTS

Viruses were identified in 6083 (32.8%) of 18,561 NPA tested. Among the former 4796 (78.8%) were RSV, 508 (8.3%) IA, 473 (7.8%) AV, 293 (4.8%) PIV and 13 (0.2%) IB. RSV and IA peaked during the coldest and dampest months, whereas PIV did so in early spring and AV lasted throughout the year. For RSV and IA an inverse correlation with mean monthly temperature (r = -0.9 and r = -0.87, respectively, p<0.0001) and solar UVB radiation (r = -0.92 and r = -0.80, respectively, p<0.0001) was detected, while it was positive when relative humidity was considered (r = 0.6, p<0.0001 and r = 0.47, p=0.0068, respectively).

CONCLUSIONS

This study highlights the seasonal variation of ALRI and allows the implementation of adequate healthcare strategies and practice guidelines.

Correlation between Torque tenovirus infection and serum levels of eosinophil cationic protein in children hospitalized for acute respiratory diseases

Children with bronchopneumonia have considerably higher Torque tenovirus (TTV) loads than do children with milder acute respiratory diseases (ARDs). Moreover, in children with ARDs, high TTV loads correlate with low percentages of circulating CD3+ and CD4+ T cells and with elevated percentages of B cells, suggesting that TTV might be immunomodulatory. Here, we show that, in children with ARDs, the presence of TTV and TTV load correlate with concentrations of serum eosinophil cationic protein. The possible mechanisms whereby TTV infection might lead to augmented activity of eosinophils and the implications for pathogenesis are discussed.

A prospective, community-based study on virologic assessment among elderly people with and without symptoms of acute respiratory infection

Background and objective

Community-based elderly studies concerning microbiology of acute respiratory infections are scarce. Data on subclinical infections are even totally absent, although asymptomatic persons might act as a source of respiratory infections.

Methods

In a 1-year community-based study, we prospectively investigated the possible virologic cause of acute respiratory infections in 107 symptomatic case episodes and 91 symptom-free control periods. Participants, persons ⩾60 years, reported daily the presence of respiratory symptoms in a diary. Virologic assessment was performed by polymerase chain reaction (PCR) and serology.

Results

In 58% of the case episodes a pathogen was demonstrated, the most common being rhinoviruses (32%), coronaviruses (17%), and influenzaviruses (7%). The odds ratio for demonstrating a virus in cases with symptoms vs. controls without symptoms was 30.0 (95% confidence interval 10.2–87.6). In 4% of the symptom-free control periods a virus was detected.

Conclusion

This study supports the importance of rhinovirus infections in community-dwelling elderly persons, whereas asymptomatic elderly persons can also harbor pathogens as detected by PCR, and thus might be a source of infection for their environment.

Equine herpes virus 2 infection in horse populations in Poland

The prevalence of Equine herpesvirus 2 (EHV-2) infections in the horse populations in Poland was investigated. Peripheral blood leukocytes (PBLs) of 139 horses were tested. The animals were divided into four groups: clinically healthy horses, horses suffering from respiratory disorders, mares with a recent abortion and horses with diagnosed ataxia. Thirty-four virus isolates were obtained from leukocytes of the tested animals by cocultivation with equine dermal cells and were identified as EHV-2 by PCR using primers for the gB gene of EHV-2 and/or primers for the sequence located upstream of the gene homologous to the equine interleukin 10 (IL-10) gene. These results indicate that EHV-2 is prevalent in horse populations in Poland. As the virus was most frequently isolated from horses with respiratory disorders its etiological importance may be considered.

Association of porcine circovirus 2 with porcine respiratory disease complex

A retrospective study was performed on natural cases of porcine respiratory disease complex (PRDC) to determine the association and prevalence of PRDC with porcine circovirus 2 (PCV2) and other co-existing pathogens in Korea. Histologically, alveolar septa were markedly thickened by infiltrates of mononuclear cells. Moderate to marked multifocal peribronchial and peribronchiolar fibrosis were present and often extended into the airway lamina propria. Among the 105 pigs with PRDC, 85 were positive for PCV2, 66 were positive for porcine reproductive and respiratory syndrome virus (PRRSV), 60 were positive for porcine parvovirus (PPV), and 14 were positive for swine influenza virus (SIV). There were 80 co-infections and 25 single infections. A co-infection of PCV2 with another additional bacterial pathogen is frequently diagnosed in PRDC. The combination of PCV2 and Pasteurella multocida (38 cases) was most prevalent followed by PCV2 and Mycoplasma hyopneumoniae (33 cases). The consistent presence of PCV2, but lower prevalence of other viral and bacterial pathogens in all pigs examined with PRDC, has led us to speculate that PCV2 plays an important role in PRDC.

Retrospective analysis of etiologic agents associated with respiratory diseases in pigs

Twenty-eight hundred and seventy-two cases of respiratory disease in pigs were analyzed for their etiologic agents. Two or more pathogens were detected from 88.2% of the cases, indicating that porcine reproductive and respiratory syndrome virus (PRRSV) or swine influenza virus (SIV) combined with other bacterial agents was a common cause for porcine respiratory diseases in the mid-western USA.

Prevention of HIV-associated respiratory illness in children in developing countries: potential benefits

Respiratory disease accounts for a substantial proportion of illness in human immunodeficiency virus-infected children. A number of interventions are available to prevent respiratory complications; these interventions may be beneficial especially in low-income countries where the burden of human immunodeficiency virus and infectious diseases are high and where antiretroviral therapy is unavailable or unaffordable. This article reviews the potential benefits and risks for interventions that are available to prevent respiratory complications including chemoprophylaxis for Pneumocystis carinii pneumonia and tuberculosis, use of immunisation for prevention of specific respiratory infections and non-specific measures including nutrition and micronutrient supplementation.

TT virus loads and lymphocyte subpopulations in children with acute respiratory diseases

TT virus (TTV) produces chronic plasma viremia in around 90% of healthy individuals of all ages and has, therefore, been proposed as a commensal human virus. We recently demonstrated that in children hospitalized for acute respiratory diseases high TTV loads were associated with severe forms of disease. Here, we report that in such children TTV loads showed an inverse correlation with the percentage of circulating total T and helper T cells and a direct correlation with the percentage of B cells. Thus, florid TTV replication might contribute to lymphocyte imbalances and, possibly, immunosuppressive effects, thus resembling related animal viruses.

Impact of oseltamivir treatment on influenza-related lower respiratory tract complications and hospitalizations

BACKGROUND

Influenza causes lower respiratory tract complications (LRTCs), particularly bronchitis and pneumonia, in both otherwise healthy adults and those with underlying conditions. The aim of this study was to assess the effect of oseltamivir treatment on the incidence of LRTCs leading to antibiotic treatment and hospitalizations following influenza illness.

METHODS

We analyzed prospectively collected data on LRTCs and antibiotic use from 3564 subjects (age range, 13-97 years) with influenzalike illness enrolled in 10 placebo-controlled, double-blind trials of oseltamivir treatment.

RESULTS

In adults and adolescents with a proven influenza illness, oseltamivir treatment reduced overall antibiotic use for any reason by 26.7% (14.0% vs 19.1% with placebo; P<.001) and the incidence of influenza-related LRTCs resulting in antibiotic therapy by 55% (4.6% vs 10.3% with placebo; P<.001). In those subjects considered at increased risk of complications, 74 (18.5%) of 401 placebo recipients developed an LRTC leading to antibiotic use compared with 45 (12.2%) of 368 oseltamivir recipients (34.0% reduction; P =.02). Hospitalization for any cause occurred in 18 (1.7%) of 1063 placebo recipients compared with 9 (0.7%) of 1350 oseltamivir-treated patients (59% reduction; P =.02). In contrast, among subjects with an influenzalike illness but without a confirmed influenza infection, the incidence of LRTCs (6.7% vs 5.3%), overall antibiotic use (19.7% vs 19.3%), or hospitalizations (1.7% vs 1.9%) was similar between placebo and oseltamivir recipients, respectively.

CONCLUSION

Oseltamivir treatment of influenza illness reduces LRTCs, antibiotic use, and hospitalization in both healthy and "at-risk" adults.

Transcriptional analysis of the response of poultry species to respiratory pathogens

Respiratory tract diseases are the single most important cause of economic loss due to infections among poultry populations worldwide. However, the molecular mechanisms of the host response to infections remain unknown. Here, we review the literature and describe the adoption of a conceptually simple approach to understand the genetic and biochemical responses of host cells during infection with respiratory pathogens, such as avian pneumovirus (APV). The strategy that we have adopted integrates the powerful techniques of cDNA subtraction hybridization and microarray analysis for global transcriptional profiling. The results of our investigations identify the specific transcriptional alterations in host-cell gene expression that result from an attempt by the host to combat and limit the spread of the pathogen or by the pathogen to enhance its own survival and ability to reproduce. Our studies suggest that a molecular description of host-pathogen interactions in terms of differential gene expression will provide key insights on the molecular basis of disease pathogenesis, pathogen virulence, and host immunity. In addition, the results suggest that the identification of genes and pathways with a role in host response to infection has considerable practical implications for the future design and development of effective immunomodulators and vaccines.

Pulmonary involvement in a case of juvenile-onset recurrent respiratory papillomatosis

Juvenile-onset recurrent respiratory papillomatosis is primarily a disease of children and adolescents. Although most patients experience spontaneous regression at a later age, some patients continue to be affected throughout their lives. We report the case of a 35-year-old woman with a 33-year history of juvenile-onset recurrent respiratory papillomatosis who developed pulmonary dissemination with malignant transformation. Malignant transformation is the most feared sequela of pulmonary dissemination, and it should be addressed aggressively. If treated promptly, the patient can enjoy prolonged survival. Computed tomography is superior to plain radiography for detecting and evaluating the extent of disease.

Human metapneumovirus infections in hospitalized children

We evaluated the percentage of hospitalizations for acute respiratory tract infections in children < or =3 years of age attributable to human metapneumovirus (HMPV) and other respiratory viruses in a prospective study during winter and spring 2002. We used real-time polymerase chain assays and other conventional diagnostic methods to detect HMPV, human respiratory syncytial virus (HRSV), and influenza viruses in nasopharyngeal aspirates of children. HMPV was detected in 12 (6%) of the 208 children hospitalized for acute respiratory tract infections, HRSV in 118 (57%), and influenza A in 49 (24%). Bronchiolitis was diagnosed in 8 (68%) and pneumonitis in 2 (17%) of HMPV-infected children; of those with HRSV infection, bronchiolitiss was diagnosed in 99 (84%) and pneumonitis in 30 (25%). None of the HMPV-infected children was admitted to an intensive-care unit, whereas 15% of those with HRSV or influenza A infections were admitted. HMPV is an important cause of illness in young children with a similar, although less severe, clinical presentation to that of HRSV.

Equid herpesvirus (EHV-1) live vaccine strain C147: efficacy against respiratory diseases following EHV types 1 and 4 challenges

The temperature sensitive and host range mutant clone 147 of equine herpesvirus 1 (EHV-1) was assessed for its ability to protect conventional, susceptible adult horses against respiratory infection by EHV-1 and equine herpesvirus 4 (EHV-4). Intranasal (IN) vaccination with 5.2 log(10) TCID(50) did not cause adverse clinical reactions although a limited virus shedding and viraemia (leukocytes) was observed in 11 of 15 and 10 of 15 vaccinated horses respectively. All 15 vaccinated horses showed a significant seroresponse to both EHV-1 and EHV-4 for virus neutralising (VN) antibody. None of 14 control horses shed virus or became viraemic or seroconverted prior to challenge. EHV-1 challenge (dose 6.0 log(10)) 6 weeks after vaccination resulted in pyrexia in all eight control horses while eight vaccinated horses remained unaffected. Six control horses developed nasal discharge, five of which were mucopurulent nasal discharge (mean duration 3.2 days) which also occurred in four vaccinated horses for 1 day. All eight control horses shed challenge EHV-1 at a significantly higher level (group mean titre 2.6+/-0.4 log(10) TCID(50) per sample) and for much longer (mean duration 4.8+/-1.5 days) than that (group mean titre 1.4+/-0.8 log(10) TCID(50) per sample and mean duration 1.5+/-0.5 days) in six vaccinated horses. Furthermore, all eight control horses became viraemic (mean duration 2.9 days) but viraemia did not occur in eight vaccinated horses. Following EHV-1 challenge, all eight control horses showed a significant VN antibody rise to both EHV-1 and EHV-4 but this occurred in only one vaccinated horse and to EHV-4 only. In EHV-4 challenge (dose of 4.2 log(10) TCID(50)) of a separate pair of seven vaccinated and six control horses, 6 weeks after EHV-1 vaccination resulted in pyrexia (mean duration 2.3 days) and nasal discharge (mean duration 1.8 days) in three and five control horses respectively but the only reaction observed in the vaccinated group was nasal discharge for 1 day in one animal. All six control animals shed virus (mean titre 2.5+/-0.6 log(10) TCID(50) per sample and mean duration 2+/-0.6 days) compared to one vaccinated animal. Although EHV-4 viraemia is rare, 3 of 6 control horses became viraemic after EHV-4 challenge but this was not observed in vaccinated horses. After EHV-4 challenge 3 and 5 of 6 control horses seroconverted for VN antibody to EHV-1 and EHV-4 respectively; a non-responsive control horse had high level of pre-existing VN antibody to EHV-4. However, only 1 of 7 vaccinated horses showed a significant antibody rise and only to EHV-4.

Respiratory consequences of rhinovirus infection

Rhinoviruses, a genus of the family Picornaviridae, are the cause of more than 50% of respiratory tract infections. Complications of rhinovirus infections, which include otitis media, sinusitis, exacerbations of asthma, and other pulmonary diseases, can be significant in certain populations. Reverse transcriptase-polymerase chain reaction has allowed the identification of rhinoviruses and led to a greater appreciation of the role of this pathogen in upper and lower respiratory tract disease. Furthermore, antiviral agents with broad activity against rhinoviruses have recently been developed, have undergone clinical trials, but have not been approved for clinical use. By altering the clinical course of picornavirus infections, it may be possible to minimize their potential adverse consequences.

TT virus in the nasal secretions of children with acute respiratory diseases: relations to viremia and disease severity

The natural history and pathogenic potential of the recently identified TT virus (TTV) are currently a matter of intensive investigation. In an attempt to shed some light on these issues, nasal and blood specimens of 1- to 24-month-old children hospitalized with a clinical diagnosis of acute respiratory disease (ARD) were examined for the presence, load, and genetic characteristics of TTV. The results have indicated that at least in young children, the respiratory tract not only represents a route by which abundant TTV can be shed into the environment but also may be a site of primary infection and continual replication. Although we found no compelling evidence that TTV was the direct cause of ARD in some of the children studied, the average loads of TTV were considerably higher in patients with bronchopneumonia (BP) than in those with milder ARD, raising interesting questions about the pathophysiological significance of TTV at this site. Furthermore, group 4 TTV was detected almost exclusively in children with BP.

Respiratory disease due to parainfluenza virus in adult leukemia patients

Reports of human parainfluenza viruses (HPIV) in patients with leukemia have been limited to a few cases or as a portion of general surveys. In order to expand the knowledge of these infections in this patient group, the frequency and clinical course of HPIV infections was determined among 1,787 patients with leukemia treated at The University of Texas M.D. Anderson Cancer Center between July 1994 and December 1997. HPIV was isolated from 47 (6.2%) of the 770 patients who were cultured for respiratory viruses. HPIV type 3 accounted for 39 of the 47 HPIV infections. Twenty-six patients developed pneumonia, and the associated mortality was 27%. Multivariate analysis revealed that a low absolute lymphocyte count and pneumonia were associated with increased mortality. Concurrent respiratory and other infections were associated with an increased frequency of pneumonia. Only five patients with pneumonia received antiviral therapy and four of them survived the infection. HPIV infection in leukemic patients is frequently associated with pneumonia and the mortality rate from pneumonia is substantial among lymphopenic patients.