Respiratory syncytial virus infection in young hospitalized children. Identification of risk patients and prevention of nosocomial spread by rapid diagnosis

Rates and risk factors of severe respiratory syncytial virus infection in 2008-2016 compared with 1986-1998

AIM

Since the introduction in 1979 of rapid testing using immunofluorescence, we have collected information about children hospitalised for confirmed respiratory syncytial virus (RSV) infection in the northern Stockholm area. We here report hospitalisation rates, risk factors and complications in 2008-2016 compared with 1986-1998.

METHODS

Microbiological laboratory reports and retrospective chart review. Comparison of the two periods was complicated by changing testing routines, with a more sensitive method and increased testing of older children in the late period.

RESULTS

In infants, there was an 12.3% increase in the population-based rate of hospital admission for RSV infection from 12.2 to 13.7/1000. Including all children <5 years, there was a 48% increase from 2.7 to 4.0/1000. The median length of stay remained unchanged at 3 days. The need of intensive care decreased in healthy infants but remained high in older children with comorbidity.

CONCLUSION

Considering the changed diagnosis routines, we believe that the rate of hospital admission of infants for RSV infection was unchanged throughout the observed years. The increased rates of older children with confirmed RSV likely resulted from increased testing of children with risk factors for a complicated course.

Factors predicting prolonged hospital stay for infants with bronchiolitis

BACKGROUND

Prior prediction models for length of stay (LOS) in bronchiolitis have focused more on birth- and disease-related risk factors than on early hospital course factors, particularly common clinical markers including respiratory status and caloric intake.

OBJECTIVES

1) Study the associations of various clinical markers and LOS; and 2) develop a LOS prediction model.

DESIGN

Retrospective cohort study.

SETTING

Children's Hospital of Wisconsin.

PATIENTS

Inclusion criteria were: age < 365 days old; admission between November 1, 2004 and April 15, 2005; final diagnosis of bronchiolitis; placement on the bronchiolitis treatment protocol; and lack of concurrent condition impacting LOS.

RESULTS

During the study period, 272/347 infants admitted with bronchiolitis met inclusion criteria. On hospital day 2, infants in the prolonged LOS group (≥ 108 hours) had a significantly greater number of hours on supplemental oxygen, maximum supplemental oxygen use, minimum supplemental oxygen use, maximum respiratory rate, mean respiratory score, and number of times suctioned. They had significantly lower minimum oxygen saturation and caloric intake. Recursive partitioning demonstrated five variables (hours of supplemental oxygen, maximum respiratory rate, minimum supplemental oxygen use, gestation, and caloric intake) to predict short or prolonged LOS with an area under the receiver-operator characteristic curve of 0.89/0.72 in the learning/test trees; sensitivity, 0.85; and specificity, 0.82.

CONCLUSIONS

There are important differences between infants with bronchiolitis having short and prolonged hospital stays, including several clinical markers identifiable on hospital day 2. This model may be a useful prediction tool for targeting early interventions for high-risk infants.

Rates of hospitalisation for influenza, respiratory syncytial virus and human metapneumovirus among infants and young children

To inform the development of a national influenza immunisation programme and the potential role of antiviral drugs in young children, we studied 613 children aged 71 months or younger who attended Leicester Childrens' Hospital during winter 2001-2002. During periods of respiratory syncytial virus (RSV), influenza, and human metapneumovirus activity, an estimated 12.2% (95% CI: 11.4-13.1), 7.1% (6.3-7.9), and 2.5% (2.1-2.9), respectively, of all medical cases assessed in the hospital were associated with these infections. The respective rates of hospital assessments for RSV, influenza, and human metapneumovirus (HMPV) were 1042 (95% CI: 967-1021), 394 (348-443), and 223 (189-262) per 100,000 children, and for admissions were 517 (465-574), 144 (117-175), and 126 (101-156) per 100,000. Few children with influenza had a prior risk factor. Children with influenza were admitted a median of 4 days after onset of illness and none was coded at discharge as influenza. We conclude that antivirals have little role in the hospital management of children with influenza. Our data provide health economists with information to evaluate the place of universal immunisation of young children against influenza. Hospitalisation rates decreased markedly with referral age, so vaccine would need to be given in early infancy for maximum benefit.

Current concepts on active immunization against respiratory syncytial virus for infants and young children

Respiratory syncytial virus (RSV) is the most important causative agent of viral respiratory tract infections in infants and young children. Passive immunization against RSV became available recently, but this does not apply to an effective vaccine as a result of dramatic adverse results of immunization with a RSV candidate vaccine in the 1960s and the lack of full knowledge of the immune response induced by RSV. Nonetheless intensive research during the past two decades has resulted in several interesting candidate vaccines, of which some have gone through testing in humans. These include the subunit vaccines PFP-1, PFP-2, BBG2Na and cold-passaged/temperature-sensitive mutants. The development of candidate vaccines against RSV is discussed. Because of questions, uncertainties and difficulties with the development of effective vaccines against RSV, it will probably be at least another 5 to 10 years before routine immunization against RSV becomes available.

The viral association of neonatal cholestasis in Sweden: a possible link between cytomegalovirus infection and extrahepatic biliary atresia

BACKGROUND

In addition to earlier reports on the association between viral infections and intrahepatic neonatal cholestasis, in recent studies, investigators have suggested a similar link to extrahepatic biliary atresia.

METHODS

Fifty-nine cholestatic infants (mean age 8 weeks) were investigated for signs of infection with a large spectrum of viruses. Twenty-one infants had extrahepatic biliary atresia, 38 had intrahepatic cholestasis. The virologic methods included serologic investigation in 59 infants and 54 mothers, virus isolation from stools (49 infants), urine (58 infants) and liver biopsies (40 infants). Polymerase chain reaction was used to detect cytomegalovirus DNA in 25 of the liver biopsy specimens. Two control groups, one with 35 noncholestatic infants and one with 111 healthy, pregnant women were checked for serologic signs of cytomegalovirus.

RESULTS

Nineteen of 59 (32%) cholestatic infants, including 8 of 21 (38%) with extrahepatic biliary atresia, compared with 2 of 35 (6%) control infants had cytomegalovirus-immunoglobulin (Ig) M detected in serum (p < 0.01). Fifty-one of 54 (94%) tested mothers of cholestatic infants were seropositive for cytomegalovirus, compared with 83 of 111 (75%) control mothers (p < 0.01). Cytomegalovirus DNA in liver specimens was detected by polymerase chain reaction in 9 of 18 (50%) analyzed patients with biliary atresia and in specimens from 3 of 7 patients with intrahepatic cholestasis.

CONCLUSIONS

Cytomegalovirus infection may play a role, not only in intrahepatic neonatal cholestasis, as was suggested earlier, but also in extrahepatic biliary atresia. The pathogenetic mechanism for this link remains to be established.

Respiratory syncytial virus immune globulin treatment of RSV lower respiratory tract infection in previously healthy children

OBJECTIVE

To evaluate the efficacy of high titer respiratory syncytial virus (RSV) immune globulin (RSVIG) in the treatment of previously healthy children hospitalized with proven RSV lower tract infection (LRI).

METHOD

Infants and young children </=2 years of age with RSV LRI of </=4 days duration, and respiratory scores >/=2. 5 were enrolled.

RESULTS

One hundred and one previously healthy children hospitalized with RSV LRI received either 1500 mg/kg of RSVIG (RespiGam, MedImmune Inc, Gaithersburg, MD) or albumin placebo in a randomized, double-blind, placebo-controlled trial. Forty-six RSVIG and 52 recipients of placebo met all eligibility criteria. Demographic characteristics of the two groups were similar. More RSVIG recipients (46% vs 29%) had an SaO2 </=85% at entry than did placebo recipients, but a higher proportion of placebo recipients required intensive care unit (ICU) care and mechanical ventilation at study entry. The mean RSV hospital stay was 5.52 +/- 0.69 days (SE) for placebo and 4.58 +/- 0.40 days for RSVIG. Additionally, there was an interaction between treatment group and entry respiratory score, which led to subgroup analysis. Children with modest respiratory illness did not receive any benefit from RSVIG therapy. RSVIG recipients with more severe illness (entry respiratory scores >/=3.0) had 1.6 fewer hospital days and 2.7 days less ICU stays.

CONCLUSION

RSVIG infusions seemed safe and generally well tolerated. Although some beneficial effect trends were seen for those with more severe disease who were treated there was no evidence that treatment with RSVIG resulted in reduced hospitalization and reduced ICU stays in all children with RSV disease.

Influence of maternal infections with viral agents or Toxoplasma gondii during pregnancy on fetal IgE production

The importance of maternal infections with Toxoplasma gondii, cytomegalovirus (CMV), Parvovirus B19, respiratory syncytial virus (RSV), and influenza A and B on fetal IgE synthesis was studied in 153 pregnant women. No case of specific IgM activity or viral DNA in cord blood, indicating a congenital infection, was found. From gestational week 15 to delivery, maternal IgG-Ab seroconversion to Parvovirus B19, RSV, influenza A, or influenza B occurred in 47 women. At delivery, serologic signs of past infection with T. gondii were observed in 29 (19%) women, and the corresponding figure for CMV was 117 (77%). The number of women with positive IgG seroconversion during pregnancy or positive IgG-Ab activity toward the studied infectious agents at delivery did not differ significantly among infants with an increased (> or = 1.3 kU/l; n = 51) or with an undetectable (< 0.1 kU/l; n = 102) cord-blood IgE level. These results show that genetic and other environmental factors probably have a greater influence on fetal IgE synthesis than do maternal infections during pregnancy.

Respiratory syncytial virus (RSV) immune globulin intravenous therapy for RSV lower respiratory tract infection in infants and young children at high risk for severe RSV infections: Respiratory Syncytial Virus Immune Globulin Study Group

OBJECTIVES

To evaluate the efficacy of high-titer intravenous respiratory syncytial virus immune globulin (RSVIG) in the treatment of children at high risk for severe RSV infection who were hospitalized with proven RSV.

METHODS

Infants and young children younger than 2 years with bronchopulmonary dysplasia, chronic lung disease, congenital heart disease, or prematurity (<32 weeks' gestational age), hospitalized with a history of lower respiratory tract infection (LRI) of less than 4 days, were enrolled in this study. Patients were randomized in a blinded fashion to receive either 1500 mg/kg RSVIG or placebo in equal volumes. They were evaluated daily for safety and respiratory scores and for RSV nasal shedding.

RESULTS

One hundred seven high-risk children were randomized--54 in the RSVIG group and 53 in the placebo group. Of these children, 51 in each group were considered evaluable. Children with pulmonary disease, congenital heart disease, or prematurity were equally distributed between the two treatment groups. However, two important differences were found in baseline variables between the two groups: there were more patients in the placebo group who had histories of previous LRI and there was a trend toward more severe disease at study entry in the RSVIG group. This was manifested by a higher entry respiratory score in the RSVIG group than in the placebo group (3.4 +/- 0.2 vs 3.1 +/- .01). A higher proportion of children in the RSVIG group (47%) than in the placebo group (28%) required intensive care at entry and mechanical ventilation at study entry (31% RSVIG-treated vs 18% placebo-treated patients). No significant difference was found between groups in the mean unadjusted duration of hospitalization (RSVIG group, 9.10 +/- 1.18 days; control group, 8.17 +/- 1.08 days). When the mean was adjusted for entry respiratory score, likewise, no difference was observed between each group (8.41 +/- 0.97 vs 8.89 +/- .99 days). The lack of efficacy observed in the study primary endpoint was observed in all diagnostic groups. No differences between the RSVIG and placebo groups were observed in the following secondary endpoints: duration of intensive care unit stay, duration of intensive care unit stay for RSV, mechanical ventilation, or supplemental oxygen. No significant differences in adverse events were reported in the RSVIG group (16 children) when compared with the control group (10 children).

CONCLUSION

RSVIG treatment was safe but not efficacious in the treatment of children with bronchopulmonary dysplasia, congenital heart disease, or premature gestation who were hospitalized with RSV LRI.

Clinical observations on lower respiratory tract infections with special reference to serum IgE levels

To examine if the occurrence of wheezing among children with lower respiratory tract infections is associated with atopic predisposition, serum levels of IgE were determined for groups of children with or without wheezing, during infection with Mycoplasma pneumoniae or respiratory syncytial virus (RSV). In M. pneumoniae infection, more than 60% of wheezy children over 2 years of age showed a high IgE level (200 IU/mL or more), while IgE levels were less than 200 IU/mL in 73% of non-wheezy children. In RSV infection, the incidence of high IgE levels among wheezy children was nearly double that of non-wheezy children, although the difference was not significant. These results suggest that in children an allergic disposition is involved in the occurrence of wheezing during the course of lower respiratory tract infections.

Use of nasal and pharyngeal swabs for rapid detection of respiratory syncytial virus and adenovirus antigens by enzyme-linked immunosorbent assay

Nasal and pharyngeal swabs from 134 children with acute respiratory diseases were examined for the presence of respiratory syncytial (RS) virus and adenovirus antigens by enzyme-linked immunosorbent assay (ELISA). The results were compared with those obtained by virus isolation and serology. Altogether, 56 RS virus-positive (prospective study), 51 adenovirus-positive (retrospective study), and 27 negative (prospective study) samples were examined. The sensitivities of ELISA were 96 and 98% for RS virus and adenovirus antigen detection, respectively. No false-positive results were observed. It is concluded that the joint eluate from a nasal and a pharyngeal swab, properly taken and handled, serves well for the detection of RS virus and adenovirus acute respiratory infections by ELISA.

Risk factors for occasional and recurrent wheezing after RSV infection in infancy

Sixty-seven children who were hospitalized with a verified RSV infection were reexamined after 4 years at the age of 4 to 7 years. Twenty-four children had had no subsequent respiratory symptoms, 22 had wheezed 1-3 times and 21 had recurrent wheezing. A family history of atopy and a personal history of neonatal respiratory problems were more common in the group with recurrent wheezing, whereas paternal smoking was more frequent in the group with occasional wheezing. RSV infection in early infancy was more related to occasional wheezing than recurrent episodes. The spirometric data obtained from the force expirograms were normal, compared to the predicted normal values. In the children with recurrent wheezing, however, the values for PEF and the MEF25 were significantly lower in comparison with all the other children showing a mild obstruction.

Contribution of rhinoviruses to respiratory viral infections in childhood: a prospective study in a mainly hospitalized infant population

A prospective study was carried out to investigate the contribution of rhinoviruses to respiratory viral infections in children and to investigate the influence of age, passive smoking, and educational level of the head of the family on the clinical course of viral respiratory disease. Nasopharyngeal aspirates from 519 infants (90.8% inpatients, 9.2% outpatients) were screened for the presence of rhinoviruses, respiratory syncytial virus (RSV), adenoviruses, parainfluenza virus types 1, 2, 3, influenza virus types A and B, and enteroviruses by tissue culture isolation procedure, enzyme-linked immunosorbent assay, and/or indirect immunofluorescence method. The total detection rate was 42.4%. The rate decreased with increasing age. Higher detection rates were observed in specimens from children suffering from a more severe respiratory disease, and the highest rate of virus-positive specimens was found in those aged 0-6 months. Second to RSV (23.1%), rhinoviruses were the most frequently recovered pathogens found in 11.8% of children with acute respiratory tract infections (RTI). In the age group 0-6 months the majority of severe respiratory illnesses was due to RSV. In infants aged 6 months to 1 year a decrease in the number of severe illnesses caused by RSV and an increase in the number of children suffering from a more severe RTI caused by rhinoviruses was found. With the possible exception of one group of children infected with rhinoviruses, a negative effect of passive smoking on the incidence and severity of viral RTI could not be established. A beneficial effect of breast feeding on the severity of viral RTI could not be definitely demonstrated.

Value of rapid diagnosis of respiratory syncytial virus infection on management of small infants

Respiratory syncytial virus (RSV) is a common cause of infection in infancy and early childhood. A presumptive diagnosis of RSV infection can frequently be made on clinical grounds. Confirmation can be made by viral culture, which may take 3 to 7 days. Immunofluorescent assay (IFA) is a specific and sensitive test that can provide laboratory confirmation of RSV infection the same day. Rapid diagnosis of RSV infection may have implications regarding prevention of nosocomial spread of RSV, early initiation of anti-viral therapy, use of antibiotics, and duration of hospital stay. Data are presented regarding the use of RSV-IFA and its effect on patient management.

Rapid detection of respiratory syncytial virus in nasopharyngeal secretions by enzyme-linked immunosorbent assay

A new enzyme-linked immunosorbent assay (ELISA) respiratory syncytial virus antigen detection kit (Ortho Diagnostics, Inc., Raritan, N.J.) was compared with virus culture and with the indirect fluorescent antibody test (FAT) by using fresh nasal washings from children with suspected respiratory syncytial virus infection. Both uncentrifuged nasal washings and pellets from centrifuged split specimens were examined by ELISA. The ELISA was considered positive when the optical density was greater than the mean background optical density plus 0.15. Specimens positive by ELISA but negative by culture and FAT were reexamined in an ELISA blocking assay. Of 337 uncentrifuged specimens, 124 (37%) were positive by culture, 107 (32%) were positive by FAT, and 166 (49%) were positive by ELISA. Blocking assays showed that 21 of 30 (70%) of the seemingly false-positive ELISA tests were, in fact, true-positives and that the cultures and FATs were falsely negative. A patient specimen was considered positive when it was positive by virus culture, FAT, or blocking assay. The sensitivity, specificity, and positive predictive value of the ELISA test were 88, 94, and 95%, respectively. Centrifugation of nasal washings raised the sensitivity from 88 to 92% but reduced the specificity from 94 to 81%. We conclude that the Ortho ELISA test of uncentrifuged nasal washings is more sensitive than virus culture or indirect FAT and is highly specific.

Isolation of pathogenic bacteria from the nasopharynx of children with respiratory syncytial virus infection. Predictive value of chest roentgen examination and laboratory tests

Potentially pathogenic bacteria were isolated from the nasopharynx in 33/66 hospitalized infants and children with verified respiratory syncytial virus (RSV) infection. The value of chest roentgenograms and blood counts for the prediction of concomitant bacterial infection was evaluated. Abnormal chest roentgenograms were found in 89% whether pathogenic bacteria were present or not. The most common finding was general hyperinflation of the lungs, with or without infiltrates. This occurred more frequently in the group with isolated RSV infection. Fever, leucocytosis and an elevated ESR were found during the illness in more than half the cases. These findings were more frequent in children who harboured potential pathogenic bacteria, though the difference was not significant. For optimal evaluation of a case all available information about it should be taken into consideration.