Respiratory syncytial virus activity--United States, 1999-2000 season

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract illness (LRTI) among infants and children worldwide (1) and is an important cause of LRTI among older children and adults (2). Despite the presence of maternal antibodies, most hospitalizations occur among infants aged <6 months, and nearly all children are infected by age 2 years (3). Although primary infection is usually most severe, reinfection throughout life is common (4). In temperate climates, RSV infections occur primarily during annual outbreaks, which peak during winter months (5). In the United States, RSV activity is monitored by the National Respiratory and Enteric Virus Surveillance System (NREVSS), a voluntary, laboratory-based system. This report summarizes trends in RSV activity reported to NREVSS from July 1999 through June 2000 and presents preliminary surveillance data from July 8 through November 21, 2000, which indicate that RSV community outbreaks are becoming widespread.     

Respiratory syncytial virus activity--United States, 2000-01 season

Respiratory syncytial virus (RSV) has a worldwide distribution and can cause serious lower respiratory tract illness (LRTI). RSV is most commonly considered a pathogen among infants and young children; however, it can cause serious LRTI throughout life, especially among those with compromised respiratory, cardiac, or immune systems and the elderly. In temperate climates, RSV infections occur primarily during annual outbreaks, which peak during winter months. In the United States, RSV activity is monitored by the National Respiratory and Enteric Virus Surveillance System (NREVSS), a laboratory-based surveillance system. This report summarizes trends in RSV activity reported to NREVSS during July 2000-June 2001 and presents preliminary surveillance data from the weeks ending July 7 through December 8, 2001, indicating the onset of the 2001-02 RSV season. Health-care providers should consider RSV in the differential diagnosis of lower respiratory tract disease in persons of all ages, use isolation procedures to prevent nosocomial transmission, and consider use of immune globulin or monoclonal antibody prophylaxis in premature infants or infants and children with chronic lung disease.     

Respiratory syncytial virus activity--United States, 2003-2004

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections (LRTIs) (i.e., bronchiolitis and pneumonia) among young children, resulting in an estimated 51,000-82,000 hospitalizations annually. RSV causes severe disease among older adults and persons of all ages with compromised respiratory, cardiac, or immune systems, and can exacerbate chronic cardiac and pulmonary conditions. In temperate climates, RSV infections occur primarily during annual winter season outbreaks. This report summarizes trends in RSV activity reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS) during July 2003-June 2004 and presents preliminary data from the weeks ending July 3-December 4, 2004, indicating the onset of the 2004-05 RSV season. Health-care providers should consider RSV in the differential diagnosis for persons of all ages with LRTIs, implement appropriate isolation precautions to prevent nosocomial transmission, and provide appropriate immune prophylaxis to eligible children, including certain premature infants or children and infants with chronic lung and heart disease.     

Brief report: respiratory syncytial virus activity--United States, 2004-2005

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections (LRTIs) (e.g., bronchiolitis and pneumonia) among young children, resulting in an estimated 51,000-82,000 hospitalizations annually in the United States. RSV also causes severe disease and death among older persons and persons of all ages with compromised respiratory, cardiac, or immune systems and can exacerbate chronic cardiac and pulmonary conditions. In temperate climates, most RSV infections occur during a distinct seasonal peak. This report presents preliminary data from RSV activity reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS) for the weeks ending July 2 through December 3, 2005, indicating the onset of the 2005-06 RSV season, and summarizes trends during July 2004-June 2005. Health-care providers should consider RSV in the differential diagnosis for persons of all ages with LRTIs, implement appropriate isolation precautions to prevent nosocomial transmission, and provide appropriate immune prophylaxis to eligible children, including certain premature infants or infants and children with chronic lung and heart disease.     

Brief report: respiratory syncytial virus activity--United States, 2005-2006

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections (LRTIs) (e.g., bronchiolitis and pneumonia) among young children in the United States. RSV also causes severe respiratory disease and a substantial number of deaths among older adults and persons with compromised respiratory, cardiac, or immune systems. RSV is transmitted person to person through close contact or inhalation of large droplets from a sneeze or cough; infection also can occur through contact with fomites (i.e., contaminated surfaces or objects). In temperate climates, peak RSV activity typically occurs during the winter. This report presents preliminary data on RSV activity reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS) for the weeks ending July 8-November 18, 2006, indicating the onset of the 2006-2007 RSV season, and summarizes RSV trends during July 2005-June 2006. Health-care providers should consider RSV in the differential diagnosis for persons of all ages with LRTIs and implement appropriate isolation precautions to prevent nosocomial transmission from RSV-infected patients. Immune prophylaxis should be considered for certain infants and young children at high risk for complications from RSV infection (e.g., certain premature infants or infants and children with chronic lung and heart disease).     

Brief report: respiratory syncytial virus activity--United States, July 2006-November 2007

Respiratory syncytial virus (RSV), the most common cause of severe lower respiratory tract disease among infants and young children, typically infects persons by age 2 years and can cause subsequent infections throughout life. RSV infection primarily manifests as bronchiolitis or pneumonia and results in approximately 75,000 to 125,000 hospitalizations in the United States each year. Persons at increased risk for severe disease or death include premature infants, older adults, and persons of any age with compromised respiratory, cardiac, or immune systems. RSV is transmitted from person to person via close contact, droplets, or fomites. In temperate climates, peak RSV activity typically occurs during the winter. However, year-to-year national and regional variability in the RSV season onset and offset occurs in the United States. RSV circulation also varies by geographic location; for example, Florida has an earlier season onset and a longer season than the rest of the United States. Using data reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS), this report summarizes RSV temporal and geographic trends in the United States during the weeks ending July 8, 2006-June 30, 2007, and for the first 5 months of the current reporting season (the weeks ending July 7-November 24, 2007). Appropriately timed diagnostic tests can provide data that indicate when the RSV season begins nationally and regionally, information that has been critical in determining when to begin RSV prophylaxis for infants and children at high risk for infection.     

Respiratory syncytial virus--United States, July 2007-June 2011

Each year in the United States, an estimated 75,000-125,000 hospitalizations related to respiratory syncytial virus (RSV)occur among children aged <1 year, and RSV infection results in approximately 1.5 million outpatient visits among children aged <5 years. In the United States, RSV season begins in the fall, peaks in winter, and ends in the late winter and early spring. However, the exact timing and duration vary from year to year and by geographic region. To describe trends in RSV seasonality, data from the National Respiratory and Enteric Virus Surveillance System (NREVSS) were used to determine the onset, offset, and peak of the July 2010--June 2011 RSV season, and for an aggregate analysis of the four most recent RSV seasons (July 2007--June 2011). During 2010--11, excluding Florida, season onset occurred from mid-November to early January, and offset occurred from mid-March to late April across all 10 U.S. Department of Health and Human Services (HHS) regions. Florida is reported separately because it has an earlier onset and longer duration than the rest of the country. During the four seasons from 2007 through 2011, onset among the HHS regions excluding Florida ranged from mid-October to early January, and offset ranged from early February to early May. Information on national and regional patterns can be used by clinicians and public health officials to guide diagnostic testing during respiratory disease outbreaks and determine when to provide RSV immunoprophylaxis for children at high risk for serious complications.     

Update: influenza activity--United States and worldwide, 2003-04 season, and composition of the 2004-05 influenza vaccine

During the 2003-04 influenza season, influenza A (H1), A (H3N2), and B viruses co-circulated worldwide, and influenza A (H3N2) viruses predominated. Several Asian countries reported widespread outbreaks of avian influenza A (H5N1) among poultry. In Vietnam and Thailand, these outbreaks were associated with severe illnesses and deaths among humans. In the United States, the 2003-04 influenza season began earlier than most seasons, peaked in December, was moderately severe in terms of its impact on mortality, and was associated predominantly with influenza A (H3N2) viruses. This report 1) summarizes information collected by World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, state and local health departments, health-care providers, vital statistics registries, and CDC and 2) describes influenza activity in the United States and worldwide during the 2003-04 influenza season and the composition of the 2004-05 influenza vaccine.     

The use of palivizumab monoclonal antibody to control an outbreak of respiratory syncytial virus infection in a special care baby unit.

An outbreak of respiratory syncytial virus (RSV) infection affected seven premature infants in a special care baby unit during November and December 1999. Conventional infection control measures (cohorting infected babies, strict reinforcement of the use of gloves and aprons, emphasis on hand disinfection) failed to prevent spread. Palivizumab, a respiratory syncytial virus monoclonal antibody, was given to eight high-risk preterm infants. There were no further cases of RSV in the unit and none of the babies given palivizumab developed RSV. One baby who acquired RSV during the outbreak (and who was not given palivizumab) was subsequently admitted to hospital with another episode of RSV bronchiolitis. The role of palivizumab in the control of hospital outbreaks of RSV infection merits further investigation.     

Experience with the use of palivizumab together with infection control measures to prevent respiratory syncytial virus outbreaks in neonatal intensive care units

Respiratory syncytial virus (RSV) frequently causes nosocomial outbreaks in general paediatric wards and occasionally in neonatal intensive care units (NICUs). Conventional infection control measures often fail to prevent the spread of RSV, and it can cause significant morbidity especially in preterm and young infants. We report our experience in preventing an outbreak on a NICU after RSV had been detected in a premature infant. The index case was a 34-day-old premature infant who presented with clinical infection and RSV was detected in a clinical specimen. There were 11 patients in the ward at the time including the index case. The RSV-positive patient was isolated, the ward closed to admissions and infection control measures were implemented. Two patients were transferred to another hospital. Palivizumab 15 mg/kg i.m. was given to all patients and no further cases occurred. All subsequent RSV tests on nasal secretions were negative. Palivizumab combined with conventional infection control measures appeared to prevent the spread of RSV in this NICU. Strategies for the prevention of RSV outbreaks on NICUs all recommend the reinforcement of routine infection control measures. Recommendations concerning the use of palivizumab range from monthly prophylaxis to all infants at risk, to prophylaxis of selected cases only. Currently there are no guidelines for the use of palivizumab in NICUs or for the control of RSV outbreaks.     

Formalin-inactivated bovine RSV vaccine influences antibody levels in bronchoalveolar lavage fluid and disease outcome in experimentally infected calves

Respiratory syncytial virus (RSV) causes severe respiratory disease in calves and human infants. In response to outbreaks, formalin inactivated (FI)-RSV vaccines were developed and found to exacerbate disease following a live RSV infection. We have reproduced vaccination induced disease enhancement in calves and screened various antibody isotypes in bronchoalveolar lavage fluid (BALF) from two studies: one with disease enhancement and another where moderate protection resulted from FI-bovine RSV (BRSV) vaccination. Semi-protected vaccinated calves produced BRSV-specific BALF IgG1, but not IgA and IgG2 prior to infection; whereas, calves with enhanced disease failed to develop BRSV-specific IgG1 in BALF. Ultimately, the formulation and delivery of RSV vaccines influences protective antibody levels in respiratory secretions.     

Use of palivizumab to control an outbreak of syncytial respiratory virus in a neonatal intensive care unit

To evaluate the safety and effectiveness of a humanized respiratory syncytial virus (RSV) monoclonal antibody (palivizumab) to control an outbreak of RSV in a neonatal intensive care unit (NICU), we retrospectively analysed two RSV outbreaks. Between 11 November 1998 and 18 March 1999, two separate RSV outbreaks occurred in a large (26 beds) NICU. All procedures for preventing nosocomial spread of RSV (including the use of palivizumab in the second outbreak) were retrospectively analysed. The cumulative incidence (CI), secondary attack rate (SAR) and risk ratio of infection were determined before and after the use of palivizumab for all patients and for those with gestational age below and above 32 weeks in the NICU during the second outbreak. Standard infection control measures were effective in the first outbreak (three cases). In the second outbreak, after three index cases, five additional infants were newly RSV-infected within one month. Three infants had RSV pneumonia and required mechanical ventilation; one infant died. Standard infection control procedures were initiated from the beginning of this outbreak. Palivizumab was given to all infants in the NICU after the fifth case was identified. CI was 2.4% in the first 15 days and 10.5% in the second, and SAR was 2.9 per thousand in the first 15 days and 14.1 per thousand in the second, both dropping to zero after the administration of palivizumab. The risk ratio of infection was 4.65 times higher in infants under 32 weeks gestational age. After the use of palivizumab, there were no additional identified cases. In addition to careful infection control procedures, the use of palivizumab might have contributed to arresting the outbreak of RSV infection in the NICU, suggesting that it could be an additional resource in the control of severe nosocomial RSV outbreaks.     

Climatic, temporal, and geographic characteristics of respiratory syncytial virus disease in a tropical island population

Respiratory syncytial virus (RSV) is an important cause of morbidity in children worldwide, although data from equatorial regions are limited. We analysed climatic, spatial, and temporal data for children presenting to hospitals in Lombok island, Indonesia with clinical pneumonia. During the study period, 2878 children presented and 741 RSV cases were identified. In multivariate analysis with an 8-day lag, occurrence of rain was associated with 64% higher incidence of RSV disease [incidence rate ratio (IRR) 1.64, 95% confidence interval (CI) 1.13-2.38]. A 1% rise in mean relative humidity and 1 degree C increase in mean air temperature was associated with a 6% (IRR 1.06, 95% CI 1.03-1.10) and 44% (IRR 1.44, 95% CI 1.24-1.66) increase in RSV cases, respectively. Four statistically significant local clusters of RSV pneumonia were identified within the annual island-wide epidemics. This study demonstrates statistical association of monsoon-associated weather in equatorial Indonesia with RSV. Moreover, within the island-wide epidemics, localized RSV outbreaks suggest local factors influence RSV disease.     

Timing of monoclonal antibody for seasonal RSV prophylaxis in the United Kingdom

Respiratory syncytial virus (RSV) infection produces more severe disease and increased hospitalization rates in high-risk babies. The monoclonal antibody palivizumab offers protection against complications, and the first of five monthly doses should be administered before the onset of community RSV activity. However, the required real-time prediction of this onset is problematic. We attempted to identify seasonal RSV patterns by retrospectively examining 10 years of laboratory reports for RSV and clinical episode reports for certain respiratory presentations in both primary and secondary care. Analysis of hospital laboratory reports, incidence of acute bronchitis in primary care, and hospital admissions for acute bronchitis and bronchiolitis in young children revealed a consistent increase in RSV activity during week 43 each year. Promptly commencing prophylaxis during the second week of each October (week 42) would precede the onset of the RSV season in the United Kingdom, and provide coverage until its decline in mid-March.     

Prevention of respiratory syncytial virus infection among Puerto Rican infants

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory illness in children. Prevention of this infection is available with the use of intravenous immunoglobulin or an intramuscular humanized monoclonal antibody (palivizumab). Palivizumab has been available in Puerto Rico since 1999. The objective of this study was to follow-up infants who received RSV prophylaxis with palivizumab in Puerto Rico to assess its efficacy and safety. A total of 230 infants who received RSV prophylaxis during the 2000-2001 and 2001-2002 seasons were followed-up. Adverse events from injections were minimal including erythema (2%), fever (5%), pain (4%), and rash (2%). In none of the patients prophylaxis was discontinued due to side effects. Forty-four infants (19%) had at least one respiratory hospitalization throughout the season, with RSV confirmed in seven (3%). Most hospitalizations occurred in the month of August when infants had received only one dose of palivizumab and on December, a peak month for RSV infections. Five infants (2.2%) required admission to an intensive care unit. In none of them, RSV was confirmed. This study confirms that monthly intramuscular administration of palivizumab is effective in preventing serious RSV infections in high risk infants.     

Update: influenza activity--United States and worldwide, May 21-September 9, 2006

In the United States, CDC uses seven systems for national influenza surveillance, four of which operate year-round: 1) the World Health Organization (WHO) and the National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratory systems; 2) the U.S. Influenza Sentinel Provider Surveillance System; 3) the 122 Cities Mortality Reporting System; and 4) a national surveillance system that records pediatric deaths associated with laboratory-confirmed influenza. Data from these four systems are included in this report.     

Seasonal trends of viral respiratory tract infections in the tropics.

To evaluate the seasonal trends of viral respiratory tract infections in a tropical environment, a retrospective survey of laboratory virus isolation, serology and immunofluorescence microscopy in two large general hospitals in Singapore between September 1990 and September 1994 was carried out. Respiratory tract viral outbreaks, particularly among infants who required hospitalization, were found to be associated mainly with respiratory syncytial (RSV) infections (72%), influenza (11%) and parainfluenza viruses (11%). Consistent seasonal variations in viral infections were observed only with RSV (March-August) and influenza A virus (peaks in June, December-January). The RSV trends were associated with higher environmental temperature, lower relative humidity and higher maximal day-to-day temperature variation. Although the influenza A outbreaks were not associated with meteorological factors, influenza B isolates were positively associated with rainfall. These data support the existence of seasonal trends of viral respiratory tract infections in the tropics.     

Viral diagnoses using the rapid immunofluorescence technique and epidemiological implications of acute respiratory infections among children in different European countries

From November 1978 to October 1981, a total of 7716 specimens of nasopharyngeal secretions were examined by the rapid immunofluorescence technique to determine the frequency of infections caused by the respiratory syncytial virus (RSV), influenza virus A, and parainfluenza viruses 1 and 3. The tests were carried out in six different virus laboratories located in Newcastle upon Tyne (England), Copenhagen, Oslo, Stockholm, Turku (Finland), and Vienna; laboratories in Lisbon and Paris participated in the study for shorter periods. The specimens were collected from infants and children less than 6 years of age who had been admitted to hospital with an acute respiratory infection. Standardized techniques and quality controlled reagents were used. At least one of the above viruses was detected in 1927 (25%) of the specimens: RSV in 1475, influenza virus A in 123, parainfluenza virus 1 in 110, and parainfluenza virus 3 in 237 specimens. Respiratory syncytial virus dominated in all centres, but in some Scandinavian centres distinct outbreaks due to this virus occurred only once or twice during the 3 years'' study period. Three outbreaks of RSV were observed in Newcastle, but here an unprecedented delay of the first winter''s epidemic occurred. The delay was associated with prolonged school closures in the area, and with a very early outbreak of influenza. Parainfluenza virus 3, which was predominantly a summer virus in Newcastle, was most frequently encountered during the colder months of the year in the other centres.     

Respiratorisches-Syncytial-Virus Ursache einer signifikant gesteigerten Morbidität akuter Atemwegsinfekte in Arztpraxen?

Since 1992 the working group on influenza in Germany (AGI) records the appearance of acute respiratory tract infections (ARI) in selected primary care offices during wintertime. In some offices swabs are taken and screened for the presence of influenza viruses in the national influenza centre and other laboratories. In the winter of 1998/99 the nation-wide sentinel of 550 offices indicated an increase in ARI morbidity that could not be explained by influenza activity. The symptoms reported by the general practitioners (GPs) and the age group of affected patients as well as the markedly increased hospitalisation of infants (age 0–4 years) indicated Respiratory Syncytial Virus (RSV) as the causative agent. Furthermore influenza activity was moderate over that period of time. The data of other laboratory reporting systems and data from several hospitals confirmed the observed increase in RSV activity with some delay. The data discussed in the paper give evidence that RSV was probably the agent responsible for the increased ARI-morbidity, however they were not sufficient to clearly confirm this. Thus a much more systematic and improved RSV surveillance is desirable. Improvement in RSV surveillance will also allow a better evaluation of the influenza activity itself, particularly of its impact on children.     

Rapid testing for respiratory syncytial virus in a paediatric emergency department: benefits for infection control and bed management

Respiratory syncytial virus (RSV) is responsible for annual winter outbreaks of respiratory tract infection among children in temperate climates, placing severe pressure on hospital beds. Cohorting of affected infants has been demonstrated to be an effective strategy in reducing nosocomial transmission of RSV, and may keep cubicles free for other patients who require them. Testing of symptomatic children for RSV is standard practice, but unfortunately traditional laboratory testing is not rapid enough to aid decision-making processes. Rapid point-of-care testing (POCT) in the emergency department has been suggested as an alternative. We performed a prospective study to quantify the amount of cubicle time saved by using POCT results to allow a targeted cohorting strategy. Over the four-month study period, the POCT allowed 183 children to be admitted directly to a designated cohort area, thus saving 568.5 cubicle-days for other patients. This is equivalent to five cubicles being left free for each day of the study period. This is the first time the benefits of using POCT have been quantified in this way. POCT for RSV is a safe, cost-effective and efficient way to improve bed management.