Up to 200,000 children under-5 each year could be dying due to acute lower-respiratory tract infections (ALRIs) caused by the respiratory syncytial virus (RSV). The data clearly establish RSV as a major cause of death in this age group and new treatment strategies are needed to reduce this burden. The findings are reported in an Article Online First and in an upcoming edition of the Lancet, written by Dr Harish Nair and Professor Harry Campbell, Centre for Population Health Sciences, University of Edinburgh, UK, and colleagues.
ALRI is the leading cause of global child mortality. RSV is believed to be the most important viral pathogen causing ALRI in young children, although its contribution to ALRI deaths is uncertain. Many data for incidence of and mortality from RSV-associated ALRI in developing countries remain unpublished. To prepare this new research, the authors formed a RSV study group to supplement a systematic literature review with unpublished data. They estimated the incidence of RSV-associated ALRI in children younger than 5 years, using data from a systematic review of studies published between January, 1995, and June, 2009, and ten unpublished population-based studies.
The researchers found that, in 2005, an estimated 33•8 million new episodes of RSV-associated ALRI occurred worldwide in children younger than 5 years (22% of all ALRI episodes), with at least 3•4 million episodes representing severe RSV-associated ALRI necessitating hospital admission. An estimated 66 000-199 000 children younger than 5 years died from RSV-associated ALRI in 2005, with 99% of these deaths occurring in developing countries. A substantial proportion of RSV-associated disease occurs in the first year of life, with incidence in infants that is twice or three times greater than is reported for children younger than 5 years overall. The authors also found that incidence and mortality due to RSV can vary substantially from year to year in any one setting. They say: "We cannot deduce how much of this variation is due to methodological differences and how much is due to variation in RSV epidemiology between study populations."
The authors also found that in high-income countries, the case fatality ratio (the proportion of hospitalised children that die) was 0.7% in children under one, falling to 0.3% when looking at all children under five years. In developing countries, the case fatality rate was 2.1% for both children under-one and children under five years old.
By comparison, around 13•8 million episodes of pneumococcal pneumonia and 7•9 million episodes of Haemophilus influenzae type b pneumonia occurred in the same age group. The authors conclude: "Globally, RSV is the most common cause of childhood ALRI and a major cause of admission to hospital as a result of severe ALRI. Mortality data suggest that RSV is an important cause of death in childhood from ALRI, after pneumococcal pneumonia and Haemophilus influenzae type b. The development of novel prevention and treatment strategies should be accelerated as a priority..... Until the widespread delivery of an effective RSV vaccine, measures such as promotion of health service use, provision of regular oxygen supplies at health centres and hospitals, and immunoprophylaxis with monoclonal antibodies (when appropriate and affordable) can be expected to substantially reduce mortality associated with this disease."
In an accompanying Comment, Dr Caroline B. Hall, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA, says: "Nair and colleagues provide the best current estimates of the global under-5 burden of RSV-associated acute lower respiratory-tract infections, and convincingly posit the virus as the foremost cause of all lower respiratory-tract infections in young children worldwide. The current increase and preponderance of the burden of RSV in nations with limited resources, suggested by these findings, should help focus strategies for control of RSV. Equally important are missing unavailable data. Both are pivotal to establish the allocation of resources necessary to diminish the outcomes of this ubiquitous infection, borne predominantly by the youngest and poorest of the world's children. As Charles Dickens observed in the middle of the 19th century: 'There should be nothing so preventable…as the death of a little child'."
Dr. Harish Nair, Centre for Population Health Sciences, University of Edinburgh, UK. T) +44 (0)131-6506963 E) Harish.Nair@ed.ac.uk
Professor Harry Campbell, Centre for Population Health Sciences, University of Edinburgh, UK. T) +44 (0)131-650 3218 E) Harry.Campbell@ed.ac.uk
Dr Caroline B. Hall, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA. T) +1 585-275-5242 E) caroline_hall@urmc.rochester.edu
For full Article and Comment, see: http://press.thelancet.com/rsv.pdf
Journal
The Lancet