THE GLOBAL BURDEN OF LOWER RESPIRATORY TRACT INFECTION IN CHILDREN
Lower respiratory tract infection (LRTI), predominantly pneumonia, remains a major cause of morbidity and mortality in children globally despite a substantial decline in the incidence in the last decade. Advances in immunization, improvements in socioeconomic status, and effective human immunodeficiency virus (HIV) preventative and treatment strategies have been effective in reducing the burden of childhood LRTI and severe disease. However, recent estimates are that globally pneumonia still causes approximately 15% (or just under 1 million) of an estimated 6.3 million deaths annually in children younger than 5 years of age. Pneumonia is the main single cause of death in children outside the neonatal period. This burden is disproportionately high in Africa and Southeast Asia, where almost 90% of all global childhood deaths occur. Five high-burden countries, either in Africa (Nigeria and the Democratic Republic of Congo) or Southeast Asia (Pakistan, India, and China), account for more than 50% of childhood deaths globally. Respiratory syncytial virus (RSV) causes a high incidence of LRTI in children, approximately 34 million LRTI episodes or 22% of all LRTIs. Of these, 10% of episodes result in severe illness and hospitalization, and 99% of deaths occurr in low- and middle-income countries (LMICs). This proportion can be expected to increase as immunization against bacterial pathogens is strengthened as shown by recent case-control studies in children well vaccinated with 13-valent pneumococcal conjugate vaccine (PCV13), which reported RSV to be a predominant pathogen in children with LRTI. The incidence and severity of pneumonia are highest in the first year of life, especially in the first 6 months.
Several risk factors or exposures that may render a child vulnerable to LRTI or to severe disease may be especially prevalent in LMICs. They include smoke exposure, lack of breastfeeding, chronic underlying disease, prematurity or low birth weight, low socioeconomic status, crowded living conditions, malnutrition, or HIV. Pediatric HIV is largely confined to sub-Saharan Africa, where 90% of HIV-infected children reside; HIV infection is an important risk factor for pneumonia, severe disease, and mortality, with HIV-infected children having a 6-fold higher risk of developing severe pneumonia compared to uninfected children and a 6-fold higher risk of death. Furthermore, HIV-exposed but uninfected children, an increasingly important population as mother-to-child HIV transmission programs are strengthened, are emerging as another important vulnerable group who have a higher risk of developing pneumonia than do HIV-unexposed infants.
Lack of access to care and unavailability of effective management strategies are further factors that place children in LMICs more at risk of developing severe disease and of mortality from LRTI. Use of case management guidelines, with effective use of antibiotics, has been shown to substantially reduce pneumonia and all-cause mortality in children younger than 5 years. Community-based interventions including use of case management guidelines by community workers can reduce the mortality associated with pneumonia. Use of oxygen for hypoxic disease is an effective intervention and is ...