Acute respiratory infections in the developing world: strategies for prevention, treatment and control.

Substantial reduction of the still unacceptable infant and child mortality rates in the developing world will be difficult to achieve without a strategy to avert deaths due to acute respiratory infections (ARI). An estimated 2 to 5 million infant and childhood deaths each year are due to ARI; up to 98% might be pre­ vented if case-fatality ratios could be reduced to those observed in the industrialized world. However, the heterogeneity of clinical presentations and causative organisms has hampered efforts to address this leading cause of death among children.' The classification and management of ARI in the industrialized world is founded upon radiologic and microbiologic data, in addition to the clinical history and physical examination. ARI syndromes, which are complex clinical conditions of varying etiology and severity, have been categorized primarily on the basis of anatomical location. Common diagnostic categories for uncomplicated ARI with etiologic and clinical correlates are detailed in Table 1. Although acute upper respiratory infections, such as the common cold, are of great public health importance due to their high incidence, only the acute lower respiratory infections such as pneumonia and bronchiolitis are major causes of mortality. Although little is known about the incidence and etiologies of respiratory illnesses in developing countries, the available data suggest that more than 75% of ARI deaths are caused by pneumonia, both bacterial and viral. 2 Bacterial pneumonias, which account for the majority of deaths due to ARI in the developing world, remain the most treatable of causes of severe ARI. They may also become, with emerging vaccine tech­ nologies, preventable. This review focuses primarily on the prevention and treatment of the bacterial pneu­ monias in less developed countries. INCIDENCE Comparison and compilation of results from inves­ tigations on ARI in different countries is all but pre­ vented by wide variations in study design, case defi­ nitions and culture techniques. The few community­ based prospective studies performed suggest that ARI is very common. The incidence observed in urban 3 areas is four to eight episodes per child per year.:-This is comparable to the incidence documented in longitudinal studies in the United States"' among both middle class and lower class urban children under age 5. The rate is inversely related to age, peaking at eight to nine infections in the first 2 years of life and dropping to three to four per year by school age. ARI accounts for between 20 and …