Epidemiology
ARIs continue to account for almost one in five childhood deaths (WHO, 2011). Early recognition and prompt treatment of ARIs--especially pneumonia--can be lifesaving (WHO, 2009). In a study of cause-specific mortality worldwide, pneumonia, which is a particularly severe form of ARI, accounted for one of the highest percentage of deaths in children under 5 years old worldwide between 2000 and 2003 (Figure 1). Life-threatening episodes which require hospitalization represent 7-13% of all cases (Rudan et al, 2011). Pneumonia accounts for 90% of the Acute Lower Respiratory Infections (ALRIs, a category which includes pneumonia, bronchiolitis and bronchitis) (USAID HaRP, 2006). An estimated 10% of all deaths in children under 5 years old are caused by pneumonia and sepsis (a blood-borne bacterial infection) during the neonatal period (Bryce et al., 2005). 

Figure 1. Global distribution of cause-specific mortality among children under-five, 2000-2003

(Source: Child Health Epidemiology Resources Group (CHERG), with additional data from UNICEF) 

Extent and Scope

In developing countries, infants and young children have 7-10 episodes of ARI per year, one tenth of which are severe enough to require hospitalization. Although most episodes are self-limiting infections of the upper respiratory tract, such as viral bronchitis and otitis media, they represent a huge economic burden to the public health system and increase the risk of progression to more severe disease (McCracken, 2000). This is especially true in situations in which children are exposed to environmental factors such as indoor air pollution (Bruce, Perez-Padilla, & Albalak, 2000). Over two-thirds of pneumonia mortality occurs in Africa, South Asia and Southeast Asia (Figure 2., USAID HaRP, 2006).

Figure 2. Distribution of deaths from pneumonia and other causes in children aged less than 5 years, by WHO region

Key: AFR, African Region; AMR, Americas Region; EMR, Eastern Mediterranean Region; EUR, European Region; SEAR, South-East Asia Region; WPR, Western Pacific Region

(Source: USAID HaRP, 2006)