Acute respiratory infections (ARI) are the leading cause of mortality in children under five years of age worldwide and most of these deaths are due to bronchiolitis and pneumonia. Recent evidence from studies using genome detection systems such as polymerase chain reaction or micro-array technology show that, in most cases, these deaths are caused or precipitated by viruses. In this paper, the definitions of upper and lower respiratory tract infections are reviewed. The principal signs of disease severity and the burden of viruses as causes of ARI are described. The prominent role of Respiratory Syncytial Virus is stressed, with data from epidemiological and clinical studies. Other important viral pathogens, such as Human Metapneumovirus, Human coronaviruses and Influenza are examined. The role of newly described viruses, such as bocavirus, is also discussed. The impact of HIV/AIDS in ARI burden and presentation assessed and the weight of Pneumocystis jiroveci and Mycobacterium tuberculosis infections is recognized. It is concluded that there is an urgent need to improve diagnostics, therapeutics and vaccines, as well as macro and micronutrient intake of children of the world, particularly in developing countries.
Acute respiratory infections; Children; Viruses
