Respiratory Syncytial Virus Infection

More than 50% of all common colds are caused by rhinoviruses. In infants and young children, human rhinovirus (HRV) is associated with many cases of acute otitis media and sinusitis. HRVs are members of the Picornaviridae family and positive-sense, single-stranded ribonucleic acid (RNA) viruses with icosahedral symmetry. Serotypes of HRVs are based on amino acid differences in the four capsid proteins. The pathogenesis of HRV infections is through infection of the upper respiratory tract. After deposition of HRV in the eye or nose, there is attachment to host cell epithelium. When tracheal epithelial cells were infected simultaneously with HRV and Streptococcus pneumoniae, there was increased adherence of the streptococci.

Respiratory tract infections, including pneumonia, are among the commonest causes of death worldwide. Contaminated oropharyngeal secretions are often aspirated into the lower respiratory tract. Although aspiration of oropharyngeal secretions is common, the host defense mechanisms are usually able to clear potential pathogens and thus prevent parenchymal infections. A significant part of normal host defenses against pulmonary infection relates to the anatomical and mechanical barriers provided by the upper respiratory tract. From the nasopharynx to the distal terminal bronchiole, the inner surface of the respiratory tract is lined with a pseudostratified ciliated epithelium interspersed with secreting cells (goblet cells) and other cells such as the dendritic cells. The respiratory epithelial cells are also the source of powerful antimicrobial peptides such as the cathelicidins and human B defensins that can act as chemokines at the level of the T lymphocytes and dendritic cells.

Cough is a very common problem; other symptoms may accompany it and help to make a diagnosis. The patient may seek help because the cough is persistent, interferes with sleep or because of anxiety that infection is ‘going to the chest’. Most acute coughs are due to the common cold or acute bronchitis; although acute bronchitis may sometimes be caused by bacteria, antibiotics provide little benefit in this condition unless there is co-morbidity. Quite often a friend or a relative has suggested that the patient should seek medical help. Mothers may fear that their children may choke in the night. Cough medicines for chesty coughs can exacerbate cough. Heart failure may cause a persistent cough, with fine crackles at both lung bases and a typical history of being worse when lying down and producing frothy, non-purulent sputum.

Human respiratory syncytial virus (hRSV) is the primary viral cause of respiratory diseases, leading to bronchiolitis and pneumonia in vulnerable populations. The only current treatment against this virus is palliative, and no efficient and specific vaccine against this pathogen is available. The authors describe the disease symptoms caused by hRSV, the economic and social impact of this infection worldwide, and how this infection can be modulated using pharmacological treatments, preventing and limiting its dissemination. The authors discuss the use of antibodies as prophylactic tools -such as palivizumab- and the use of nonspecific drugs to decrease the symptoms associated with the infection -such as bronchodilators, corticoids, and antivirals. They also discuss current vaccine candidates, new prophylactic treatments, and new antivirals options, which are currently being tested. Today, many researchers are focused on developing different strategies to modulate the symptoms induced by hRSV. However, to achieve this, understanding how current treatments are working and their shortcomings needs to be further elucidated.

Introduction: Respiratory syncytial virus (RSV) is the most common cause of acute lower respiratory tract infections in infancy. While many infants are infected with RSV, the nature and severity of the disease vary among individuals. RSV causes bronchiolitis, pneumonia, and asthma exacerbation. However, most children infected with RSV have only mild upper airways disease and may be asymptomatic. Areas covered: Despite efforts to elucidate mechanisms for the various clinical responses to RSV infection, they remain largely unknown, suggesting that susceptibility and disease are influenced by multiple intrinsic and extrinsic factors. This article reviews the available literature on the field of RSV disease severity and discusses important factors associated to susceptibility and different disease outcome. Expert opinion: The severity of RSV-induced illness is a phenomenon that depends on a variety of graded mechanisms of interaction between the host, virus, and environment.

When a child under 2 years of age presents in midwinter with a runny nose, dry cough, and mild to moderate fever, chances are that he or she has respiratory syncytial virus infection. Although the illness usually runs its course in 2 to 3 weeks, infection can be life-threatening in very young infants and those with high-risk conditions such as congenital heart disease. Drs Kuzel and Clutter describe appropriate measures for both outpatient and inpatient care and also discuss the benefits of aerosolized antiviral therapy for serious infection.