Seminars in respiratory and critical care medicine
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During the Northern Hemisphere spring of 2009, a novel H1N1 influenza A virus emerged in Mexico, causing widespread human infection and acute critical respiratory illness. The 2009 H1N1 virus spread initially to the United States and Canada, with subsequent rapid global dissemination, leading the World Health Organization (WHO) to declare "a public health emergency of international concern" in April 2009, and upgrading the viral threat to pandemic status in June 2009. ⋯ The 2009 H1N1 pandemic led to rapid implementation of health care initiatives, including the provision of critical care services, to limit the effect of the influenza outbreak on the community. This review focuses on the critical care response to the H1N1 pandemic and examines whether the implementation of critical care services as planned a priori matched the reality of the clinical workload and the patient burden that transpired during the 2009 H1N1 influenza pandemic.
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Adenoviruses (AdV) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal (GI) tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or encephalitis. Adenovirus infections are more common in young children, owing to lack of humoral immunity. ⋯ Treatment of AdV infections is controversial because prospective, randomized therapeutic trials have not been done. Cidofovir is considered the drug of choice for severe AdV infections, but not all patients require treatment. Vaccines have been shown to be highly efficacious in reducing the risk of respiratory AdV infection but are currently not available.
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Viral respiratory infections cause significant morbidity and mortality in infants and young children as well as in at-risk adults and the elderly. Although many viral pathogens are capable of causing respiratory disease, vaccine development has to focus on a limited number of pathogens, such as those that commonly cause serious lower respiratory illness (LRI). Whereas influenza virus vaccines have been available for some time (see the review by Clark and Lynch in this issue), vaccines against other medically important viruses such as respiratory syncytial virus (RSV), the parainfluenza viruses (PIVs), and metapneumovirus (MPVs) are not available. This review aims to provide a brief update on investigational vaccines against RSV, the PIVs, and MPV that have been evaluated in clinical trials or are currently in clinical development.
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Respiratory syncytial virus (RSV), an enveloped RNA virus in the Paramyxovirus family, is the most important cause of lower respiratory tract infection in infants and young children, accounting for ~100,000 pediatric hospitalizations and 250 deaths annually in the United States. Despite primarily being recognized as a pediatric pathogen, RSV reinfection causes substantial disease in all adult populations, including healthy young persons, old and frail individuals, those with chronic obstructive pulmonary disease and immunocompromised patients. Most illnesses are mild in adults, but significant morbidity and mortality can develop. ⋯ Currently, specific antiviral therapy is generally reserved for severely immunocompromised patients or severe respiratory failure. The greatest promise for reducing the impact of RSV in adults may be through immunization. However, an effective vaccine for RSV is not currently available.
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Human metapneumovirus (hMPV) is a common pathogen that can cause both upper and lower respiratory tract infections, particularly in children, elderly adults, and immunocompromised hosts. Since its initial identification in 2001, hMPV has been isolated from individuals with acute respiratory tract infections (ARTIs) in virtually every continent. Serological studies indicate that it has caused human infection since 1958 or earlier. ⋯ Ribavirin has similar activity in vitro and in animal models against hRSV and hMPV, but its efficacy in vivo is unproven. Monoclonal antibodies have activity in murine models but are not available in humans. Several vaccines are promising in animal models, but their safety and efficacy have not yet been evaluated in humans.