Seminars in respiratory and critical care medicine
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Influenza viruses are major human pathogens with a global distribution, accounting for more than 500,000 annual deaths worldwide and with considerable impact on the quality of life and productivity of the society. Due to the limited efficacy of vaccination, antiviral drugs constitute a complementary approach in the control and prevention of influenza infections and thus play an important role in the management of influenza outbreaks and pandemics. Currently, adamantanes and neuraminidase inhibitors (NAIs) are the only two classes of anti-influenza agents approved for clinical use. ⋯ Nevertheless, oseltamivir-resistant strains have also been reported quite frequently, as in the case of seasonal H1N1 viruses that circulated between 2007 and 2009. Indeed, the emergence of drug-resistant virus variants is always a matter of concern because it could significantly compromise the usefulness of such intervention. This highlights the need for continuous monitoring of resistance markers, as well as the development of new anti-influenza drugs and combination therapies.
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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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Rhinoviruses and coronaviruses cause significant morbidity in immunocompetent people of all ages and in patients with underlying chronic medical or immunosuppressed conditions. Newer diagnostic tests, such as polymerase chain reaction (PCR), have expanded our understanding of these respiratory viruses in clinical infections. These sensitive diagnostic tests have been used to describe new members of these virus families, such as human rhinovirus C (HRVC) and human coronavirus NL-63 (HCoV-NL63). The epidemiology of these newly described viruses will help us develop better intervention strategies.
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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.