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These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients. [ABSTRACT FROM AUTHOR]

Guidelines for the treatment of persons with influenza virus infection were prepared by an Expert Panel of the Infectious Diseases Society of America. The evidence-based guidelines encompass diagnostic issues, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal (interpandemic) influenza. They are intended for use by physicians in all medical specialties with direct patient care, because influenza virus infection is common in communities during influenza season and may be encountered by practitioners caring for a wide variety of patients. [ABSTRACT FROM AUTHOR]

The goals of antiviral treatment for influenza are to decrease symptoms and functional disability and, more important, to decrease associated complications, hospitalizations, and mortality. Four drugs have been approved for treatment of and prophylaxis against influenza in the United States, but they are underutilized. The M2 ion channel inhibitors amantadine and rimantadine are effective for prophylaxis, and they decrease the duration of symptoms if they are used for early treatment of influenza A. The rapid emergence of resistance during therapy and, recently, the circulation of resistant H3N2 viruses in the community have decreased the usefulness of these M2 ion channel inhibitors. Early therapy with neuraminidase (NA) inhibitors, either oseltamivir or zanamivir, reduces the duration of symptoms, the duration of disability, and the risk of lower respiratory tract complications. Oseltamivir has been shown to decrease antibiotic use, the number of hospitalizations, and, probably, the risk of death after influenza. NA inhibitors might provide substantial benefits in the treatment of pandemic influenza, with reductions in the numbers of hospitalizations and deaths occurring if such treatment (1) is made available in sufficient time, through rapid distribution, and (2) is available in sufficient quantities as a result of stockpiling. Both of the aforementioned NA inhibitors are highly effective for prophylaxis. Geographically targeted mass chemoprophylaxis might contain the spread of a pandemic virus, but multiple hurdles to successful implementation exist. Resistance to oseltamivir occurs with the H274Y variant in viruses that contain N1; however, to date, such variants have been less fit, have not been transmitted from person to person, and have retained susceptibility to zanamivir. Alternative agents and approaches, including parenteral and combination therapy, for the treatment of influenza are needed in the near and long term. [ABSTRACT FROM AUTHOR]

There is a continued need to improve the state of preparedness for a potential influenza pandemic in the United States despite the publication of a pandemic influenza plan by the Department of Health and Human Services. Of particular importance are the sense of urgency for a coordinated response plan, an allocation of adequate funds to deal with this issue, and the need for a national leader to coordinate the development and execution of a national plan, including its relationship to the control of seasonal influenza. In addition, an infrastructure needs to be established in the United States to enable the rapid development and large-scale production of a safe and effective vaccine for new influenza strains; methods to treat influenza pneumonia need to be evaluated; a coordinated public health response needs to be defined; a nationally developed blueprint to deal with logistics of pandemic prevention is required; and there is a need to establish reliable communication systems on a national and local basis, to provide accurate information to the lay public, health care workers, and the agricultural sector. [ABSTRACT FROM AUTHOR]

In late 1983, five patients living near Charlottesville, Virginia, were treated for an unusual syndrome of fever, headache, altered mentation, multifocal neurologic signs, and cerebrospinal fluid pleocytosis. Clinical signs of brainstem disease developed in four patients. All five had had recent exposure to forests or wood and contact with flea-infested dogs. Two patients died; one survivor has had recurrent seizures. Brain biopsy samples in two patients and autopsy findings in another showed cerebral vasculitis and perivasculitis involving mostly venules and capillaries. In the autopsy, the severest vascular lesions involved the brainstem and thalami, where they were accompanied by acute fibrinoid necrosis, but discrete vascular lesions of lesser intensity were randomly distributed in the white matter and cortex. Serologic studies on paired specimens in four patients showed significant cross-reacting antibody responses to rickettsial (typhus-group) antigens in the indirect hemagglutination, latex agglutination, and IgM microimmunofluorescence tests, but no agent was visualized or isolated. The cause of this serious inflammatory disorder is unknown. [ABSTRACT FROM AUTHOR]

The availability of immunogenic, licensed H5N1 vaccines and the anticipated development of vaccines against "swine" influenza A(H1N1) have stimulated debate about the possible use of these vaccines for protection of those exposed to potential pandemic influenza viruses and for immunization or "priming" of populations in the so-called "prepandemic" (interpandemic) era. However, the safety of such vaccines is a critical issue in policy development for wide-scale application of vaccines in the interpandemic period. For example, wide-scale interpandemic use of H5N1 vaccines could lead to millions of persons receiving vaccines of uncertain efficacy potentially associated with rare severe adverse events and against a virus that may not cause a pandemic. Here, we first review aspects of the 1976 National Influenza Immunization Programme against "swine flu" and its well-documented association with Guillain-Barré syndrome as a case study illustration of a suspected vaccine-associated severe adverse event in a mass interpandemic immunization setting. This case study is especially timely, given the recent spread of a novel influenza A(H1N1) virus in humans in Mexico and beyond. Following this, we examine available safety data from clinical trials of H5N1 vaccines and briefly discuss how vaccine safety could be monitored in a postmarketing surveillance setting.

RT-PCR is more sensitive for rhinovirus detection than cell culture, but healthy controls are frequently rhinovirus (or picornavirus) positive in cross-sectional studies. Fifteen healthy children were followed over at least three seasons of the year with weekly sampling of nasal/nasopharyngeal secretion for RT-PCR testing for picornavirus and daily recording of respiratory symptoms. One sample positive for picornavirus was diagnosed as an infection; consecutive positive weekly samples constituted a single infection. Picornavirus illness was diagnosed if RNA was detected 7 days prior through 21 days after onset. One hundred fifty-five (21%) of 740 weekly samples were picornavirus positive and associated with illness; 37(5%) positives were not associated with illness (P = 0.001). The 192 positive samples occurred in 121 infections, 74 with a single positive and 47 with "runs" of positives in two or more consecutive samples. Forty five (96%) of the 47 runs comprised 2 or 3 consecutive positives. Ninety six (52%) of 185 reported illnesses during 235 child-months were picornavirus positive (0.4/child-month); 25 infections were asymptomatic (0.11/child-month). The infection rate was highest in fall (0.66/child-month); the winter rate (0.44/child-month) was similar to that in spring (0.5) and summer (0.43). Picornavirus infections in healthy children were common (0.51/child-month), episodic, and usually associated with brief illness; one fifth of infections were asymptomatic. The infection rate was highest in fall; infections in winter occurred at the same rate as in spring and summer., (Copyright 2006 Wiley-Liss, Inc.)

Background: Antiviral agents could play a significant role in the response to a future influenza pandemic, especially if an effective vaccine is unavailable. There is, however, a limited availability of antiviral drugs, as was the case during the A/Fujian(H3N2) epidemic in the 2003-2004 season. There are major differences among the available antiviral agents in terms of clinical pharmacology, adverse effects and resistance profiles, all of which must be considered when selecting agents for pandemic use and stockpiling. The logistic issues involved in delivering the drug to large populations must also be considered. The M2 ion channel inhibitors amantadine and rimantadine are partially effective for chemoprophylaxis of pandemic influenza, and when used for early treatment they provide some symptom relief. Interpandemic studies demonstrate that the neuraminidase inhibitors would be effective for both prevention and treatment of influenza., Conclusion: Given the limited supply and the previously demonstrated inability of the manufacturing sector to meet surging needs, an effective antiviral response could not currently be launched in the United States. Antiviral agents could be important in managing and treating pandemic influenza and reduce lower respiratory complications and hospitalizations.