Lynch Joseph P, Walsh Edward E
Division of Pulmonary, Critical Care Medicine, and Hospitalists, Department of Internal Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA.
Semin Respir Crit Care Med. 2007 Apr;28(2):144-58. doi: 10.1055/s-2007-976487.
Influenza A and B are important causes of respiratory illness in all age groups. Influenza causes seasonal outbreaks globally, and (rarely) pandemics. In the United States, seasonal influenza epidemics account for > 200,000 hospitalizations and > 30,000 deaths annually. More than 90% of deaths are in the elderly. The toll is considerably higher during pandemics. Clinical features of influenza infection overlap with other respiratory pathogens (particularly viruses). The diagnosis is often delayed due to low suspicion and the limited use of specific diagnostic tests. Rapid diagnostic tests are widely available and allow detection of influenza antigen in respiratory secretions within 1 hour; however, sensitivity ranges from 40 to 80%. Currently, four drugs are available to treat or prevent influenza. These include the adamantanes (i.e., amantadine and rimantadine) and the neuraminidase inhibitors (i.e., oseltamivir and zanamivir). Adamantanes are active against influenza A but not influenza B. However, recent emergence of adamantane resistance has rendered these agents ineffective. Hence, adamantanes are not currently recommended in the United States. The neuraminidase inhibitors (NAIs) are effective in treating influenza A or B, and for prophylaxis in selected adults and children. Resistance to NAIs is rare, but influenza strains resistant to oseltamivir have been detected. Vaccines are the cornerstone of influenza control. Currently, trivalent inactivated vaccine (TIV) and live attenuated influenza vaccine (LAIV) are available. These agents reduce mortality and morbidity in high-risk patients (i.e., the elderly or patients with comorbidities), and expanding the use of vaccines to healthy children and adults reduces the incidence of influenza, pneumonia, and hospitalizations due to respiratory illnesses in the community.
甲型和乙型流感是所有年龄组呼吸道疾病的重要病因。流感在全球引发季节性疫情，（极少情况下）还会引发大流行。在美国，季节性流感疫情每年导致超过20万例住院病例和超过3万例死亡。超过90%的死亡病例为老年人。在大流行期间，死亡人数要高得多。流感感染的临床特征与其他呼吸道病原体（尤其是病毒）重叠。由于怀疑指数低以及特定诊断检测手段使用有限，诊断往往会延迟。快速诊断检测广泛可得，能在1小时内检测呼吸道分泌物中的流感抗原；然而，其灵敏度在40%至80%之间。目前，有四种药物可用于治疗或预防流感。这些药物包括金刚烷类（即金刚烷胺和金刚乙胺）和神经氨酸酶抑制剂（即奥司他韦和扎那米韦）。金刚烷类对甲型流感有效，但对乙型流感无效。然而，最近出现的金刚烷类耐药性使这些药物失效。因此，美国目前不推荐使用金刚烷类药物。神经氨酸酶抑制剂对甲型或乙型流感的治疗以及选定的成人和儿童的预防有效。对神经氨酸酶抑制剂的耐药性很少见，但已检测到对奥司他韦耐药的流感毒株。疫苗是流感防控的基石。目前，有三价灭活疫苗（TIV）和减毒活流感疫苗（LAIV）。这些制剂可降低高危患者（即老年人或患有合并症的患者）的死亡率和发病率，将疫苗的使用范围扩大到健康儿童和成人可降低社区中流感、肺炎以及呼吸道疾病导致的住院率。
