关于流感病毒的类型、症状和治疗方式，你应该了解的
What to Know About the Flu Virus

Each fall, the flu emerges as a formidable force, spreading through the droplets produced when people cough, sneeze or talk, and sometimes hitching a ride to our noses by way of the infected surfaces that we touch. Influenza viruses cause tens of millions of illnesses and thousands of deaths in the United States each year.
每年秋天，流感都会强势出现，通过人们咳嗽、打喷嚏或说话时产生的飞沫传播，有时还会通过人们接触的受感染表面进入我们的鼻子。流感病毒每年在美国造成数千万人患病，数以千计人死亡。

There are two players every flu season: influenza Type A and Type B. Influenza A tends to pop up early in the season and accounts for more than 75 percent of all cases, while influenza B typically has a distinct but much smaller peak in late February or March.
每个流感季节都有两种流感病毒：甲型流感和乙型流感。甲型流感往往在流感季节早期出现，占所有病例的75%以上，乙型流感通常在2月底或3月出现明显高峰，但规模要小得多。

“You tend to have one or the other virus predominant at any given time,” said Anice Lowen, an associate professor of microbiology and immunology at the Emory University School of Medicine. Here’s what to know about the flu viruses.
埃默里大学医学院微生物学和免疫学副教授阿尼斯·罗文说：“在任何特定时间，往往都会有一种或另一种病毒占主导地位。”以下是关于流感病毒的一些知识。

What’s the difference between Type A and Type B?
甲型流感和乙型流感有什么区别？

Influenza A viruses come in many varieties. Four subtypes commonly affect humans, Dr. Lowen said — you may have heard of H1N1, for example. But many more influenza A viruses have been identified in animals, which makes it a potential source of pandemics whenever a new type of influenza A jumps to humans, she said. All four flu pandemics — in 1918, 1957 and 1968 and the swine flu pandemic of 2009 — were caused by Type A viruses.
甲型流感病毒有很多变种。罗文说，通常有四种亚型会影响人类，例如，你可能听说过H1N1。但是，她说，在动物身上发现的甲型流感病毒还有很多，因此，每当一种新的甲型流感跃迁到人类身上，都有可能成为流行病的潜在来源。所有四次流感大流行——1918年、1957年、1968年，以及2009年的猪流感大流行——都是由甲型病毒引起的。

Influenza B viruses, however, only circulate in humans. They are divided into just two lineages that cause seasonal outbreaks, Dr. Lowen said. Because influenza B viruses evolve more slowly than influenza A viruses, they have shorter and more predictable flu seasons.
而乙型流感病毒只在人类中传播。罗文说，它们只分为两种会引起季节性爆发的谱系。由于乙型流感病毒的进化速度比甲型流感病毒慢，所以它们的流行季节更短，更容易预测。

Still, each year experts closely monitor flu patterns all over the world and try to predict how the viruses might mutate, said Dr. Sean Liu, an assistant professor of infectious disease at the Icahn School of Medicine at Mount Sinai in New York City. “We haven’t come up with a 100 percent accurate way to do it,” Dr. Liu said. “That’s why the efficacy of flu vaccines varies from season to season.”
纽约市西奈山伊坎医学院传染病学助理教授肖恩·刘（音）博士说，尽管如此，每年专家们都在密切监测世界各地的流感模式，并试图预测病毒可能如何变异。“我们还没有找到百分之百准确的方法，”肖恩·刘说。“所以流感疫苗的功效在每个流行季都不一样。”

In the United States, flu shots are updated annually to include two types each of influenza A and B viruses; scientists pick strains of the viruses expected to be dominant that year. “Your antibodies and your immunity toward these viruses wane over time,” Dr. Liu said. “So the updated vaccine helps remind your body how to react when you face new versions of the virus.”
在美国，流感疫苗每年更新，包括甲型和乙型流感病毒的各两种类型；科学家们会挑选预计在当年占主导地位的病毒株。“你对这些病毒的抗体和免疫力会随着时间的推移而减弱，”肖恩·刘说。“因此，更新的疫苗有助于提醒你的身体在面对新版本的病毒时如何应对。”

Public health officials recommend everyone six months and older get an annual flu shot.
公共卫生官员建议所有六个月及以上的人每年接种流感疫苗。

What are symptoms of an influenza infection?
流感感染有哪些症状？

If you do get sick with the flu, the most common symptoms include a sudden onset of fever, chills, muscle aches, fatigue and respiratory ailments, such as a cough or sore throat.
如果感染流感，最常见的症状包括突然发烧、发冷、肌肉疼痛、疲劳和呼吸道疾病，如咳嗽或喉咙痛。

Most otherwise healthy people are sick for three to seven days, Dr. Liu said. In some cases, the cough and fatigue can linger for two weeks.
肖恩·刘说，大多数健康者病程为三到七天。在某些情况下，咳嗽和疲劳可能持续两周。

In the past, doctors thought that Type A infections were more severe than Type B. But studies have shown that both Types A and B result in similar numbers of hospitalizations and deaths in adults. In children, however, influenza B may cause more severe disease and is associated with higher rates of mortality.
过去，医生们认为甲型流感比乙型流感更严重。但研究表明，甲型和乙型流感导致的成人住院和死亡人数相当。然而，在儿童中，乙型流感可能导致更严重的疾病，并与更高的死亡率相关。

The most common complication of severe influenza is pneumonia, a lung infection that can result from the flu virus or from a secondary bacterial infection, Dr. Liu said. The flu can also trigger an extreme inflammatory response in the body and worsen existing chronic conditions like asthma or heart disease.
肖恩·刘说，严重流感最常见的并发症是肺炎，这是一种由流感病毒或继发性细菌感染引起的肺部感染。流感还会引发体内极端的炎症反应，使哮喘或心脏病等现有慢性疾病恶化。

How do you know which type you have?
如何知道自己患上的是哪种类型的流感？

Some rapid tests available at doctors offices and urgent care centers can distinguish between influenza A and B, although they tend to have low sensitivity, a measure of how well a test performs at catching cases of flu. . Doctors can also order more sensitive P.C.R. tests to identify the specific flu virus causing infection, Dr. Liu said, “but it doesn’t change management much.”
医生办公室和紧急护理中心提供的一些快速检测可以区分甲型流感和乙型流感，尽管其敏感性往往较低（敏感性是衡量一种检测方法在发现流感病例方面表现如何的一个指标）。医生还可以要求进行敏感性更高的PCR检测，以确定引起感染的特定流感病毒，肖恩·刘说，“但这不会对治疗产生太大影响。”

How do you treat influenza?
如何治疗流感？

The approach to treating the flu, regardless of type, revolves around relieving symptoms and supporting the body’s natural defenses, Dr. Liu said. There are four approved antiviral medications, including Tamiflu, that are commonly prescribed to shorten the duration and severity of illness. Doctors typically reserve these antivirals for people at risk of developing severe complications, Dr. Liu said, including people 65 years and older; those who are pregnant or have chronic conditions like asthma, diabetes or heart disease; and children younger than 5. Because the drugs shave off only a day or so of illness, experts believe the benefits are not worth the cost of treatment for most people.
肖恩·刘说，无论哪种类型，治疗流感的方法都围绕着缓解症状和支持身体的自然防御展开。包括达菲在内的四种已获批准的抗病毒药物，通常用于缩短病程和减轻病情。肖恩·刘说，医生通常会把这样的抗病毒药物留给有可能出现严重并发症风险的人群，包括65岁及以上的人；孕妇；患有哮喘、糖尿病或心脏病等慢性疾病的人；以及五岁以下儿童。由于这些药物只能缩减一天左右的病程，专家认为，对大多数人来说，这样的益处不能抵消治疗成本。

For those recovering at home, doctors recommend staying hydrated, getting plenty of rest and using over-the-counter medications to reduce fever as needed. But if your symptoms persist, you develop a sustained fever of 102 degrees or higher, you have difficulty breathing or you experience severe chest or stomach pain, it is important to seek medical attention immediately. These may be signs that you need a stronger influenza treatment.
对于在家恢复的患者，医生建议保持水分，充分休息，并根据需要使用非处方药退烧。但是，如果症状持续，持续发烧39摄氏度或更高，出现呼吸困难，或严重的胸痛或胃痛，请务必立即就医。这些症状可能表明需要更强力的流感治疗。