Here are a few basics about the swine flu outbreak in the U.S. and Mexico.

What is swine flu?

It's flu that occurs in pigs. In rare cases, humans contract swine flu from close contact with pigs. The strain circulating now is cause for concern because it can pass directly from person to person. Like routine human flu, cases of swine flu can range from mild to severe.

Is the disease the same in Mexico and the U.S.?

The virus appears to be the same. But the disease has caused at least 20 deaths in Mexico, while it has appeared more mild in the 20 confirmed U.S. cases, with no deaths and most patients recovering without needing to be hospitalized. It's unclear why confirmed cases have been more severe in Mexico than in the U.S. A CDC official warned on Sunday that as cases continue to emerge in the U.S., some may prove fatal.

What are the symptoms?

Symptoms are similar to those of regular flu: fever, along with problems such as cough, sore throat, body aches, headaches, chills and fatigue. Some cases have also included reports of vomiting or diarrhea.

What should I do if I feel sick?

People with ordinary flu symptoms do not need to seek emergency care, New York City officials said. But people with certain warning signs in addition to basic symptoms should seek urgent attention. In children, those signs include difficulty breathing; bluish skin color; flu symptoms that begin to improve, then return with fever and worse cough; and fever with a rash. In adults, warning signs include difficulty breathing, pain or pressure in the chest or abdomen, sudden dizziness, confusion, and severe or persistent vomiting.

Can the swine flu be treated with drugs?

Two drugs, sold under the brand names Tamiflu and Relenza, are believed to reduce the severity and the duration of the disease. But most of the patients who contracted swine flu in the U.S. have recovered without taking the drugs. Both drugs have also been approved to reduce the risk of contracting the flu. But, unlike a vaccine, they do not provide long-lasting protection. So their preventive use is typically for short-term situations, such as for family members of someone who has the flu. The drugs, which are included in the federal government's pandemic stockpile, are only available with a doctor's prescription.

Does this year's flu vaccine protect against the swine flu?

The CDC says the seasonal flu vaccine is 'unlikely to provide protection' against the swine flu. The agency has created a 'seed vaccine' specifically tailored to this swine flu. That could be used to manufacture a targeted vaccine if officials deem it necessary to do so. But manufacturing a new vaccine would take months.

Are there ways to reduce the spread of disease?

Cover your nose and mouth when you cough or sneeze. Wash your hands often. Avoid touching your eyes, nose or mouth. Avoid close contact with infected people. People who have mild symptoms should stay home from school or work until 48 hours after the symptoms have passed, to avoid spreading disease, New York health officials said. 

以下是有关在美国和墨西哥爆发的猪流感的一些基本知识。

何谓猪流感？

这是猪身上爆发的流感。在很少一些案例中，人类因与猪密切接触而感染猪流感。目前流行的病毒毒株之所以令人担忧，就是它能在人与人之间直接传染。同普通的人流感一样，猪流感病情也有从轻微到严重之分。

墨西哥与美国爆发的同一种猪流感吗？

致病的病毒看来是相同的。但墨西哥的猪流感已导致至少20人死亡，而美国已确诊的20例猪流感则要轻微的多，其中并没有死亡病例，大多数患者都在康复之中，无需住院治疗。目前还不清楚为何墨西哥确诊的病例要比美国严重的多。美国疾病控制预防中心(CDC)一位官员周日警告说，随着美国继续发现猪流感病例，其中一些可能会有生命危险。

猪流感有何症状？

症状同普通流感相似：发热，并伴有咳嗽、咽喉痛、肌肉痛、头痛，发冷和疲劳。还有一些病例会有呕吐或腹泻的情况。

如果我感觉患病，应该怎么做？

纽约市官员说，出现普通流感症状的患者不需看急诊。但除了基本症状外，还出现一些危险症状的患者应该看急诊。对儿童来说，这些症状包括呼吸困难；皮肤颜色变青；流感症状开始改善，然后又出现发热和咳嗽加剧；以及伴有皮疹的发热等。对成人而言，危险的症状包括呼吸困难、胸腹部疼痛或有压迫感、突然的头晕或神志不清、以及严重或持续的呕吐。

能用药物治疗猪流感吗？

据信达菲(Tamiflu)和瑞乐沙(Relenza)这两种药物能够降低猪流感的病情和发病时间。但在美国，感染猪流感的大多数患者在没有服药的情况下病情也出现了好转。这两种药物也获批可以用来降低感染流感的风险。但与疫苗不同，它们并不能带来长期持续的保护作用。因此，它们一般只具有短期的预防作用，如在某位家庭成员感染流感的情况下。这两种药物都在美国政府的疫情储备药物当中，且只能凭医生处方购买。

今年的流感疫苗能预防猪流感吗？

美国疾病控制预防中心说，季节性的流感疫苗不太可能预防猪流感。该机构已经开发了专门针对猪流感的“种子疫苗”。如果政府部门认为有必要，这种疫苗可用于生产有针对性的疫苗。但生产一种新疫苗可能需要数月时间。

有没有减少猪流感扩散的办法？

纽约市卫生官员说，在咳嗽或打喷嚏时遮住你的鼻子和口。经常洗手。避免接触你的眼睛、鼻子和嘴。不要与受感染者密切接触。出现轻微症状的人在症状消失48小时之内应呆在家中，不要上学或上班，以避免传染疾病。