what is swine flu?
it is a contagious respiratory disease of pigs caused by type a influenza viruses. pigs are hit by regular outbreaks. there are many different types of swine flu and the current cases involve the h1n1 strain of type a influenza virus.
how do humans catch it?
while people do not normally catch it, humans can contract the virus, usually if they have been in close contact with pigs. it is also possible for the constantly changing infection to spread from person to person, which has happened in the latest outbreak. experts believe it spreads in the same way as seasonal flu - through coughing and sneezing.
what are the symptoms?
the symptoms of swine influenza in people are similar to the symptoms of regular human seasonal influenza infection and include fever, fatigue, lack of appetite, coughing and sore throat. some people with swine flu have also reported vomiting and diarrhoea.
what is the difference between swine flu, avian flu and the flu commonly seen in the uk during the winter?
influenza viruses are commonly circulating in the human and animal environment, with different strains causing illness in humans, bird and pigs. seasonal influenza is caused by viruses that are adapted to spread in humans. humans have some natural immunity to the strains that are in common circulation, and this immunity can be boosted by immunisation with a vaccine. avian influenza is caused by influenza viruses adapted for infection in birds. similarly, swine influenza is caused by influenza viruses adapted for infection in pigs. these illnesses all cause the same respiratory symptoms in sufferers and can be passed between one another.
how dangerous is it?
more than 80 people have died and thousands made ill, in mexico in particular, although cases have also been reported in the us and new zealand. however, testing has shown that the antiviral drugs oseltamavir (tamiflu) and zanamivir (relenza) appear to be effective against the human swine influenza h1n1 strain,
why should we be worried about it?
the world health organisation warned the outbreak had "pandemic potential" and countries were advised to step up surveillance and preparation in case the infection spreads rapidly. flu viruses have the ability to change and mutate, making it difficult for drugs manufacturers to ensure effective vaccines are available. the new version of the h1n1 virus is a mix of different animal and human versions of the disease. mixing can lead to the development of changed viruses to which humans have little immunity.
what is a pandemic?
if the flu spreads over a wide geographic area and affects a large proportion of the population it goes beyond an epidemic and becomes a pandemic. according to the health protection agency, an influenza pandemic is defined as a new or novel influenza virus that spreads easily between humans. when new influenza viruses are introduced into the environment, humans do not have any natural immunity to protect against them. therefore, there is a risk that that new influenza viruses could develop into a pandemic if the virus passes easily from human-to-human.
will it spread to the uk?
it is too early to say whether the cases reported so far will lead to a larger outbreak, the hpa said. no cases have been reported in the uk although experts are monitoring the situation closely. anyone who has recently returned from affected countries should consult a doctor if they notice flu-like symptoms.
what is being done in the uk to prevent the infection?
the hpa said it is working with the uk government to review the current incident and any threat it poses to uk public health. it advised people to follow general infection control practices and good hygiene to reduce transmission of all viruses. this includes covering their nose and mouth when coughing or sneezing, disposing of dirty tissues promptly and carefully, washing hands frequently with soap and water and cleaning surfaces which are regularly touched.
什么是猪流感？
猪流感是由a型流感病毒引起的猪呼吸道传染病，病毒的定期爆发会引起猪患病。猪流感的种类很多，现在的病例则与a型病毒的h1n1类有关。
人为何会患病？
虽然患病概率不高，但人类还是有可能被该类病毒感染，被感染者通常与病猪有过密切接触。从最近一次疫情爆发中可以看到，病毒会变异，并在人与人之间传染。专家认为，猪流感和季节性流感一样，都是通过咳嗽和喷嚏传播。
有何症状？
人患猪流感的症状同正常人类患季节性流感的症状相似，包括发烧、疲劳、食欲不振、咳嗽和喉咙痛，还有报告显示猪流感患者会出现呕吐和腹泻症状。
猪流感、禽流感和英国冬天常见的流感有何区别？
流感病毒常在人类和动物世界传播，导致人类、禽类和猪患病的病毒种类各不相同。季节性流感由适应在人类中传播的病毒引起。人类对这种普通病毒的传播具有天然的免疫力，并可通过接种疫苗加强免疫力。禽流感由适应在鸟类中传播的病毒引起，类似地，猪流感由适应在猪中传播的病毒引起。这些疾病在患者体内引起相同的呼吸道症状，并可以互相传播。
它的危害有多大？
尽管在美国和新西兰也有病情报告，但就墨西哥一国，便已有80多人死亡，几千人患病。不过，测试已经发现，抗病毒药神经氨酸酶抑制剂（达菲）和扎那米韦（乐瑞沙）似乎可以有效抵抗人类猪流感h1n1型病毒。
为什么我们会担心？
世界卫生组织警告说，本次疫情爆发“有在全世界大范围传播的可能性”，并建议各国加强监督和准备工作，以防止病情迅速蔓延。流感病毒有变异和突变能力，这使得制药商难以保证疫苗的有效性。新变异的h1n1病毒是不同种类动物和人类流感病毒的混合体，而人类对病毒混合变异出的种类几乎毫无免疫力。
何为大规模流行病？
如果流感在广阔的地理区域内传播，并影响到相当一部分人口，那么它就不再为地区性流行病（epidemic），而是大规模流行病（pandemic）。根据英国健康防护署的定义，大规模流感是一种能轻易在人类中传播的新型流感。当新型流感病毒进入到环境中以后，人类对它们没有任何自然抵抗力。因此，如果病毒能够轻易在人与人之间传播，那么它就有演变成大规模流感的可能性。
它会传播到英国吗？
健康防护署称，迄今报告的案例会不会引起更大规模的疫情爆发，现在还难下定论。尽管专家在密切监视疫情，但在英国尚未出现猪流感病例。最近从疫情国家回到英国的任何人，如果感觉有类似流感的症状，那么应该去看医生。
英国为了防止传染，采取了什么手段？
健康防护署表示，它在与英国政府合作，以评价现在的疫情及其对英国公众健康构成的威胁。它建议人们遵守惯常的防传染措施，保持良好的个人卫生，从而遏制一切病毒的传播。这包括在咳嗽、喷嚏时捂住口鼻，及时并小心丢弃不干净的纸巾，勤用肥皂和水洗手，以及经常清洗易与外界接触的皮肤表面。