原版英语RAZ 教案(Z) InFLUenza_DS.pdf

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1、Visit www.readinga- for thousands of books and materials.InFLUenzaA Reading AZ Level Z Leveled BookWord Count:2,286www.readinga-InFLUenzaLEVELED BOOK ZTWZWritten by Ned JensenInFLUenzaWritten by Ned Jensenwww.readinga-24microorganism(n.)an organism of microscopic size,such as a virus or single bacte

2、rial cell(p.5)mutating(v.)changing into a different form (p.9)pandemic(n.)the rapid,worldwide spread of a disease(p.19)parasites(n.)organisms that live inside of and take nourishment from other organisms(p.6)phagocytes(n.)cells that eat invading microbes in the body(p.12)protein(n.)an essential nutr

3、ient found in the cells of all living things(p.5)respiratory tract(n.)the passages in the nose,mouth,throat,and lungs through which air travels during breathing(p.7)strain(n.)a group of microbes of the same type(p.9)submicroscopic(adj.)too small to be seen with an ordinary microscope(p.5)vaccines(n.

4、)medicines made of weak or dead viral strains that teach the body to fight stronger viruses of the same type(p.15)virus(n.)a microorganism that enters the body,gets into cells,rapidly reproduces,and causes illness;a disease caused by a virus(p.5)24InFLUenza Level Z 23Glossaryantibiotic(adj.)relating

5、 to a medicine that fights infections in the body from certain types of microbes(p.17)antibodies(n.)chemicals produced by the body that attack invading germs(p.11)antigens(n.)substances that trigger immune responses in the body(p.12)congested(adj.)filled up or blocked(as with mucus in the nose and t

6、hroat)(p.7)contagious(adj.)able to spread from one organism to another(p.14)epidemic(n.)an outbreak of disease that spreads rapidly through a group of living things(p.18)fatigued(adj.)tired or weary from mental or physical labor(p.4)genetic material(n.)the part of a cell that carries the basic infor

7、mation about an organisms characteristics(p.5)germs(n.)microorganisms that often cause disease and sickness(p.4)hosts(n.)organisms in or on which other organisms live(p.6)immunity(n.)the ability of a body to resist infection(p.11)intracellular(adj.)existing within cells(p.6)invasive(adj.)relating to

8、 moving into a new area or body with harmful or disruptive effects(p.11)InFLUenzaLevel Z Leveled Book Learning AZWritten by Ned JensenIllustrated by Cende Hill All rights reserved.www.readinga-CorrelationLEVEL ZUVN/A50Fountas&PinnellReading RecoveryDRAPhoto Credits:Front cover:iS Perkins;back cover:

9、Santos06/D;title page:iS Wilson;pages 3,8,16:courtesy of James Gathany/CDC;page 4:Photodisc/C Squared Studios/Getty Images;page 5:courtesy of Cynthia Goldsmith/CDC;pages 7,10(top left,top right,bottom right),13,14,22:Jupiterimages Corporation;page 9(top):iS Martin;page 9(bottom):iS Campbell;page 10(

10、left):iS Davis;page 12:Sebastian Kaulitzki/D;page 18:courtesy of Library of Congress,Prints&Photographs Div LC-USF34-039530-D;page 19:courtesy of Knowland Collection/Oakland,CA Public Library/Edward A Rogers;page 21:REUTERS/Beawiharta EN/RCS23InFLUenza Level Z Table of ContentsIntroduction .4What Is

11、 the Flu?.5Changing Viruses .9The Body Fights Back .11Preventing the Virus from Taking Over .14Treating the Flu .17History of the Flu .18Conclusion .22Glossary .23322ConclusionInfluenza has been around for hundreds of years.Because flu viruses can change and develop into new strains,influenza may ne

12、ver be wiped out.When you have the flu,the most important thing you want to do is take care of yourself and prevent others from getting it.Youll want to drink as much water as a camel drinks and sleep like a bear.Get a vaccine if one is available.Most importantly,remember to attack back!Good food an

13、d rest allow the healthy cells in your body a chance to win the battle.IntroductionHave you ever shivered with chills or burned up with a fever?Have you ever had a sore throat,a stuffy nose,a pounding headache,and muscle aches?Have you ever felt really fatigued even though youve just woken up in the

14、 morning?If you feel symptoms such as these,flu germs may have invaded your body.By learning about the fluwhat it is,what causes it,what its symptoms are,and how to treat ityou can fight back against this illness and stay healthy.4A water bottle and a blanket can help when you have the flu.InFLUenza

15、 Level Z 21Masks that fit around the nose and mouth are sometimes worn to help prevent the spread of viruses.However,the masks do not work all the time.Other outbreaks have caused widespread concern without developing into actual pandemics.These include the Russian flu in 1977 and the avian flu in 1

16、997 and 1999.Both of these strains of flu began in regions of China and spread to other countries.Doctors are always on the lookout for the next major outbreak.They believe that if they can detect outbreaks quickly enough,they can keep them from becoming worldwide pandemics.InFLUenza Level Z What Is

17、 the Flu?The flu is also called influenza(in-floo-EN-zah).Its caused by a virus that has the ability to quickly spread between people.A virus is a tiny microorganisma microbe,or germthat is invisible to the naked eye.A virus is composed of a little bit of genetic material surrounded by a hard protei

18、n shell that protects it.Viruses are submicroscopicso small that scientists must use extremely powerful microscopes to see them.Even when viewed through a microscope,a virus can only be seen after its image has been magnified to one thousand times its original size.In fact,viruses are so small that

19、hundreds of thousands of them can live on the head of a pin.Viruses are everywhere.Some wont bother you at all,but some can be dangerous,even deadly,to people and other animals.And during flu season,which lasts from October through May in the northern hemisphere,viruses are widespread.Like many othe

20、r organisms,viruses need a particular type of home in order to survive and reproduce.Unfortunately for humans and other animals,that home is inside us!5Avian influenza virus20But the pandemic of 1918 was not the only major influenza outbreak in history.The Asian flu,which appeared in 1957,caused abo

21、ut 70,000 deaths in the United States.It got its name because it first appeared in China before coming to the United States in June 1957.Another strain of flu,the Hong Kong flu,was first detected in Hong Kong,China.In 1968,this virus caused another pandemic,resulting in 34,000 deaths in just the Uni

22、ted Statesas many people as live in a small city.And in 2009,the H1N1 swine flu became the first pandemic in 41 years,infecting people in over 70 countries.This map shows an example of how pandemics,such as the Asian flu of 19571958,might spread from one area to many others.ChinaJapanPACIFIC OCEANIn

23、diaRussiaMongoliaViruses act as intracellular parasites.Although they can live on their own for a period of timesometimes for yearseventually they must find organisms to serve as hosts and get inside their cells in order to reproduce.Once a virus infects a human being,it uses its hard protein shell

24、to make a hole in a cell,which it then invades.Once inside the host cell,the virus inserts its own genetic information into the cell and begins to rapidly make copies of itself.One to four days after infection,the host may begin to experience symptoms and feel sick.6A virus invades a cell in a human

25、 body.The virus takes over the cell and makes copies of itself.Copies of the virus break out of the cell and start invading other cells.How a virus spreads in the body123InFLUenza Level Z 19The history of any influenza outbreak begins with a single person.On March 11,1918,a young man in the U.S.Army

26、 reported to a hospital with a fever,sore throat,and a headache.Shortly after,many other soldiers at his base developed the same symptoms.In one week,the Army hospital was treating more than five hundred sick soldiers.By the end of spring,forty-eight of those people had died.At first,no one knew why

27、,not even the doctors and scientists.Doctors later learned that the illness was caused by a particular strain of the influenza virus.In total,this strain of influenza,known as the Spanish flu,killed more than 600,000 Americans and 25 to 40 million people worldwide.When an outbreak reaches this size,

28、it is known as a pandemica disease that spreads rapidly around the world.1918 Spanish flu patientsInFLUenza Level Z There are many kinds of flu,and each is caused by a specific virus.But even though there are different types of flu,their symptoms are very similar.Flu is an infection of the respirato

29、ry tract that usually causes you to feel achy,feverish,congested,fatigued,and sick to your stomach.7Flu viruses attack the respiratory tract.lungsmouthnosepharynxwindpipe(trachea)larynx18A doctor gives children shots of vaccine in 1941.History of the FluThroughout history,there have been many outbre

30、aks of influenza.Some of them have been mild and not very widespread.Other outbreaks have been severe,spreading throughout the world and killing millions of people.Once a flu virus develops and infects a few people,it can spread rapidly to become an epidemic.Scientists have evidence suggesting that

31、flu epidemics date back hundreds and possibly even thousands of years.Each epidemic has killed thousands of people or more.Influenza has three basic types:Influenza A,Influenza B,and Influenza C.Influenza A can cause serious illness in humans and other animals and is usually responsible for large ou

32、tbreaks.Influenza B is milder,causes smaller outbreaks,and affects only humans(mostly children).Influenza C usually causes only mild illness in humans.All types of influenza can be passed from an infected person to a healthy person through the air or through contact with objects such as eating and d

33、rinking utensils.The influenza virus is often transmitted in saliva from an infected persons mouth and on droplets of mucus sneezed or coughed into the air.For this reason,it is always important to cover your mouth and nose when you cough or sneeze.Its also important to wash your hands after going t

34、o the bathroom and before eating or preparing food.If you are infected,the very best thing you can do is to stay home and away from other people so you dont spread your germs.8Tiny drops of saliva and mucus fill the air when you sneeze.InFLUenza Level Z 17Treating the Flu Preventing the flu is not a

35、lways possible.However,once viruses infect your body,you still can do several things to fight back.Pharmacies offer many over-the-counter medicines that can help relieve the symptoms of the flu.These medicines can eliminate the achy feeling in your head and muscles.They can also help reduce a fever.

36、Drinking plenty of fluids,such as water or fruit juices,can also help.You should get plenty of rest so your body can better fight the viruses that have invaded your cells.Think about all the work your immune system has to do when its fighting an infection.Its no wonder you feel pain and exhaustionth

37、eres a war going on inside your bloodstream!Give your body plenty of water and rest so it can do its job.Most people recover from the flu without receiving any special medical treatment.For very serious cases of the flu,however,doctors do have some medicines that they can use.Although antibiotic dru

38、gs have no effect on viruses,some antiviral drugs do target flu viruses.However,antiviral drugs and medicines that work well against one strain of virus might be useless against another strain.Viruses can also develop resistance and even immunity to drugs over time.InFLUenza Level Z Changing Viruses

39、Viruses are capable of changing,or mutating.Flu viruses are among the most changeable of all viruses.Each type of virus that mutates from another virus is called a strain of that virus.Many influenza viruses start in wild animals,most often in birds.These viruses can easily mutate into strains that

40、infect ducks and chickens on farms.Once a virus has infected birds on farms,it can further mutate into strains that can infect animals such as pigs,and even humans.9Wild birds(above)often pass viruses to farm chickens(right),which come into more contact with people.16Vaccines for most viral strains

41、have an eighty-percent prevention rate,which means that eighty percent of the time,youll be immune and wont get sick from a strain you have been vaccinated against.Thats pretty high,but its not perfect,so you might still get the flu even if youve received a vaccine.But if youve had the vaccine,your

42、symptoms will be milderyou wont ache so much,and you wont feel so hot.However,if you become infected with a strain that is different from those in your flu shot,you can still get sick.Scientists must be good detectives to predict which strains to put into the shot each year.Not everyone has the same

43、 risk of catching the flu,and some people get more seriously ill than others.People who are very young or very old,or who already have health conditions such as diabetes and heart disease,are at greater risk of catching the flu than others.Since chickens,pigs,and humans come in close contact on farm

44、s,the spreading and mixing of viruses can be deadly.The chain of animals infected as the infection moves from wild animals to humans varies from virus to virus.A single virus chain may include animals as different as dogs and whales.Sometimes a virus takes a shortcut in the chain,such as the avian v

45、irus of 1997,which jumped directly from birds to humans.10A sample virus chainwild duckpigchickenhumanInFLUenza Level Z However,even the most cautious people can become infected.Fortunately,medical scientists have found a way to keep the flu virus from taking over your body.They have developed vacci

46、nes.Vaccines are weakened or dead flu viruses that are injected into a persons body before the person gets sick.These weakened viruses cause the body to produce antibodies that attack and destroy the weakened or dead germs.Once the body has“rallied the troops”and produced antibodies to destroy the v

47、iruses injected into the body,it is on alert and prepared to attack stronger viruses that may invade during flu season.Each strain of a virus requires a different vaccine.Some flu vaccines contain several strains.When these strains are injected into the body,each one causes the body to produce a par

48、ticular antibody to destroy it.Exposing the immune system to multiple strains prepares the body to defend against many forms of viruses that doctors think might be present during a particular flu season.15Do You Know?British physician Edward Jenner developed the first vaccine in 1796 when he injecte

49、d patients with cowpox virus to protect them from the similar but much more dangerous smallpox virus.InFLUenza Level Z The Body Fights BackThe human body has ways of fighting back against the invasion of flu viruses.The immune system protects against the invasion of harmful microbes by producing che

50、micals called antibodies,which travel in the blood and patrol the body in search of invaders.Antibodies are programmed to destroy a specific type of microbe.When they find an invasive microbe,antibodies attack and destroy any cells that contain the virus.Because viruses have the ability to mutate,in