英文阅读题目,求原文和答案.scratching the surface[parasite / insect bites

1.B
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9.True
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Scratching the surface
Itching sensations often have psychosomatic,not physical causes,writes David Hambling
They are insidious skin parasites,infesting the occupants of factories and offices.They cause itching,prickling and crawling sensations in the skin that are almost untreatable.These creatures may only exist in the mind,but their effects are real and infectious.
The classic case occurred in a US laboratory in 1966.After new equipment was installed,workers started to suffer from itching and sensations of insects crawling over them.Complaints multiplied and the problem,attributed to "cable mites",started to affect families.A concerted effort was made to exterminate the mites using everything from DDT and mothballs to insecticide and rat poison.
Nothing worked.Thorough examination by scientific investigators could not locate any pests,or even signs of actual parasite attacks.However,they did find small particles of rockwool insulation in the air,which could cause skin irritation.A cleaning programme was introduced and staff were assured the problem had been solved.The cable mite infestation disappeared.
Another 1960s case occurred in a textile factory,where workers complained of being bitten by insects brought into the factory in imported cloth.Dermatitis swept through the workforce,but it followed a curious pattern.Instead of affecting people in one particular part of the factory,the bugs seemed to be transmitted through social groups.No parasites could be found.
A third infestation spread through clerical staff working with dusty records.They attributed their skin problems to "paper mites",but the cause was traced to irritation from paper splinters.
These are all cases of illusions of parasitosis,where something in the environment is misinterpreted as an insect or other pest.Everyone has heard of delirium tremens,when alcoholics or amphetamine users experience the feeling of insects crawling over their skin,but other factors can cause the same illusion.Static electricity,dust,fibres and chemical solvents can all give rise to imaginary insects; the interesting thing is that they spread.The infectious nature of this illusion seems to be a type of reflex contagion.Yawn,and others start yawning; if everyone around you laughs,you laugh.Start scratching and colleagues will scratch,too.
Dr Paul Marsden is managing editor of the Journal of Memetics,the study of infectious ideas.He suggests that this type of group behaviour may have had an evolutionary purpose.In our distant past,one individual scratching would have alerted others that there were biting insects or parasites present.This would prime them to scratch itches of their own.Anyone who has been bitten several times by mosquitoes before they realised it will recognise the evolutionary value of this kind of advance warning.It may also promote mutual grooming,which is important in the bonding of primate groups.
The problem comes when the reflex contagion is not related to a real threat.Normally,everyone would soon stop scratching,but people may unconsciously exaggerate symptoms to gain attention,or because it gets them a break from unappealing work.The lab workers were scanners,who spent the day laboriously examining the results of bubble-chamber tests; textile workers and clerical staff poring over records may also find their jobs tedious.Add the factor that skin conditions are notoriously susceptible to psychological influence,and it is easy to see how a group dynamic can keep the illusory parasites going.
Treatment of the condition is difficult,since few will accept that their symptoms are the result of what psychologists call a hysterical condition.In the past,the combination of removal of irritants and expert reassurance was enough.However,these days,there is a mistrust of conventional medicine and easier access to support groups.
Sufferers can reinforce each other's illusions over the internet,swapping tales of elusive mites that baffle science.This could give rise to an epidemic of mystery parasites,spreading from mind to mind like a kind of super virus.Only an awareness of the power of the illusion can stop it.
You can stop scratching now...