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wrong parts of the body and 鈥済o kind of crazy；鈥潯n the words of dr。
bryan marsh； an infectious diseases specialist at dartmouth鈥揾itchcock medical center inlebanon； new hamphire。 鈥渋t happens all the time with car accidents when people sufferinternal injuries。 microbes that are normally benign in the gut get into other parts of thebody鈥攖he bloodstream； for instance鈥攁nd cause terrible havoc。鈥�
the scariest； most out…of…control bacterial disorder of the moment is a disease callednecrotizing fasciitis in which bacteria essentially eat the victim from the inside out； devouringinternal tissue and leaving behind a pulpy； noxious residue。 patients often e in withparatively mild plaints鈥攁 skin rash and fever typically鈥攂ut then dramaticallydeteriorate。 when they are opened up it is often found that they are simply being consumed。
the only treatment is what is known as 鈥渞adical excisional surgery鈥濃�攃utting out every bit ofinfected area。 seventy percent of victims die； many of the rest are left terribly disfigured。 thesource of the infection is a mundane family of bacteria called group a streptococcus； whichnormally do no more than cause strep throat。 very occasionally； for reasons unknown； someof these bacteria get through the lining of the throat and into the body proper； where theywreak the most devastating havoc。 they are pletely resistant to antibiotics。 about athousand cases a year occur in the united states； and no one can say that it won鈥檛 get worse。
precisely the same thing happens with meningitis。 at least 10 percent of young adults； andperhaps 30 percent of teenagers； carry the deadly meningococcal bacterium； but it lives quiteharmlessly in the throat。 just occasionally鈥攊n about one young person in a hundredthousand鈥攊t gets into the bloodstream and makes them very ill indeed。 in the worst cases；death can e in twelve hours。 that鈥檚 shockingly quick。 鈥測ou can have a person who鈥檚 inperfect health at breakfast and dead by evening；鈥潯ays marsh。
we would have much more success with bacteria if we weren鈥檛 so profligate with our bestweapon against them： antibiotics。 remarkably； by one estimate some 70 percent of theantibiotics used in the developed world are given to farm animals； often routinely in stockfeed； simply to promote growth or as a precaution against infection。 such applications givebacteria every opportunity to evolve a resistance to them。 it is an opportunity that they haveenthusiastically seized。
in 1952； penicillin was fully effective against all strains of staphylococcus bacteria； to suchan extent that by the early 1960s the u。s。 surgeon general； william stewart； felt confidentenough to declare： 鈥渢he time has e to close the book on infectious diseases。 we havebasically wiped out infection in the united states。鈥潯ven as he spoke； however； some 90percent of those strains were in the process of developing immunity to penicillin。 soon one ofthese new strains； called methicillin…resistant staphylococcus aureus； began to show up inhospitals。 only one type of antibiotic； vanycin； remained effective against it； but in 1997a hospital in tokyo reported the appearance of a strain that could resist even that。 withinmonths it had spread to six other japanese hospitals。 all over； the microbes are beginning towin the war again： in u。s。 hospitals alone； some fourteen thousand people a year die frominfections they pick up there。 as james surowiecki has noted； given a choice betweendeveloping antibiotics that people will take every day for two weeks or antidepressants thatpeople will take every day forever； drug panies not surprisingly opt for the latter。
although a few antibiotics have been toughened up a bit； the pharmaceutical industry hasn鈥檛given us an entirely new antibiotic since the 1970s。
our carelessness is all the more alarming since the discovery that many other ailments maybe bacterial in origin。 the process of discovery began in 1983 when barry marshall； a doctorin perth； western australia； found that many stomach cancers and most stomach ulcers arecaused by a bacterium called helicobacter pylori。 even though his findings were easily tested；the notion was so radical that more than a decade would pass before they were generallyaccepted。 america鈥檚 national institutes of health； for instance； didn鈥檛 officially endorse theidea until 1994。 鈥渉undreds； even thousands of people must have died from ulcers whowouldn鈥檛 have；鈥潯arshall told a reporter from forbes in 1999。
since then further research has shown that there is or may well be a bacterial ponent inall kinds of other disorders鈥攈eart disease； asthma； arthritis； multiple sclerosis； several typesof mental disorders； many cancers； even； it has been suggested （inscience no less）； obesity。
the day may not be far off when we desperately require an effective antibiotic and haven鈥檛got one to call on。
it may e as a slight fort to know that bacteria can themselves get sick。 they aresometimes infected by bacteriophages （or simply phages）； a type of virus。 a virus is a strangeand unlovely entity鈥斺�渁 piece of nucleic acid surrounded by bad news鈥潯n the memorablephrase of the nobel laureate peter medawar。 smaller and simpler than bacteria； viruses aren鈥檛themselves alive。 in isolation they are inert and harmless。 but introduce them into a suitablehost and they burst into busyness鈥攊nto life。 about five thousand types of virus are known；and between them they afflict us with many hundreds of diseases； ranging from the flu andmon cold to those that are most invidious to human well…being： smallpox； rabies； yellowfever； ebola； polio； and the human immunodeficiency virus； the source of aids。
viruses prosper by hijacking the genetic material of a living cell and using it to producemore virus。 they reproduce in a fanatical manner； then burst out in search of more cells toinvade。 not being living organisms themselves； they can afford to be very simple。 many；including hiv； have ten genes or fewer； whereas even the simplest bacteria require severalthousand。 they are also very tiny； much too small to be seen with a conventional microscope。
it wasn鈥檛 until 1943 and the invention of the electron microscope that science got its first lookat them。 but they can do immense damage。 smallpox in the twentieth century alone killed anestimated 300 million people。
they also have an unnerving capacity to burst upon the world in some new and startlingform and then to vanish again as quickly as they came。 in 1916； in one such case； people ineurope and america began to e down with a strange sleeping sickness； which becameknown as encephalitis lethargica。 victims would go to sleep and not wake up。 they could beroused without great difficulty to take food or go to the lavatory； and would answer questionssensibly鈥攖hey knew who and where they were鈥攖hough their manner was always apathetic。
however； the moment they were permitted to rest； they would sink at once back intodeepest slumber and remain in that state for as long as they were left。 some went on in thismanner for months before dying。 a very few survived and regained consciousness but nottheir former liveliness。 they existed in a state of profound apathy； 鈥�