Lawo Magciwane Azabalazayo—Indlela Abuya Ngayo

AMA-VIRUS, ama-bacterium, ama-protozoa, ama-fungus, namanye amagciwane kubonakala sengathi abelokhu ekhona selokhu kwathí nhlo. Ukuzivumelanisa nezimo ngendlela ekhexisayo kwala magciwane, ayizidalwa ezincane kakhulu kunazo zonke ezinye, kuye kwawasiza akwazi ukuphila nasezindaweni okungayi lubuyayo kuzo. Atholakala eziphethwini ezinamanzi abilayo eziphansi ezinzulwini zolwandle kanye nasemanzini ashubisa umnkantsha e-Arctic. Manje la magciwane aphunga impi enkulu kunazo zonke ake abhekana nazo—imithi elwa nawo.

Eminyakeni eyikhulu edlule, kwakwaziwa ukuthi amanye amagciwane, noma izilokazane ezincane kakhulu, ayedala izifo, kodwa akekho noyedwa kwababephila ngaleso sikhathi owayeke wezwa ukuthi kunemithi yokulwa namagciwane. Ngakho uma umuntu elaliswe isifo esithathelwanayo esiyingozi, odokotela abaningi babengenayo indlela yokuselapha ngaphandle kokumduduza. Kwakudingeka ukuba amasosha omzimba ayilwe wodwa impi yokumelapha. Uma amasosha omzimba engenamandla anele, ngokuvamile umphumela wawudabukisa. Ngisho negciwane elalingene ngomhuzukwana ngokuvamile lalimbulala umuntu.

Ngakho, ukutholakala kwemithi yokuqala ephephile elwa namagciwane—ama-antibiotic—kwaletha izinguquko ezinkulu kwezokwelapha.a Ukusetshenziswa kwemithi yokwelapha eyenziwe nge-sulfa ngawo-1930 nemithi enjenge-penicillin ne-streptomycin ngawo-1940 kwaholela ekutholakaleni kwendathane yemithi emashumini eminyaka alandela. Ngawo-1990, inqolobane yezikhali zokulwa namagciwane yayisinezithako ezingaphezu kuka-150 ezihlelwe ngezigaba ezingu-15.

Amathemba Okunqoba Aphele Nyá

Ngawo-1950 nangawo-1960, abanye abantu base beqalile ukugubha ukunqotshwa kwezifo ezithathelwanayo. Ezinye izazi zesayensi yamagciwane zazikholelwa nokuthi kungakabiphi lezi zifo zaziyobe zingasekho. Ngo-1969 udokotela ohlinzayo e-United States wafakaza phambi koMkhandlu ukuthi isintu kwakungenzeka maduzane “singabe sisazikhathaza ngezifo ezithathelwanayo.” Ngo-1972, owazuza indondo kaNobel, uMacfarlane Burnet kanye noDavid White babhala: “Esingakusho ngekusasa lezifo ezithathelwanayo ukuthi cishe liyoba lufifi impela.” Ngempela, abanye babenomuzwa wokuthi izifo ezinjalo kwakungenzeka ziqedwe nya.

Inkolelo yokuthi izifo ezithathelwanayo kwase kufana nokuthi zinqotshiwe, yabangela ukuzethemba ngokweqile kuyo yonke indawo. Omunye umhlengikazi owayejwayelene nosongo olukhulu amagciwane ayeyilo ngaphambi kokuba kutholakale imithi yokulwa nawo waphawula ukuthi abanye abahlengikazi abasebasha base bedebesela kakhulu enhlanzekweni evamile. Lapho ebakhumbuza ukuba bageze izandla, babethi: “Ungakhathazeki, manje sesinemithi elwa namagciwane.”

Nokho, ukuthembela emithini elwa namagciwane nasekusetshenzisweni kakhulu kwayo kuye kwaba nemiphumela eyinhlekelele. Izifo ezithathelwanayo ziye zaphikelela. Ngaphezu kwalokho, ziye zabuya ngamandla kangangokuthi seziyimbangela enkulu yokufa emhlabeni! Ezinye izici eziye zaba nomthelela ekusakazekeni kwezifo ezithathelwanayo zihlanganisa iziyaluyalu ezidalwa yizimpi, ukwanda kokungondleki kwabantu emazweni ampofu, ukuntuleka kwamanzi ahlanzekile, ukuntuleka kwezindlela zokukhuculula indle, ukushesha kwezindlela zokuhambela amanye amazwe, nokushintsha kwesimo sezulu embulungeni yonke.

Ukuzabalaza Kwamagciwane Ohlobo Lwama-bacterium

Ukuzabalaza ngendlela emangalisayo kwamagciwane ansuku zonke kuye kwaziveza kuyinkinga enkulu, ebingalindelwe neze. Nokho, uma sekubhekisiswa bekufanele kulindelwe ukuthi kwakuyohamba kuhambe amagciwane abe namandla okumelana nemithi. Ngani? Ngokwesibonelo, cabangela okuthile okuhlobene nalokhu okwenzeka lapho kutholakala isibulali zinambuzane i-DDT maphakathi nawo-1940.b Ngaleso sikhathi abasebenza ngobisi bajabula lapho izimpukane zinyamalala ngempela uma ufutha nge-DDT. Kodwa idlanzana lezimpukane alizange life, futhi abantwana bazo baba namandla okumelana ne-DDT. Ngokushesha lezi zimpukane, ezazingasenandaba ne-DDT, zanda zaba ziningi kakhulu.

Ngisho nangaphambi kokusetshenziswa kwe-DDT, nangaphambi kokuba i-penicillin itholakale emakhemisi ngo-1944, ama-bacterium ayingozi aveza izimpawu zokuthi ayakwazi ukuzivikela ngendlela emangazayo. UDkt. Alexander Fleming, okunguyena owathola ikhambi le-penicillin, wakuqaphela lokhu. Esegunjini ayenzela ukuhlola kulo wabona izizukulwane zamagciwane okuthiwa i-Staphylococcus aureus (igciwane elibangela amathumba) ziba nolwelwesi oluqinile olwaluya ngokuya lukwenza kuba nzima ngalo muthi ayewutholile ukuba ulufohle.

Lokhu kwenza ukuba eminyakeni engaba ngu-60 edlule uDkt. Fleming axwayise ngokuthi ama-bacterium ayingozi akumuntu angase akwazi ukumelana ne-penicillin. Ngakho uma umuntu esenikwe i-penicillin kodwa yangawabulala ngobuningi amagciwane ayingozi, abantwana bawo abakwaziyo ukumelana nayo babeyokwanda. Ngenxa yalokho, isifo sasiyobuya singasadle nkobe zamuntu i-penicillin eyayingeke isenze lutho.

Incwadi ethi The Antibiotic Paradox iyaphawula: “Ukubikezela kukaFleming kwazihlonza kuyiqiniso ngendlela eshaqisa ngaphezu kwalokho naye ngokwakhe ayekucabanga.” Kanjani? Phela, kwatholakala ukuthi kwezinye izinhlobo zama-bacterium, izakhi zofuzo—amapulani amancanyana atholakala kuyi-DNA ye-bacterium—zikhiqiza amakhemikhali enza ukuba i-penicillin ingasebenzi. Ngenxa yalokho, ngisho nokusebenzisa i-penicillin isikhathi eside ngokuvamile kuba nhlanga zimuka nomoya. Yeka isimanga!

Emzamweni wokunqoba izifo ezithathelwanayo, kwakulokhu kuvezwa njalo imithi elwa namagciwane kusukela ngawo-1940 kuya ko-1970, kanye nembalwa eyenziwa ngawo-1980 nangawo-1990. Le mithi yayikwazi ukubulala amagciwane ayeye amelana nemithi yokuqala. Kodwa ngemva kweminyaka embalwa, kwavela izinhlobo zama-bacterium ezazingenandaba nanayo le mithi emisha.

Abantu sebeyazi ukuthi ukuzabalaza kwama-bacterium kuwubunyoninco obumangazayo. Ama-bacterium ayakwazi ukushintsha ulwelwesi lwawo oluqinile ukuze avimbele umuthi olwa nawo ukuba ungangeni noma ukushintsha ingxube yamakhemikhali awo ukuze imithi yamagciwane ihluleke ukuwabulala. Ngakolunye uhlangothi, ama-bacterium angase awududule awukhiphe umuthi wokuwabulala lapho nje ungena, noma angamane nje enze lo muthi ungasebenzi.

Njengoba ukusetshenziswa kwemithi elwa namagciwane kuye kwanda, namagciwane amelana nayo aye anda futhi asakazeka. Inhlekelele, akunjalo? Cha, okungenani akunjalo ezimweni eziningi. Uma omunye umuthi olwa namagciwane ungasebenzi esifweni esithile, ngokuvamile kuba nomunye osebenzayo. Ukumelana kwala magciwane nomuthi wokuwabulala kuye kwaba uhlupho, kodwa kuze kube muva nje, ngokuvamile bekulokhu kulawuleka.

Ukumelana Nemithi Eminingi

Nakho-ke ososayensi bezokwelapha sebethuka bephela lapho bethola ukuthi ama-bacterium ayakwazi ukwenanana ngezakhi zofuzo. Ekuqaleni kwakucatshangwa ukuthi ngama-bacterium ohlobo olulodwa kuphela ayengananiselana ngezakhi zofuzo. Kodwa kamuva wona lawo mandla okumelana nemithi abe esetholakala nakwezinye izinhlobo zama-bacterium ezihluke ngokuphelele. Ngokusebenzisa lokho kwenanana, ama-bacterium ezinhlobo ezihlukahlukene aye akwazi ukunqwabelanisa amandla okumelana nemithi eminingi evame ukusetshenziswa.

Njengokungathi nalokhu kwakunganele, ucwaningo olwenziwa ngawo-1990 lwabonisa ukuthi ama-bacterium athile ayakwazi ngokwawo ukumelana nemithi ewabulalayo. Ngisho nalapho kusetshenziswa uhlobo olulodwa lomuthi wokulwa nawo, ezinye izinhlobo zama-bacterium ziba namandla okumelana nezinhlobo eziningi zemithi elwa nawo, ezingokwemvelo nezenziwe ngamakhemikhali.

Ikusasa Elethusayo

Nakuba iningi lemithi elwa namagciwane namuhla lisasebenza kubantu abaningi, le mithi iyoqhubeka isebenza kangakanani esikhathini esizayo? Incwadi ethi The Antibiotic Paradox iyaphawula: “Asisakwazi ukulindela ukuthi zonke izifo ezithathelwanayo ziyokwelapheka ngomuthi wamagciwane ozowusebenzisa kuqala.” Le ncwadi iyanezela: “Kwezinye izingxenye zomhlaba, ukuba nesitokwe esilinganiselwe semithi elwa namagciwane kusho ukuthi ayikho imithi elwa namagciwane eyanele engaba usizo. . . . Iziguli ziphathwa futhi zibulawe izifo abanye ababikezela eminyakeni engu-50 edlule ukuthi ziyobe seziphelile ebusweni bomhlaba.”

Akuwona wodwa ama-bacterium angamagciwane aye aba namandla okumelana nemithi esetshenziswayo kwezokwelapha. Amagciwane ohlobo lwama-virus nama-fungus kanye nezinye izilokazane ezincane ezingomaphila ngezinye nawo aye aziveza ekwazi ukuzivumelanisa nale mithi ngendlela emangalisayo, eveza izinhlobo ezintsha zamagciwane ezisongela ukuyibhuntshisa yonke imizamo eyenziwe yokuthola nokukhiqiza imithi elwa nawo.

Khona-ke, yini engenziwa? Ingabe ikhona indlela yokuqeda noma okungenani yokunqanda la mandla awo okuzabalaza? Ukunqoba okuye kwatholakala ngokusetshenziswa kwama-antibiotic neminye imithi elwa namagciwane kungalondolozwa kanjani ezweni elibhokelwe yizifo ezithathelwanayo?

[Imibhalo yaphansi]

[Ibhokisi/Isithombe ekhasini 16]

Ayini Ama-antimicrobial?

Ama-antibiotic udokotela akunikeza wona angena ngaphansi kwemithi okuthiwa ama-antimicrobial. Le mithi ididiyelwa ngaphansi kwesihloko esikhulu esithi “chemotherapy” okuyigama elibhekisela ekwelapheni isifo ngamakhemikhali. Nakuba igama elithi “chemotherapy” ngokuvamile lisetshenziswa ngokuqondene nokwelapha umdlavuza, ekuqaleni lalisetshenziselwa—futhi lisasetshenziselwa—ukwelapha izifo ezithathelwanayo. Kulezo zimo kuthiwa yi-antimicrobial chemotherapy.

Ama-microbe, ayizilokazane ezincane ezibonakala kuphela ngokusebenzisa isibonakhulu. Ama-antimicrobial angamakhemikhali alwa nalezi zilokazane ezidala izifo. Ngeshwa, kuyenzeka ukuba ama-antimicrobial alwe nanezilokazane eziwusizo.

Ngo-1941, uSelman Waksman, omunye walabo abathola i-streptomycin, wasebenzisa igama elithi “antibiotic” emithini elwa namagciwane eyenziwa ngezilokazane. Ama-antibiotic kanye namanye ama-antimicrobial asetshenziswa kwezokwelapha awusizo ngoba anobuthi ngokuyinhloko obuyingozi emagciwaneni adala izifo. Lokhu kusho ukuthi angabulala amagciwane kodwa angabi yingozi etheni kuwe.

Kodwa-ke, empeleni wonke ama-antibiotic anesilinganiso esithile sobuthi obuyingozi nakithi. Izinga lokuphepha komuthi owunikezwayo ozolwa namagciwane nelokuba kwawo yingozi kithi libizwa ngokuthi izinga lokwelapha. Uma izinga lokuphepha kwethu lilikhulu, kusho ukuthi lo muthi ungasetshenziswa ngokuphephile; kodwa uma lilincane, kusho ukuthi ungaba yingozi enkulu. Empeleni, kunezinkulungwane zezinto eziye zatholakala ezingase zisetshenziswe njengama-antibiotic, kodwa eziningi azilona usizo kwezokwelapha ngenxa yokuthi zinobuthi obuningi obuyingozi kubantu noma ezilwaneni.

I-antibiotic engokwemvelo yokuqala umuntu ayengayisebenzisa ngaphakathi kwakuyi-penicillin, eyenziwa ngesikhunta okuthiwa yi-Penicillium notatum. I-penicillin yasetshenziswa ngokokuqala ngqa ngo-1941 njengomjovo. Ngokushesha ngemva kwalokho, ngo-1943, kwatholakala i-streptomycin egciwaneni eliyi-bacterium okuthiwa i-Streptomyces griseus, elitholakala enhlabathini. Njengoba isikhathi siqhubeka, kwenziwa indathane yamanye ama-antibiotic ngezinto eziphilayo kanye nalawo enziwe ngezinye izithako. Noma kunjalo, ama-bacterium aye afunda izindlela zokumelana namaningi alama-antibiotic, okudalela ezokwelapha inkinga yembulunga yonke.

[Isithombe]

Isikhunta i-“penicillin” esibonakala phansi endishini sivimbela ukukhula kwama-“bacterium”

[Umthombo]

Christine L. Case/Skyline College

[Ibhokisi/Izithombe ekhasini 17]

Izinhlobo Zamagciwane

Ama-virus amagciwane amancane kunawo wonke. Yiwo adala izifo ezivamile ezinjengomkhuhlane, imfuluwenza, nobuhlungu emphinjeni. Ama-virus adala nezifo ezesabekayo njengovendle, i-Ebola, nengculaza.

Ama-bacterium ayizilokazane ezinengqamuzana eyodwa encane kangangokuthi ayinayo ne-nucleus futhi ngokuvamile ane-chromosome eyodwa kuphela. Kunezigidigidi zama-bacterium emizimbeni yethu, ikakhulukazi emgudwini wokugaya ukudla. Asiza ekugayeni ukudla futhi awumthombo oyinhloko kavithamini K, odingekayo egazini ekunqandeni ukopha.

Kuma-bacterium angu-4 600 asohlwini, acishe abe ngu-300 kuphela okucatshangelwa ukuthi adala izifo. Noma kunjalo, ama-bacterium adala izifo eziningi ezitshalweni, ezilwaneni, nakubantu. Kubantu lezi zifo zihlanganisa isifo sofuba, ikholera, uklilo (diphtheria), umbendeni, ukubola kwamazinyo, izinhlobo ezithile zenyumoniya, nezifo eziningana ezithathelwana ngobulili.

Ama-protozoa, anengqamuzana eyodwa njengama-bacterium, kodwa kuyenzeka abe ne-nucleus engaphezu kweyodwa. Phakathi kwawo kunama-amoeba nama-trypanosome kanye nesilokazana esidala umalaleveva. Ingxenye yesithathu yezidalwa eziphilayo ingomaphila ngezinye—kunezinhlobo ezingaba ngu-10 000—yize kungezimbalwa kuphela kulezi zilwanyana ezidala izifo kubantu.

Ama-fungus nawo angadala izifo. Lezi zilokazane zinayo i-nucleus futhi zenza amayephuyephu anezagilana aphicaphicene okukamata. Izifo ezivamile azidalayo umbandamu, njengalowo ohlasela izinzwani, kanye ne-candidiasis (Candida). Izifo eziyingozi ezidalwa ama-fungus ngokuvamile ziphatha kuphela abantu abanesimiso somzimba sokuzivikela esibuthaka noma abaye benziwa buthaka ukungondleki kahle, umdlavuza, imithi, noma izifo ezidalwa ama-virus ezicindezela amasosha omzimba.

[Izithombe]

I-“virus” ye-Ebola

Ama-“bacterium” i-“Staphylococcus aureus”

I-“protozoa” ye-“Giardia lamblia”

I-“fungus” edala umbandamu

[Imithombo]

CDC/C. Goldsmith

CDC/Janice Carr

Courtesy Dr. Arturo Gonzáles Robles, CINVESTAV, I.P.N. México

© Bristol Biomedical Image Archive, University of Bristol

[Isithombe ekhasini 14]

U-Alexander Fleming, owathola umuthi we-“penicillin”