Ukuhlonzwa kokukhuphuka mawala komiyane i-Anopheles gambiae abamelana nesibulalazinambuzane sezinguquko eziphindwe kathathu kuhlinzeka inhlolo yangaleso sikhathi yokukhishwa kokungenelela ekulweni nomalaleveva

Ukunyuka kwezinga lomiyane abakwazi ukumelana nemithi yokubanqanda kubeka izindlela zokulawula izifo ezisabalaliswa izinambuzanye engcupheni kuphinde kusivule amehlo ngezinguquko ezingalawuleki zemvelo ezikwazi ukweqa izinsiza ezakhelwe ukuzigwema.

Ukulawulwa kukamalaleveva kusalokhu kuncike kakhulu ekutshalweni kwezibulala-zinambuzane ze-pyrethroid, ikakhulukazi emanethini ahlala isikhathi eside ezinambuzane (LLINs), kodwa ukumelana nezifo eziwumalaleveva ezinkulu kwenyukile eminyakeni eyi-15 edlule ekhonsathini nokwanda okumangalisayo kokusatshalaliswa kwe-LLIN.

Ukuhlonza izindlela zofuzo ezikomiyane eziqukethwe ekumelaneni kwezinga eliphezulu, okungagcina kunqobe ukusebenza kwe-pyrethroid, kubalulekile ukuthuthukisweni nokusetshenziswa kwamathuluzi anagse aqede ukumelana nemishanguzo.

Ngokusebenzisa idatha ye-Anopheles gambiae 1000 genomes (Ag1000g) sihlonze ukushanela omiyane kwakamuva kakhulu abasuka e-Uganda okufakwe endaweni kuqoqo lezakhi zofuzo ze-cytochrome P450, okuhlanganisa okuvame ukuthinteka ekulandiseni.

Ukuphenywa okwengeziwe kwembula i-haplotype ebandakanya ukuguqulwa kwezakhi ezintathu, ukuguqulwa kwephoyinti elingaziwa ku-Cyp6p4 (I236M), ukufakwa phezulu nomfula kwengxenye efana neZanzibar transposable element (TE) kanye nokuphindwaphindwa kofuzo lwe-Cyp6aa1.

Ukuguqulwa kwezakhi zofuzo kubonakala sengathi kuqale kamuva nje ku-An. i-gambiae evela esifundeni sasemngceleni we-Kenya-Uganda ezungeze iLake Victoria, ngokushintsha kancane esikhundleni kwe-double-mutant (efana ne-Zanzibar TE kanye ne-Cyp6p4-236M) nge-triple-mutant haplotype (okuhlanganisa ukuphindaphinda kwe-Cyp6aa1), esisabalele naseDemocratic Republic of Congo kanye neTanzania.

I-haplotype eguquguqukayo kathathu ihlotshaniswa kakhulu nokwanda kokubonakaliswa kwezakhi zofuzo ezikwazi ukuhlanganisa i-pyrethroids futhi ibikezela ngokuqinile ukumelana ne-pyrethroids ikakhulukazi i-deltamethrin, isibulala-zinambuzane se-LLIN esivame ukusetshenziswa.

Kuke kwabanesikhathi lapho khona elike laba phezulu izinga lokufa kohlobo lomiyane abazala uhlobo elingabulawa imithi uma behlangane nenethi yokuvikela efakwe ikhemikhali ebizwange (i-PBO).

Ukuvama kwe-haplotype ye-triple-mutant haplotype kusalokhu kuguquguquka ngokwendawo phakathi kwamazwe, okuphakamisa isistimu yomaka esebenzayo ukuze iqondise izinqumo zokusatshalaliswa kwempahla elinganiselwe yama-LLIN aphathwe nge-PBO-pyrethroid emazweni wonke ase-Afrika.

Ososayensi bathi ukwengeza umuthi womiyane i-PBO emanethini okuvimba omiyane abathwala isifo sikamalaleveva kungasiza ukunqana ukubhebhetheka kwale sifo kwezinye zezindawo.

Ukuphindaphinda kofuzo lwe-Cyp6aa1 kuvamile ku-An. i-gambiae yonkana i-Afrika futhi, uma kubhekwa umsebenzi wokwenziwa kwama-enzyme, kungenzeka kube ukuxilonga okuwusizo kwamazinga aphezulu okumelana ne-pyrethroids.

Kunohlobo lomiyane elisabalalisa isifo sikamalaleveva esilliqala likujwayela ukumela izinhlobo eziningi zemithi yokubulala omiyane ejwayelekile ngenxa yofuzo ezalwe nalo.

Lokhu kuveza ukuthi uma omiyane bekwazi ukuhlula amanethi anobuthi bamakhemikhali obubulalayo, izimpilo zabantu zesengcupheni enkulu yokuchaphazeleka ngesifo sikamalaleveva.

Abacwaningi sebeyitholile i-gene eyimbangela yokuthi omiyane bakwazi ukuguquka bamelane nobuthi bemithi yokubanqanda.

Bathi ukufaka ikhemikhali ebizwa nge-piperonyl-butoxide (PBO) emanethini okugwema omiyane, Kungasiza ukugwema noma uhlobo olulodwa lomiyane elingabulawa imithi yomiyane ejwayelekile.

Isifo sikamalaleveva siyisofo esibulalayo esithwala ohlobo elithize lomiyane.

Enye yezindlela izisetshenziswa ezindaweni eziningi yokulwa nokusabalala kwesifo sikamalaleveva ukufaka inethe eyakhelwe ukuhlala esikhathi eside efakwe i-pyrethroid.

I-Pyrethoid emenye yemithi engamakhemikhali anobuthi bokubulala izinambuzane ezifana nomiyane.

Okubi kakhulu ukuthi loluhlubo lomiyane seliguqukile alisafi uma lihlangabezane nalo muthi, lokhu kukuveza ngokusobala ukuthi amanethi ane-pyrethoid awasakulungele ukugwema ukusabalala kwesifo sikamalaleveva kwezinye zezindawo.

Abacwaningi bafuna ukwazi ngokugcwele imbangela yoshintsho olwenzeke kwi-DNA yomiyane bakwazi ukumelana ne-pyrethroid.

Inhloso yabo bekungukuthola lawo ma-genes abhebhethekisa lokhuba wokuthi omiyane bakwazi ukumelana ne-pyrethroid, nanokuthi lendlela yokumelana nemithi isebenza kanjani (indlela ezisebenza ngayo).

Ngamanye amazwi bebefuna ukuthola ukuthi umzimba womiyane ukwazi kanjani ukumumutha i-pyrethoid ngoba inobuthi ebubulalayo.

Laba bacwaningi bahlaziye ama-genes ohlobo likamiyane i-Anopheles gambie olwande kakhulu ezweni lase-Kenya, Uganda nakwamanye amazwe ase-Afrika.

Emuva kokuba bekwazile ukobona uhlobo oluthize lwama-genes nembangela yokuthi omiyane ungabulawa i-pryethroid, bazama ukufaka amakhemikhali ahlukahlukene emanethini ukuze babone ukuthi bazophila noma bazofa yini omiyane.

Abacwaningi bathola izinguquko ezintanthu zama-genes ezenza ukuthi omiyane bangabulawa i-pyrethroid.

Baphinde bathi loluguquko lwama-genes alibavikeli ubuthini kuphela omiyane, kodwa base bande kakhulu mebeqhathaniswa nalabo abacwaningi abaqala ngabo ukuhlaziya.

Kubukeka sengathi loluguquko lomiyane lakhula kakhulu emgceleni ohlukanisa iKhenya ne-Uganda, ohlukaniswe umfula omkhulu iVictoria.

Baphinde bathi lokhu kuguqulwa okuphindwe kathathu kubonakala kukhulisa ukubonakaliswa kwezakhi zofuzo ezikwazi ukugawula isibulala-zinambuzane, futhi kubikezela ngokuqinile amandla okumelana nama-pyrethroids.

Ekugcineni, banquma ukuthi ukwengeza ikhemikhali i-pieronyl-butoxide (PBO) kuyi-pyrethroid lapho ukwelapha amanetha kwaphumelela kakhulu ekunqobeni ukumelana kwalemiyane.

Uncwaningo olwedlule lalugxile kakhulu ekuxilongeni uhlobe oluthize lwama-genes, ososayensi ababecabanga ukuthi yilo elinomthelela wokwenza omiyane bakwazi ukuzivikela ebuthini okwakumele engabe buyababulala.

Lolu cwaningo lwandisa ukusesha ngokuhlola izinkulungwane zezakhi zofuzo ukuze kutholwe ukuguqulwa kwezakhi zofuzo ezintsha ezivamile komiyane abangazweli.

Abacwaningi bathi akwenzeki ukwazi ocwaningweni lwabo ukuthi yimiphi eminye imiphumela ukuguqulwa abayikhombile okungaba nayo, noma ukuthi ukuguqulwa ngakunye kukuthinta kanjani ukumelana ne-pyrethroid.

Bathi kunolunye uhlobo lomiyane elinezinguquko zama-genes afanayo nalawa aseke abalulwa, eseliguqukele ekwazini ukubhekana nomuthi obulala izinambuzane ipyrethroid.

Akucacile kodwa ukuthi ukwengeza isibulalizinambuzane esifanane-PBO kuzozibulala yini ezinye izinhlobo ezizimelana naso nazo.

Abacwaningi eKhenay, Yuganda, Khongo, Thanzaniya, Kilifi, e-UK nase-USA bahlanganyele kulolu cwaningo.

Bagxile komiyane abatholakal ukugudla umgcele waseKhenya neYuganda, kanye nomcabango wabo omush wokwengeza i-PBO emanethini ungasindisa izimpilo eziningi zase-Afrika.