YADDA ZAZZAƁIN SCARLET YA SAKI RIƘONSA A KAN LONDON

Zazzaɓin scarlet (scarlet fever) yana ɗaya daga cikin cututtukan yara da aka fi tsoro a ƙarni na 19. Tsakanin kusan 1820 da 1880, annoba masu tsanani sun mamaye Turai da Arewacin Amurka. A tsakiyar ƙarnin, tana kashe kusan mutane 10,000 a shekara a Ingila da Wales, galibi ƙananan yara — wani lokaci cikin ’yan kwanaki, daga ciwon maƙogwaro zuwa ƙurajen ja na musamman har zuwa mutuwa.

Ƙwayar bacteria Streptococcus pyogenes (streptococcus na rukunin A) ce ke haddasa ta. George da Gladys Dick ne suka tabbatar da wannan alaƙa a 1924. Kuma ana iya kamuwa da ita fiye da sau ɗaya: kamuwa ɗaya ba ta tabbatar da kariya ba.

Wuyar warwarewa

A London, mutuwa daga zazzaɓin scarlet ta ragu da fiye da ninki goma shekaru da dama kafin maganin antibiotics — sulfonamides sun zo a 1935, penicillin kuma a 1945. A lokaci guda, salon annobar ma ya sauya. Shin tsarin lissafi zai iya bayyana waɗannan sauye-sauye ta hanyar sauyawar wasu sigogi kaɗan a hankali?

Bayanan mako-mako na ƙarni ɗaya

Kevin Zhao da David Earn, na Jami’ar McMaster a Kanada, sun yi amfani da rahotannin mako-mako na Babban Magatakarda (Registrar General) na London:

• mutuwa daga zazzaɓin scarlet a kowane mako, 1842–1939, da masu cutar da aka bayar da rahotonsu, 1901–1939;
• haihuwa a kowane mako, mutuwa daga kowane dalili, da ƙidayar jama’a ta kowace shekara goma — London ta girma daga kusan mutane miliyan 2.25 zuwa miliyan 8.6 a wannan lokacin.

Sun bar tsofaffin bayanan coci, waɗanda suka koma har zuwa 1696: a cikinsu ana yawan rikita zazzaɓin scarlet da kyanda, kuma tsarin yana rushewa bayan 1830. Sun tsaya a Satumba 1939, lokacin da aka kwashe mutanen London miliyan 1.5, yawancinsu yara, a farkon yaƙi. An kwafo adadin masu cutar na 1901–1939 daga hotunan kundaye da taimakon kayan aikin AI (ChatGPT da OpenAI Codex), kuma an duba wani samfuri da hannu.

Abin da bayanan suka nuna

• Annoba a kowace shekara, mafi tsananinta a kaka.
• A kan haka, zagaye na shekaru da yawa wanda ke ƙara tsawo: daga kusan shekaru 4 zuwa kusan shekaru 8 tsakanin 1880 da 1920.
• A cikin waɗannan shekaru, mutuwa ta faɗi daga kusan 2,300 zuwa kusan 80 a shekara.

Tsarin lissafi

Ƙungiyar ta daidaita wani tsarin SIR na gargajiya (Masu Saurin Kamuwa – Masu Cutar – Waɗanda Suka Warke) a kan mutuwa da masu cutar tare. Yaɗuwa tana tashi tana faɗuwa da yanayi — tana yawa idan makarantu a buɗe suke. Sun bar abubuwa uku su sauya a tsawon lokaci: matsakaicin yaɗuwa, ƙarfin sauyin yanayi, da kason masu cutar da suka mutu, wanda ke raguwa a tsawon lokaci, daidai da wani hasashe na tarihi cewa wani nau’in cuta mai sauƙi ya mamaye a kusan shekarun 1890. Wata hanya ta biyu mai zaman kanta ta ba da kusan sakamako iri ɗaya.

Sannan suka tambayi wane zagaye na annoba tsarin ke hasashe a kowane zamani — har da raunanan girgizar da haihuwa da mutuwa na bazuwar ke raya su — suka kwatanta su da zagayen da aka gani.

Sakamakon

• Kusan dukkan sauye-sauyen salon annobar sigogi biyu ne ke bayyana su: lambar haihuwar cuta (reproduction number) (mutane nawa mai cuta ɗaya ke harba) da ƙarfin sauyin yanayi.
• Zagaye mai tsawo, daga kusan shekaru 3.5 a 1842 zuwa shekaru 7–8 a kusan 1920, ya dace da wata girgiza a hankali da tsarin ya yi hasashe wadda ta dogara kusan gaba ɗaya ga lambar haihuwar cuta. Yayin da take raguwa, zagayen suka yi tsawo. Raguwar ta samo asali galibi daga ci gaba da raguwar sauƙin yaɗuwar cutar.
• Waɗannan sauye-sauye suna nuna sauye-sauyen yawan haihuwa da aka gani tare da sauye-sauyen yaɗuwa da aka ƙiyasta, waɗanda wataƙila wani ɓangarensu ya samo asali daga sauyin halittar ƙwayar bacteria kanta.
• Ga kyanda, sauye-sauyen haihuwa sun isa su bayyana komai. Ga zazzaɓin scarlet, ba su isa ba.

Abin da ya rage ba a bayyana ba

Zagaye na kusan shekaru 5 kafin 1857, zagaye na kusan shekaru 3 tsakanin 1887 da 1897, da wataƙila wasu, sun rage ba a bayyana su ba. Tsarin ma yana sauƙaƙawa: yana ɗaukar kariya ta tsawon rai (ba gaskiya ba ne ga zazzaɓin scarlet), yana watsi da kariyar da jarirai ke samu daga iyayensu mata, kuma yana ɗaukar sauyin nau’in cuta ɗaya kawai.

Karanta annoba a tsofaffin kundaye

Binciken ya faɗaɗa irin wannan nazari — wanda ya riga ya yi nasara ga kyanda a New York — zuwa cutar bacteria da bayanan mutuwa, yana ƙiyasta abubuwan da ba a taɓa gani kai tsaye ba, kamar yawan mace-mace da yaɗuwa. Ana iya amfani da waɗannan kayan aikin a kan wasu bayanan tarihi na cututtuka masu yaɗuwa.